Abnormal Involuntary MovementsCHAPTER 1

Involuntary movements are conspicuous presentations of different neurological disorders with their own characteristic features of involuntary motor activity as against voluntary movement disorders like bradykinesia, akinesia. Involuntary group of muscles like smooth muscles present in most of the organs are innervated by autonomic nerves are not controlled by will.

Basic considerations of muscle, basal ganglia and cerebellum will be a preferable prelude for better comprehension of subsequent narrations.

Discussion of physiology of voluntary muscle may be inappropriate at this juncture, although involuntary muscle physiology has relevance. Involuntary muscle (smooth muscle) present in almost all organs and smooth muscle fibres are elongated (fusiform cells) and the only nucleus is centrally placed. Smooth muscle fibres may be simple unit (visceral and multiunit). Smooth muscle contraction and relaxation process is slow. They are supplied by autonomic nerve fibres which do not end in the end plate but end on smooth muscle fibres. Phosphorylation of myosin is followed by activation of myosin ATPase and phosphorylated myosin gets attached to actin which is responsible for the contraction of muscle and dissociation of calcium calmodulin complex results in relaxation of the muscle (calcium from extracellular fluid with a protein is called calmodulin and forms calcium calmodulin complex). The activity of the smooth muscle fibres are controlled by nervous factors and humoral factors, i.e. hormones and neurotransmitters. Relaxation is facilitated by adenosine, lactic acid, nitric oxide (endothelium-derived relaxing factor) apart from lack of oxygen and excess of carbon dioxide.

Basal ganglia are a group of nuclei situated deep within cerebral hemispheres and consist of caudate nucleus and lentiform nucleus (putamen and globus pallidum) substantia nigra and subthalamic nucleus. Basal nuclei (basal ganglia) form part of the extrapyramidal system. They are concerned with control of muscle tone, motor activity reflex and automatic associated movements. Disorders of basal ganglia leads to Extrapyramidal syndromes (Parkinson's disease, Wilson's disease, Chorea athetosis, ballismus and kernicterus). The seat of most of the involuntary movements lies here only. The basal ganglia circuit both efferent and afferent connections are depicted (Figs. 1.1A and B).

This occupies most of the posterior cranial fossa and lies dorsal to pons and medulla. It consists of two lateral cerebellar hemispheres and central vermis. Anatomically it is divided into anterior, posterior (middle) and flocculonodular lobes. Physiologically it is divided into spinocerebellum, vestibulocerebellum and corticocerebellar divisions. Depending on phylogeny the morphological subdivisions are archicerebellum (oldest part), paleocerebellum and neocerebellum (recent past).2

There are four cerebellar nuclei, i.e. dentate (lateral), fastigial (medial), emboliform, globose and three peduncles (superior, middle and inferior) connecting cerebellum to brainstem through cerebellar connections (Figs. 1.2A and B). The anterior lobe includes parts of the superior vermis. Posterior (middle) lobe consists of lateral portions of cerebellar hemispheres and rest of the superior vermis as well as inferior vermis. Flocculonodular lobe includes nodulus and flocculus.

Note: To get an inside of the afferent and efferent connections of basal ganglia and cerebellum is imperative as the same influence their functions accordingly.

Note: The vermis is concerned with coordination of gait and posture.

Thus you can realise that cerebellar dysfunction produce hypotonia and intention tremor whereas that of basal ganglia in an increased tone and resting tremor.

Abnormal movements result from disturbances of posture and motor control as well as diseases in basal ganglia (causing symptoms due to an imbalance in the activities of dopaminergic neurons and cholinergic neurons and their receptors). Dopamine is the neurotransmitter in the nigrostriatal pathways. There is depletion of pigmented dopaminergic neurons in substantia nigra and presence of synuclein and other protein inclusions in niagral cells (Lewy bodies). Loss of dopaminergic neurotransmission is the hallmark. Degenerative conditions, like multiple system atrophy is characterised by parkinsonism and cerebellar features wherein syncuclein containing inclusions are found in basal ganglia, cerebellum and also cerebral cortex.

