Research Review By Dr. Demetry Assimakopoulos©

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Date Posted:

July 2016

Study Title:

Symptomatic, Magnetic Resonance Imaging-Confirmed Cervical Disk Herniation Patients: A Comparative-Effectiveness Prospective Observational Study of 2 Age-and Sex Matched Cohorts Treated with Either Imaging-Guided Indirect Cervical Nerve Root Injections or Spinal Manipulative Therapy

Authors:

Peterson CK, Pfirrmann CWA, Hodler J et al.

Author's Affiliations:

Radiology Department, Orthopedic University Hospital Balgrist; Chiropractic Medicine Department, Faculty of Medicine, Orthopedic University Hospital Balgrist, University of Zurich, Switzerland.

Publication Information:

Journal of Manipulative and Physiological Therapeutics 2016; 39(3): 210-217

Background Information:

Cervical radiculopathy (CR) is a disabling condition, often presenting as a result of severe cervical disc degeneration and/or cervical disc herniation. The C6 and C7 nerve roots are most commonly affected.

Cervical nerve root injections (CNRI’s) are a commonly used intervention for the treatment for CR. However, use of CNRIs was recently criticized due to potentially serious associated complications, namely ischemic myelopathy, transient or permanent tetraplegia, brain infarction, arterial dissections and cortical blindness. Fewer complications have been demonstrated with use of a recently created, modified, imaging-guided, indirect CNRI (1, 2).

Evidence in favour of cervical spinal manipulative therapy (CSMT) as a treatment for patients suffering from symptomatic cervical disk herniation (CDH) is mounting. A recent outcomes study (from these same authors, also reviewed on RRS Education) demonstrated that ~75% of patients suffering subacute and chronic cervical radiculopathy reported clinically relevant improvement after 3 months of treatment (3).

In this study, these authors sought to compare the treatment effects of CSMT to indirect CNRIs in patients suffering from MRI-confirmed CDH.

Pertinent Results:

Twenty-six females and 68 males were included. The C6 and C7 nerve roots were most frequently involved in both treatment groups (SMT and CNRI). In general, 85% of the patients who received CSMT reported clinically relevant “improvement” after 3 months of care, compared to 49% of patients who received a single indirect CNRI treatment. Both groups showed a statistically significant improvement in pain scores at 3-month follow-up. However, the CSMT group demonstrated a superior statistically significant overall improvement.

Interestingly, there were no between-group differences in patients suffering from acute CDH at 3-month follow-up. However, 78.3% of the patients endorsing subacute/chronic CDH who received CSMT reported a clinically meaningful improvement. On the other hand, only 37.5% of subacute/chronic patients who received CNRI reported clinically meaningful improvement. The between-group difference in clinical improvement in the subacute/chronic pain subgroups was statistically significant (p = 0.002). Also, the CSMT group generally showed significantly lower median scores on the Patient’s Global Impression of Change (PGIC) scale, meaning that these patients endorsed superior subjective improvement, compared to the cohort that received CNRI. The average treatment cost per CSMT patient was CHF 973.48 (Swiss Francs), while the average cost of CNRI group was CHF 931.01.

Clinical Application & Conclusions:

The researchers compared the effectiveness of CSMT to indirect CNRI in patients suffering from acute, subacute and chronic, MRI-confirmed CDH. There was a statistically significant difference in clinically relevant improvement in favour of CSMT, specifically in the subacute/chronic subgroups. There was no statistically significant between-group difference in acute pain subgroups. The authors attribute the lack of change in acute pain patients to the natural history of the condition (4, 5). Treatment costs were very similar between groups and no adverse events were reported.

The abovementioned findings are important, because chronic, recalcitrant radiculopathies are difficult to treat both conservatively, interventionally and pharmacologically. Often, practitioners who utilize CSMT as a treatment modality, worry about worsening their patient’s condition. The fact that SMT provided superior significant pain relief and subjective overall improvement, without complication, should mitigate some of the fear associated with performing CSMT in these patients.

EDITOR’S NOTE: It is tempting to interpret the findings of this study as a ‘free pass’ to treat patients with (even suspected) cervical disc herniation with high-velocity manipulation. Although this study and the other work emerging form this author group is promising, representing an important and novel contribution to the literature as a whole, there are a couple of things clinicians should also keep in mind. First, these authors practice in Switzerland, where chiropractors are intimately integrated into the healthcare system. They work in multidisciplinary environments and have easy access to things like advanced imaging. This is unlike many other regions in the world. Second, it is worth emphasizing the fact that the patients in this cohort KNEW they have a disk herniation (MRI-confirmed). This certainly changes the risk-reward dynamic (or potential for blame) when applying SMT to a neck pain patient. Clinicians should still be vigilant in monitoring neck pain patients for signs of progressive disc issues and modify treatment approaches accordingly.

