The vast majority of mild-to-moderate cases of carpal tunnel syndrome respond to conservative management – meaning  that the earlier this progressive entrapment neuropathy is diagnosed, the more likely it is to respond to physical or occupational therapy, along with wrist splinting, nonsteroidal anti-inflammatory drugs and steroids.

But therein lies the rub. Carpal tunnel syndrome does not always present with classic symptoms, an unfortunate habit that can prevent earliest possible detection when diagnosing by medical history and observed signs alone.

A good illustration of the problem comes from Italy’s University of Siena. Writing in the February 2008 issue of the journal Muscle & Nerve, researchers there report new evidence of a long-suspected association between carpal tunnel syndrome and impairment of ulnar sensory nerve fibers. The university contends that subclinical damage to the ulnar nerve at the wrist can cause carpal tunnel syndrome to appear as something other than what it is. Moreover, ulnar nerve damage may disguise it long enough that, by the time clinicians realize they are dealing with carpal tunnel syndrome, the infirmity may have progressed to the severe stage.

The lesson is obvious: Cases that do not appear to be carpal tunnel syndrome should nonetheless be suspected as that very thing until proven otherwise by “gold standard” tests – and, in this instance, the gold standard is electrodiagnostic testing.

Extra-median spread

An important insight emerging from the University of Siena research is that approximately 42% of carpal tunnel syndrome patients can be expected to experience sensory symptoms outside the typical median nerve distribution.

“According to previous reports, an extra-median spread of symptoms is more frequent in the mild than in the severe or extreme stage of carpal tunnel syndrome,” the investigators write.

They offer an explanation for this: “Damage to ulnar nerve axons in carpal tunnel patients may be caused indirectly by compressive forces transmitted to the ulnar nerve by high pressure in the carpal tunnel, rather than reflecting comorbidity of carpal tunnel syndrome and Guyon’s canal syndrome.”

Elaborating, the researchers assert that these transmitted forces are sufficient to obstruct venous outflow and produce back pressure, edema formation and nerve ischemia.

“It could be advanced that in early carpal tunnel syndrome, ectopic discharges from damaged ulnar sensory afferents play a dominant role in conditioning extra-median spread of symptoms.”

This leads the researchers to conclude that central mechanisms may suppress or mask symptoms. “For example, chronic stimulation of nociceptive afferents of the median nerve could exert some gating of sensory processing from low-threshold ulnar fibers,” they write. Further, peripheral factors such as indirect ulnar nerve  compression acting in concert with plastic changes at a subcortical or cortical level might also contribute to the extra-median spread of symptoms, the team proposes.

What electrodiagnostics can reveal.

As you know, symptoms of carpal tunnel syndrome include numbness, swelling, achiness and/or tingling of the wrist, hand, palm and/or fingers, often accompanied by a pronounced decrease in the ability to grip objects. White females are at highest risk of developing carpal tunnel. A free informational journalr the medical com munity published by syndrome. Also prone to it are individuals whose job (or recreational activities) involve repetitive hand-wrist motions – particularly true in situations where workplace ergonomics are subpar or nonexistent.

There are a number of avenues to diagnose carpal tunnel syndrome. By far the best way is with electrodiagnostic testing.

It is demonstrably reliable and cost-efficient when administered in accordance with American Board of Electrodiagnostic Medicine standards/guidelines and is conducted or overseen by a board-certified specialist.

Electromyography and nerve conduction studies are the two most relevant such tests for identifying abnormalities associated with specific symptoms and signs of carpal tunnel syndrome. Both can also indicate entrapment neuropathy severity: A finding of sensory abnormalities by themselves usually indicates a mild stage of carpal tunnel syndrome, but sensory abnormalities present with motor dysfunction typically signifies a moderately severe stage. (Carpal tunnel syndrome is at its most advanced stage when sensory and motor responses distal to the carpal tunnel or neuropathic abnormalities are appreciably degraded or entirely absent.)

Conclusions

The ulnar nerve may be subject to compression in Guyon’s canal as a consequence of high pressure in the carpal tunnel, and this may help explain extra-median spread of sensory symptoms in carpal tunnel syndrome patients.

Prospects for a good outcome in the treatment of carpal tunnel syndrome are at their best if intervention begins earlier rather than later.

Carpal tunnel syndrome should be suspected when patients – with or without extra-median spread – present with symptoms even loosely characteristic of the condition. These patients should promptly undergo electrodiagnostic testing to establish or rule out carpal tunnel syndrome as the diagnosis.

Resist ambiguously reported electrodiagnostic test results or those that are not delivered in a timely manner. At the offices of Eric R. Beck, MD, PhD, FAAPMR in Huntsville, Fort Payne and Birmingham, Alabama, our standard operating procedure is to compile electrodiagnostic test reports that are clear and informative. When a study is abnormal, we articulate for you the degree of severity so that you can confidently proceed with treatment planning. Further, we report back to you in summary form within 24 hours and deliver a detailed report a short time later.

We also see your patients quickly, usually seven days after we are contacted with a request to schedule an appointment.

Once your patient arrives here, he or she is treated with utmost courtesy. Moreover, we strive to make the  examination as painless and stress-free as possible by offering ethyl chloride numbing of the skin prior to needle testing.

We welcome your referrals of patients suspected of carpal tunnel syndrome and other musculoskeletal-neurologic problems. We can perform comprehensive evaluations of your patients and, if you desire, initiate treatment and perform follow-up, keeping you apprised every step of the way. But no matter the way you choose to utilize us, know that your patients will be satisfied by the high-quality services and interactions delivered at each encounter and will return to you as willing as ever to continue entrusting you with their ongoing care.

Please call Valley Center for Nerve Studies and Rehabilitation in Huntsville, Fort Payne and Birmingham, Alabama at (256) 382-1603 for more information about our services and approaches to care or simply to schedule an electrodiagnostic test.

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