Endoscopic management of carpal tunnel syndrome

Arthroscopy: The Journal of Arthroscopic and Related Surgery X1):11-18 Published by Raven Press, Ltd. 6 1989 Arthroscopy Association of North America

Endoscopic Management of Carpal Tunnel Syndrome Ichiro Okutsu, M.D., Setsuo Ninomiya, M.D., Yoshio Takatori, M.D., and Yoshikazu Ugawa, M.D.

Summary: This article describes a subcutaneous endoscopic operative procedure for carpal tunnel syndrome and analyzes its effectiveness using electrophysiological data. Subcutaneous transverse carpal ligament release under universal subcutaneous endoscope (USE) was performed using local anesthesia without pneumotoumiquet in 54 hands of 45 patients since June 1986. The mean follow-up period was 13.8 months. Sensory disturbances began to subside immediately after the operation and disappeared within 2 months in all cases. After the disappearance of sensory disturbances, we performed postoperative electrophysiological studies in 27 patients (33 hands). Postoperative electrophysiological data were significantly improved in all cases. Patients did not suffer from any serious complications such as motor branch injuries of the median nerve, hypesthesia of the palm, or injuries of the superficial palmar arch. From these results, we conclude that the transverse carpal ligament can be safely incised by this procedure. Key Words: Subcutaneous endoscopyCarpal tunnel syndrom+Endoscopic operation-Arthroscope-Distal sensory latency-Distal motor latency.

the experience of these two surgeons will be of help to those who are attempting to advance the frontiers of arthroscopic surgery.

Editor’s comments: It appears that the uses to which the arthroscope can be put are unlimited, and the following two articles illustrate this. There are some doubts as to the wisdom of using arthroscopic carpal tunnel release. Certainly, it is more risky than doing it open, and one has only to read the admonitions of the authors in these articles to realize that they too are keenly aware of this. One other obvious disadvantage is that bleeding cannot be controlled, and there may be a greater incidence of hematoma when the surgery is performed arthroscopically. Just because an operation can be done is no indication that it should be done, especially if the risks seem to outweigh the advantages. This operation is probably being done elsewhere in the world, and

Carpal tunnel syndrome is a compression neuropathy where the median nerve is compressed in the carpal tunnel due to a variety of reasons (1,2). An operative procedure for carpal tunnel syndrome was introduced by Learmonth in 1930 (3). His hypothesis, which is accepted today, was that decompression of the median nerve could be achieved by division of the transverse carpal ligament. For 60 years, this procedure has commonly been performed by open surgery (3-5) to insure safety during operations, especially to avoid injury to the motor branch of the median nerve. For this reason, a skin incision of several centimeters is necessary at the wrist region. If the transverse carpal ligament, however, could be safely incised under endoscopic vision with a 5-10 mm skin incision at the forearm, a wide skin incision would not be necessary. The purpose of this article is to describe an endoscopic approach for carpal tunnel syndrome.

From the Department of Orthopaedic Surgery, Japanese Red Cross Medical Center (LO.), and Department of Orthopaedic Surgery (S.N., Y.T.), Department of Neurology, Institute of Brain Research (Y.U.), Faculty of Medicine, University of Tokyo, Tokyo, Japan. Address correspondence and reprint requests to Dr. I. Okutsu at Department of Orthopaedic Surgery, Japanese Red Cross Medical Center, 4-l-22, Hiroo, Shibuya-ku, Tokyo 150, Japan.

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I. OKUTSU ET AL.

