Robert J. Rodine, BSc, DC, Howard Vernon, DC, PhD, FCCS(C)
Graduate Student, Graduate Education and Research Programs,
Canadian Memorial Chiropractic College,
Cervical radiculopathy (CR), while less common than conditions with neck pain alone, can be a significant cause of neck pain and disability; thus the determination of adequate treatment options for patients is essential. Currently, inadequate scientific literature restricts specific conservative management recommendations for CR. Despite a paucity of evidence for high-velocity low-amplitude (HVLA) spinal manipulation in the treatment for CR, this strategy has been frequently labeled as contraindicated. Scientific support for appropriate outcome measures for CR is equally deficient. While more scientific data is needed to draw firm conclusions, the present review suggests that spinal manipulation may be cautiously considered as a therapeutic option for patients suffering from CR. With respect to outcome measures, the Neck Disability Index appears well-suited for spinal manipulative treatment of CR.
From the FULL TEXT Article
Cervical radiculopathy (CR) can be a significant cause of neck pain and disability. The reported annual incidence of CR is 83.2/100,000 persons , while the reported prevalence is 3.5/1000 persons.  Gender preference varies. [2, 3] Individuals are most commonly affected in the 5th and 6th decades of life. [1, 4] Physical exertion or trauma at onset is rare, involving less than 15%.  Causal relationship to an automobile accident ranges from 3–23%. [1, 4]
Patients presenting with CR most frequently complain of neck pain, paresthesia and radicular pain.  While sensory symptoms typically present along a dermatome, pain is often myotomal.  When present, dermatomal pain patterns are more frequent at the C4 level (60%) as compared to the C7 (34.2% of cases) and C6 levels (35% of cases).  Scapular pain is found in 51.6% of cases.  Physical examination typically reveals painful cervical spine range of motion (ROM) and decreased deep tendon reflexes.  Upper limb weakness involves only 15% of cases.  Decreased sensation is found in 1/3 of cases; however, muscle atrophy presents in less than 2% of cases.  Level of involvement is most typically the C7 (39.3%–46.3%) and C6 (17.6%–42.6%) nerve roots. [1, 3] Bilateral involvement is reported in 5–36% of cases. [1, 4]
The intervertebral disc has be found to be causative in only 22% of cases, while 68% of cases appear to arise from a combination of discogenic and spondylotic causes.  With respect to therapy, the Task Force on Neck Pain and Its Associated Disorders (TFNPAD) extensively reviewed the literature to make best-evidence recommendations on the management of neck pain disorders. The review found insufficient evidence to draw firm conclusions or make appropriate treatment recommendations for CR, or identify contraindicated therapies. 
This begs the question as to the role of spinal manipulative therapy (SMT) for CR patients’. In fact, Saal et al, stated that “forceful joint manipulation was not used” in their protocol for CR,  while Haas et al stated that intervertebral disc herniation and CR are contraindications to manipulation.  Unfortunately, statements such as these are unsupported by both basic science evidence which justifies a plausible risk, and epidemiological evidence suggesting hazard or ineffectiveness.
Recently, the first systematic review of manipulative therapy for radiculopathy (including CR) was published. Leininger et al. concluded that evidence for manipulative therapy in CR is minimal, low in quality and presents a high risk of bias.  Despite this, 93% of surveyed chiropractors stated they would use SMT despite a suspected or confirmed cervical disc herniation.  Therefore, a more detailed review of the existing studies may prove clinically valuable.
A secondary issue concerns the most appropriate outcome measure for determining the effectiveness of SMT for CR? Given that the Neck Disability Index (NDI) is the most commonly used outcome measure of self-rated disability due to non-specific mechanical neck pain,  use in a specific cause of neck pain (such as CR) should be evaluated.
The purpose of this paper is to systematically search and descriptively present the evidence as it applies to general chiropractic practice. Therefore, the primary objective of this paper is to review the use of high-velocity low-amplitude (HVLA) SMT for CR, reflecting on chiropractic treatment practices. A secondary objective is to review the use of the NDI, designed for use in neck pain patients, in the management of patients with neck and arm pain.
Strengths & Limitations of the Presented Research
Howe et al’s randomization of a treatment and a control group offered the highest quality design, though only a sample subset presented with arm and hand symptoms.  BenEliyahu utilized a lower quality retrospective design and consisted of a small sample size not adequately stratified for cervical case evaluation.  Murphy et al. was strengthened by prospective data, though pragmatic application complicated the evaluation of treatment specifics. 
Manipulative procedures, examination techniques and outcome measures were highly variable between studies. [3, 13, 33]
Murphy et al. was the only study to adequately describe the indications for SMT, consisting of dysfunctional motion segments identified on palpation in the sitting or prone position, responding with abnormal resistance compared to asymptomatic levels and the presence of clinical symptoms.  While Howe et al defines a manipulable lesion to be palpatory evidence of reduced segmental motion and/or palpatory atlas asymmetry, motion parameters, symptom response and positioning details were omitted.  BenEliyahu identified only a loss of cervical ROM. 
