MEASUREMENT OF BLOOD PRESSURE BY SPHYGMOMANOMETRY
Blood pressure can be of two types:
- End-pressure or perfusion pressure
- Lateral pressure.Although perfusion pressure or endpressure represents blood pressure more accurately, under normal physiological conditions, end-pressure and lateral pressure closely correspond to each other. Therefore, as end-pressure determination requires invasive procedures, clinicians rely on estimating blood pressure by measuring lateral pressure with a sphygmomanometer—specially designed for this purpose.Now, let us explain some definitions:
- Systolic blood pressure: It is the highest BP in a cardiac cycle found during systole. Normal range is 100–140 mmHg.
- Diastollc BP: It is the lowest BP in a cardiac cycle found during diastole. Normal range is 60–90 mmHg.
- Pulse pressure: It is the difference between systolic and diastolic BP.
- Mean pressure: It is diastolic BP + 1/3rd pulse pressure. [It is not equal to the arithmetic mean of systolic and diastolic BP, because the durations of systole (0.3 sec) and diastole (0.5 sec) are different.]
INSTRUMENT
- Stethoscope: It consists of three parts: (a) Earpiece, (b) chestpiece and (c) a single tube or paired tubes connecting the two.
- Sphygmomanometer: This is, in essence, a mercury manometer, connected to an arm cuff which is inflatable by a hand-pump fitted with a valve. This instrument was invented by Riva-Rocci, and subsequently modified by Von Recklinghausen.The limbs of the mercury manometer are unequal. The proximal one, connected to the cuff by a tube is very short and acts as a mercury reservoir. The other limb is long and calibrated and the cuff pressure corresponds to the upper level of the mercury column in this limb.4The cuff is enclosed in a cloth covering and connected to the hand-pump via a tube. The width of a standard arm-cuff is 12.5 cm. It is to be noted that in obese persons, a wider cuff should be used to counter the greater tissue pressure. Otherwise, the recorded BP would be falsely higher. On similar grounds, an 18 cm wide cuff is applied around the thigh, when BP is measured over the popliteal artery in the legs with the subject lying prone. Also, in children, a narrower cuff is required for proper estimation of BP.The hand-pump is connected to the cuff through a one-way valve for raising the cuff pressure. There is an adjustable screw, which deflates the cuff after use.
Some points to note while measuring blood pressure
- Ideally, the subject should be supine, but BP is also measured in sitting position.
- The cuff should be at the level of the heart. If the cuff, wrapped around the arm with the brachial artery within it, is at a lower or upper level than the heart, then the BP within the artery will differ from the true BP owing to the action of gravity.
- The left arm is preferred because the left brachial artery is a continuation of left subclavian artery, which is a direct branch of the aorta unlike the right subclavian, which is a branch of brachiocephalic artery. Thus, the BP measured from the left arm reflects BP more accurately than when measured from right arm.
- Position of the arm-cuff should be such that the lower border of the cuff is 1 inch above the cubital fossa. The tubes of the cuff should not interfere with the placement of the chestpiece of the stethoscope.
- Prolonged inflation of the cuff must be avoided because it may cause reflex vasoconstriction and raised BP leading to error in measurement.
- BP should be ideally measured in both arms. Gross difference may bring to light anatomical defects like coarctation of aorta.
PRINCIPLE
The BP (lateral pressure) in the brachial artery lying within the cuff is undergoing cyclic variation in each cardiac cycle with the pressure reaching its peak at systolic BP and reaching the trough at diastolic BP. Now, when the cuff is inflated at a pressure above the systolic BP, flow through the artery ceases and narrowing of the artery occurs. The cuff pressure is now released slowly. Just as the cuff pressure reaches a point just below the systolic BP, blood jets through the narrowed vessel at a great velocity at the height of systole. (Velocity increases when a vessel is narrowed.) This increased velocity leads to turbulent flow, which creates sounds in the form of Korotkoff's sounds.
Another point to note is that this turbulent flow is intermittent in character. Imagine that the cuff pressure is at a point somewhere between systolic and diastolic BP. Obviously, blood will flow through the artery during that portion of the cardiac cycle, when the pressure in the artery is above the cuff pressure. Since diastolic BP is less than cuff pressure in this case, flow stops when the pressure in the artery goes below the cuff pressure as it descends from the peak systolic pressure to reach the diastolic level. Thus, in a particular cardiac cycle, flow is intermittent. When cuff pressure 5equals diastolic BP, the flow becomes continuous and the sound disappears. This intermittent type of flow influences the nature of Korotkoff's sounds—imparting a typical ‘staccato’ character to the sounds.
PROCEDURE
Palpatory method
Before measuring BP by auscultatory method, estimation of systolic BP should be done by palpatory method. (Diastolic BP cannot be measured by palpatory method.) This is because of two important reasons.
- To get an approximate idea about the systolic BP, which will help the examiner to raise the cuff pressure to an appropriate level, thereby sparing the subject from undue discomfort.
- To prevent an error arising due to auscultatory gap (discussed later).
- Procedure:
- The cuff is wrapped around the arm taking the above precautions.
- The radial pulse is palpated and the pulsations felt clearly.
- The cuff pressure is slowly raised. The approximate point, at which pulse is obliterated, is noted and the pressure raised about 30–40 mmHg higher.
- Now, the cuff pressure is slowly deflated. The point at which the pulse reappears, corresponds to the systolic BP by palpatory method.
Auscultatory method
- The brachial pulse is palpated in the cubital fossa. It is felt at the medial border of the biceps muscle.
- The chestpiece of the stethoscope is placed with the center overlying the brachial artery.
- The cuff pressure is raised to 30 mmHg higher than systolic BP measured by palpatory method and then slowly decreased at a speed of approx 2–3 mmHg/sec. (At this rate of fall of Hg column, inertia of air coming out through the rubber tubes is supposed to match the inertia of the falling mercury column in the manometer and the readings taken are free of any error caused by mismatched inertia.)
- The first tap sound heard corresponds to the systolic BP and this is followed by a series of sounds known as Korotkoff's sounds, which can be classified into five phases.
- Phase I — Tap sound, denotes SBP.
- Phase II — Sound resembling a murmur.
- Phase III — Sound becomes loud, resembling that arising from a gong.
- Phase IV — The sounds become muffled.
- Phase V — All sounds disappear.
- There is some controversy about the point which corresponds to diastolic BP. Some are of the opinion that it corresponds to the point where the sounds become muffled (start of phase IV) while some maintain that it corresponds to the point where the sound disappears completely (start of phase V).
DISCUSSION
Normal range of BP:
Systolic BP—100–140 mmHg
Diastolic BP— 60–90 mmHg.
BP varies with:
- Age: Both systolic and diastolic BP rise with age. SBP rises because of decreased distensibility of the arterial tree which decreases its capacity to accommodate blood.
- Sex: BP is lower in females.
- Diurnal variation: BP is lower at night.
- Emotion: It increases BP by increasing cardiac output. Increased BP caused by nervousness, when examined by a doctor, is known as ‘White coat hypertension’.Other factors which influence cardiac output or peripheral resistance, also affect BP, because BP = Cardiac output × Peripheral resistance (see p. 285).
APPLIED
Hypertension: This implies increase of BP. It may be of two types.