Study Methods:

The authors performed a comparative-effectiveness, observational outcomes study. Patients suffering from MRI-confirmed cervical disk herniations were retrieved from a prospective cohort outcomes database. One cohort of patients underwent a single imaging-guided indirect cervical nerve root injection (CNRI) at baseline, while the other cohort underwent several weeks of cervical spine manipulative therapy (SMT). No crossover was done. Patients were age and sex-matched, and blinded to the clinical outcomes. Each patient’s signs and symptoms had to match the MRI findings in terms of the level affected.

Patients who had spinal fractures, inflammatory arthropathies, infection or Paget’s disease, were excluded from the cervical SMT group. Those who suffered a bacterial infection, or bleeding diathesis were excluded from receiving the CNRI.

Both groups of patients were asked to provide their baseline pain rating (0-10/10). At 3-month follow-up, patients were asked to provide their pain ratings and score the Patient’s Global Impression of Change (PGIC) scale. The answers ‘much better’ or ‘better’ on the PGIC were considered clinically relevant improvements. Patients suffering from pain for ≤ 4weeks were categorized as acute, while those suffering from pain for > 4 weeks were categorized as subacute/chronic.

Cervical Indirect Nerve Root Injection (CNRI) Procedure:
CT fluoroscopic guided injections were performed by medical radiologists on an outpatient basis. The needle was advanced until it landed on the lateral bony aspect of the intended facet joint. 0.5 mL of iopamidol contrast material was injected to ensure correct needle position. Subsequently, 4 mg (1 mL) of dexamethasone was slowly injected, followed by 1 mL of 0.2% ropivicaine.

Spinal Manipulative Therapy (SMT) Procedure:
A high-velocity, low-amplitude cervical spine manipulation was performed at the level of the disk herniation (2). Treatments were provided 3-5 times per week for the first 2-4 weeks, and then 1-3 times per week thereafter, if required. The goal of the SMT was to produce an audible release. No other therapies were performed during the chiropractic visits.

Statistical Analysis:
The X2 statistic was used to track between-group clinically relevant “improvement” (a combination of “much better” or “better”) and “worsening” over the 3-month period. This was the primary outcome measure. The X2 test was also used to compare the between-group treatment effect in “acute” and “subacute/chronic” patients. The Student t-test was used to compare the baseline and 3-month pain ratings percentage change for both treatment groups. The unpaired t-test was used to compare between-group baseline and 3-month pain ratings percentage change. Between-group median 3-month PGIC scores were also assessed. The average treatment cost for each treatment group was calculated.

Study Strengths / Weaknesses:

Weaknesses:
  • The SMT group had a larger treatment volume compared to the CNRI group. This might lead to superior non-specific treatment effects (i.e. placebo), and physiological/biomechanical effects.
  • Suter et al. (2) revealed that there was no statistically significant difference in analgesic effect when comparing indirect to direct cervical nerve root injections. Interestingly, the data collection period for the Suter et al. study appears to be approximately 20-30 minutes post-intervention. I am uncertain why the authors of this study would compare a new, indirect method of treatment and track it over a 3-month period, when the indirect method has not been compared longitudinally against the direct intraforaminal method. The authors also did not discuss the longer-term effectiveness of the direct method. It is unclear if the results would have been different had they compared SMT to the direct method, particularly over a 3-month period.
  • There were only 2 data points: baseline, and 3-months post-intervention. The authors did not interview the patients at other time points. It is unclear if the magnitude of the between-group differences would have been similar at those other time periods.
Strengths:
  • Only cervical SMT was performed during treatment. No other area was treated, which provides a truer comparison.
  • The authors addressed specifically why they used a comparative-effectiveness observational trial, rather than an RCT.

Additional References:

  1. Hodler J, Boos N & Schubert M. Must we discontinue selective cervical nerve root blocks? Report of two cases and review of the literature. Eur Spine J 2013; 22(Suppl 3): S466-470.
  2. Sutter R, Pfirrmann CWA, Zanetti M, et al. CT-guided cervical nerve root injections: comparing the immediate post-injection anesthetic-related effects of the transforaminal injection with a new indirect technique. Skeletal Radiol 2011; 40: 1603-1608.
  3. Peterson CK, Schmid C, Leemann S, et al. Outcomes from magnetic resonance imaging–confirmed symptomatic cervical disk herniation patients treated with high velocity, low-amplitude spinal manipulative therapy: a prospective cohort study with 3-month follow-up. J Manipulative Physiol Ther 2013; 36: 461-467.
  4. Kolstad F, Leivseth G & Nygaard OP. Transforaminal steroid injections in the treatment of cervical radiculopathy. A prospective outcome study. Acta Neurochir (Wien) 2005; 147: 1065-1070.
  5. Rao R. Neck pain, cervical radiculopathy and cervical myelopathy. Pathophysiology, natural history and clinical evaluation. J Bone Joint Surg (Am) 2002; 84-A: 1872-1881.