The manipulative procedure was adequately described in all studies. BenEliyahu described using rotational “high-velocity short-lever manipulation.”  Howe et al. described moving joints to a comfortable endpoint and delivered a “quick thrust of moderate force” intending to move the joint(s) “as far as comfortably possible.”  Murphy et al. moved the spinal joints until “a barrier of resistance” was felt, and delivered a “short and quick thrust.”  Only Murphy et al. and BenEliyahu commented that an audible release was usually perceived. [3, 33]
BenEliyahu suggested therapy be modified for stages of healing, utilizing traction and pain-relieving modalities during the acute phase while rotational manipulation was “judiciously added” during the subacute phase.  While Murphy et al. did not address this formally, pragmatic treatment showed that only 18 of the 35 patients received HVLA procedures.  The remainder of the patients received LVLA techniques and over-the-door traction.  Howe et al. did not amend their manipulative protocol; they added an analgesic injection where pain interfered with thrust delivery.  While injection therapy is technically part of our exclusion criteria, less than 10% of the subjects in this trial received an ancillary injection, therefore this was not felt to interfere with outcomes. 
Unfortunately, the mechanism of injury/onset was not adequately described within these studies. As traumatic onset is less common in CR and presents an alternate pathophysiology, this detail is relevant,  though affect on prognosis or treatment has not been commented on in systematic reviews. [39–41]
Conclusions on clinical course from these studies are difficult to draw. Howe et al. detailed a short timeline for outcome measure assessment, following subjects for only 3 weeks and excluded management details.  BenEliyahu did not specifically report CR outcomes, aside from the return to work rate at 1 year follow-up.  Murphy et al. however provided excellent insight into the clinical course of manipulative therapy as 89% of the patients described their improvement as excellent or good after a mean of 11.7 (4–24; SD 5.2) treatment sessions at a frequency of 2–3 times per week.  Long-term follow-up was available for 27/31 subjects, indicating that over 90% maintained clinically significant improvement. 
Comparisons of HVLA-SMT versus the natural course of CR are also difficult to draw. Due to high levels of pain and disability, a true no-treatment comparison is difficult to evaluate and control. Therefore, the clinical course of various conservative therapies remains.
For consideration, CR sufferers randomized to hard collar immobilization did not demonstrate statistically different pain scores from baseline at either 4 or 12 month follow-up.  Meanwhile, a population based study found that while 90% of CR sufferers reported mild or no symptoms at 4–5 years follow-up, recurrence was observed at 31.7%. 
Based on the reported details of the three included studies, it is felt that Murphy et al. provides the best insight into the clinical-course of CR treated with HVLA-SMT. 
While limited, non-randomized and without reference to a true control group, this trial may still assist the general practitioner in reasonably designing a trial of therapy. 
Reporting of Adverse Events
As previously alluded, concern has been reported regarding the safety of HVLA procedures for confirmed or suspected CR. [8, 10] In fact, published case reports have indicated cervical disc herniation and CR as adverse events related to SMT. [42–44]
While the included studies reported no major adverse events, safety conclusions of HVLA procedures for CR cannot be drawn from this data. [3, 13, 33] While Murphy et al. found a mild transient increase in pain in 16.7% of the subjects receiving HVLA procedures,  this is considerably lower than other estimates of similar events experienced in 44–62% of patients receiving SMT for non-specific neck pain. [45–52] Additionally, the TFNPAD did not find SMT to be contraindicated in CR patients.  Further research exploring this area is needed to determine proposed mechanisms as well as incidence.
Only one study reported on the test-re-test reliability of the NDI in neck and arm pain patients.  The value obtained, 0.68 (0.30,0.90) is somewhat lower than previously reported for neck pain-only patients.  Several studies provided data on the responsiveness of the NDI in neck and arm pain patients. Two studies reported minimum clinically important differences of 7.5 and 7 NDI points, respectively. [28, 38] These values are only slightly higher than those previously reported.  One study reported that 20% improvement is a reasonable criterion of clinical success  while Carreon et al. provided an estimate of Substantial Clinical Benefit of 9.5 NDI points (19%).  Several studies have reported on factors which predicted outcome as measured by the NDI.  While varied, these factors generally appear to indicate that low initial pain and distress levels and low impact on neck/arm function predict greater improvement in NDI scores at both 28 days and at 1–3 years.
Taken together, these data support the use of the NDI in studies of SMT for CR.
First, the existing interventional evidence-base for CR is small and principally composed of low quality study designs. This foundation is further compressed when isolated to a distinct therapy.
Secondly, the inclusion process lacked quality assessment. As this review targets a clinical rather than an academic audience, the limitation is justified. Additionally, in the absence of data pooling, this factor has minimal impact.
Thirdly, the inclusion/exclusion process for each objective lacked consensus. Given the small evidence-base and clearly defined criteria, consensus is unlikely to have altered results.
Lastly, study designs required a threshold of 10 subjects for inclusion. Of the included studies, BenEliyahu presented the smallest sample size, pooling data for 11 CR subjects.  During our literature consolidation, no studies were identified that included less than 10 subjects while reporting pooled data. Therefore, it is not felt that this criterion generates bias.
As CR evidence for LVLA and exercise therapy continues to grow, [7, 16–23, 25, 27–32] minimal research concerning HVLA procedures remains. Despite this, existing literature does provide support for the cautious application of HVLA procedures in cases of confirmed or suspected CR.
Currently, randomized trials in the field of CR are lacking. Additionally, the lack of HVLA-related research for CR, particularly comparing HVLA to LVLA procedures, offers a unique and timely opportunity for chiropractic science. In designing such trials, as well as for clinical use, the NDI is well-suited as an outcome measure.