Why Patient's Hand Weakness May Not Improve After the Carpal Tunnel Surgery

Why Patient's Hand Weakness May Not Improve After the Carpal Tunnel Surgery
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Have you heard of anyone going through the carpal tunnel release surgery for confirmed carpal tunnel with no benefit? If so, this article will help explain the reasons.

Imagine a patient that goes to a primary care doctor complaining of progressive hand grip weakness. That doctor sends this patient to a neurologist to get an electromyography, nerve Conduction Testing (EMG/NCS) of the hand to confirm that the problem is due to a pinched median nerve in the middle of the wrist, also known as carpal tunnel syndrome. The neurologist does the EMG/NCS test, and promptly finds some slowing of the median nerve conduction across the wrist and states that this nerve has suffered some damage. Since the story of wrist weakness appears to be a classic one for carpal tunnel, the doc does not feel it is necessary to perform more thorough EMG testing, which is normally reserved for ruling out other causes of hand weakness. Upon completion of the test, the patient is told to begin wearing a wrist splint at night and gets a referral to go see a hand surgeon. The patient gets carpal tunnel release surgery to free up that pinched median nerve and intra-operatively there are no complications. After this procedure, for a few weeks, the patient is careful not to move the wrist much.

As weeks go by, the patient engages the hand more, only to notice that weakness has not improved one bit. After a couple of months still, no change is seen. Finally he goes back to see that neurologist who concludes the carpal tunnel problem must have gone beyond repair.

Carpal tunnel surgery results in ~70% improvement for patients. So what could this be?

This patient ends up going to another neurologist, perhaps even a concierge neurologist who has more time to do a thorough history taking and exam. This neurologist performs a more detailed EMG testing of the arms and uncovers that there is a severely pinched nerve in the neck. In technical terms, this would be called cervical radiculopathy of a cervical root number eight. The neurologist explains to the patient that the cause of his wrist weakness had little to do with a carpal tunnel problem at the wrist, and a lot more to do with a nerve pinched by either a disk bulge and/or a bone overgrowth that leads to narrowing of a space through which the root exists. So the key point is that carpal tunnel release surgery is not indicated for every carpal tunnel, and unnecessary surgery can be avoided with a more detailed screening for cervical radiculopathy by electromyography.

For those patients where the weakness is from the pinched median nerve at the wrist, the carpal tunnel surgery would be of great benefit. If vital information is elicited from the patient about neck pain radiating into the arm and hand, cervical radiculopathy gets placed high on differential diagnosis and the erroneous conclusion that the hand weakness is from only carpal tunnel is avoided. A patient can have both a mild carpal tunnel and a cervical radiculopathy; the challenge is to find out which is contributing the greatest to the weakness of the hand. Without detailed clinical history and examination, patients may end up on the operating table for a carpal tunnel release that was so mild it would have improved on its own with a nightly wrist splint and hand rest. Each patient deserves a thorough approach in history-taking and examination, so carpal tunnel release surgery is performed only for the case where such a release will actually make a difference. 

Galina Nikolskaya, MD
ABPN Board Certified Neurologist
Clinical Neurophysiology Subspecialist 
Website: Myneuro.care