J Neurosurg 49:316-318, 1978
Surgery of the carpal tunnel Technical note NOEL EBOH, M.D., AND DONALD H. WILSON, M.D.
Department of Neurosurgery, Dartmouth-Hitchcock Medical Center, Hanover, New Hampshire The authors describe a modified technique for surgery of the carpal tunnel. The primary cause of the carpal tunnel syndrome is the same as other entrapment neuropathies: an enlarged nerve within a tight tunnel. Electrical studies have shown that the area of compression is in the middle of the tunnel. Treatment is surgical: a palmar incision, which begins at the wrist medial to the palmaris longus, to avoid damage to the sensory branch of the median nerve; and section of the retinaculum from the exit of the tunnel toward the entrance. KEY WORDS
T
9
carpal tunnel
HE carpal tunnel syndrome is an entrapment neuropathy of the median nerve within the hand, beneath the flexor retinaculum. Like the similar condition of the ulnar nerve at the elbow, 4 it is probably caused by mild hypertrophy of the retinaculum and overgrowth of epineurium within a congenitally narrow tunnel. Occasionally, a synovitis will compromise the tunnel and press on the nerve, but this occurred in only 4% of Phalen's large series of 212 hands; 2 and he strongly advised against routine synovectomy. The syndrome is characterized by painful dysesthesia in the distribution of the median nerve in the hand, frequently referred to the forearm, and particularly uncomfortable at night. Where compression is severe, the thenar muscle atrophies. Clinical diagnosis is made by the typical history, by flexing the wrist, which increases discomfort in the hand, and by a Tinel sign over the nerve at the wrist crease. It is confirmed by nerve conduction studies. These show unequivocally that "the point of maximum compression of the nerve is a segment about 5 to 8 mm long beneath midpoint of the retinaculum. ''1 316
9 median nerve
9 technique
Treatment consists of opening the tunnel by dividing the retinaculum. The simplest and most effective method is an incision in the palm, which neither utilizes the skin crease at the wrist nor extends into the forearm; and spares the inconstant sensory branch of the median nerve that supplies a small area of skin proximal to the thenar eminence? Our
FIG. 1. Various combinations of incisions I, II, and III are used, but usually only incision I is required. Note that incision I ends at the wrist in line with the axis of the ring finger. J. Neurosurg. / Volume 49 / August, 1978
Surgery of the carpal tunnel own refinement of this well described technique has been to make a more medial incision, which spares the sensory branch, and to divide the retinaculum from its distal end in the palm rather than the crowded proximal area at the wrist.
Technique Before surgery is recommended, the clinical diagnosis is always confirmed by nerve conduction studies. The patient is placed under general, mask anesthesia, supine on the operating table, with the appropriate arm outstretched on a board. The hand is immobilized by taping down the fingertips. The thumb is splayed and fixed in the same manner. The volar surfaces
of the hand and forearm are cleansed with Betadine detergent, alcohol, and Betadine wash. Plastic and linen drapes isolate the incision. This is curvilinear, about 5 cm in length, and parallel to the thenar eminence. Its proximal end must be in line with the long axis of the ring finger, which brings the incision medial to the palmaris longus muscle (Fig. 1). The subcutaneous tissue is infiltrated with a solution of Xylocaine (1%) (lidocaine) and epinephrine (1/200,000). A tourniquet is unnecessary. The wound is opened to expose subcutaneous fat and spread by placing a small self-retaining retractor at its center. This brings the distal, tenuous portion of the flexor retinaculum immediately into view (Fig. 2 upper left). A mosquito hemostat
FIG. 2. Operative photographs. Upper Left: The distal, tenuous portion of the flexor retinaculum is immediately exposed by retractor. Upper Right: Mosquito forceps enter the distal end of the carpal tunnel. Note how fat still overlies the proximal flexor retinaculum. Lower Left: A grooved director is inserted into the most medial aspect of the tunnel. Lower Right: After the scalpel has divided the thickest portion of the retinaculum over the director, small remaining slips beneath the wrist are divided by scissors. Note how the retractor is moved proximally to improve observation of the median nerve.
J. Neurosurg. / Volume 49 / August, 1978
317
N. E b o h a n d D. H. W i l s o n separates one of the slips of this ligament until a "bubble" of fat appears, heralding the exit of the carpal tunnel (Fig. 2 upper right). A grooved-director (the curved rather than the straight kind) easily slides into the most medial part of the tunnel (Fig. 2 lower left). As a No. 11 blade divides the ligament over the director and the retractor is tightened, the median nerve is seen. The thickest portion of the retinaculum is transected up to the wrist. The remaining slip beneath the wrist is divided by scissors (Fig. 2 lower right). The wound is flushed with a solution of Bacitracin and closed in two layers with 4-0 silk. The inner layer just catches the most superficial portion of the retinaculum, and only three sutures are used. This maneuver brings the edges together and takes tension off the skin sutures. Petroleum gauze is placed on the wound and the hand is wrapped in a bulky dressing. The patient is discharged the following morning, and sutures are removed in 5 days.
