Thermodiscoplasty in cervical discopathy and rhizolysisChapter 1

The management of cervical disc and zygapophyseal joint (Z-joint) pain has taken advantage of recent advances in lumbar pain treatment, with a trend toward minimizing the collateral damage to adjacent structures while accessing the ‘pain generator’ for treatment. These scientific advances, and the development of minimally invasive techniques, have improved the management of neck pain, thereby offering a wider range of possibilities to patients with diseases such as DDD and ZJO.

In this regard, one of the therapies that have significantly changed the management of discogenic and facetogenic pain has been the use of devices that produce nociceptor ablation and decompress neural elements through delivery of high temperatures. Two of these procedures are thermodiscoplasty (TDP) and medial branch neurolysis, which use heat in the treatment of DDD and ZJO respectively. These minimally invasive delivery techniques have proved their efficacy in lumbar pain treatment and their implementation in the cervical zone has been growing gradually. They have made thermal ablation therapies, whether laser or radiofrequency (RF) even more attractive for the treatment of neck pain.

In this chapter, the authors intend to show that both procedures have proved to be effective in treating axial neck pain, and that their implementation in the cervical area is expected to grow steadily.

There are a number of different anatomic structures that can cause neck pain. The most relevant pain generators may include disc degeneration (cervical discopathy) and Z-joint osteoarthritis. It thought that about 16% of axial pain is discogenic in nature and Z-joint related pain has been estimated to be present in 55% of patients (Yin et al. 2008).

The intervertebral disc and Z-joint provide biomechanical stability of the cervical vertebral motion segment. In addition, they facilitate coordinated cervical movement, absorb impacts, separate vertebral bodies, and maintain the stability of the foraminal window. However, there are degenerative processes, widely related to aging, which can cause diseases that result in a loss of balance in the normal spine anatomy and generate neck pain as a result.

Disc degeneration is part of the normal aging process and starts as a biochemical alteration affecting a percentage of the normal disc components, mainly through a decrease in proteoglycans and chondrocytes (Roh et al. 2005). As a result, the intervertebral disc has a decreased rehydration capacity, altering the disc volume and structure (Buckwalter 1995). In addition, the annulus fibrosus undergoes changes due to the loss of collagen, causing fissures and neurogenesis. The progressive annular weakening in advanced stages of degeneration, results in herniation of the nuclear material and compression of the adjacent zones such as the dural sac or nerve root. This loss of continuity of the disc tissue creates a change in the structural balance of the intervertebral joint and thus activates Z-joint degeneration. Moreover, neuroanatomic, neurophysiologic, and biomechanical studies have all demonstrated the presence of free and encapsulated nervous terminations in the Z-joint as well as nerves containing substance-P (pain) (Bogduk et al. 1982, Masini et al. 2005, Ohtori et al. 2000).

As in the lumbar segment, the exact source of axial neck pain is controversial, as is its treatment. It has recently been postulated that the degenerative processes and ongoing microtrauma cause the disc and Z-joint to undergo hypertrophic phenomena and neurogenesis, which generate new nervous terminations on the disc posterior edge and in the fibrocartilage of the facet joints (Eubanks et al. 2007).

Additional diagnostic clues may be obtained from the history and physical examination. Pain in the posterior neck that is exacerbated by neck extension and rotation may suggest discogenic pain. Pain that is provoked by forward flexion is typically myofascial in nature. Symptoms may be further obscured by referred axial neck pain. Therefore, other etiologies such as temporomandibular joint pain, infection, or neoplasm, also need to be excluded.

The surgeon must also confirm a positive discogenic test, whereby the patient reports an increase in the familiar concordant sign of at least 5 points on a visual analog scale (VAS) of 0 to 10 upon injection of affected level (a concordant sign is defined as the pain or symptom that is familiar to the patient, i.e. usually the symptom for which the patient is seeking physical therapy). Discography and its interpretation is controversial and its clinical value has been described by some authors as limited and by others as essential to understand axial neck pain. For this reason, is essential that the attending physician should perform the discogenic test, because he/she knows the patient and has previously explained to the patient the purpose of the procedure. The test becomes invalid if it is performed by a different doctor or radiologist.

It is very important to bear in mind that patients with axial neck pain should be carefully evaluated with a thorough history and physical examination to avoid unnecessary and expensive diagnostic tests.

