PainSci summary of Rainville 2016?This page is one of thousands in the PainScience.com bibliography. It is not a general article: it is focused on a single scientific paper, and it may provide only just enough context for the summary to make sense. Links to other papers and more general information are provided at the bottom of the page, as often as possible. ★★★☆☆?3-star ratings are for typical studies with no more (or less) than the usual common problems. Ratings are a highly subjective opinion, and subject to revision at any time. If you think this paper has been incorrectly rated, please let me know.
The dermatome patterns most professionals are familiar with were established several decades ago, and have not be studied much since. This study carefully checked the exact location of symptoms in 120 patients with suspected radiculopathy (symptoms in a dermatomal pattern, caused by nerve root compression). Perhaps unsurprisingly, they found that the dermatomal patterns were not as precise as the old maps would lead us to believe, and exhibit significant overlap, “to the extent that caution should be exercised when predicting compression of either the C6 or C7 nerve roots based on locations of impaired sensation.”
Nevertheless, the patterns are still mostly reliable: for instance, you don't have to worry about finding the symptoms of a C6 radiculopathy way over in the C4 dermatome. But adjacent dermatomes likely do overlap more than most professionals think.
Importantly, this interpretation is clearly challenged by some researchers (e.g.
~ Paul Ingraham
original abstract†Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.
BACKGROUND CONTEXT: Cervical radiculopathy is a common disorder caused by compression of the cervical nerve roots and is characterized by arm pain and altered sensory-motor function. Incongruity in the locations of C6 and C7 dermatomes in competing versions of historical dermatome maps has plagued interpretation of impaired sensation associated with C6 and C7 radiculopathies. Magnetic resonance imaging (MRI) allows accurate identification of the C6 or C7 nerve root compression and therefore makes it possible to explore sensory findings that are associated with compression of specific nerve root.
PURPOSE: This study compared the locations of impaired sensation in subjects with cervical radiculopathy from MRI-confirmed C6 and C7 nerve root compression.
STUDY DESIGN: Case series was used for this study.
PATIENT SAMPLE: A total of 122 subjects with symptoms suggestive of cervical radiculopathy were recruited by 11 spine specialist from 5 practice locations. Of these, 30 subjects had MRI-confirmed C6 and 40 subjects C7 radiculopathy.
OUTCOME MEASURES: Standardized pinprick sensory examination of the forearm and hand of every subject was performed, and the locations of sensory impairments were recorded.
METHODS: Sensory examination was performed before reviewing MRI results or performing motor or reflex examination. Areas of impaired sensation were recorded on drawings of the palmar and dorsal forearm and hand, and translated using a grid into 36 specific areas for analysis. Chi-square was used to compare frequencies of findings for each grid area for C6 and C7 radiculopathies. Power analysis suggested that a minimum of 27 subjects in each group were needed to detect a 30 percentage point difference in frequency of sensory impairments. Significance was set at ≤.05.
RESULTS: Approximately 80% of subjects had impaired sensation in at least 1 grid area, most often in the distal forearm and hand, and many had findings in multiple areas. There was nearly complete overlap for locations of impaired sensation for C6 and C7 radiculopathy, and the frequencies of impaired sensation differed only in the dorsal aspect of the distal radial forearm where it was twice as common in C6 radiculopathy (p=.02).
CONCLUSIONS: The location of sensory impairments associated with symptomatic C6 and C7 nerve root compression overlap to the extent that caution should be exercised when predicting compression of either the C6 or C7 nerve roots based on locations of impaired sensation. Impaired sensation in the radial aspect of the distal forearm is more common in C6 radiculopathies.
- “Anatomic issues related to cervical and lumbosacral radiculopathy,” an article in Phys Med Rehabil Clin N Am, 2002.
- “The anatomic relation among the nerve roots, intervertebral foramina, and intervertebral discs of the cervical spine,” an article in Spine (Phila Pa 1976), 2000.
- “Do L5 and s1 nerve root compressions produce radicular pain in a dermatomal pattern?,” an article in Spine (Phila Pa 1976), 2013.
- “Symptom provocation of fluoroscopically guided cervical nerve root stimulation. Are dynatomal maps identical to dermatomal maps?,” an article in Spine (Phila Pa 1976), 1998.
- “Pain patterns and descriptions in patients with radicular pain: does the pain necessarily follow a specific dermatome?,” an article in Chiropr Osteopat, 2009.
These two articles on PainScience.com cite Rainville 2016 as a source:
- PS Save Yourself from Low Back Pain! — Low back pain myths debunked and all your treatment options reviewed
- PS Save Yourself from Neck Pain! — A complete guide to chronic neck pain and the disturbing sensation of a “crick”
This page is part of the PainScience BIBLIOGRAPHY, which contains plain language summaries of thousands of scientific papers & others sources. It’s like a highly specialized blog. A few highlights:
- A Bayesian model-averaged meta-analysis of the power pose effect with informed and default priors: the case of felt power. Gronau 2017 Comprehensive Results in Social Psychology.
- Association of Spinal Manipulative Therapy With Clinical Benefit and Harm for Acute Low Back Pain: Systematic Review and Meta-analysis. Paige 2017 JAMA.
- Incidence of Spontaneous Resorption of Lumbar Disc Herniation: A Meta-Analysis. Zhong 2017 Pain Physician.
- How much is too much? (Part 1) International Olympic Committee consensus statement on load in sport and risk of injury. Soligard 2016 Br J Sports Med.
- Chiropractic spinal manipulative therapy for migraine: a three-armed, single-blinded, placebo, randomized controlled trial. Chaibi 2016 Eur J Neurol.