To minimize the risk of inadvertently cutting any nemovascular structure, this operation was first done on cadaver specimens. The dissection in Figs. 1 through 4B illustrates the precise location of all the anatomical structures and the positioning of the endoscopic sheath and the knife used to divide the transverse carpal ligament. From the cadaver experiences, we found that our sheath protected the median nerve (including the motor branch) from the hook knife used inside the carpal canal. Even if an anomalous motor branch exists in the carpal canal, transverse carpal ligaments can be safely incised by our procedure. MATERIALS AND METHODS Forty-five patients (30 women and 15 men), or 54 hands, underwent subcutaneous release of the transverse carpal ligament at the Japanese Red Cross Medical Center from June 1986 to September 1987. Among those patients, 18 hemodialysis patients and one continuous ambulatory peritoneal dialysis patient were referred to our clinic from several hemodialysis centers in Tokyo for the treatment of the carpal tunnel syndrome. The ages of the patients ranged from 29 to 73 years (mean, 51.1 years). Conditions associated with those patients with carpal tunnel syndrome included idiopathic or no apparent cause, 23 cases; hemodialysis, 18 cases; pregnancy, two cases; rheumatoid arthritis, one case; and continuous ambulatory peritoneal dialysis, one case (Table 1). Postoperative follow-up periods ranged from 9 to 23 months (mean, 13.8 months). Diagnosis of carpal tunnel syndrome was confirmed by clinical symptoms: 3-g algesiometer for pain sensation, 2-g von, Frey hair for touch sen-

T-Y \

/

sation at the hand, Tinel’s sign at the wrist, Phalen’s test, manual muscle testing (MMT) of abductor pollicis brevis, adductor pollicis, flexor pollicis brevis, and forearm flexor and pronator muscle groups, and electrophysiological studies (6) using the Medelec (type MS-6) system. The indication for surgery was distal sensory and motor latencies >3.5 msec and 4.5 msec, respectively, and electromyogram of abductor pollicis brevis revealing abnormalities in cases that failed to respond to conservative treatments over a period of 3 months. In cases with atrophied abductor pollicis brevis, we recommended surgery without an initial period of conservative treatment. Postoperative electrophysiological studies were performed after the disappearance of the sensory disturbances in 27 patients or 33 hands. Matched pre- and postoperative data were analyzed using the paired Wilcoxon signed-rank test. Preop-

Transverse Carpal Lig.

\

I

Hook

Median Nerve

Knife

hive&l

Palmarls Longus Tendon

Endoscope

FIG. 1. Schema of wrist showing precise location of anatomical structures and the positioning of the endoscopic sheath and knife used to divide the transverse carpal ligament.

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FIG. 2. Hook knife catches the transverse carpal ligament. UA, ulnar artery; H, hook knife; TCL, transverse carpal ligament; SPA, superficial palmar arch; S, sheath; MN, median nerve.

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FIG. 3. Half of the transverse carpal ligament is dissected by the hook knife. H, hook knife; S, sheath; MN, median nerve. Arrows show sectioned transverse carpal ligaments.

ENDOSCOPIC

MANAGEMENT

OF CARPAL

TUNNEL SYNDROME

13

4A,B

FIG. 4. A: Carpal canal is completely released. Median nerve trunk and motor branch are protected by sheath from the hook knife. Case illustrates that motor branch is located in a standard anatomical location. Motor branch is separated from the nerve trunk at the exit of the carpal canal. m, motor branch of median nerve; S, sheath; H, hook knife; UA, ulnar artery; MN, median nerve. Arrows show sectioned transverse carpal ligaments. B: Same as A but motor branch penetrates the transverse carpal ligament. m, motor branch of median nerve; MN, median nerve: S, sheath: H, hook knife: UA, ulnar artery. Arrows show sectioned transverse carpal ligaments. 4A,B

erative distal sensory latencies were undetectable in 14 hands, and preoperative distal motor latencies in three hands. None of these hands was included in the statistics presented herein. SURGICAL PROCEDURE We designed a clear plastic outer tube or sheath for a standard 30” forward oblique viewing arthroscope (Karl-Storz GmbH & Co.). The tube has an outer diameter of 6 mm, inner diameter of 4 mm, and a bevel-shaped barrel with a length of 175 mm. We designated the procedure using this instrument the universal subcutaneous endoscope (USE) system (7,8) (Fig. 5). The arthroscope is used in conjunction with a halogen light source (Shinko Optical Co.), video-camera (Shinko Optical Co.), and Umatic video recorder (SONY Corp.). The procedure was photographed with an Olympus camera loaded with a Kodak tungsten color film ISO/ or Konica black and white film ISO/ZOO,shot at a speed ranging from 1/15to l/125s. TABLE 1. Causes