- Systolic hypertension—SBP>160 mmHg
- Diastolic hypertension—DBP>90 mmHg.Hypertension may be essential or primary (idiopathic) when no definite cause of the condition can be detected. 90% of cases of hypertension belong to this group.Secondary hypertension: This is caused by some known disease, e.g.
- Renal diseases: Glomerulonephritis and renal artery stenosis.
- Endocrine: Cushing's syndrome, Pheochromocytoma and Conn's syndrome.
- Congenital: Coarctation of aorta.
- Iatrogenic: Oral contraceptives.
Complications of high BP: Cerebral hemorrhage, heart failure, etc.Hypotension: This signifies decreased BP. This may be found in—- Acute hemorrhage.
- Severe diarrhea—Due to fluid loss.
- Severe burns when plasma from vascular compartment goes into the extravascular space due to increased permeability of blood vessels.
Complications of low BP: Acute renal failure, tissue ischemia, etc.
EFFECT OF EXERCISE ON BP (SEE P. 291)
Auscultatory gap
Sometimes, in some hypertensive individuals, the Korotkoff's sounds are inaudible in a certain pressure range and this may lead to error in determining BP. As for example, let us suppose that someone has a BP of 190/100 mmHg and in this person, no auscultatory sound is heard in between 170 and 140 mmHg. Thus, if the cuff pressure is raised to, say, 200 mmHg and lowered slowly, the first sound appears at 190 mmHg but disappears at 170 mmHg. The sound reappears at 140 mmHg and continues upto 100 mmHg which is the diastolic BP. Now, while estimating the BP of such an individual, if someone does not take the precaution of having an idea of the systolic BP by measuring it by the palpatory method and thus raises the cuff pressure to a value within the auscultatory gap, say, 160 mmHg and then gradually lowers it, the first sound will occur at 140 mmHg, which will falsely be assumed as the systolic BP. So, one should always measure the systolic BP by palpatory method before confirming it by the auscultatory method.
AUSCULTATION OF HEART SOUNDS
There are four heart sounds. Usually, the first two heart sounds designated S1 and S2 are audible with the stethoscope. The heart sounds are mainly caused by closure of valves in addition to muscular and vascular components. 4 areas have been named after the 4 valves of the heart and the sounds coming from these valves are best heard in respective areas. It is to be noted that the four areas do not represent, and actually, differ from the anatomical locations of the corresponding valves.
So, there are four areas—
- Mitral area: This corresponds to the apex beat, which is located ½ inch inside the midclavicular line in the left 5th intercostal space.
- Tricuspid area: It is located just to the left of the lower part of the sternum – between the sternum and mitral area.
- Pulmonary area: It is located in the left 2nd intercostal space, just to the left of the sternum.
- Aortic area: It is located in the right 2nd intercostal space, just to the right of the sternum.
Posture of the patient
Sitting or lying.
Procedure
- The subject should be examined in a noise-free room.
- The chest should be bare.
- The examiner should stand on the right side of the subject and the subject's face should be turned to the left side.
- The stethoscope should be placed on the appropriate areas, one by one, while the left thumb is placed gently on the carotid artery lying just medial to the anterior border of the sternocleidomastoid muscle at the level of the thyroid cartilage (superior border).
Observation
First sound and second sound are audible in all four areas. However, first sound is better heard in the apical areas (mitral and tricuspid). The second sound, in contrast, is better heard in the “bases”, that is, in the aortic and pulmonary areas.
First sound and second sound can be distinguished by the differences shown in Table 1.
Inference
On auscultation, heart sounds are found to be normal (in a normal person).
Discussion
Of the four heart sounds, only the first and second heart sounds are constantly audible through a stethoscope. Heart sounds are inaudible or difficult to hear over thick chest wall, emphysema and pericardial effusion.
First heart sound is produced by closure of mitral and tricuspid valves at the onset of systole. Though mitral and tricuspid valves close slightly asynchronously, splitting of the first heart sound is difficult to detect as the interval is very small and the sounds are low-pitched.
Intensity of the first heart sound depends on the position of the valve cusps at the end of the diastole.
In bradycardia and increased P-R interval, the A-V valve leaflets are very close to each other at the end of the diastole and the first heart sound is soft.
Conversely, in mitral stenosis and tachycardia, the valve leaflets are wide apart at the end of diastole and the first heart sound is loud.
Second heart sound is produced by closure of aortic and pulmonary valves. In systemic and pulmonary hypertension, the aortic component and pulmonary component are loud respectively. Normally, the aortic component is louder and heard earlier than the pulmonary component.
PHYSIOLOGICAL SPLITTING OF THE SECOND HEART SOUND (S2)
This may be heard in the pulmonary area in children and young adults. This is accentuated in inspiration. This is because, during inspiration, decreased intrathoracic pressure causes increased venous return and increased entry of blood in right ventricle. Ejection of this increased volume of blood from right ventricle delays closure of pulmonary valves. So, P2 (pulmonary component of second heart sound) is delayed.
On the other hand, during inspiration, the left ventricle receives less blood from the dilated pulmonary veins in the expanded lungs and so, the aortic valves close earlier leading to an earlier A2 (aortic component of second heart sound). Thus, the interval between aortic and pulmonary components of second heart sound is increased. This leads to splitting of S2 during deep inspiration. In expiration, the opposite occurs and the splitting is diminished.
9In atrial septal defect, the second sound is split; but the splitting is fixed, that is, respiration has no effect on the split heart sound.
In aortic stenosis, the splitting is reversed, that is, the pulmonary component occurs earlier than the aortic component. This is because of the delayed closure of the aortic valve due to prolonged passage of blood through the stenosed (aortic) valve. In this case, the splitting is increased in expiration and decreased in inspiration. That's why the splitting is called ‘reversed’.
Third heart sound is a low-pitched sound that occurs with the onrush of blood into the ventricle during the first rapid filling phase of diastole. It is sometimes audible in young healthy individuals. It is also present in congestive heart failure. It is heard almost in the middle of the diastole because the sound is produced only after the ventricular wall, initially very slack, attains some degree of elasticity following entry of some blood into it.
Fourth heart sound is also a low-pitched sound produced during atrial systole. It may be heard in systemic hypertension and cardiac ischemia.
When either the third or fourth heart sound is heard in addition to the first and second sounds, the three heart sounds resemble the cadence of a galloping horse and hence, this is known as “gallop” rhythm. When the third heart sound (which occurs near protodiastole) is heard in addition to first and second heart sounds, it is called protodiastolic gallop. When the fourth heart sound (which occurs just before systole) is heard in addition to first and seond heart sounds, it is known as presystolic gallop. Rarely, all four sounds may be heard when it is called “summation gallop”.
MURMURS
Murmurs are blowing or musical sounds produced by turbulent flow of blood. This may be present with normal valves or distorted valves.
In presence of normal heart valves, they may be caused by hyperdynamic circulation as in anemia.