Non-operative treatment options for cervical discogenic pain and Z-joint arthrosis are centered around activity modification, short-term bracing, rest, and judicious use of nonsteroidal anti-inflammatory drugs and analgesic pain medications. It is important to highlight that more than 80% of these cases respond to conservative therapy (Peh 2011, Schubert & Merk 2014). Often, spontaneous resolution of symptoms may occur. Another non-operative treatment alternative is the use of spinal injections (nerve root, epidural, facet joint blocks), which have an important therapeuctic and diagnostic value.

Interventional treatments and, in select cases, even surgery is recommended in patients with chronic, disabling and unrelenting symptoms that are non-responsive to a minimum of 6 weeks of conservative measures. Recently postulated advances from lumbar surgery include minimally invasive alternatives. Cervical thermodiscoplasty (CTDP) and facet rhizotomy have recently been described as alternative treatments that take advantage of the effect of heat on disc and Z-joint degenerated tissues.

Currently, thermoablation of the intervertebral disc is referred to as thermodiscoplasty. The effectiveness and safety of this method in the treatment of lumbar pain was described early by the same authors, who performed the technique in 25 patients with chronic discogenic pain who were unresponsive to conservative treatment. Positive outcomes were claimed on the basis that 80% of patients reported a decrease of two points in the VAS and 72% tolerated a reduction in medication (Saal et al. 2000). Similarly, the use of a laser at the intradiscal level proved its effectiveness in the lumbar zone (Choy 2004).

Subsequently, the lumbar IDET procedure was subjected to more scrutiny and its effectiveness and superiority in comparison to other treatments for discogenic low back pain was questioned (Helm 2012).

Promising results in the lumbar spine quickly prompted implementation of similar techniques in the cervical disc. The first CTDP reports were prepared by Choy (1995) and Siebert (1995). They presented a percutaneous thermodiscoplasty technique using lasers for cervical discopathy and cervical herniation treatment. The senior author of this chapter has also performed cervical percutaneous procedures since 1997, first using lasers and now using RF to generate high intradiscal temperatures. The results of a clinical series are presented in this chapter. It is important to underline that with the aim of increasing the safety margin, the authors have carried out certain variations of the percutaneous techniques originally reported. The percutaneous approach is not performed with a needle but with a blunt-ended cannula and a 4-mm incision.

For the 360° rhizolisis, the techniques involve the ablation of the medial branch and the nerves present around the joint capsule that are the result of neurogenesis due to the joint degeneration, and which are potential pain generators (Eubanks et al. 2007). This technique was first undertaken in lumbar segments by Shealy (1975), who employed thermal energy with electrodes, similar to those used in the treatment of trigeminal neuralgia, causing nerve ablation of the medial branch, and thereby developing the ‘facet denervation’ technique, which reported a success rate of around 80%. Later, Bogduk reported a new technical description, and renamed the technique ‘lumbar medial branch neurotomy’.

Now, for RF, neurolysis is performed in the medial branch and also directly in the joint capsule, to generate nociceptor ablation. These methods are described in Chapter 12.

Radiologic tests (X-rays, MRI) must provide images compatible with degenerative disc disease (Figure 1.1), ‘black disc’, disc bulging, annular tear, contained herniated disc, and/or Z-joint osteoarthritis.

In order to widen the intervertebral space and thus facilitate the advance of the cannula into the disc, the patient is placed in the supine position in cervical extension. In addition, cervical lordosis is restored by placing a pillow under their shoulders. There is no need to use any type of mechanical hyperextension system.

The level and point of entry of the blunt-ended cannula is determined previously using biplanar fluoroscopy. The anatomic landmarks correspond to the intersection of the level affected and the medial edge of the sternocleidomastoid muscle (Figure 1.2). Once this point is identified, the patient's head is slightly tilted toward the contralateral side of the approach. The surgeon's finger is firmly pressed on the space between the muscle and trachea (tracheoesophageal groove), thus allowing displacement of the esophagus and trachea medially and of the neurovascular bundle laterally. The trajectory of the needle can be deduced by aiming for the uncovertebral corner opposite to the entry side in the anteroposterior (AP) plane and for the posterior one-third of the disc in the lateral plane.

Under local anesthetic infiltration, a small 4-mm incision is made in the skin, allowing the entrance of the cannula and the dilator toward the disc by turning it gently (Figure 1.3). Using AP and lateral fluoroscopic views, the correct position of the cannula tip on the anterior edge of the annulus is verified and the needle is then advanced through the cannula up to the posterior third of the disc. If the surgeon chooses to, this is the point at which the discography and discogenic test can be performed (Figure 1.4).