The operation is carried out under a local anesthesia using 10 ml of 1% Iidocaine solution that contains epinephrine in a concentration of 1:1OO,OOO, which is applied to the skin over the palmaris longus tendon, 3 cm proximal to the distal transverse carpal crease, and into the carpal tunnel. Pneumotourniquet is not used. A transverse incision of S-10 mm is made at the anesthetized area, as well as at the fascia of the same region. The obturator is then gently inserted into the carpal tunnel from the radial side of the palmaris longus tendon, which helps guide insertion of the scope to observe the median nerve. The clear plastic tube is introduced following the removal of the obturator. The scope slowly advances into the clear plastic tube (Fig. 6A). We observe the median nerve, flexor tendons, and trans-

of the carpal tunnel syndrome

Cause Idiopathic or no apparent cause Hemodialysis Pregnancy Rheumatoid arthritis Continuous ambulatory peritoneal dialysis

Number of patients

Number of hands

23 18 2 1

26 23 3 1

1

1

FIG. 5. Universal subcutaneous endoscope (USE). This operative instrument consists of a clear pIastic outer tube (patented in the United States) and a standard arthroscope. The outer tube creates a space in subcutaneous areas without inherent space.

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I. OKUTSU ET AL.

6A,B

6E.F

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verse carpal ligament. With active or passive finger flexion and extension, the gliding motion of the tendon can be clearly observed under the scope. This maneuver is important to differentiate between the nerve and tendons. The transverse carpal ligament is examined through the USE placed in the carpal tunnel. The ligamentum fiber can be seen to be arranged in an arch form, running transversely (Fig. 6B). To incise the transverse carpal ligament, the endoscope is removed from the carpal tunnel and then inserted from the ulnar side of the palmaris longus tendon into the carpal tunnel through the same skin incision and advanced to the palm. We check the location of the superficial palmar arch, which is located 10-15 mm distal from the distal end of the transverse carpal ligament. In some cases, arterial pulsation is observed under endoscopic vision. Then the arthroscope is drawn inside the sheath which is located inside of the carpal tunnel in the proximal direction to check the transverse carpal ligament and to visually confirm the absence of the motor branch of the median nerve or any abnormalities at the site of the incision. Sometimes, the transverse carpal ligament is covered by the synovial membrane of the flexor tendons. In such cases, scraping the synovium with an L-shaped probe enables us to observe the transverse carpal ligament. If the motor branch of the median nerve or any anatomical abnormalities are evident at the site of the incision, endoscopic procedure should be terminated and open surgery performed. A retrograde hook knife is introduced along the ulnar side of the sheath from the previously made incision at the forearm (Fig. 6A). The transverse carpal ligament is caught by the knife under endoscopic vision and then incised at the ulnar side (Fig. 6C). While moving the arthroscope inside the sheath which is located inside of the carpal tunnel, proximally, the knife is simultaneously drawn toward the operator. The transverse carpal ligament is released under complete endoscopic vision. When the ligament or forearm fascia is incised, subcutaneous fatty tissue of the wrist or forearm, respectively, should be visible through the endoscope. The entire length of the ligament can be completely divided with little bleeding (Fig. 6D and E).