In distorted valves, they are produced in stenosis or incompetence of valves. Examples are:
Aortic stenosis → midsystolic murmur
Aortic incompetence → early diastolic murmur
Mitral stenosis → middiastolic murmur
Mitral incompetence → pansystolic murmur
[Flow of blood is of two types—(a) Streamline and (b) turbulent. Upto a certain velocity called critical velocity, the flow within the blood vessel is streamline or laminar. In laminar blood flow, the blood column consists of numerous concentric laminae, extending from the periphery towards the center of blood vessel and the velocity of blood gradually rises from the periphery towards the center. But, when the velocity of blood exceeds a critical value, this regular alignment is lost and turbulent flow takes place accompanied by sounds. These sounds are called murmur when they occur in the heart, and are called “bruit” when they occur elsewhere. The factor that determines whether turbulent flow will occur or not is the Reynold's number. This is expressed as:
R = ρDV/η
Where, R = Reynold's number
ρ = Density of blood
D = Diameter of blood vessel
V = Velocity of blood
η = Viscosity of blood
Murmur occurs in anemia, because in anemia, viscosity of blood falls causing greater rise of Reynold's number.
Stenosis = This is caused by distortion of heart valves, where the margins of the valve leaflets fuse together in pathological conditions like rheumatic heart disease, resulting in narrowing of the valve openings. When flow occurs through the stenosed valves, murmur may occur due to turbulence.
Incompetence or regurgitation = When the disease process affecting the valves erode the margin of the valves in such a way that when they close, gaps are present and they cannot prevent the retrograde (backward) leaking of blood. Murmur occurs due to turbulent retrograde flow during closure of valves.
APEX BEAT
Definition: It is the downmost and outermost part on the precordium where a definite cardiac pulsation can be felt.
Normal position: Normally, the apex beat is felt at the left 5th intercostal space ½ inch inside the left midclavicular line.
Method of palpation: The cardiac pulsation is felt by the flat of the hand placed on the precordium and a rough localization of the apex beat is made. Next, the exact position of the apex beat is determined by palpating with the tip of the finger.
When the apex beat is difficult to detect:
- The supine patient is turned to the left. The apex beat may now be felt but its position is shifted from its normal location.
- The patient may be asked to lean forward in a sitting position. The apex beat is sometimes better felt in this position.
Causes of abnormal locations of apex beat
- Shifted upwards in the 4th intercostal space: Pregnancy, ascites, children.
- Pulmonary causes:
- Shifted to the opposite side: Pleural effusion, pneumothorax.
- Shifted to the same side: Collapse of the lung, fibrosis of the lung.
- Cardiac causes:
- Left ventricular hypertrophy—Shifted downwards and outwards.
- Right ventricular hypertrophy— Shifted to the left horizontally.
- Shifted to the right side of the chest:
- Dextrocardia
- Situs inversus.
- Others: Scoliosis, kyphosis, kyphoscoliosis.
Character of the apex beat
- Tapping: In mitral stenosis.
- Forceful: The finger is lifted up but not sustained, e.g. in aortic incompetence, mitral incompetence.
- Heaving: The finger is lifted up and this is sustained for some time, e.g. aortic stenosis.Apex beat not palpable:
- Located behind a rib
- Obesity
- Pulmonary emphysema
- Pericardial effusion.
ARTERIAL PULSE
The intermittent ejection of blood from the heart into the aorta produces alternate expansion and contraction of the aorta 11setting up waves which are transmitted along the wall of blood vessels to peripheral sites to be felt as ‘pulse waves’.
Thus, the pulse wave felt at the radial artery is called the radial pulse, the pulse felt at the carotid artery is called the carotid pulse, etc.
It is to be noted that the pulse wave is transmitted at a very high velocity of about 5 meter/sec. This is in sharp contrast to the velocity of circulating blood which is only about 0.5 meter/sec. In the latter case, the velocity is much lower as the blood actually moves physically.
The radial pulse is felt at the wrist classically with three fingers—the distal finger preventing backflow from distal tissues, the proximal finger adjusts pressure while the middle finger senses the features of pulse.
The radial pulse has the following important features:
- Rate: It is about 72/min. Two points are to be remembered while determining pulse rate:
- The examiner should wait for some time for any tachycardia due to nervousness of the patient to subside.
- The examiner should count the pulse rate for full 60 seconds.
- Rhythm: It is the comparison of intervals between successive beats and this may be regular or irregular.An irregular rhythm may again be regularly irregular, e.g. as found in some types of heart block; or the irregular rhythm may be irregularly irregular, e.g. in atrial fibrillation.
- Volume: It is the amplitude of the expansion of the pulse wave.The volume may be high, e.g. in thyrotoxicosis, aortic incompetence etc.The volume may be low, e.g. in severe diarrhea, burns, etc.
- Condition of arterial wall: Normally, this is just palpable or not palpable. It is usually palpated against the underlying bone after the artery is emptied properly.Thickening of the arterial wall occurs in atherosclerosis.
- Radiofemoral delay: The right radial pulse and the femoral pulse are palpated simultaneously and any delay between them is looked for. This is called radiofemoral delay. Radioradial delay (delay between two radial pulses) may also be looked for.Radiofemoral delay is typically found in coarctation of aorta.
- Character: Special characters in the radial pulse are looked for. Some of the special characters are as follows:
- Anacrotic pulse: This type of pulse, found in aortic stenosis, has a slowly rising ascending limb with a notch and low amplitude. In this condition, due to stenosed valve with a smaller orifice, quantity of ejected blood in unit time is less. This causes the slowly rising ascending limb with low amplitude.
- Water-hammer pulse: In this type of pulse, there is a sharp upstroke and a rapid downstroke with no sustenance.
- Pulsus alternans: This type of pulse is characterized by alternate low and high volume pulse. It may be found in heart failure.
- Pulsus bisferiens: In this type of pulse found when aortic stenosis is combined wih aortic incompetence, two kicks are felt in each pulse beat (double-kicking pulse).
- Pulsus paradoxus: In this type of pulse found in pericardial effusion or in acute severe asthma, the pulse becomes almost impalpable during inspiration. Although this is called ‘pulsus paradoxus’, actually it is an exaggeration of normal physiological event as the left ventricular output normally decreases during inspiration leading to a low volume pulse.The paradox lies in the fact that although heart sound is present, pulse is impalpable.
- Pulse deficit: When the pulse rate is lower than heart rate, it is called pulse deficit. This condition is characteristically observed in atrial fibrillation.Explanation: During atrial fibrillation, the heart beats are irregularly irregular. Sometimes, two successive ventricular beats (contractions) are very close to each other. The shortened period between the two beats diminishes ventricular filling and the subsequent (second) beat is very weak, i.e. so weak that the systolic ejection can just open the aortic valve to produce a heart sound but fails to produce a pulse wave. So, in this case, there is heart beat but there is no corresponding pulse wave. This explains the lower pulse rate in pulse deficit.It should be noted that, to diagnose pulse deficit, heart rate and pulse rate must be simultaneously recorded. Obviously this requires two different examining persons. It is impossible for a single examiner to diagnose pulse deficit clinically.
EXAMINATION OF THE RESPIRATORY SYSTEM AND AUSCULTATION OF BREATH SOUNDS
Examination of respiratory system can be grouped under four headings: (a) Inspection, (b) palpation, (c) percussion and (d) auscultation.
Inspection
- The subject should lie supine with his chest bare.
