Surgery for carpal tunnel syndrome
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Transcript of Surgery for carpal tunnel syndrome
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Surgery for carpal tunnel syndrome
Author
Alice A Hunter, MD
Barry P Simmons, MD
Section Editor
Jeremy M Shefner, MD, PhD
Deputy Editor
John F Dashe, MD, PhD
Last literature review for version 17.1: January 1, 2009 | This topic last updated:
September 11, 2007
INTRODUCTION — Carpal tunnel syndrome (CTS) is a common nerve entrapment disorder
manifested by pain, paresthesias, and ultimately muscle wasting of the hand. Appropriate
treatment can interrupt the progression of this disorder and avoid the development of permanent
disability. Conservative therapy may be sufficient, although many patients require surgery.
Surgical treatment may involve open or endoscopic technique. The goal of either approach is to
decrease pressure upon the median nerve at the wrist by dividing the transverse carpal ligament
and antebrachial fascia.
This topic review will discuss the surgical treatment of CTS. The clinical manifestations, diagnosis,
and conservative therapy of this disorder are reviewed elsewhere. (See "Clinical manifestations
and diagnosis of carpal tunnel syndrome" and see "Treatment of carpal tunnel syndrome").
GENERAL PRINCIPLES — Indications for surgery include persistent numbness and pain, motor
dysfunction with diminished grip or pinch grasping, or thenar eminence flattening.
Prior to contemplating surgical carpal tunnel release, one must be sure of the correct diagnosis.
Although median nerve entrapment at the wrist is the most common and most well-studied
manifestation of CTS, it is often confused with other disorders, especially cumulative trauma
disorder.
With a clearly defined history and physical examination, electrodiagnostic studies are not
necessary. The symptoms include numbness and tingling in the hand, especially if confined to the
median nerve distribution. The symptoms are often worse at night but can also be present in the
daytime in the worker with a provocative job. Symptoms are often worse with driving or holding a
book, newspaper, or telephone [1].
Electrodiagnostic studies are helpful if the history or physical examination is equivocal. The
American Association of Electrodiagnostic Medicine found high sensitivity and specificity with the
use of nerve conduction studies to evaluate CTS [2]. However, symptomatic median nerve
compression can occur in the presence of normal electrodiagnostic studies [3]. These observations
were made in patients with clinical evidence of CTS. One must be very skeptical about proceeding
to surgery in a patient with normal electrodiagnostic studies in combination with an equivocal
history and physical examination.
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ANATOMY OF THE CARPAL TUNNEL — To better appreciate the possible surgical approaches for
carpal tunnel release, one must understand the anatomy of the carpal tunnel and the median
nerve at the wrist. The carpal tunnel is a defined anatomic space with the following characteristics.
The dorsal surface is formed by the carpal bones, while the volar surface is formed by
the transverse carpal ligament (flexor retinaculum) which attaches ulnarly to the
hamate and pisiform and radially to the trapezium and scaphoid tuberosity (show figure
1).
The antebrachial fascia of the forearm is continuous with the transverse carpal ligament
of the palm. The four flexor digitorum profundus tendons, four flexor digitorum
superficialis tendons, the flexor pollicis longus tendon, and the median nerve pass
within this canal (show figure 2).
Median nerve — The median nerve lies directly under the transverse carpal ligament. The
median nerve at the level of the distal forearm and wrist has three main branches: two sensory
and one motor. The first sensory branch is the palmar cutaneous nerve which branches from the
median nerve approximately 5 cm proximal to the wrist crease. This nerve gives sensation to the
thenar eminence and, because its take off is proximal to the carpal canal, it is not affected by CTS.
However, it can easily be injured in the release of the transverse carpal ligament if the incision is
not meticulously placed.
The second sensory branch passes through the carpal canal as part of the main trunk. After
passing through the canal, it divides into multiple branches to innervate the thumb, index, middle
and radial half of the ring finger. Because these sensory branches pass through the canal, they are
affected by compression of the median nerve at the level of the transverse carpal ligament.
Branches of these sensory nerves can also be injured during surgery, more commonly with an
endoscopic carpal tunnel release.
The motor branch innervates the two radial lumbricals, opponens pollicis, abductor pollicis brevis,
and the superficial head of the flexor pollicis brevis. The motor branch takes a more variable route
to its destination. It most often branches off distal to the transverse carpal ligament. However, it
may branch off within the tunnel or pass directly through the transverse carpal ligament. The
motor branch is in jeopardy during carpal tunnel if meticulous planning is not carried out.