OF CARPAL

TUNNEL

SYNDROME

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The skin incision at the forearm is closed with a single stitch, which completes the operation (Fig. 6F). POSTOPERATIVE CARE On the day of the operation, patients elevate their hands to reduce the swelling and bleeding at the site of the operation. On the following day, patients are encouraged to perform gentle active range of motion exercises. RESULTS In this series, all of the patients were operated by the endoscopic procedure. Endoscopic procedure was never abandoned in favor of open standard operative procedure. Sensory disturbances such as hypesthesia and paresthesia began to subside immediately after the operation, and the symptoms disappeared within 2 months following the operation in all hands. Preoperative distal sensory latency was 5.3 -+2.9 msec (mean 2 SD), ranging from 2.2 msec to 13.8 msec in 19 hands. Postoperative distal sensory latency was 3.1 4 0.7 msec, ranging from 2.2 msec to 5.2 msec in 19 hands. Preoperative distal motor latency was 7.7 -1-3.3 msec, ranging from 3.4 msec to 18.9 msec in 30 hands. Postoperative distal motor latency was 4.6 + 0.7 msec, ranging from 3.0 msec to 5.8 msec in 30 hands (Table 2). Values of distal sensory latency were significantly improved postoperatively (p < 0.05). Values of distal motor latency were significantly improved postoperatively (p < 0.01) as well. There were no serious complications during the operation such as injuries of the recurrent motor branch, palmar cutaneous branch of the median nerve, flexor tendons, or the superficial palmar arch. Postoperatively, three patients complained of discomfort and subcutaneous hematama at the wrist, which disappeared within 1 month after the operation. Immediate use of the hands did not cause any problems such as subluxation or synovitis of the flexor tendons. We experienced one recurrent case, where a patient presented with discomfort of the median nerve sensory distribution area 12

PIG. 6. Operation. A: USE inserted in the carpal tunnel. Hook knife inserted from the ulnar side of the USE. B: Internal view of the transverse carpal ligament. C: Hook knife in contact with transverse carpal ligament. D: Released transverse carpal ligament. Arrows show the sectioned transverse carpal ligaments. Little bleeding is visible between the segments of sectioned transverse carpal ligaments. E: Released transverse carpal ligament and subcutaneous fatty tissue. Arrow shows the cut surface of the sectioned transverse carpal ligament. Asterisk shows subcutaneous fatty tissue of the wrist. F: Postoperative status of the operative site. Arrow shows the skin incision.

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I. OKUTSU

TABLE 2. Pre- and postoperative Patient no.

Age

Sex

(Gird

Cause

2 3 6

F F F

46 56 29

Hemodialysis Hemodialysis Pregnancy

7 a

M M

51 46

9 10 11 12 18 20 21 22

F

55 51

; F M F F F

4: 51 31

Hemodialysis Continuous ambulatory peritoneal dialysis Hemodialysis Idiopathic Idiopathic Idiopathic Hemodialysis Idiopathic Idiopathic Idiopathic

24 26

F F

54 57

Idiopathic Idiopathic

28 31 32 33 34 36

F F F F M F

57 70 61 53 56 54

Idiopathic Idiopathic Hemodialysis Idiopathic Hemodialysis Idiopathic

38 39 40 41 42 49

F M F M M F

52 54 73 51 64 44

Idiopathic Hemodialysis Idiopathic Hemodialysis Hemodialysis Hemodialysis

_-

:;

a Time of latest postoperative R, right; L, left.

-

Preoperative

R L R L R R L

Undetectable Undetectable 5.7 3.7 5.7 Undetectable Undetectable

:: R R L R R R L R R L R R R L L R L L L L R L R L

2.8 2.2 5.5 Undetectable 6.9 3.4 Undetectable 4.5 3.7 2.9 Undetectable Undetectable 3.1 Undetectable 13.8 6.7 Undetectable 4.0 5.1 Undetectable 10.6 3.2 Undetectable 7.4 Undetectable Undetectable

Postoperative 5.7 4.2 2.9 2.8 3.4 4.6 5.2

2.2 3.3 3.1 4.6 3.6 2.4 2.2 2.5 2.4 2.9 4.6 3.0 2.6 5.1 3.2 3.6 3.3 3.2 2.5 Undetectable 5.2 3.3 Undetectable 3.2 Undetectable 4.6

-

Distal motor latency (msec)

Weeks” 40 16 8 6 6 11 6

74 73 10 4 5 58 57 18 18 9 8 36 33 35 29 38 31 32 28 11 43 9 9 9 11 11

Preoperative 9.8 8.1 4.6 4.6 7.2 9.6 6.3

3.4 5.1 7.6 5.5 5.3 4.8 8.3 6.7 5.0 6.7 Undetectable 9.1 7.9 Undetectable 10.0 Undetectable 6.7 13.4 7.1 5.7 13.7 5.4 12.3 7.6 18.9 4.9

