Jason S Schliesser, DC, MPH, Ralph Kruse, DC, L.Fleming Fallon, MD, DrPH
Northwest Ohio Consortium for Public Health,
Toledo, Ohio, USA.
BACKGROUND: Although flexion distraction performed to the lumbar spine is commonly utilized and documented as effective, flexion distraction manipulation performed to the cervical spine has not been adequately studied.
OBJECTIVE: To objectively quantify data from the Visual Analogue Scale (VAS) to support the clinical judgment exercised for the use of flexion distraction manipulation to treat cervical radiculopathy.Design and setting A retrospective analysis of the files of 39 patients from a private chiropractic clinic that met diagnostic criteria for inclusion. All patients were diagnosed with cervical radiculopathy and treated by a single practitioner with flexion distraction manipulation and some form of adjunctive physical medicine modality. Main outcome measures The VAS was used to objectively quantify pain. Of the 39 files reviewed, 22 contained an initial and posttreatment VAS score and were therefore utilized in this study.
RESULTS: This study revealed a statistically significant reduction in pain as quantified by visual analogue scores. The mean number of treatments required was 13.2 +/- 8.2, with a range of 6 to 37. Only 3 persons required more treatments than the mean plus 1 standard deviation.
CONCLUSION: The results of this study show promise for chiropractic and manual therapy techniques such as flexion distraction, as well as demonstrating that other, larger research studies must be performed for cervical radiculopathy.
From the FULL TEXT Article
Defining radiculopathy is important to having a clear understanding of the clinical phenomenon. According to Cramer and Darby,  radicular pain is caused by activation of sensory fibers at the level of the dorsal root. It is described as a thin band of sharp shooting pain along the distribution of the nerve(s) supplied by the affected dorsal root. This is also termed the dermatomal pattern. Other descriptions can include long tract radiation into the upper or lower extremity. It may be accompanied by paresthesia, hypesthesia, or decreased reflexes, as well as being coupled with motor weakness secondary to compromise of the ventral roots. 
There are several possible causes of radicular pain, such as disk lesion, abscess, tumor, spondylolisthesis, malformation of the vertebral canal, malformation of the spinal nerve root and/or sheath, diseases of surrounding bone, and chemical inflammation due to degeneration of the intervertebral disk. Disk herniation is the most common cause of radiculopathy. However, other nonmechanical causes of radiculopathy include the following: leptomeningitis, meningeal carcinomatosis, and herpes zoster. 
One common cause of cervical radiculopathy is due to encroachment of the cervical intervertebral foramen. The anatomy of a cervical foramen has been described as an hourglass with a narrowing at the center. Foraminal cross-sectional area of the cervical spine may be one of the causes of radiculopathy.  Humphreys et al  studied symptomatic and asymptomatic patients with cervical radiculopathy. They found that the inferior foraminal width, but not the height, tends to decrease with age.
The primary diagnosis of cervical radiculopathy is based on a patient’s subjective symptoms.  Patients commonly report neck pain and pain that radiates along specific dermatomes. Many patients also commonly present with a positive Bakody’s sign (holding one’s hand on one’s own head to relieve the pain on the affected side).  Bakody’s sign has also been described as the shoulder abduction relief test.  Other orthopedic testing that decreases the size of the cervical intervertebral foramina will increase the radicular symptoms. Conversely, tests that increase the cervical intervertebral foramina usually decrease the radicular findings.
The prognosis varies for cervical radiculopathy. In cases of radiculopathy, the first changes of denervation are found in the paraspinal muscles within 7 to 10 days.  Within 2 to 3 weeks, deficits in the limb muscles of the affected myotome become evident. Healing and reinnervation can be seen at 3 to 6 months after the original injury.
Magnetic resonance imaging (MRI) is the primary imaging modality when radiculopathy is suspected.  Needle electromyography (EMG) is the gold standard for an electrodiagnostic evaluation.  However, both tests have their disadvantages. EMG will not display radiculopathies if they are mild or primarily sensory. MRI may show structural changes that are not clinically significant. The timing of the study may also influence MRI results. According to Nardin et al,  some studies have shown that large disk herniations regress with time. Therefore, radiculopathy that is due to a disk herniation may show differing disk appearances depending on the time that the diagnostic study was performed relative to the time of injury.
