Journal Club
June 2012
Brought to you by the AOCPMR Student Council
Article title:
The Electrodiagnosis of Cervical and Lumbosacral Radiculopathy
Authors:
Bryan Tsao, MD
Journal/Source:
Neurologic Clinics, 2007; 25:473-494.
Discussion:
Neck and back pain are the two of the most common reasons for outpatient PM&R office visits. This article
discusses the anatomy and physiology of nerve root disease and the electrodiagnostic (EDX) approach to
diagnosing cervical and lumbosacral radiculopathy. The electrodiagnostic examination can guide treatment if
done correctly, and is done to confirm the presence of the radiculopathy, establish the nerve root level,
determine the severity of disease, and rule out other peripheral nerve diseases with similar clinical
presentations.
As physiatrists, it is imperative to understand the anatomy and pathophysiology of radiculopathies. Take the
time to study the anatomy of the nerve root complex, the cervical and lumbosacral nerve roots that can be
evaluated with EDX, the muscles innervated by each terminal nerve branch and the actions of the muscles.
There are compressive and noncompressive causes of nerve root injury that present with similar
electrodiagnostic patterns. Compressive nerve root injury is commonly caused by disk herniation or other
degenerative spine elements. Ischemia, trauma, neoplastic infiltration, spinal infections, postradiation injury,
immune-mediated diseases, lipomas, and congenital conditions cause noncompressive nerve root injury. The
severity of nerve root injury is based upon the amount and duration of compression or disease. To maximize
diagnostic yield, the EDX examination should be structured based on the patient’s clinical history and physical
examination.
This article recommends that routine nerve conduction studies (NCS) and needle electrode examinations (NEE)
should be performed on patients with suspected cervical or lumbosacral radiculopathies. NCS are performed by
electrically stimulating peripheral nerves and measuring the nerves’ responses, such as onset latency, amplitude,
and conduction velocity. The NEE is a sensitive technique used to detect motor axon loss and is the most useful
diagnostic tool in radiculopathy after at least 3 weeks from the onset of symptoms. This exam is done by
inserting a needle electrode into the muscle and detecting the electrical
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potential generated by muscle fibers after the electrode is stimulated. The NEE evaluates spontaneous activity,
motor unit potential morphology, and motor unit potential recruitment. Muscle fibers that have abnormal nerve
supplies will have distorted electrical potentials such as fibrillation potentials or positive sharp waves. Other
methods of EDX such as somatosensory evoked potentials, thermography, and motor evoked potentials were
discussed in this article, however they were found to be not useful routinely and to add little information to the
EDX examination.
Questions:
1. Describe the nerve root complex.
2. Which spinal nerve levels have limb representations that can be assessed by electrodiagnostic
examination?
3. Which spinal nerve roots exit cephalad vs. caudal to the vertebral body of the same number?
4. Discuss the sequence of events that results from nerve root compression and eventual altered nerve
conduction.
5. Name the cervical nerve roots, terminal nerves, and the corresponding muscles that they innervate (Hint:
See table 4).
6. Name the lumbosacral nerve roots, terminal nerves, and the corresponding muscles that they innervate
(Hint: See table 5).
Reviewer:
Mona Shalwala, OMS-III, TouroCOM-NY, Educational Committee Co-Chair, AOCPMR Student Council
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