Upon verifying that the disc is positive to the test and that the symptoms are consistent with familiar concordant pain, the dilator is replaced with the trephine and advanced with a rotating hand motion until the annulotomy is accomplished. This maneuver enables the entry of the graspers into the nucleus to perform the mechanical discectomy, which is then followed by CTDP (Figure 1.5).

For the latter procedure, the authors apply thermal energy to the disc using the RF fiber of the Disc-FX system (Elliquence LLC, NYC, US), whereby the thermal energy is transmitted from the console to the bipolar tip, which provides the trigger.

Although injury to vital structures using this approach is extremely uncommon, an important factor in achieving a successful technique is appropriate and sufficient training. The learning curve of this procedure is steep, and the outcomes are directly related to the skill of the surgeon. The authors typically recommend performing between 20 and 30 cases using the same technique on the lumbar area, and later performing the first 10–15 cases on the cervical area under the supervision of surgeon already experienced in this procedure. It is also strongly recommended to practice the techniques in cadaver labs and to attend workshops and training centers.

Under constant fluoroscopic verification, the cannula is advanced and positioned at the radiologic point where the Z-joint is observed. Subsequently, a 4-mm incision and blunt dissection of the skin and subcutaneous tissue is performed. The cannula and dilator of the Disc-FX system (Elliquence LLC, NYC, US) are advanced through the incision to the joint capsule.

Once inside the joint capsule, the dilator is replaced with the RF fiber and its bipolar probe is monitored fluoroscopically to ensure that it is placed precisely in the central area of the Z-joint. The anatomic boundaries and specifically the cervical intervertebral neuroforamen must be respected and clearly understood prior to initiating the RF ablation part of the procedure. The surgeon must ensure that the fiber probe does not extend beyond the borders of the intervertebral foramen.

The Z-joint may be divided into four quadrants. All four quadrants are the ablated in a counterclockwise direction, completing a 360° circumference, and thus covering the entire Z-joint capsule. The procedure is performed using the RF power generator Surgimax (Elliquence LLC, NYC) in default mode: bipolar hemo, at a standard 25 intensity for 6 seconds per shot.

The results obtained in this retrospective cases series were, according to the Macnab criteria, excellent and good (improves), 85%; fair, 12%; and bad, 3%, at 12 months’ follow-up. The corresponding VAS scores, changed from 7 preoperatively, to 2 at the first year of follow-up. In this sample, no complications or reinterventions were reported.

Manchikanti et al. (2013) reviewed the clinical evidence on interventional treatments of spinal pain in an attempt to develop evidence-based clinical practice guidelines. They determined that the clinical 8evidence for ‘therapeutic cervical facet joint interventions is fair for conventional RFN and cervical medial branch blocks, and limited for cervical intra-articular injections.’

Boswell et al. (2007) studied the formulation of essential guidelines and a series of potential evidence linkages representing conclusions and statements about relationships between clinical interventions and outcomes. The authors graded the clinical evidence from Level I (conclusive), Level II (strong), Level III (moderate), Level IV (limited), to Level V (indeterminate). The authors also found that there was strong evidence for diagnostic interventions, such as high accuracy of facet joint nerve blocks for cervical facet joint pain. The evidence for cervical medial branch blocks was found to be moderate. The evidence for cervical medial branch neurotomy was also found to be moderate. In comparision, the evidence for cervical nerve root pain was moderate.

van Eerd et al. (2014) evaluated the therapeutic effect and duration of cervical facet joint ablation with the single posterior-lateral approach. The authors initially considered 130 consecutive patients with axial neck pain referred to a University Pain Center of which 67 fulfilled the authors’ inclusion criteria and 65 of which were available for follow-up. Measuring therapeutic effect with the Patients’ Global Impression of Change (PGIC) scale, the authors found an overall pain relief of 55.4% at 2-month follow-up. They also noted ‘… moderately, important change of improvement and substantial change of improvement…’ in 50.8% of their patients. Even at 3-year follow-up, some 30% of the patients still reported less pain. The authors used retrospective data PGIC follow-up data and performed Kaplan–Meier curve evaluation to assess the long-term therapeutic effect and to identify possible predictors of clinical outcomes, of which only the cervical level of surgical treatment was found. The authors concluded that radiofrequency treatment of the cervical facet joints through a single posterior-lateral approach warranted further randomized controlled trials to further validate the efficacy of cervical facet joint RF treatment for chronic axial neck pain.

