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Loren Fishman, MD

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New Method Diagnoses Chronic Unexplained Nerve Pain

Posted: 06/06/11 06:14 PM ET

Last Tuesday, a 40-year-old communications expert came to me for help with the intense pain in his back and awful, lightning-like sensations going down his leg. It was worst when he walked and not so bad when he rode his bicycle. An MRI showed two problems: spinal stenosis (a narrowing of the spinal cord) and a herniated disc. The likelihood was that one of these two problems was the greatest source of this poor fellow's pain. If he needed surgery, it would be a different surgery for each of his problems. In these types of situations, mistakes are sometimes made. I needed a firm diagnosis to make any rational treatment decision.

The old way of using EMG (electromyography) -- the gold standard of testing nerve function to find nerve injury -- would have been useless for this patient. It would have shown damaged nerves in his spine that were causing pain and sciatica. But EMG could not tell me the origin of the pain -- whether it was coming from the stenosis or from the herniated disk. Without that information, I could only guess at what treatment to recommend.

Departing From Standard Use of EMG
I have seen many difficult-to-diagnose cases of nerve pain with two different possible explanations -- cases of back pain, shoulder and arm pain and cases of pain in the butt. Over the years, I have been frustrated by being unable to give these pain-sufferers a definite diagnosis that would lead to rational treatment. About five years ago, I decided to become a detective. For starters, I noticed that many of these patients had movement-related pain. Sometimes, if they weren't moving or weren't in a specific position, there was no pain at all. Many had pain in some positions but not in others. As these patients with mysterious nerve pains came to me and left unsatisfied, I began to think about using the EMG differently than I had been taught in medical school.

Hope for Medical Nomads
I embarked on an original course, one I knew some of my colleagues might think was a radical departure. I began using the EMG in a new way. Instead of having the patient lie still while the test was being done, as is standard procedure, I had the patient assume different positions, especially painful ones, and tested nerve conduction in each of them. I also tested nerve conduction in positions that are part of a good physical exam. Then I wrote up the significant results of how these investigations lead to diagnosis in a book called "Functional EMG: Provocative Maneuvers in Electrodiagnosis," recently published by Springer.

New use of an old EMG test has enabled me, as well as neurologists and other specialists in physical medicine and rehabilitation, to identify three conditions that are difficult or impossible to diagnose by any other means. It has been a breakthrough for many of my desperate patients. The new method I use right in my office has immediate results and may cost only about 20 percent of an MRI!

Using functional EMG testing to quantify neurological changes brought about by these maneuvers widens the scope, deepens the reach and refines the outcome of electromyography and of my ability to help frustrated patients who have become medical nomads, trudging from physician to physician to try to find out what's wrong.

Diagnosing Spinal and Piriformis Problems and TOS
The EMG method I have developed can successfully determine whether back pain and sciatica are caused by spinal stenosis or herniated disc, even when both are present at the same level. Applying this method to my patient last Tuesday, it turned out he had a painful herniated disc, but one that didn't need surgery. His stenosis was not what was hurting. That was a relief to both of us and helped me direct the course of his physical therapy. In other cases, functional EMG not only diagnoses lumbar spinal stenosis, which can also be hard to pinpoint, but it can also follow its course of improvement.

Many in the medical establishment believe that piriformis syndrome is both uncommon and difficult to diagnose. I have shown that this is untrue. My use of the functional EMG method can identify nearly all cases of piriformis syndrome, a form of sciatica that can affect a large percentage of people. Some authorities using nerve-sensitive MRIs estimate it to be at least as common as a herniated disc.

The new EMG method can also find the nerves involved in thoracic outlet syndrome, where pain going down the arm might come from a number of locations and causes. Thoracic outlet syndrome is considered rare, but this is partly because of the difficulty in diagnosing it. The American Thoracic Outlet Syndrome Association acknowledges that doctors often have inconclusive results when trying to figure out if a patient has it.

In my opinion, patients who in the past had little hope of being certain about sometimes crippling nerve pain now have new hope. By comparing nerve conduction in and out of painful positions, the proper diagnosis often comes to light.