- The shape of the chest is noted for any peculiarity. There are some characteristic abnormal shapes of the chest. These are:
- Barrel-shaped chest found in emphysema. Normally, the antero-posterior diameter of the chest has a ratio of 5:7 with transverse diameter. But, in emphysema, the anteroposterior and transverse diameter become equal, giving the chest the shape of a barrel.
- Pigeon-shaped chest found in rickets. Here, the bones take abnormal shape due to the softness caused by calcium deficiency.
- Any localized swelling (which may be caused by a condition, such as, an abscess) or any localized flattening (which may be produced by fibrosis) should be looked for.
- The spine should be inspected for presence of scoliosis or kyphosis (exaggerated lateral or anteroposterior curvature of the spine).
- Rate of respiration should be counted. Normally, it varies from 12–18/minute. Increased rate (tachypnea) may be caused by exercise, fever or respiratory infection. Decreased rate of respiration (bradypnea) occurs in narcotic poisoning, e.g. morphine poisoning.
- Rhythm of respiration should also be noted. The patient should not be aware when the rate or rhythm of respiration is being counted, because this may disrupt normal rate or rhythm. Presence of any characteristic type of breathing, such as, Cheyne-Stokes or Biot's or Kussmaul's type of breathing is looked for.
- Type of respiration: Whether it is abdominal, thoracic or abdomin-othoracic. In females, respiration is predominantly thoracic, whereas, in males, respiration is mainly abdomin-othoracic.
- Respiratory movements: Most diseases of the lungs cause decreased movements of respiration. So, generalized or localized reduction in movement compared to normal, should be carefully looked for.
Palpation of the chest
During palpation, points to be noted are—
- Position of the trachea.
- Position of the apex beat.
- Corroboration of respiratory movements by palpatory method.
- Vocal fremitus.
Position of the trachea: With the patient, either supine or sitting, and the chest and neck aligned in a straight line, the examiner puts his index finger in the suprasternal notch in the midline. In a centrally placed trachea, the tip of the finger touches it in the midline at its maximal convex part, but in a laterally deviated trachea, the fingertip meets it at the side. This is further confirmed by examining the gaps between the trachea and the sternomastoids on either side. In case of deviation to one side, the gap on that side will be reduced for obvious reasons while the gap on the other side widens. In spite of all said and done, examination of the trachea should never be casually taken and should be diligently practised to perfect the method.
Position of the apex beat: See palpation of apex beat (discussed separately).
14
Corroboration of respiratory movements by palpatory method: The findings about the respiratory movements obtained on inspection can be confirmed more accurately by palpatory method. With the patient supine or sitting, hands are placed on the upper, middle and lower thirds of chest—both in front and back and the movements of the two sides compared. While examining the middle third of the chest, the thumbs are approximated so that their tips touch after expiration and move apart during inspiration, thus showing the degree of relative movements on the two sides of the chest.
Vocal fremitus: One hand is placed on one area on one side while the subject utters ‘ninety-nine’ or ‘one-one-one’ and the vibration caused in the chest wall is noted. The hand is then placed on the corresponding area on the other side and the procedure is repeated. The two findings are compared. In this way, the whole chest is palpated symmetrically for any localized alteration in findings.
Percussion
This is an important method of examination giving a lot of information with great consistency and accuracy. In this method, the middle finger of the left hand is placed along a particular intercostal space. The middle finger of the other hand—directed vertically and moving from the wrist, strikes the finger of the left hand on the upper surface of the middle phalanx firmly. The note produced over the underlying lungs is noted carefully. Obviously, the method needs a lot of practice to become perfect. The normal note has to be distinguished from the following abnormal notes—
Hyperresonant note—obtained in emphysema.
Tympanitic (a special type of hyperresonant note) note — obtained in pneumothorax.
Dull note—As found in pleural effusion, consolidation.
Auscultation
Here, the findings are obtained by placing the stethoscope on the chest wall and can be described under three headings—(a) Breath sounds, (b) vocal resonance and (c) added sounds.
Breath sounds
These are of two types: (1) Vesicular breath sounds and (2) bronchial breath sounds.
The main points of difference between them are in Table 2.
Breath sounds are absent in pneumothorax, pleural effusion, etc.
Mechanism of production of vesicular and bronchial breath sounds:
In normal lungs, the high frequency components of the breath sound are filtered out by the alveoli during transmission to a stethoscope placed on the chest wall due to poor conducting properties of air in the alveoli. As a result, we hear the low-pitched vesicular breath sound. However, we get bronchial breath sound over an area of consolidation. In consolidation, an inflammatory exudate due to infection fills the alveoli over a circumscribed area causing solidification of the tissue. This provides an excellent conducting medium for the breath sounds to be transmitted to the chest wall.
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As a result, there is transmission of both low-frequency and high-frequency sounds to the stethoscope placed on the chest wall and we hear a high-pitched bronchial breath sound.
The chest wall is divided, for convenience, into the following areas, as follows:
In front—Supraclavicular, infraclavicular, mammary and inframammary.
In axilla—Axillary, infra-axillary.
Behind—Suprascapular, interscapular and infrascapular.
Vocal resonance
This is the sound heard by the stethoscope over the chest wall when the subject utters ‘ninety-nine’ or ‘one-one-one’. The observation is the same as that of vocal fremitus, which is now confirmed.
Added sounds
These may be—(a) Rhonchi, (b) crepitations and (c) pleural rub. All of them are pathological.
Rhonchi are associated with bronchoconstriction as found in bronchial asthma.
Crepitations are due to presence of exudates in alveoli. They may be fine or coarse in quality. They are found in: (1) Pulmonary edema due to left ventricular failure, (2) pneumonia and (3) bronchiectasis, etc.
Pleural rub is found in pleurisy, due to friction between two inflamed pleural surfaces.
EXAMINATION OF THE CRANIAL NERVES
Before going into the details, it may be mentioned that examination of cranial nerves is done by adopting the following sequence:
- History
- Inspection
- Examination.
Other points to note are:
- Advice to the patient given during examination.
- Precautions.
- Applied, where applicable.
FIRST CRANIAL NERVE (OLFACTORY NERVE)
History related to olfactory nerve
- Whether there is no sensation of smell (anosmia).
- Whether there is excessive sensation of smell (hyperosmia).
- Whether there is distorted sensation of smell (parosmia).
- Whether smell is felt even when there is no smell (olfactory hallucination).[Common cause of anosmia is nasal catarrh as occurs in common cold. Olfactory hallucination occurs in the 16premonitory stages of epilepsy of certain varieties.]Objects required for testing are torch, vials of liquids and cotton.
Inspection
The thumb is placed on the ball of the nose and the external nares are inspected for any nasal catarrh or deviation of the septum.
Tests
- Classical objects like oil of wintergreen, clove oil and tincture asafetida may be used. However, for the sake of convenience, common objects like toothpaste, scented soap, etc. may also be used as alternatives.
- Objects with pungent odor must be avoided because they stimulate trigeminal nerve and smell is felt even if the olfactory nerve is damaged.
Method
- Eyes should be closed.
- One nostril to be closed at a time.
- The substance is to be gently sniffed with the other nostril.
- The subject will now tell about the presence, character and identity of the smell.
SECOND CRANIAL NERVE (OPTIC NERVE)
It has three components: (1) Visual acuity, (2) field of vision and (3) color vision.
