Neural Scan Gold Standard For Sensory Electrodiagnostics

By David Akinpelu, MD

When it comes to determining the appropriate diagnostic test to assess spine and intervertebral disc structure, the gold standard has been MRI imaging. Likewise, the new gold standard for assessing nerve function secondary to nerve injury from trauma or radiculopathy from pathologies in the neck, thoracic or lumbar vertebrae, is now the nerve conduction study, sensory electrodiagnostic test. This test assesses nerve function based on the voltage conduction of the nerves and is not affected by the skin resistance. It is a painless procedure that does not involve the use of needles.

According to Dr. Cork, former President of the American Academy of Sensory Medicine, The Academy of Sensory Electrodiagnostic Medicine fills a huge need in sensory diagnosis. There is no doubt that EMG and NCV are worthwhile technologies, but the problem is that these electrodiagnostic examinations (EDX) cannot test the small-pain-fibers, which cause 90% of patients to seek medical consultation. Most patients have purely pain related symptoms without motor deficits, so EMG/NCV is of little to no value. However, Small-Pain-Fiber (SPF) Nerve Conduction Study (NCS) can assess these pain nerves.

In a three-year study carried out by Dr. Cork and his colleagues at LSU Health Services Center in Shreveport they found in 49 chronic low back pain patients, of which 25 were failed back surgery cases, that SPF-NCS has 95% sensitivity in locating the nerve root causing symptoms. In the LSU Pain Center, SPF-NCS has literally replaced conventional EMG/NCV, and they perform half the number of MRI studies they did before its introduction.

In summary, as a form of a nerve conduction study, neural scanning has a much higher sensitivity and specificity compared to older forms of testing such as NCV and EMG, which are less specific in determining the source of nerve irritation or pathology. This is because neural scanning is able to target the delta fibers or small fibers of pain conduction that are highly specific in correlating to specific skin dermatomes.

The results of the neural scan in conjunction with MRI findings can be used to determine the level of nerve irritation and hypofunction to appropriately target the level of pathology, whether it is secondary to spinal stenosis, a herniated disc, degenerative disc disease or other pathology in the neck or lumbar region, prior to instituting IDD therapy.

Neural scanning can be used to objectively assess improvement in nerve function after a course of IDD therapy is complete. This approach continues to be the best way to determine and document clinical improvement in patient's symptoms with regards to the chronicity of nerve irritation and improvement in addition to the standard Oswestry Pain Scale (OPS), which is a more subjective assessment.