2. Diagnosis by clinical features and nerve conduction test was accurate. Two patients were not relieved. Later, it became clear that one patient had multiple sclerosis and the other a polyneuropathy. 3. Complications were rare. Only one patient had a wound infection. This was soon discovered, and quickly cured without residual defect. Scars were not tender and healed to a hairline. No patient had sensory loss in the distribution of the palmar cutaneous branch of the median nerve. 4. These were consecutive cases, indicating how rare it is to encounter other causes of the carpal tunnel syndrome which require a more extensive incision into the forearm.
Operative Results
1. Hunt WE, Luckey WT: The carpal tunnel syndrome. Diagnosis and treatment. J Neurosurg 21:178-181, 1964 2. Phalen GS, Gardner WJ, La Londe AA: Neuropathy of the median nerve due to compression beneath the transverse carpal ligament. J Bone Joint Surg 32A:109-112, 1950 3. Taleisnik J: The palmar cutaneous branch of the median nerve and approach to the carpal tunnel. J Bone Joint Surg 55A:1212-1217, 1973 4. Wilson DH, Krout R: Surgery of ulnar neuropathy at the elbow: 16 cases treated by decompression without transposition. Technical note. J Neurosurg 38:780-785, 1973
Seventy operations were performed between 1974 and 1976. Most patients were in their fifth decade and 57% were women. Sixty-two percent of the operations were performed on the right hand. Although the syndrome was often bilateral, it was only necessary to operate on both hands in 8% of the patients. By relieving the more injured hand and waiting for 3 months, it was usually found unnecessary to operate upon the other hand. Analysis of results led to the following observations: 1. The operation was simple and effective. No patient required reoperation in a followup period ranging from 1 to 3 years. All patients returned to their previous occupations.
3]8
This slightly more medial incision in the palm and division of the flexor retinaculum from its distal end seems to fulfill the requirements for effective surgical treatment of the carpal tunnel syndrome.
References
Address reprint requests to: Donald H. Wilson, M.D., Department of Neurosurgery, Hitchcock Clinic, Hanover, New Hampshire 03755.
J. Neurosurg. / Volume 49 / August, 1978
Surgery of the carpal tunnel Technical note NOEL EBOH, M.D., AND DONALD H. WILSON, M.D.
Department of Neurosurgery, Dartmouth-Hitchcock Medical Center, Hanover, New Hampshire The authors describe a modified technique for surgery of the carpal tunnel. The primary cause of the carpal tunnel syndrome is the same as other entrapment neuropathies: an enlarged nerve within a tight tunnel. Electrical studies have shown that the area of compression is in the middle of the tunnel. Treatment is surgical: a palmar incision, which begins at the wrist medial to the palmaris longus, to avoid damage to the sensory branch of the median nerve; and section of the retinaculum from the exit of the tunnel toward the entrance. KEY WORDS
T
9
carpal tunnel
HE carpal tunnel syndrome is an entrapment neuropathy of the median nerve within the hand, beneath the flexor retinaculum. Like the similar condition of the ulnar nerve at the elbow, 4 it is probably caused by mild hypertrophy of the retinaculum and overgrowth of epineurium within a congenitally narrow tunnel. Occasionally, a synovitis will compromise the tunnel and press on the nerve, but this occurred in only 4% of Phalen's large series of 212 hands; 2 and he strongly advised against routine synovectomy. The syndrome is characterized by painful dysesthesia in the distribution of the median nerve in the hand, frequently referred to the forearm, and particularly uncomfortable at night. Where compression is severe, the thenar muscle atrophies. Clinical diagnosis is made by the typical history, by flexing the wrist, which increases discomfort in the hand, and by a Tinel sign over the nerve at the wrist crease. It is confirmed by nerve conduction studies. These show unequivocally that "the point of maximum compression of the nerve is a segment about 5 to 8 mm long beneath midpoint of the retinaculum. ''1 316
9 median nerve
9 technique
Treatment consists of opening the tunnel by dividing the retinaculum. The simplest and most effective method is an incision in the palm, which neither utilizes the skin crease at the wrist nor extends into the forearm; and spares the inconstant sensory branch of the median nerve that supplies a small area of skin proximal to the thenar eminence? Our
FIG. 1. Various combinations of incisions I, II, and III are used, but usually only incision I is required. Note that incision I ends at the wrist in line with the axis of the ring finger. J. Neurosurg. / Volume 49 / August, 1978
Surgery of the carpal tunnel own refinement of this well described technique has been to make a more medial incision, which spares the sensory branch, and to divide the retinaculum from its distal end in the palm rather than the crowded proximal area at the wrist.