Visual acuity
History
Whether there are complaints like difficulty in reading the number of buses (distant vision) or difficulty in threading a needle (near vision).
Inspection
Whether there is presence of conjunctivitis in the eye.
Testing materials
Snellen's chart for distant vision. For near vision, Jaeger's chart is used.
Procedure
- Snellen's chart consists of letters of different sizes arranged in lines marked 60, 36, 24, 18, 12, 9, 6, 5 meters.
- The subject is seated at a distance of 6 meters (20 feet).
- The subject should see with one eye.
- Both eyes are to be kept open. The eye not used should be covered with the subject's hand cupped over it but not pressing it (myopia is enhanced on pressing the eye).
- The subject reads from above downwards.
- Visual acuity = d/D,where,d = The distance of the subject from the chart.D = The distance at which a person with normal vision can just see what the subject sees at 6 meters.
- If visual acuity is less than 6/60, the subject is gradually moved towards the chart. The distance at which the subject is just able to see the top letter is determined. If, say, he just sees the top letter at a distance of 2 meters from the chart, his visual acuity = 2/60.
- If visual acuity is less than 1/60, finger counting and finger movement tests are employed.
- If the person is still unable to see, perception of light and if present, 17projection of rays are tested. (In perception of light, a lighted torch is focussed on the eye and the subject is asked whether he sees any light. In the test for projection of rays, a beam of light is focussed on the eye from different directions and the subject is asked to determine the direction of light).These tests help to determine whether the optic nerve is functioning or not.
Applied
- If the optic nerve is nonfunctioning, there is no use of a cataract operation as it will fail to restore vision.
- For the illiterate, in place of Snellen's chart, E-chart or C-chart is used. The subject is asked to find the direction of the gaps in the letters.
Field of vision
Definition
When a person fixes his gaze with one eye, the surrounding area which he can also see, is the field of vision of that eye.
History
Whether the person frequently collides with other people while walking.
Inspection
Nothing significant.
Procedure: (Confrontation perimetry)
- The subject is to be seated at a distance of 1 meter (handshaking distance) from the examiner.
- Eyes of subject and examiner should be at the same level.
- The subject should look at the examiner's confronting eye (e.g. examiner's left eye with the subject's right eye).
- Gaze should be fixed.
- Head should be fixed.
- The eyes not used are shut with one finger gently placed from the side so as to keep the field of vision unhindered.
- The examiner's index finger should be kept moving and it is moved in the mid-plane between the subject and examiner as it is brought from outside inwards in various directions. The subject indicates when he just sees the examiner's finger from the corner of his eye. The examiner compares this with his own findings. Thus, the examiner compares the subject's field of vision with his own. Supposing that the examiner's field of vision is normal, abnormality in subject's field of vision can be detected.
Applied
Scotoma: Localized loss of field of vision, commonly found in glaucoma.
Hemianopia: Loss of one-half of field of vision.
Homonymous hemianopia: Loss of either left or right halves of field of vision (symmetrical).
Binasal hemianopia : Loss of the nasal halves of field of vision.
Bitemporal hemianopia: Loss of both temporal halves of field of vision. (Found in tumor of pituitary gland which presses on the central part of optic chiasma.)
Color vision
Color vision is tested with Ishihara charts (see p. 800).
3RD, 4TH AND 6TH NERVES
Anatomy
- The oculomotor (3rd), trochlear (4th) and abducent (6th) nerves innervate 18the extrinsic muscles of the eyeball. The extrinsic muscles of the eyeball are:
- Levator palpebrae superioris
- Superior rectus
- Inferior rectus
- Medial rectus
- Lateral rectus
- Superior oblique
- Inferior oblique.
- The lateral rectus is supplied by abducent nerve, the superior oblique is supplied by trochlear nerve while the rest are supplied by oculomotor nerve.
- The levator palpebrae superioris muscle elevates the upper eyelid. In the abducted eye, the superior rectus elevates the eyeball while the inferior rectus depresses the eyeball. In contrast, in the adducted eye, the inferior oblique elevates the eyeball while the superior oblique depresses the eyeball (see below). The medial rectus adducts and the lateral rectus abducts the eyeball. (Adduction is movement to the nasal side while abduction is movement to temporal side).
- The long axis of the recti muscles makes an angle of about 25° on the lateral side with the optical axis whereas the long axis of the oblique muscles makes an angle of 51° with the optical axis on the nasal side. From this, it is evident that in the abducted position, the recti muscles become the sole elevator or depressor while in the adducted position, the oblique muscles become the sole depressor or elevator.
- Parasympathetic fibers arising from Edinger-Westphal nucleus accompany the oculomotor nerve and supplies the ciliary muscle and sphincter pupillae. Ciliary muscle helps in accommodation while sphincter pupillae constricts the pupil.
History
Whether there is presence of diplopia (double vision).
Inspection
Whether there is presence of ptosis and strabismus/squint. The pupil is also inspected.
[Ptosis: It is drooping of upper eyelid. It may be due to paralysis of levator palpebrae superioris. This is to be distinguished from ptosis due to lesion of sympathetic nerves supplying MÜller's muscle. In third nerve paralysis, pupil is dilated whereas in sympathetic paralysis, pupil is constricted.
Squint: It is loss of ocular parallelism, i.e. the visual axes of the two eyeballs are no longer in their normal parallel position. Squint or strabismus is seen due to paralysis of 3rd, 4th or 6th cranial nerves. This is known as paralytic squint which is distinct from the other type of squint called concomitant squint. Concomitant squint is characterized by the following: (a) Usually present from childhood, (b) no complaint of diplopia and (c) individual eye shows full range of movement, i.e. there is no paralysis.]
Pupil: One should look for the size of the pupil, i.e. whether the pupil is constricted or dilated. Normal size of the pupil varies between 3–4 mm.
Pupil is constricted on exposure to bright light, parasympathetic overactivity, morphine poisoning, etc. Pupil is dilated in darkness, sympathetic overactivity, in anger and fear, in 3rd nerve palsy, etc.
The shape of the pupil is normally circular but it may be irregular due to adhesion of the iris to the lens in iritis or neurosyphilis.19
Tests
- Tests for muscle movement:
- The finger is moved at eye-level at a distance of about 2 feet away from the eyes, from the left extreme to the right extreme of the subject's visual field and then in the reverse direction. The subject's head is fixed but the eyes follow the moving finger. The lateral and medial rectus are thus tested.
- Now the finger at one extreme, say, to the left of the subject, is moved first upwards and then downwards. During the upward movement, in the left abducting eye the superior rectus elevates the eyeball while in the right adducting eye, the inferior oblique elevates the eyeball.
- During the downward movement, in the left abducting eye, the inferior rectus depresses the eyeball while in the right adducting eye, the superior oblique depresses the eyeball.
- The test is then done in the right extreme of the subject. The remaining muscles are thus tested.
- Light reflex:
- A shining torch is brought slowly from the side on to the pupil. The pupil constricts as soon as light falls on it. This is the direct reflex.
- The torch is shone on one pupil while the hand is placed on the nose-bridge (to prevent rays of light from falling on the other eye). The other pupil constricts. This is the indirect or consensual reflex.
- While eliciting these reflexes, the torch should not be shone from the front because then the accommodation reflex will take place causing miosis and there will be confusion regarding the true cause of pupillary constriction.