He et al. (2015) reported recently on the treatment of axial discogenic cervical upper back pain using coblation procedures as a means of providing pain relief for neck and radicular pain related to contained cervical disc herniation. They evaluated its efficacy in a prospective, observational study of 28 consecutive patients who underwent anterior cervical disc coblation. Primary outcome criteria were ≥ 50% pain relief on VAS scoring and ≥ 50% reduction in utilization of pain medicine. The authors also used modified Macnab criteria to record pain intensity, the degree of pain relief, and functional status after 12 months of follow-up. Using the intradiscal cervical coblation procedure, they noted improvements from a preoperative pain VAS score of 6.5 ± 1.1 (95% confidence interval (CI, 6.085–6.915), to a postoperative VAS score of 2.4 ± 1.3 (95% CI, 1.929–2.928), 2.5 ± 1.5 (95% CI, 1.963–3.109), 2.7 ± 1.4 (95% CI, 2.157–3.271), 3.1 ± 1.6 (95% CI, 2.457–3.686), and 3.1 ± 1.6 (95% CI, 2.471–3.743) at 1 week and 1, 3, 6, and 12 months postoperatively, respectively (P < 0.05). Twenty-two (78.6%), 21 (75.0%), 20 (71.4%), 19 (67.9%), and 18 (64.3%) of the patients expressed significant pain relief at 1 week and 1, 3, 6, and 12 months postoperatively, respectively. Twenty-four (85.7%), 23 (82.1%), 23 (82.1%), and 22 (78.6%) reported significant reduction in pain medication intake at 1, 3, 6, and 12 months postoperatively, respectively. According to the Modified Macnab criteria, the numbers of patients with; excellent or good ratings were 22 (78.6%), 21 (75.0%), 20 (71.4%), and 18 (64.3%) at 1, 3, 6, and 12 months postoperatively, respectively. The authors did not report any serious complications with the procedure and concluded that cervical intradiscal coblation is both effective and safe. They also highlighted the advantages of this less painful, minimally invasive outpatient procedure for the patient.

Lee et al. (2007) assessed the clinical efficacy of RF cervical zygapophyseal joint neurotomy in patients with cervicogenic headache. A total of 30 consecutive patients suffering from chronic cervicogenic headaches for longer than 6 months and showing a pain relief of > 50% from diagnostic/prognostic blocks were included in the study. These patients were treated with RF neurotomy of the cervical zygapophyseal joints and were subsequently assessed at 1 week, 1 month, 6 months, and at 12 months following the treatment. The results of this study showed that RF neurotomy of the cervical zygapophyseal joints significantly reduced headache severity in 22 patients (73.3%) at 12 months after the treatment. The authors concluded that ‘RF cervical zygapophyseal joint neurotomy has shown to provide substantial pain relief in patients with chronic cervicogenic headache when carefully selected.’

Husted et al. (2008) reported on the success rate and duration of pain relief of repeat RFN for zygapophyseal joint pain. In their retrospective review, the authors identified 14 women and 8 men with a mean age of 47 years (range, 34–66 years) who underwent repeat RFN for recurrent symptoms after the initial RFN procedure. The authors performed a total of 64 RF ablation procedures, which produced pain relief of > 50% at an average follow-up of 12.5 months (range 3–25 months). Forty-two RFNs were performed after the initial RFN, of which 41 (98%) were available for follow-up. Thirty-nine of the 41 RFNs (95%) were successful. The authors reported that a subgroup of 11 patients underwent two RFNs, seven had three RFNs, two had four RFNs, one had six RFNs, and one had seven RFNs. Twenty-two patients had a second RFN, which was successful in 20 of the 21 (95%) patients who were available to follow-up but was unsuccessful in one patient (5%). The mean duration of relief in these patients was 12.7 months (range 3–30 months) with continued pain relief in two patients. The authors also reported that 11 of their patients underwent a third RFN, which was successful in 10 patients (91%) and unsuccessful in the remaining patient in that subgroup (9%), with a mean duration of pain relief in eight patients at an average of 9.5 months, and ongoing pain relief in the remaining two patients. In the four patients who underwent a fourth RFN, it was successful in all of them, with a mean duration of pain relief of 8.75 months. In the two patients who had a fifth RFN, the postprocedural pain relief was similar with a mean duration of 9 months. In addition, the two patients who underwent a sixth RFN did well, with one patient experienced continued pain relief for 18 months and the other patient still enjoying pain relief at the time the authors published their report. Even the one patient who had a seventh RFN was still enjoying pain relief at the time the study concluded. The 9frequency of success and the durations of pain relief remained consistent after each subsequent RFN. Husted and colleagues concluded that repeat RFN for recurrent symptoms can be successful in carefully selected patients who have undergone previous RFN. However, they did not elaborate further on the specific selection criteria.