SURGICAL TECHNIQUES — Surgery can be divided into two main techniques:
The classic open carpal tunnel release, which can be performed through a standard
incision or a limited incision
Endoscopic carpal tunnel release, which can be performed through a single or double
portal
Each procedure has its risks and benefits, and there is controversy among prominent hand
surgeons as to the best technique. Proponents of open carpal tunnel release feel that it is the
safest means of decompressing the nerve. However, there is less trauma with the endoscopic
technique.
Surgery for carpal tunnel release is usually performed using local anesthesia only, or local
anesthesia with intravenous sedation, according to patient preference.
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Open technique — The classic open approach allows one to better view the anatomy and
possible anomalies, thereby decreasing the risk of injury to critical structures. Prior to making an
incision, the surgeon must keep in mind the location of the superficial palmar arch, the motor
branch of the median nerve, Guyon's canal and the palmar cutaneous branch.
Standard incision — A variety of longitudinal incisions describe the classic incision. Most
commonly, the incision starts just proximal to Kaplan's cardinal line. It moves in a curvilinear
manner staying just ulnar to the thenar crease. This keeps the incision ulnar to the palmaris
longus, which reduces the likelihood of affecting the small palmar cutaneous nerve branches that
pass from radial to ulnar in the palm.
Few surgeons carry this incision proximal to the wrist crease unless the patient needs a repeat
release. If the incision does cross the crease, it should do so obliquely to avoid a flexion
contracture at the wrist and it should be directed ulnarly to avoid the palmar cutaneous nerve. The
incision is then deepened either bluntly or sharply through the palmar fascia to the transverse
carpal ligament.
The transverse carpal ligament and antebrachial fascia are divided longitudinally and the median
nerve may be identified. The division should occur along the ulnar border of the transverse carpal
ligament to avoid damage to the motor branch. Care must be taken to obtain a complete release
while avoiding damage to the vital structures. The flexor tendons can be retraced radially to
inspect the floor of the canal for lesions. Meticulous hemostasis must be achieved prior to closure.
With open carpal tunnel release, the question often arises whether or not to perform internal
neurolysis. At one time, neurolysis was felt to be important to a primary carpal tunnel release
[4,5]. However, later studies found no significant difference between primary carpal tunnel release
performed with or without internal neurolysis [6,7]. This applies even to patients with severe CTS
defined by thenar atrophy and/or a fixed sensory deficit [7]. Neurolysis is accomplished by incising
the epineurium to further decompress the nerve fascicles.
Small palmar incision — Open carpal tunnel release can also be performed through a small
palmar (or "limited") incision [8]. This permits better exposure to avoid complications and keeps
the incision out of the painful portion of the palm.
Carpal tunnel release through a small palmar incision uses a longitudinal palmar incision that
starts just proximal to Kaplan's cardinal line and moves proximally for 2 to 2.5 cm. This allows
visualization of the transverse carpal ligament; the more proximal portion of the ligament can be
identified by elevating the tissue proximally above and below it. Then, under direct vision, the
ligament can be incised or cut with a carpal tunnel tome.
The improved exposure with this technique decreases the risk of injury to vital structures and
avoids a longer scar at the base of the palm that increases morbidity. Furthermore, the palmar
fascia is left intact over the proximal portion of the transverse carpal ligament, reducing
postoperative incision pain [8].
Endoscopic technique — Due to preservation of the palmar fascia, subcutaneous fat, and skin,
endoscopic median nerve decompression may result in less scar tenderness and an earlier return
to work compared with the open technique. However, good visualization is essential for the
endoscopic technique. If this cannot be achieved, one must switch to the open technique.
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Both a one-portal and a two-portal approach have been used [9-12]. The success rates are
equivalent, and the choice is surgeon-dependent [9,12].
One-portal approach — The one- and two-portal techniques use a transverse portal at the
wrist. A flap of antebrachial fascia is elevated and dilators are passed distally. The path is just
radial to the hook of the hamate, in line with the ring finger. Care must be taken not to pass
Kaplan's cardinal line in order to avoid injury to the palmar arch. The neurovascular bundle is 1 to
4 mm from the distal edge of the transverse carpal ligament [13].