- The accommodation reflex or reaction: When a subject fixes his gaze on an object close to his eyes, the accommodation reflex occurs. This has three components—(a) Miosis or constriction of the pupil, (b) convergence of the eyeballs, and (c) increase in the anterior curvature of the lens. The first two components are visible and can be tested in the following way:A finger is placed in front of the nose while the subject is asked to look at a distance. Now, suddenly the subject is asked to look at the fingertip. The convergence of the eyeballs and pupillary constriction can be seen to occur.
TRIGEMINAL NERVE (FIFTH CRANIAL NERVE)
Anatomy
- It is a mixed nerve. The sensory part carries sensations from different parts of the face and the motor part supplies the muscles of mastication.
- The nerve has three divisions. The ophthalmic and maxillary branches are purely sensory but the mandibular division is mixed in nature.
- The ophthalmic division carries sensation from the skin of the forehead and of scalp as far back as a line joining the two ears. It also receives sensation from the upper eyelid, conjunctiva, cornea and other intraocular structures, the frontal, ethmoidal and sphenoidal air sinuses, the upper part of the nasal cavity and nasal septum.
- The mandibular division receives sensation from the skin of the lower jaw with the exception of the angle of the jaw, lower teeth and gums, the tongue, the floor of the mouth. Also, the mandibular division supplies the masticatory muscles—Masseter, temporalis, medial and lateral pterygoid through its motor fibers.
Tests
Sensory
Sensory function is tested by examining touch, pain and temperature sensation as follows:
- Touch is tested by a wisp of cotton-wool. The following points should be kept in mind: (a) The subject must close his eyes. (b) The piece of cotton-wool should be just touched and not rubbed or scratched, because on doing so, the pain fibers, and not the touch fibers are stimulated by the tickling sensation. (c) The application of the stimulus should be irregular and in random fashion so that the subject can not predict or anticipate it. (d) Testing should be done for each side and each division of the nerve separately.
- Pain sensation is tested by a pin with a sharp and a blunt end. The skin is touched lightly with the sharp and blunt ends randomly and the subject is asked whether the sensation felt is sharp or blunt.Precaution: (a) The subject's eyes should be closed and (b) pressure applied should be uniform.
- Temperature sensation is tested by applying test tubes containing hot but not too hot or cold but not too cold water, to the skin. The subject, with eyes closed, is asked whether it is hot or cold.
Motor
Inspection: (a) Whether there is presence of temporal or infratemporal hollowing, which occurs in paralysis of temporalis or masseter. (b) Any deviation of the jaw, on opening the mouth, is noted. If there is unilateral paralysis of medial and lateral pterygoids, the jaw tends to deviate to the paralyzed side, on opening the mouth.
Palpation
- The subject is asked to clench his teeth. The temporalis and masseter are palpated as they stand out firmly.
- The subject is asked to open his jaws without resistance and then against resistance. This is a test of lateral pterygoid muscle.
- The jaw is tested for side-to-side movement without resistance and then against resistance. It is to be noted that the medial and lateral pterygoids, acting together, move the jaw to the opposite side. That is why, in unilateral paralysis, the jaw is deviated to the side of paralysis by the unopposed action of pterygoids of the healthy side.
Reflexes
- Corneal reflex:
- A wisp of cotton-wool is touched on the lateral part of the cornea, bringing the hand from the lateral side when a brisk closure of the eyelids occur.
- Never scratch the cornea with the tip of the cotton-wool as this may result in corneal ulceration.
- Afferent path — Ophthalmic division of trigeminal; efferent path — facial nerve (bilateral).
- Jaw jerk
- Keeping the mouth partially open, the left thumb is placed on the chin and struck by a tendon hammer when the mouth closes shut.
- Both afferent and efferent path run through 5th nerve.
- This is a stretch reflex—Often not elicited in individuals below the age of 40 years.
FACIAL NERVE
It has three components: (a) Secretomotor component supplying lacrimal, submandibular and sublingual glands, (b) sensory component carrying taste sensation and (c) motor component.
Secretomotor component
History
(a) Whether there is any loss of salivation. (b) Although lacrimation is decreased in damage to the nerve, the common symptom is overflow of tears due to failure of closure of the palpebral fissure as a result of paralysis of orbicularis oculi.
Inspection
Nothing particular.
Test
Palatable food is held before the patient and salivation of the patient noted. Also, a strong ammoniacal solution is held before the eyes and lacrimation is noted.
Sensory
Facial nerve carries special sense of taste through chorda tympani.
History
If there is any loss of taste.
Inspection
Nothing particular.
Test
Objects taken—Sugar solution for sweet taste, saturated common salt solution for salty taste, vinegar for sour taste, quinine for bitter taste.
Advice to the patient
(1) The patient is asked to protrude the tongue. (2) The eyes should be closed. (3) The test material is applied to his tongue on one side. The other side will be tested later. (4) He will perceive the sensation and then, opening the eyes, point to cards written salt, sugar, sour and bitter. (5) He should never try to talk because this will allow saliva to flow from one side to the other or to the posterior one-third of the tongue preventing proper testing.
Precaution
(1) Quinine should be applied last because bitter taste persists for a long time. (2) The tongue is to be rinsed thoroughly after each testing.
Motor
Facial nerve supplies all the facial muscles except levator palpebrae superioris.
History
The patient is asked about whether:
- He fails to close the eye.
- There is overflow of tears in one eye.
- Dribbling of saliva occurs from the angle of the mouth.
- There is hyperacusis, i.e. the sounds that he hears, are of increased intensity.
Inspection
- Masked facies may be present in bilateral lower motor neuron paralysis.
- Absence of transverse creases in the forehead and vertical creases between the eyebrows. This may be a normal finding in some individuals.
- Widened palpebral fissure.
- Flattening of nasolabial fold.
- Drawing of angle of mouth to one side during talking.
Tests
The examiner may perform the required muscle movements himself and then ask the patient to emulate him. The patient is asked to:
- Raise the eyebrows—Shows the action of frontal belly of occipitofrontalis.
- Frown—Shows the action of corrugator supercilii and procerus.
- Close the eyeball, first gently, and then as forcibly as he can. The examiner now tries to open the eyes by placing the thumbs on the eyebrows and pulling them up-shows the action of orbicularis oculi.[These constitute the upper group of facial muscles and they escape paralysis in unilateral upper motor neuron type of paralysis.]
- Blow out the cheeks. Then the examiner gently presses on the blown-out cheeks to test the tone of buccinator muscle. Note that if air passes out when the examiner presses on the cheeks, it indicates weakness of the buccinator as well as orbicularis oris muscle.
- Whistle or purse the lips—Tests the power of orbicularis oris.
- Smile—Shows the action of risorius and zygomaticus major.
- Show the teeth as hard as possible— Shows the action of risorius, zygomaticus major and platysma.
Applied
The features of upper and lower motor neuron paralysis are different. The lower motor neurons of the upper group of facial muscles receive bilateral innervation from the motor cortex through the upper motor neurons. So, in unilateral upper motor neuron paralysis, these muscles escape paralysis.
In contrast, the facial muscles of the lower group, due to their unilateral upper motor neuron innervation, are paralyzed in both upper and lower motor neuron type of paralysis.