Parkinson's disease (paralysis agitans), Secondary Parkinsonism and other neurodegenerative disorders associated with Parkinsonism (like multiple system atrophy, corticobasal ganglionic degeneration and progressive supra nuclear palsy): Refer to chapters titled ‘Dementia’ and ‘Fatigue’.

Wilson's disease: Refer to chapter titled ‘Jaundice’

Huntington's disease: Refer to chapter titled ‘Dementia’

Cerebellar lesions: Refer to chapter titled ‘Vertigo’

Cerebrovascular lesions: Refer to chapter titled ‘Coma’

Multiple sclerosis: Refer to chapter titled ‘Paraplegia’

Encephalitis: Presents with fever, acute headache, meningism, altered consciousness, seizures, focal neurological signs, psychiatric symptoms sometimes. Involuntary movements are common.

The CSF may be normal or protein increase, sugar normal, increased lymphocytes (although polymorph may be raised in the early stages).

Metabolic: Hepatic encephalopathy, carbon dioxide retention, asterixis (metabolic/liver flap)

Endocrinal: Refer to chapter titled ‘Goitre’

Toxic: Drug induced and alcohol abuse refer to chapter titled ‘weight loss’

PSYCHOGENIC: Vide infra.

The features of various (11) abnormal movements defer in their clinical exhibition which are discussed below. All except tics are indicative of disease. The movement disorders encountered are in the order of their common occurrence which are:

Akathisia (motor restlessness): It is a movement disorder with a feeling of inner restlessness requiring continuous changes of position with daytime motor restlessness and feeling of muscular quivering, exhibiting an inability to keep still. It is caused by drugs like neuroleptics, beta adrenergic blockers, serotonin antagonist (cyproheptadine). This also occurs as a symptom in bipolar disorder and occasionally seen in Parkinson's disease. Their symptoms range from disquiet, anxiety, excruciating discomfort in the knees, movements of hands, arms and trunk muscles.

Asterixis (Flapping tremor): This is seen as a flexion, extension movement at metacarpophalangeal and wrist joints. It is a jerky, coarse, irregular tremor in out stretched arms with wrist in dorsiflexion and extended fingers. It is distinctive of chronic liver disease and hepatic encephalopathy or carbon dioxide retention (carbon dioxide retention flap) or drug intoxication.

Athetosis: It means instability of posture. Athetoid movements are slow and more writhing in nature and may be unilateral or bilateral. Tongue shows protrusion and withdrawal. The lips and jaw are involved especially in bilateral cases. Dysarthria and dysphagia are due to involuntary movements of articulation and pharyngeal muscles. In the limbs peripheral segments are involved. The posture of hand is one of wrist and flexion of metacarpophalangeal joints and extension of interphalangeal joints. There may be an alteration between two postures from extension to flexion occur in one visit after another. It is caused by drugs (like phenothiazine or L-dopa), perinatal anoxia, kernicterus, Wilson's disease or familial. The lesion is situated in putamen.

Chorea: It consists of rapid irregular jerky non-rhythmic and non-repetitive, hyperkinetic, quasi-purposive involuntary movements especially in the hands. Seen bilaterally in the face, raising eyebrow, frowning, pursing the lips, and bizarre movements of the mouth and tongue occur. Patient is restless and unable to keep still in upper limbs, it occurs at all joints one limb showing flexion at elbow with fingers grasping the bed clothes and other limb seen flinging out in full extension. Hypotonia is characteristic. It is not conspicuous in the lower limbs. They disappear in sleep but intensified during voluntary movements. Most cases are due to acute rheumatic fever in children (Sydenham's chorea). The other systemic diseases in which chorea occurs are SLE and various auto immune diseases and kernicterus or during levodopa therapy. Sometimes seen during pregnancy (chorea gravidarum). If the involuntary movements are confined to one side its called hemichorea. The other type of chorea is Huntington's chorea which is a progressive autosomal disorder and involuntary choreiform movements are the hallmark. Personality changes precede dementia. Epilepsy is common. Chorea may occur in old age (senile chorea). Chorea may occur with athetosis when it is called choreoathetosis. It consists of largely peripheral and relatively rapid movement of chorea combined with slowly distal writhing movements.