Technique Before surgery is recommended, the clinical diagnosis is always confirmed by nerve conduction studies. The patient is placed under general, mask anesthesia, supine on the operating table, with the appropriate arm outstretched on a board. The hand is immobilized by taping down the fingertips. The thumb is splayed and fixed in the same manner. The volar surfaces
of the hand and forearm are cleansed with Betadine detergent, alcohol, and Betadine wash. Plastic and linen drapes isolate the incision. This is curvilinear, about 5 cm in length, and parallel to the thenar eminence. Its proximal end must be in line with the long axis of the ring finger, which brings the incision medial to the palmaris longus muscle (Fig. 1). The subcutaneous tissue is infiltrated with a solution of Xylocaine (1%) (lidocaine) and epinephrine (1/200,000). A tourniquet is unnecessary. The wound is opened to expose subcutaneous fat and spread by placing a small self-retaining retractor at its center. This brings the distal, tenuous portion of the flexor retinaculum immediately into view (Fig. 2 upper left). A mosquito hemostat
FIG. 2. Operative photographs. Upper Left: The distal, tenuous portion of the flexor retinaculum is immediately exposed by retractor. Upper Right: Mosquito forceps enter the distal end of the carpal tunnel. Note how fat still overlies the proximal flexor retinaculum. Lower Left: A grooved director is inserted into the most medial aspect of the tunnel. Lower Right: After the scalpel has divided the thickest portion of the retinaculum over the director, small remaining slips beneath the wrist are divided by scissors. Note how the retractor is moved proximally to improve observation of the median nerve.
J. Neurosurg. / Volume 49 / August, 1978
317
N. E b o h a n d D. H. W i l s o n separates one of the slips of this ligament until a "bubble" of fat appears, heralding the exit of the carpal tunnel (Fig. 2 upper right). A grooved-director (the curved rather than the straight kind) easily slides into the most medial part of the tunnel (Fig. 2 lower left). As a No. 11 blade divides the ligament over the director and the retractor is tightened, the median nerve is seen. The thickest portion of the retinaculum is transected up to the wrist. The remaining slip beneath the wrist is divided by scissors (Fig. 2 lower right). The wound is flushed with a solution of Bacitracin and closed in two layers with 4-0 silk. The inner layer just catches the most superficial portion of the retinaculum, and only three sutures are used. This maneuver brings the edges together and takes tension off the skin sutures. Petroleum gauze is placed on the wound and the hand is wrapped in a bulky dressing. The patient is discharged the following morning, and sutures are removed in 5 days.
2. Diagnosis by clinical features and nerve conduction test was accurate. Two patients were not relieved. Later, it became clear that one patient had multiple sclerosis and the other a polyneuropathy. 3. Complications were rare. Only one patient had a wound infection. This was soon discovered, and quickly cured without residual defect. Scars were not tender and healed to a hairline. No patient had sensory loss in the distribution of the palmar cutaneous branch of the median nerve. 4. These were consecutive cases, indicating how rare it is to encounter other causes of the carpal tunnel syndrome which require a more extensive incision into the forearm.
Operative Results
1. Hunt WE, Luckey WT: The carpal tunnel syndrome. Diagnosis and treatment. J Neurosurg 21:178-181, 1964 2. Phalen GS, Gardner WJ, La Londe AA: Neuropathy of the median nerve due to compression beneath the transverse carpal ligament. J Bone Joint Surg 32A:109-112, 1950 3. Taleisnik J: The palmar cutaneous branch of the median nerve and approach to the carpal tunnel. J Bone Joint Surg 55A:1212-1217, 1973 4. Wilson DH, Krout R: Surgery of ulnar neuropathy at the elbow: 16 cases treated by decompression without transposition. Technical note. J Neurosurg 38:780-785, 1973
Seventy operations were performed between 1974 and 1976. Most patients were in their fifth decade and 57% were women. Sixty-two percent of the operations were performed on the right hand. Although the syndrome was often bilateral, it was only necessary to operate on both hands in 8% of the patients. By relieving the more injured hand and waiting for 3 months, it was usually found unnecessary to operate upon the other hand. Analysis of results led to the following observations: 1. The operation was simple and effective. No patient required reoperation in a followup period ranging from 1 to 3 years. All patients returned to their previous occupations.
3]8
This slightly more medial incision in the palm and division of the flexor retinaculum from its distal end seems to fulfill the requirements for effective surgical treatment of the carpal tunnel syndrome.
References
Address reprint requests to: Donald H. Wilson, M.D., Department of Neurosurgery, Hitchcock Clinic, Hanover, New Hampshire 03755.
J. Neurosurg. / Volume 49 / August, 1978