EIGHTH OR VESTIBULOCOCHLEAR NERVE
It has two divisions: (a) Vestibular and (b) cochlear.
Cochlear division is responsible for hearing. Vestibular division is responsible for maintaining equilibrium.
History
- If there is any deafness.
- If there is any tinnitus (a buzzing sound in the ear).
- If there is any vertigo (dizziness in the head).
Inspection
Auriscope should be used. In its absence, the pinna is pulled upwards and backwards and the auditory canal is inspected. Presence of any ear-wax, any discharge or any perforation of the drum is looked for.
Test of the cochlear division
Watch test
The subject may complain of deafness. This is tested by ‘watch test’. In this, a ticking watch is brought slowly from outside the hearing range towards the ear being examined while the other ear is kept closed by a finger and the patient's eyes remain closed. The subject indicates as soon as he hears the ticking sound of the watch. This distance, at which the watch is just audible, is noted and compared with that required by a healthy ear. Obviously in a deaf ear, this distance will be reduced.
Deafness is of two types: Nerve deafness (sensorineural deafness or perceptive deafness) and conductive deafness. Two tests called Rinne's test and Weber's test are done to diagnose the type of deafness. Rinne's test:
In this test, a tuning fork (having a frequency of 256 or 512) is vibrated and held before the subject's ear. The subject hears a sound and acknowledges it. [Note that the vibrating tuning fork should be held by the stem or handle. The limbs should remain absolutely free. If the fingers touch the limbs, the vibrations will be dampened. Also, the direction of the vibrating limbs should be perpendicular to the ear (ear-drum).]
The base of the vibrating tuning fork is now placed on the mastoid process of the temporal bone. The subject indicates when the sound is no longer heard. The tuning fork is then immediately held in front of the ear. The subject normally can still hear a sound. This proves that air conduction is greater than bone conduction (AC > BC) under normal conditions. [The sound conducted through the ear (air) is heard louder than the sound conducted through the mastoid process, under normal circumstances.]
However, in otitis media, earwax, etc. conductive deafness is present and in these cases, BC > AC and so, the sound conducted through the mastoid process is heard louder than the sound conducted through the ear. This can be confirmed by holding the vibrating tuning fork in front of the ear and as soon as the subject indicates that the sound is no longer audible, the tuning fork is quickly placed on the mastoid process. In conductive deafness, the subject will be able to hear the sound conducted through the mastoid process even after the sound is no longer heard through the ear.
From Rinne's test, no conclusion can be drawn about the presence of perceptive deafness in the subject. So, Weber's test is done.
Weber's test
The tuning fork is vibrated and the base is placed on the forehead in the midline. A normal person hears the sound equally in both ears. In conductive deafness, the sound is lateralized to the diseased ear, i.e. the sound is better heard in the diseased ear. In perceptive deafness, the sound is better heard (lateralized) in the healthy ear.
Vestibular nerve test
Straight line walking test: The subject is asked to walk along a straight line, drawn on the floor with a piece of chalk, with his eyes closed. The subject may show signs 24of unsteadiness in presence of vestibular lesions.
GLOSSOPHARYNGEAL NERVE
Tests
- Taste sensation from the posterior third of the tongue — This is difficult to elicit clinically.
- Test of general sense from posterior third of the tongue —Done with a long pin or wooden stick.
Reflexes
- Palatal reflex — Contraction of the soft palate on touching it with a pin or stick.
- Gag (pharyngeal reflex) — Contraction and elevation of the posterior wall of the pharynx on touching it with a long pin.
VAGUS NERVE
History
- If there is any history of nasal regurgitation of food.
- If there is nasal intonation such as ‘eng’ for egg, ‘rum’ for rub, etc.
- If there is hoarseness of voice or aphonia (loss of voice).
Tests
The patient is asked to say ‘ah’ and the palate is inspected. In unilateral paralysis, the palate of the paralyzed side does not move but the palate of the healthy side moves up and the uvula points towards the normal side.
In bilateral paralysis, the palate does not move at all.
ELEVENTH NERVE (SPINAL ACCESSORY)
Inspection
- (Features of trapezius palsy): Flattening of the shoulder, displacement of the upper part of the scapula away from the spine while the lower part is displaced towards the spine. Drooping of the arm on the affected side and the fingers hang lower on the affected side.
- Head falls backwards in bilateral sternomastoid weakness.
Tests
For trapezius
Shrug the shoulders without resistance and then against resistance.
For sternomastoid
- Depress the chin against examiner's resistance (bilateral test).
- Move the chin to the opposite side without resistance and then against resistance.
HYPOGLOSSAL NERVE
Inspection
- Whether there is any atrophy, fasciculation or tremor in the tongue.
- Whether there is any deviation of the tongue on protrusion (in unilateral paralysis, tongue may deviate to the side of paralysis).
Tests
- The tongue is protruded and any deviation noted.
- The tongue is moved from side to side.
- The tongue is pressed against the cheek against examiner's fingers resisting from outside.
REFLEXES
A neurological reflex consists of: (a) A receptor, (b) an afferent pathway, (c) a center located in the spinal cord or in the brain, (d) an efferent path leading to (e) the effector organ (muscle or gland).
Reflexes may be superficial or deep.
Superficial reflexes are characterized by muscle contractions in response to cutaneous stimulation and are polysynaptic in nature.
Deep reflexes are also known as tendon reflexes or stretch reflexes because they are produced by stretch of tendon of muscles. These reflexes are monosynaptic involving two neurones — one afferent and the other efferent. The afferent neurone arises from the muscle spindle of the muscle being stretched. The efferent neurone is the anterior horn cell running back to the same muscle causing it to contract.
Elicitation of the tendon jerks (the following points must be kept in mind)—
- A tendon hammer with a flexible shaft and weighty head is suitable.
- The type of hammer used and the method of examination should always be the same.
- The tendon, and not the muscle, is to be tapped.
- The subject should be warm, comfortable, relaxed and reassured with the process explained to him. Attention of the subject should be diverted by talking, if necessary.
- Due attention should be paid to the privacy of the subject.
- The muscle being tested should be visible.
- The tendon jerk on one side should be immediately compared with that of the other side.
Reinforcement or Jendrassik's maneuver
When a tendon jerk is not normally elicitable, it may be elicited by asking the subject to make strong, voluntary effort such as hooking the fingers of the two hands together and trying to pull them against each other (in case of lower limb tendon jerks) or by clenching the jaw (in case of upper limb tendon jerks). This is known as reinforcement or Jendrassik's maneuver.
DEEP REFLEXES
Biceps jerk: The examiner supports the subject's forearm (flexed at the elbow) on his own forearm and then places the thumb on the biceps tendon and strikes it with the hammer.
The biceps muscle contracts with flexion of the elbow-joint. Spinal segment involved—C5, C6.
Triceps jerk: The elbow is flexed and the forearm is placed on the subject's chest, the subject remaining supine. (The triceps jerk is tested preferentially in this position). The triceps tendon is tapped just above the olecranon 2˝ above the elbow. The triceps muscle contracts with extension of the elbow-joint. Spinal segment—C6, C7.
Supinator jerk: A tap on the styloid process of the radius 2˝ above the wrist stretches the brachioradialis. Hand is placed as in the triceps test.