Dystonia: This is abnormal muscle contractions either repetitive or sustain with abnormal postures by exaggerated muscle tone with or without jerky tremor. It may be a feature of Parkinson's disease, Wilson's disease and may occur secondary to stroke or trauma or drugs. It may be focal or generalized. Torsion dystonia is a generalised form characterised by involuntary movements resulting in torsion of proximal part of the limbs and vertebral column especially in lumbar area. It may be inherited with an autosomal dominant pattern or idiopathic (it is characterised by abnormal dystonic movements of head, neck and face and postures with the history of normal birth and development as well as absence of neurological signs and past illness). Usually seen in childhood with symptoms starting in the legs. The lesion is in corpus striatum. Thalamus and cerebral cortex are possibly be incriminated. Other generalized dystonia's occur due to drugs like antiemetics, neuroleptics or levodopa (acute). Sometimes dystonia may be levodopa responsive. It may be a feature of Parkinson's disease, Wilson disease, secondary to damaged brain as in stroke. Focal form dystonia's are usually adult onset. They are:

Spasmodic torticollis (wry neck) focal dystonia: It is a representative of torticollis which constitutes several types. Contraction of neck muscles result in rotation of the head to opposite side with flexion of the neck to the side of contracted muscle or rotation of head may be without lateral flexion, i.e. deviation of the head to one side with the chin looking opposite side. Some believe that it is a fractionary variety of torsion dystonia. The causes attributed are may be organic (like encephalitis, lethargica, or forming part in the extrapyramidal syndrome) or hysterical.

Hemiballismus: It is a severe form of chorea with large amplitude and wild flinging movements on one side of the body. If it is confined to one limb affecting proximal muscles its called monoballismus. The lesion in the contralateral sub thalamic nucleus usually due to cerebrovascular accident.

Myoclonus: It consists of brief rapid involuntary shock like muscle contractions involving a whole muscle or few muscle fasciculi or muscle groups. The contraction may be slight or violent as to throw the patient on to the ground. It occurs in disorders of cerebral cortex or brainstem. Rarely arises from injury or spinal cord. It often occurs in diffuse encephalopathy or diffuse cerebral hypoxia. It may also occur in normal person when falling asleep (hypnic jerks or waking up). There are many varieties of myoclonus like facial myoclonus, spinal myoclonus. Palato-pharyngo-laryngo-oculo-diaphragmatic myoclonus or hereditary essential myoclonus or myoclonic epilepsy (occurs in association with epilepsy). Myoclonic epilepsy with ragged red fibres on muscle biopsy examination is a mitochondrial syndrome. Cortical myoclonus is a term used for a type of epilepsy originating in cerebral cortex outer layer of the brain. The other features like cerebellar ataxia, multiple lipomas, dementia and sensory neural deafness are described.

Spasms: This is involuntary muscle contraction which results in a movement.

Tardive dyskinesia: It is involuntary grimacing abnormal movements like chewing movements, lips smacking, intermittent protrusion of the tongue due to neuroleptics used for long time which include antiemetics like metoclopramide, prochlorperazine or levodopa.

Tics (habit spasm): It is involuntary compulsive stereotype movements frequently involving facial muscles like blinking or muscles of tongue, shrugging of shoulders. Patient will be able to suppress them for a short time in Tourette's syndrome multiple motor tics (like face, shoulders or neck), vocal tics (like grunts, echolalia, i.e. repetition of speech of other) and respiratory tics (like yawning, spasmodic cough or spiting are encountered). It is frequently associated with psychiatric disease like depression or obsessive compulsive neurosis (preceding compulsion to carry the tics for relief by doing so). An individual may have one or several types of tics.

Tremors: This is one of the common hyperkinetic disorders consisting of rhythmical oscillations of some part of the body (usually upper limb and less commonly jaw, lips, tongue, head (titubation) or legs resulting from alternating muscular contraction of agonist and antagonist. Physiological tremor which is induced by extreme fatigue or emotional stress or severe cold environment is transient and maybe visible or invisible.

So, there are three clinicopathological tremors apart from physiological or functional tremors:

Correct clinical diagnosis of the nature of involuntary movement will depend on carefully analysing the dyskinesia. As functional movement disorders may mimic all other organic entities shrewd observations to delineate them is very vital.