Postoperative

Weeks”

5.8 4.5 3.8 3.7 4.8 4.2 5.5

40 16 8 6

3.0 4.7 5.1 5.1 4.4 3.4 3.9 3.9 4.0 5.2 5.9 5.1 5.3 6.2 5.2 5.8 4.3 4.9 3.9 4.5 4.9

74 73 10 4

2: 6

5: 57 18 18 9 8 36 33

:; 38 31

:::

:: 11 43 9 9

::: 4.8

379 37

examinations.

Illustrative cases Case 6 (A.Z.), twenty-nine years old, female Three months following childbirth, one patient felt discomfort in both hands. When she came to our hospital, her clinical signs were sensory disturbances of the median nerve distribution areas, and muscle weakness in both hands; MMT of right abductor pollicis brevis was fair, and left was good. Phalen’s test and Tinel’s sign were positive in both hands. Electrophysiological studies were performed. The right median distal sensory latency was 5.7 msec and left was 3.7 msec. Right and left motor latencies were 4.6 msec. We diagnosed bilateral carpal tunnel syndrome. Right subcutaneous transverse carpal ligament release was performed Vol. 5, No. 1, 1989

distal sensory and motor latencies

Distal sensory latency (msec)

Side involved

months after surgery. All other patients expressed satisfaction with their postoperative clinical state.

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on November 14, 1986 and the left on December 1, 1986. Two months after the initial operation, all clinical signs and symptoms disappeared completely in both hands, and the patient did not have any complaints. She was satisfied with the operation. Postoperative electrophysiological studies revealed right distal sensory latency of 2.9 msec and the left of 2.8 msec. Right distal motor latency was 3.8 msec and the left was 3.7 msec. All of the electrophysiological data improved within 2 months after surgery and were within the normal range. 7 (S.H.), fife-one years old, male One patient suffered chronic renal failure 12 years ago. During the past 12 years, he had received hemodialysis three times a week. He presented with a complaint of discomfort in the radial three digits of his right hand. Physical examination revealed sensory disturbances of right median nerve distriCase

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MANAGEMENT

bution area, and MMT of abductor pollicis brevis was good. Phalen’s test and Tinel’s sign were positive. Electrophysiological studies revealed right median distal sensory latency was 5.7 msec and distal motor latency was 7.2 msec. We diagnosed carpal tunnel syndrome from those observations. Subcutaneous transverse carpal ligament release was performed on November 14, 1986. One month after the operation, all of the clinical signs disappeared. Six weeks after the operation, electrophysiological studies were repeated. Distal sensory latency was improved to 3.4 msec, and distal motor latency was improved to 4.8 msec. At his last follow-up examination, 1 year and 7 months after surgery, he did not have any clinical abnormalities. The patient was satisfied with the operation. DISCUSSION Endoscopic, or closed operation, in the field of orthopedic surgery dates back to 1955, when Watanabe et al. (9) first applied the procedure to the knee joint. Advantages of the endoscopic operation include a minimal skin incision, less stressful surgical invasion, short postoperative rest period, and early initiation of rehabilitation. The greatest shortcoming, however, is the fact that the endoscopic procedure is limited to areas or organs with anatomical cavities. Nagai (10) has applied the endoscope to subcutaneous areas, a procedure known as “tunemploying a standard arthronel-endoscopy,” scope. This technique is, however, clearly limited in terms of field of vision. We, therefore, developed USE (7,8) to make it possible to carry out operations under expanded endoscopic vision at sites without anatomical cavities. Open surgery for carpal tunnel syndrome requires a skin incision (45) of several centimeters at the wrist and postoperative rest period of -2-3 weeks. These requirements following surgery restrict the activity of daily living of the patients considerably. Further, it is not uncommon for the patients to experience hypesthesia of the palms and discomfort of surgical wounds (11,12). Paine and Polyzoidis (13) developed the Paine retinaculotome for transverse carpal ligament release in a closed, blind fashion to avoid these complications. Based on their extensive experience, they concluded that their procedure did not involve significant risk of damage to the anatomical structures during surgery. Even using the endoscope, however, the visual field is so limited that its clinical application should be