If the one portal technique is used, the endoscopic device is then passed. One should immediately
see the fibers of the transverse carpal ligament. If these are not seen, an attempt to clear the
ligament of synovial tissue from the ligament is carried out. If the exact position of the transverse
carpal ligament cannot be determined, the endoscopic approach must be aborted. If the fibers are
clearly seen the device is inserted just distal to the fibers. The knife device is then elevated and
pulled proximally, cutting the transverse carpal ligament under endoscopic vision. Assessment to
verify complete transection of the fibers is carried out. The antebrachial fascia can be cut under
direct vision through the portal at the wrist using scissors.
Two-portal approach — If a second portal is desired, a transverse incision is made in the
palm just over the end of the transverse carpal ligament. This portal permits distal visualization
and can be used to depress structures such as the superficial palmar arch out of the operative
field.
Complications — Although infrequent, complications of surgery for CTS include the following
[14,15]:
Inadequate division of the transverse carpal ligament
Injuries of the recurrent motor and palmar cutaneous branches of the median nerve
Lacerations of the median and ulnar trunk
Vascular injuries of the superficial palmar arch
Postoperative wound infections
Painful scar formation
Complex regional pain syndrome
Incomplete release of the transverse carpal ligament may be the most frequent complication of
surgery for CTS, and is usually due to errors in surgical technique, such poor choice of incision and
inadequate exposure [15]. It is also the most common problem leading to reoperation for CTS, in
one series accounting for 49 percent of 185 reoperations [16].
In an early series of 186 patients, 34 various complications occurred in 22 patients (12 percent),
including incomplete division of the transverse carpal ligament in 11 (6 percent), and development
of complex regional pain syndrome in 4 (2 percent) [14].
With proper surgical training, experience, and technique, it is estimated that the combined
incidence of long-term disability related to complications from carpal tunnel release surgery should
not exceed 1 to 2 percent [15].
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Open versus endoscopic complications — The types of complications seen with open and
endoscopic techniques are similar [17-20]. Proponents of the endoscopic technique cite evidence
that it leads to less postoperative incision pain and an earlier return to work compared with open
techniques [17]. However, critics of the endoscopic approach cite an apparent increased rate of
complications, which are related to the experience of the surgeon [21,22].
ASSESSMENT OF OUTCOME — Outcome studies have demonstrated that both open surgery and
endoscopic release produce subjective improvement in preoperative symptoms [8,9,12,17,23].
The choice of technique is largely surgeon-dependent. Each has its advantages and disadvantages
and each technique has a learning curve, which is greatest with the endoscopic technique.
Evaluation of pain relief and function is essential in determining the effectiveness of treatment for
musculoskeletal disorders. One study used a standardized, self-administered questionnaire to
assess the severity of symptoms and functional status at six weeks, three months, six months,
and two years after open (primarily limited open) surgery [24]. The following findings were noted:
Nocturnal pain, tingling, and numbness improved within six weeks.
Weakness and functional status improved more gradually, grip and pinch strength
initially worsened, returned to preoperative levels at about three months, and improved
significantly by two years.
Although 90 percent of patients had relief of either nighttime or daytime pain, only 73
percent said that they were completely or very satisfied with the results of the surgery.
These temporal patterns should be discussed with the patient to promote realistic expectations
about the results of surgery.
Using the same questionnaire, a prospective study was performed to determine the predictors of
return to work after carpal tunnel release (primarily open surgery) in a community-based cohort
[11]. Within six months, 77 percent had returned to their previous employment. The major risk
factors for poor outcome were scar tenderness and failure to relieve symptoms. Other negative
predictors of return to work included lack of an education beyond high school, consumption of
more than two drinks per day, smoking, female sex, use of an attorney or workers compensation
before surgery, and the presence of physical stresses such as multiple repetitive motion in the
workplace. Later follow-up of a related cohort showed that 82 percent of worker's compensation
recipients had returned to work at 30 months [25].
The outcome of endoscopic carpal tunnel release was "satisfactory" in 86 percent of 42 operations
upon 35 patients [23]. The mean time to return to ordinary daily activities and work were 14 and
25 days, respectively. One year after surgery, night pain and paresthesia were absent in 95 and
81 percent, respectively.
Open versus endoscopic techniques — In controlled trials comparing open versus endoscopic
carpal tunnel release, the long-term outcomes appear to be equivalent [26-29].