Brachioradialis contracts with flexion of elbow-joint. Spinal segment—C5, C6.
Knee jerk: The examiner passes his hand under the knee being examined and grips the other knee with his palm. The knee being tested rests on the examiner's forearm and hangs loosely. Patellar tendon is struck midway between the lower border of patella and tibial tuberosity.
Quadriceps contracts with extension of knee-joint. Spinal segment—L2–L4.
This reflex can be more easily elicited with the subject sitting—his legs dangling freely over the edge of the bed.
26
Ankle jerk: The lower limb, externally rotated and slightly flexed at the knee, is conveniently placed on the other lower limb. With one hand, the foot is slightly dorsiflexed in order to stretch tendoachilles. With the other, the tendon is struck on its posterior surface.
Contraction of the calf muscle (gastrocnemius) occurs with plantar flexion of the foot. Spinal segment—S1, S2.
It may also be elicited with the subject kneeling on a chair.
Clonus: It consists of a series of regular rhythmic movements produced by alternate contraction and relaxation of a group of muscle and their antagonists. This is often elicitable when tendon reflexes are very brisk as in pyramidal lesion.
Patellar clonus: The inferior extremity is kept extended on the bed and the patella is suddenly pushed down towards the foot holding it between the thumb and index finger.
Quadriceps shows a series of up and down clonic contractions as long as stretch is maintained.
Ankle clonus: The patient's knee is bent at a right angle and supported with one hand. The distal part of the foot is grasped and the foot is then suddenly dorsiflexed passively and the pressure is sustained. In ankle clonus, a sustained regular oscillation of contraction and relaxation occurs. It is pathognomonic of pyramidal tract lesion.
CAUSES OF ABNORMAL TENDON REFLEXES
- Diminished or absent:
- Physiological: Patient is alert and rigid.
- Pathological:
- Breach in the reflex arc— Polyneuritis (lesion affecting the afferent or efferent path), tabes dorsalis (lesion affecting the posterior root), poliomyelitis (lesion affecting the anterior horn cell), myopathies (muscle itself involved).
- In spinal shock after a severe cerebral catastrophe.
- Due to rigidity, spasticity or muscle contracture where the muscle cannot be relaxed.
- Delayed relaxation of the ankle jerk is an important diagnostic sign of hypothyroidism.
- Exaggerated:
- Physiological: In worry, anxiety, fright or hysteria.
- Pathological: Excessively brisk — In upper motor neurone lesion, thyrotoxicosis.Pendular: In cerebellar lesions.[Unilateral exaggeration of the jerk is more significant than bilateral symmetric exaggeration, which may be found in hysteria or sensitive persons.]
SUPERFICIAL REFLEXES
Plantar reflex: The patient is so positioned that knee is slightly flexed and thigh externally rotated. Outer aspect of the foot now rests on the couch. The patient is warned that the sole will be scratched and he is asked to try to let the foot remain loose. The outer aspect of the sole is then firmly stroked with a key or the end of a percussion hammer handle. The stimulator should move forwards and then curve inwards towards the middle metatarsophalangeal joint. The stimulus should be firm but not frankly painful. Spinal segment—L5, S1, S2.
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Normal response: The great toe will flex at the metatarsophalangeal joint. Other toes will also flex.
No response: (1) Thick skin, (2) in lower motor neurone lesion affecting spinal segment.
Abnormal response: Dorsiflexion of the great toe and fanning out of other toes. This is known as plantar extensor or Babinski positive sign.
This signifies pyramidal tract lesion anywhere above S1.
In infants upto 18 months, and also during sleep, plantar extensor sign may be positive. In infants, Babinski sign is positive due to lack of myelination of pyramidal tracts.
Babinski sign is very important in neurological examination because the spinal segment integrating this reflex is situated at a very low level in the spinal cord (around S1) and, therefore, lesion almost anywhere in the spinal cord leads to a positive Babinski response. So clinicians examine this reflex at the very beginning to exclude any spinal cord lesion.
SUPERFICIAL ABDOMINAL REFLEXES
The subject lies in a relaxed supine position with the abdomen uncovered. A light stimulus with a key or wooden stick is passed across the abdominal skin from the outer aspect towards midline at three levels— (1) Below costal margin, (2) at the level of umbilicus, (3) in the iliac fossa.
This evokes a ripple of contraction of the abdominal muscles concerned. The umbilicus is simultaneously drawn towards the site of contraction.
Spinal segment
Below costal margin—T7–9.
At the level of umbilicus—T10
Iliac fossa—T11, T12.
ABSENT ABDOMINAL REFLEX
Due to physiological causes
Anxious patient, pregnancy, obesity, ascites, multipara.
Due to pathological causes
Upper motor neurone lesion above spinal segment.
MUSCLE TONE AND POWER
Definition of muscle tone
Most simply, muscle tone can be defined as the degree of tension or partial state of contraction present in a healthy muscle at rest. This is examined by passive movement of the involved joint in the direction opposite to that of muscle contraction and noting the resistance.
Flexors of the elbow
First, pick up the patient's hand and forearm as if to feel the pulse. Now, the patient is asked to keep his upper limb flexed at the elbow and not to interfere or help in the examination.
Now, the examiner will try to extend the elbow-joint while putting one hand on the flexor muscles (the muscle whose tone is being assessed) and the resistance encountered in the process is noted.
Extensors of the elbow
Procedure is same as that of the flexors except that the movements are in the opposite direction. For extensors, the examiner will flex the elbow from an extended position and he will note the degree of resistance.
Causes of hypertonia
- Pyramidal tract lesion: Spasticity with clasp-knife effect.
- Extrapyramidal tract lesion: Cogwheel rigidity and leadpipe rigidity.
Causes of hypotonia
- Physiological: Limbs of children; prolonged disuse.
- Neurological:
- Breach in reflex arc: Myopathy (muscle affected), tabes dorsalis (sensory side), poliomyelitis (motor side) and cord or root compression (combined).
- Cerebellar disease.
- State of neurological shock.
POWER
Power or strength of a muscle is the amount of work that can be done by its contraction. In clinical medicine, it is examined by active movement without resistance followed by against resistance.
Here, the flexors and the extensors of the elbow are discussed.
Flexors of the elbow
- Patient is asked to flex the elbow first without resistance.
- Patient is asked to flex his elbow while the examiner will oppose the movement by placing the hand on the subject's wrist.
Extensors of the elbow
- First, the patient is asked to extend the elbow-joint without resistance.
- Then, the patient will try to extend the elbow-joint while the examiner will oppose the movement by putting the hand on the subject's wrist.In this way, muscles of all parts of the body are examined.
Gradation of muscle power according to Medical Research Council scale is done as follows:
Grade 0 | → | Complete paralysis. |
Grade 1 | → | Very feeble contraction. |
Grade 2 | → | Power detectable only when gravity is eliminated by postural adjustment. |
Grade 3 | → | Power can overcome gravity but not examiner's resistance. |
Grade 4 | → | Some degree of weakness, categorized as having poor, fair or moderate strength. |
Grade 5 | → | Normal power. |
Weakness may be due to pyramidal or extrapyramidal tract lesion, lower motor neuron lesion or due to muscle pathology itself. Examples—Hemiplegia, paraplegia, monoplegia and quadruplegia.