OF CARPAL

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SYNDROME

cautious. There are three important anatomical structures that may be injured inadvertently in the surgery: the recurrent motor branch, palmar cutaneous branch of the median nerve, and superficial palmar arch. The possibility of recurrent motor branch injury is a major complication (11,12) of carpal tunnel release. Usually, the motor branch of the median nerve is located at the anterolateral side of the carpal tunnel. Moreover, all of the anomalous motor branches that were reported (14-21) were located at the anteroradial side of the hand. In our procedure, the knife is inserted from the ulnar side of the endoscope, far from the motor branch, and the median nerve is protected by the endoscope. The next problem is the possibility of palmar cutaneous branch injury. The palmar cutaneous branch (5) is located between the flexor carpi radialis and palmaris longus tendons. If the endoscope is inserted at the ulnar side of palmaris longus tendon, the retrograde hook knife with its blade width of 2 mm can catch only the transverse carpal ligament under endoscopic vision and provide for the safety of the palmar cutaneous branch. The third problem is the possibility of superficial palmar arch injury. The palmar arch is located 10-15 mm distal to the distal part of the transverse carpal ligament. During the operation, we check the pulsation of the superficial palmar arch, if possible. All of the operative procedure is controlled by endoscopic vision, so the chance of palmar arch injury is negligible. Although no such case has occurred in our experience, the operative procedure should immediately be changed to open surgery when any anatomical abnormalities or marked synovial thickening are discovered by endoscopic vision. Other important structures such as radial and ulnar artery or ulnar nerve are located outside the carpal tunnel. From those observations, we conclude release of the transverse carpal ligament under endoscopic vision should relieve the operators from the danger of inadvertently injuring the important structures of the hand. Immediate use of the hands does not generally cause any problems in postoperative follow-up periods. We feel early range of motion exercises should prevent the sectioned transverse carpal ligament from healing in a shortened position. Postoperative results were favorable, indicating recovery to clinically normal levels within 2 months. Postoperative evaluation of patients with Arthroscopy,

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carpal tunnel syndrome is difficult, however, because of many subjective elements inherent in the condition. We, therefore, analyzed objective data such as the distal sensory and motor latencies. These results confirmed the effectiveness of our procedure and revealed the rate of recovery to be as rapid as that of the reported patients who received open surgery (22). Acknowledgment: We thank Professor Masaki Watanabe and Dr. Isao Abe for advice and Dr. George J. Schonholtz for encouragement.

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14. Bennett JB, Crouch CC, Compression syndrome of the recurrent motor branch of the median nerve. J Hand Surg [Am] 1982;7:407-9. 15. Lanz U. Anatomical variations of the median nerve in the carpal tunnel. J Hand Surg [Am] 1977;2:44-53. 16. Linburg RM, Albright JA. An anomalous branch of the median nerve. J Bone Joint Surg [Am] 1970;52A: 182-3. 17. Kessler I. Unusual distributions of the median nerve at the wrist: a case report. Clin Orthop 1969;67:124-6. 18. Papathanassiou BT. A variant of the motor branch of the median nerve in the hand. J Bone Joint Surg [Br] 1%8; 50B: 1567. 19. Rowntree T. Anomalous innervation of the hand muscles. J Bone Joint Surg [Br] 1949;31B:505-10. 20. Tountas CP, Bihrle DM, MacDonald CJ, Bergman RA. Variations of the median nerve in the carpal canal. J Hand Surg [Am] 1987;12A:708-12.

21. Spinner M. Injuries to the major branches of peripheral nerves of the forearm. 2nd ed. Philadelphia: WB Saunders Co., 1978;2036. 22. Harris CM, Tanner E, Goldstein MN, Pettee DS. The surgical treatment of the carpal-tunnel syndrome correlated with preoperative nerve-conduction studies. J Bone Joint Surg [Am] 1979;61A:93-8.