19 A Practical Approach to Recurrent Carpal Tunnel Syndrome
19.1 Patient History Leading to the Specific Problem
A 37-year-old man had a left carpal tunnel release 6 years ago. The symptoms of numbness and tingling improved but never completely resolved after the surgery. Over the past 6 months, the symptoms had become more pronounced to the point where they now interfered with the activities of daily living. Repeat nerve conduction study (NCS)/electromyogram (EMG) revealed severe median nerve compression neuropathy at the carpal tunnel.
19.2 Anatomic Description of the Patient’s Current Status
Carpal tunnel release is the most frequent surgical procedure performed by hand surgeons around the world. The prevalence of carpal tunnel syndrome in the United States is estimated to be up to 3.72% with approximately 500,000 releases performed annually. The majority of patients do well after surgery without complications or recurrent symptoms. Major complications such as permanent injury to branches of the median nerve are rare (0.01–0.12%), as is injury to the nerve proper (0.06%). A small percentage of patients (usually less than 3%, and also as high as 20%), however, experience persistent or develop recurrent symptoms after release. Despite the small number of patients who require reoperation, the surgeon is faced with the dilemma of deciding which patients may benefit from re-exploration of the median nerve at the wrist, the timing of reoperation, and exactly what to do differently to adequately release the nerve and/or prevent another recurrence.
There appears to be a number of reasons for recurrent symptoms at re-exploration. Some patients had what appeared to be an intact or reformed transverse carpal ligament, which required division a second time. Persistent symptoms in these patients may have been caused by either incomplete release of the flexor retinaculum or the antebrachial fascia. More often, the median nerve was encased in thick extraneural scar, which appeared to cause compression and/or prevented gliding of the nerve during finger and wrist motion or appeared to decrease the nerve’s blood supply within the carpal tunnel. In a few patients, the nerve was found to course outside the carpal canal and was lying in a superficial position directly under the skin. Pressure from a knife or tool handle could easily produce nerve symptoms in such patients.
The patients who develop recurrent symptoms are a more difficult problem. The author usually tries to manage them with hand therapy modalities, including massage, nerve desensitization, active and passive range of motion exercises, neural glides, Kinesio tape, deep heat, etc., for some time before agreeing to re-explore a compressed or irritable nerve. It is generally better to wait for at least 6 to 8 months after the original release and attempt therapy measures before agreeing to re-explore a symptomatic patient.
In general, simple decompression and external neurolysis alone is not favored for revision surgery due to inferior outcomes. One should not expect a better outcome by using the same operative approach for a second time, or as Dr. L. Vasconez would say: “If plan A doesn’t work, don’t make plan B the same as plan A.” A wide range of options used for revision surgery have been described. They include, but are not limited to, the use of a vascularized hypothenar fad pad flap; muscle flaps, like the palmaris brevis turnover flap, the pronator quadratus muscle flap, or abductor digiti minimi muscle flap; a radial artery perforator fascial flap, a tenosynovial flap, vein wrapping, and even the use of omentum as free flap. There are advantages and disadvantages to each of these options.
19.3 Recommended Solution to the Problem
The author’s preferred choice for patients with difficult recurrent carpal tunnel syndrome or with a scarred nerve with pale segments after tourniquet release is to wrap the nerve in well-vascularized adipofascial flap harvested as a distally based ulnar artery perforator flap from the volar wrist.
This flap has several advantages:
• Use of the previous incision.
• Extension of the incision into forearm, instead of more visible palmar hand.
• No sacrifice of a hand muscle.
• Little risk of injury to the palmar cutaneous branch.
• A reliable blood supply.
• No additional remote donor site.
• No use of microscope.
• Technically feasible without need for a specialty center.
19.4 Technique
The transverse carpal ligament is incised, and, as in primary releases, a 1- to 2-mm segment of the ligament is excised (▶Fig. 19.1a). Nerves encased in thick scar are freed by sharply excising the scar under magnification with a scalpel. The canal of Guyon is opened if not previously done. The ulnar artery fat/fascial perforator flap is dissected by extending the palmar carpal tunnel incision proximally in a zigzag or an S-shaped incision over the ulnar artery. The skin is elevated at a level just below the deep dermis, and a fat and fascial flap of approximately 2 × 4 cm is outlined over the ulnar artery. Beginning in the middle of the distal forearm, the fat and deep muscle fascia is incised and carefully elevated toward the ulnar artery. The ulnar side of the flap is similarly elevated radially toward the artery. In some larger flaps, the dorsal branch of the ulnar nerve should be identified in the proximal portion of the dissection and preserved. The fat/fascial flap is then elevated from proximal to distal toward the distal wrist crease, preserving the most distal perforating vessel from the ulnar artery, which arises approximately 1 to 1.5 cm proximal to the pisiform bone (▶Fig. 19.1b). The flap is dissected under tourniquet control, which is released prior to turning the flap over on the nerve in the carpal tunnel. Occasionally, some subcutaneous fat, synovium, or palmar fascia may be excised to provide adequate space for the transposed flap (▶Fig. 19.1c), permitting a loose palmar skin closure, again over a 19-G butterfly drain. The flap places vascularized soft tissue around the nerve and has prevented further recurrences in our patients. Occasionally, the donor site incision skin edges have experienced delayed wound healing, but none have required reoperation.