Dynamic motion is also an important factor in the cervical spine. Researchers have studied the intervertebral foramen sizes with different motions. Extension combined with axial rotation has been shown to decrease the foraminal size.  Muhle et al  also reported that, among symptomatic patients, the foraminal size increased with flexion and axial rotation to the side opposite to the pain. Biomechanical studies have shown that extension reduces the size of the spinal canal compared with neutral, with extension decreasing the canal size and area of the intervertebral foramen. [19, 20] These motions may also increase the symptoms that many patients experience.
Chronic neck pain has been effectively treated by several different approaches. [21-24] Some studies show support of manual manipulation for neck pain,  but others show that the data are inconclusive. [21, 26, 27] Traction has also been shown to be effective.  In one study of 503 patients, 246 were found to have cervical radiculopathy without myelopathy. After evaluation, only 86 were recommended for surgery.  According to these researchers, surgical patients improved significantly in regards to pain and functional status. Heller  reported that surgical intervention for neck pain without neurological deficit had no benefits.
Studies of conservatively treated patients who were treated without surgery reported larger improvements in many areas, including reflexes, motor weakness, and pain, than those treated with surgery.  Skargren and Oberg  showed that 5 different variables were involved when reviewing individuals’ responses to treatment. The factors were duration of current episode, Oswestry score  at entry into the study, number of areas involved or number of localizations, expectations of treatment, and patient well-being. In a 12-month study,  patients that had a poorer prognosis had a longer duration of pain (>1 month), more than 1 localization, and fewer positive expectations. However, Skargren and Oberg  reported that age, gender, smoking, previous history of a similar problem, neck or low back pain, pain intensity and frequency, and general health did not contribute significantly to the prediction of outcome. However, the incidence of neck pain in general has been found to be greater in women than men. 
The VAS is a form of patient perception outcome assessment that has been described as “generally relevant, valid, reliable, responsive, and safe.” [31, 32] With the VAS, patients are asked to place a mark on a horizontal line, 10 cm in length, to indicate the severity of their pain. The left end of the line represents no pain, and the right end represents severe, or unbearable, pain. A clinician can then measure the distance from the left end of the line to the patient’s mark and give it a numeric value. In this way, future assessments can be measured and compared, thereby documenting progress.
One concern of the present study was not having final VAS recordings for all patients. This occurred because they did not return for scheduled additional treatments or were not officially dismissed from care. A total of 17 individuals never completed a second VAS form and were therefore not included in the study. Neither the mean initial score for these patients nor the range of scores was significantly different from those for whom 2 VAS scores were available. Complete details can be found in Table 3.
All patients utilized in this study were diagnosed clinically with cervical radiculopathy, independent of results from supportive diagnostic testing such as MRI or EMG. Studies of individuals with cervical radiculopathy demonstrate that not all patients are candidates for surgery. This leaves a significant portion that can benefit from other means of treatment. Many conditions are showing promising results with manipulation. Flexion distraction, primarily for the lumbar spine, is one of the most commonly utilized forms of treatment among chiropractic physicians.  However, studies on cervical flexion distraction are lacking.
Within this private practice setting, the ability to perform preexaminations and postexaminations was sometimes hampered. We found that patients may not be willing to spend extra time to complete research instruments. Continued pain or other personal agendas may bias research results. Patients may also not return for follow-up care or a release examination when they believe (erroneously) that maximum improvement has occurred or they may not be satisfied with the progress of their treatments. Because patients in a private practice setting have to bear the financial costs for their treatment, they may not be fully compliant with suggestions concerning care and follow-up treatment.
This study objectively demonstrates that in this patient population, there was a significant decrease in pain levels and provides the basis for further research. This study also did not include all clinic patients, as they may have been treated with other forms of chiropractic care that did not use flexion distraction or were referred to other providers for other forms of treatment. While the results of this study show promise for chiropractic and manual therapy techniques, specifically cervical flexion distraction, it demonstrates that other, larger research studies must be performed.