Klessinger et al. (2010) performed a retrospective review of patients who underwent anterior cervical spine operations for degenerative disease and required additional treatment for residual axial neck pain with therapeutic cervical medial branch blocks. Patients with at least 80% pain relief after both therapeutic and the diagnostic block went on to have radiofrequency neurotomy. The primary outcome criterion was at least 50% pain relief or high patient satisfaction. The authors reviewed the charts of 250 patients, 125 of whom underwent artificial disc replacement, 66 of whom had stand-alone cages, and an additional 51 of whom underwent anterior cervical discectomy fusions with cage and plate. While two patients were not available at follow-up, approximately one third (31%) of the patients had axial neck pain after their index surgery. The authors determined that this pain originated from the zygapophysial joint in 32 (13.2%) of patients, who were then treated with postoperative radiofrequency neurotomy for their recurrent neck pain. Within that subgroup of 32 patients, 59.4% pain reduction was reported at 15 months follow-up. Of interest, the authors reported a significantly higher prevalence of postoperative axial neck pain after a two-level anterior cervical disc surgery (P=0.002) when compared to single level surgeries. The authors concluded that zygapophysial joints ‘are a possible source of postoperative pain after anterior cervical spine surgery’ and that ‘radiofrequency neurotomy can provide an effective treatment for persistent neck pain after ventral cervical spine surgery.

A plethora of other clinical studies have shown the effectiveness of open and percutaneous surgeries in cervical chronic pain relief (Gebremariam et al. 2012). Yang et al. (2014) presented a technique that combined discectomy and nucleoplasty, which resulted in 83.19% excellent and good results; a study by Sim et al. (2011) indicated that 77.3% of cases showed excellent and good results in 46 procedures, which was similar to the outcomes described by Yan et al. (2010), who achieved a 79.5% success rate. Recently, Schubert et al. (2014) showed a satisfactory result in 81.4% of 95 patients studied.

Treatment through open surgery by the anterior approach has been employed since it was first described in 1958 by Smith and Robinson (Smith & Robinson 1958). Among the positive outcomes published, those of Nandoe et al. (2007), with 90.1% of patients satisfied in the first 2-month follow-up, should be highlighted. Additionally, Palit et al. (1999) presented satisfactory results in 79% of 38 patients treated with anterior cervical discectomy and fusion. Notwithstanding these positive outcomes, the technique has been associated with respective complications or mortality rates of 0.42–4.09% (Skolasky et al. 2014). Despite these complications, anterior cervical discectomy with fusion (ACDF) is regarded by a majority of surgeons as the ‘gold standard’ surgical procedure for the treatment of cervical radiculopathy from a herniated disc (Schubert et al. 2014). In comparison, CTDP treatment for axial neck pain is associated with a low complication rate and no serious complications have been reported. However, there is one case report of a 54-year-old woman who presented with neck pain and weakness with cervical kyphosis following radiofrequency ablation of the third occipital nerve and C2–C4 facet joints 8 weeks after the procedure. The patient's deformity could be passively corrected and no obvious abnormality was identified on imaging studies. Ultimately, the patient underwent an instrumented posterior fusion from C2 to T2 for progressive kyphosis and chin-on-chest deformity. The authors of the report concluded that dropped-head syndrome is a rare yet potentially debilitating complication of multilevel RFN ablation (Stoker et al. 2013).

As noted, there is evidence of satisfactory results using both open and percutaneous surgery, thus determining the superiority of one technique over another is impossible. However, factors such as a lower rate of complications, reduced chance of adjacent disease segment (Schubert & Merk 2014), and the possibility of performing the procedure in elderly patients due to the type of anesthesia used, all make the CTDP MISS procedure an attractive alternative for surgeons, in spite the fact that there is hardly any clinical evidence, strong or weak, on the thermal radiofrequency discoplasty procedure. The presumption is that both procedures contribute to pain relief and the favorable outcomes shown in our studies. Obviously, this is one of the great limitations of our study and the approach to the treatment of axial neck pain must be clarified further with the implementation of comparative prospective studies with higher levels of evidence.