That carpal tunnel syndrome occurs in New Orleans comes as no surprise to anyone, that we see it in our peripheral nerve clinic is somewhat more surprising. Many might think that the diagnosis and treatment of carpal tunnel is so straightforward that there is seldom need to refer it. In general, this is true, yet there are atypical or problematic cases which we see in our peripheral nerve clinic.
In those patients with typical symptomatology, numbness and paresthesias in the median distribution, irritability of the nerve as demonstrated by a Tinel's sign at the wrist or a positive Phalen's maneuver are usually relieved of their symptoms with a carpal cunnel release (CTR). This is a successful operation with patient satisfaction at LSU being 89% in 376 operations. Resolution or reversal of the symptoms vary with their nature and severity. Numbness improved in 56% and weakness to a lesser degree of 42%.
CTR at LSU is an open one, that is to say not endoscopic. A mid-palmar incision is made and carried to but not through the transverse flexor crease at the wrist. The dissection is carried through the superficial palmar aponeurosis and the transverse carpal ligament is incised with a 15 blade under 3x loupe magnification. Alm or Heitz retractors are used to maintain exposure. A Senn retractor is used inferiorly to elevate tissue and allow the proximal transverse ligament which extends more proximally to be well seen. A Metzenbaum scissor is then used to cut the transverse ligament on the ulnar side of the nerve under direct vision. In this manner, the flexor crease is not cut and damage to the palmar cutaneous branch of the median nerve is avoided. Distally the nerve is neurolysed until loose areolar fatty tissue is well demonstrated and no bands of ligament remain. No internal neurolysis is routinely done at the first operation. No attempt is made to close the transverse carpal ligament or to re-fashion it. As an additional measure to reduce the possibility of recurrence the transverse carpal ligament is often trimmed, and the incision then closed. The hand is then wrapped in a bulky dressing and a kerlex and ace wrap applied.
It is our belief that some of the failures of CTR we have see are due in part to prolonged immobilization or splinting. Consequently early mobilization and use of the hand is actively encouraged and occupational therapy sometimes employed to achieve this goal.
Carpal Tunnel Surgery:
The problem of failed carpal tunnel surgery is more challenging than the initial treatment of carpal tunnel syndrome.Three factors need to be delineated. The presenting history and symptoms of the patient prior to presentation must be reviewed. The correctness of the original diagnosis must be established . A carpal tunnel release for median neuropathy due to use of vibratory power tools is unlikely to be successfully treated by CTR as opposed to change of job. Similarly, CTR for a distal polyneuropathy will have a significantly higher failure rate than operation in a patient without such problems and re-operation will not likely be successful.
The time course of symptoms must be analyzed. Are the complaints the persistence of the original symptoms? This would suggest either improper diagnosis or incomplete operation. Or rather, are they new symptoms, suggesting operative complications.
Finally, the adequacy of the prior carpal tunnel release must be determined. This may be very difficult. On occasion an incision will be placed to low or to high and suggest incomplete division of the transverse carpal ligament, the most common cause of failed carpal tunnel surgery. Given the steep learning curve of endoscopic approaches to carpal tunnel release either incomplete division or direct damage to the nerve may be suspected. More often than not, the incision will be appropriately placed and the operative note will document complete transection of the ligament. Re -approximation of the ligament or attempts at "z-plasty" of the ligament support the diagnosis of incomplete decompression of the nerve. The presence of operative complications, such as post-operative hematoma, infection, dehiscence, or prolonged immobilization gives support to the position that post-operative scarring is the cause of the patient's persistent symptoms. In all of these cases, re-exploration of the nerve will be offered to insure adequacy of decompression and untethering of the median nerve.
When the median nerve is re-explored the incision is significantly extended, both into the forearm as well as the palm. The median nerve is identified in the forearm where it is normal and dissection carried into the wrist and palm. If a neuroma of the palmar cutaneous branch is encountered, it is transected and the fascicle dissected back to the main portion of the median nerve. The fascicles are then transected close to the median nerve and coagulated. By this manner the expected neuroma will be far removed from a location of likely repetitive trauma and irritation.
Dissection is then carried into the wrist. If the ligament has not been completely opened it is sectioned at this time. If it has not been previously trimmed , it is trimmed. Often there is significantly redundant synovium which is sharply excised. Dissection is carried into the palm until the nerve divides into its terminal divisions. These divisions are then followed until they are all in loose areolar fatty tissue. A complete 360 degree neurolysis is done of the median nerve and its branches. Figure 1 shows the dissection of the median nerve in a recurrent carpal tunnel syndrome.
If the patient has a significant neuropathic pain complaint, internal neurolysis will be considered. Here, starting at the terminal branches the fascicles will be split away and an internal neurolysis achieved. This often helps reduce the pain, but often at the price of increased numbness and muscular weakness. This needs to be fully understood by both the surgeon and the patient prior to operation.
More recently agents have become available which may reduce post-operative scarring. ADCON-N is one such agent. It is an adsorbable medical device composed of gelatin (porcine) and a polyglycan ester in phosphate buffered saline. In animal studies it has been shown to be an effective barrier to the establishment of fibrotic adhesions. Here at LSU we are participating in a multicenter trial to determine the efficacy of ADCON-N in the treatment of failed carpal tunnel release secondary to post-operative scarring. This is a randomized, blinded study. Patients with failed carpal tunnel release and no evidence of an incomplete operation at the time of surgery are randomly assigned to either the treatment or non-treatment group. The treated group have the ADCON-N applied to the nerve immediately prior to closure while the control group is closed without administration of ADCON-N. Patients are then followed for six months and re-evaluated clinically and electrophysiologically for evidence of symptom resolution and functional performance. We are presently enrolling patients in this study. If you have any non- pregnant patients between the ages of 21 and 70 years with recurrent carpal tunnel problems we would be very glad to see and evaluated them for inclusion in this study. You may contact Ms. Judi Hickey at 504-568-6120 to schedule an initial evaluation.
The median nerve has been dissected in the palm of a patient with recurrent carpal tunnel syndrome. ADCON-N is bein applied to the nerve circumferentially to reduce post-operative scarring.
Download a larger, high-resolution picture of the median nerve as seen above.
The treatment of carpal tunnel syndrome can be rewarding for both doctor and patient if the diagnosis is proper and the surgery well planned and executed. Inspite of this there are still complications and unsatisfied patients. At LSU 6% of treated patients had major symptom persistence and 2% with operative complications. It is hoped that with newer agents and techniques that this percentage of dissatisfied patients may be further reduced and an already effective operation be made even more successful.