I am trying to be a good health care consumer by requesting copies of my medical reports and reading them. Last month, I had carpal tunnel release surgery. I understand everything in the surgeon's report except one phrase: nerve coverage with an interposition technique. Can you explain this to me?
Carpal tunnel syndrome (CTS) is a common problem affecting the hand and wrist. Symptoms begin when the median nerve gets squeezed inside the carpal tunnel of the wrist. This is a medical condition known as nerve entrapment or compressive neuropathy. Any condition that decreases the size of the carpal tunnel or enlarges the tissues inside the tunnel can produce the symptoms of CTS.
The carpal tunnel is an opening through the wrist to the hand that is formed by the bones of the wrist on one side and the transverse carpal ligament on the other. Another name for tranverse carpal ligament is the retinaculum.
The median nerve passes through the carpal tunnel into the hand. It gives sensation to the thumb, index finger, long finger, and half of the ring finger. It also sends a nerve branch to control the thenar muscles of the thumb. The thenar muscles help move the thumb and let you touch the pad of the thumb to the tips of each finger on the same hand, a motion called opposition.
The median nerve and flexor tendons pass through the carpal tunnel. The median nerve rests on top of the tendons, just below the transverse carpal ligament. You can see how pressure from this ligament can cause nerve problems. The ligament may be too tight, too thick, and/or too close to the nerve. Cutting through the retinaculum releases this pressure and give the nerve some breathing room.
Sometimes surgically releasing the retinaculum in this way is all that's needed. But in other cases, the surgeon can see that the nerve needs added protection from rubbing against structures that will irritate it further. If that's a potential problem, then it may be necessary to put some padding between the nerve and the other structures. This is called nerve coverage. It's done by taking a small piece of tendon or ligament from somewhere else and either wrapping it around the nearby tissues or placing it between the nerve and the surrounding tissues.
Peter C. Amadio, MD. Interventions for Recurrent/Persistent Carpal Tunnel Syndrome After Carpal Tunnel Release. In The Journal of Hand Surgery. September 2009. Vol. 34. No. 7. Pp. 1320-1323.
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