While some trials suggest a more rapid postoperative recovery and earlier return to
work with the endoscopic technique [17,28,30], others have found no significant
difference for time to return to work between the two techniques [26,27,29].
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The endoscopic technique may result in less postoperative pain and tenderness of the
scar [17], but the degree of this benefit appears to be modest [29].
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REFERENCES
Levine, DW, Simmons, BP, Koris, MJ, et al. A self-administered questionnaire for the
assessment of severity of symptoms and functional status in carpal tunnel syndrome. JBone Joint Surg Am 1993; 75:1585.
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Jablecki, CK, Andary, MT, So, YT, et al. Literature review of the usefulness of nerve
conduction studies and electromyography for the evaluation of patients with carpaltunnel syndrome. AAEM Quality Assurance Committee. Muscle Nerve 1993; 16:1392.
2.
Grundberg, AB. Carpal tunnel decompression in spite of normal electromyography. J
Hand Surg [Am]1983; 8:348.
3.
Curtis, RM, Eversmann, WW Jr. Internal neurolysis as an adjunct to the treatment of the
carpal-tunnel syndrome. J Bone Joint Surg Am 1973; 55:733.
4.
Rhoades, CE, Mowery, CA, Gelberman, RH. Results of internal neurolysis of the median
nerve for severe carpal-tunnel syndrome. J Bone Joint Surg Am 1985; 67:253.
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Gelberman, RH, Pfeffer, GB, Galbraith, RT, et al. Results of treatment of severe carpal-
tunnel syndrome without internal neurolysis of the median nerve. J Bone Joint Surg Am1987; 69:896.
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Lowry, WE, Follender, AB. Interfascicular neurolysis in the severe carpal tunnel
syndrome. A prospective randomized double-blind controlled study. Clin Orthop 1988;227:251.
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Lee, WP, Plancher, KD, Strickland, JW. Carpal tunnel release with a small palmar
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Chow, JCY. Endoscopic release of the carpal ligament for carpal tunnel syndrome: 22
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Katz, JN, Keller, RB, Fossel, AH, et al. Predictors of return to work following carpal
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Biyani, A, Downes, EM. An open twin incision technique of carpal tunnel decompression
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Van Heest, A, Waters, P, Simmons, B, Schwartz, JT. A cadaveric study of the single-
portal endoscopic carpal tunnel release. J Hand Surg [Am]1995; 20:363.
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MacDonald, RI, Lichtman, DM, Hanlon, JJ, Wilson, JN. Complications of surgical release
for carpal tunnel syndrome. J Hand Surg [Am]1978; 3:70.
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Bland, JD. Treatment of carpal tunnel syndrome. Muscle Nerve 2007; 36:167.15.
Assmus, H. [Correction and reintervention in carpal tunnel syndrome. Report of 185
reoperations]. Nervenarzt 1996; 67:998.
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Brown, RA, Gelberman, RH, Seiler JG, 3rd, et al. Carpal tunnel release. A prospective,
randomized assessment of open and endoscopic methods. J Bone Joint Surg Am 1993;
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75:1265.
Agee, JM, Peimer, CA, Pyrek, JD, Walsh, WE. Endoscopic carpal tunnel release: a
prospective study of complications and surgical experience. J Hand Surg [Am]1995;20:165.
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Murphy, RX Jr, Jennings, JF, Wukich, DK. Major neurovascular complications of
endoscopic carpal tunnel release. J Hand Surg [Am]1994; 19:114.
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Nath, RK, Mackinnon, SE, Weeks, PM. Ulnar nerve transection as a complication of
two-portal endoscopic carpal tunnel release: a case report. J Hand Surg [Am]1993;18:896.
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Lee, DH, Masear, VR, Meyer, RD, et al. Endoscopic carpal tunnel release: a cadaveric
study. J Hand Surg [Am]1992; 17:1003.
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Rowland, EB, Kleinert, JM. Endoscopic carpal-tunnel release in cadavera. An
investigation of the results of twelve surgeons with this training model. J Bone JointSurg Am 1994; 76:266.
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Ghaly, RF, Saban, KL, Haley, DA, Ross, RE. Endoscopic carpal tunnel release surgery:
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Katz, JN, Fossel, AH, Simmons, BP, et al. Symptoms, functional status in neuromuscular
impairment following carpal tunnel release. J Hand Surg 1995; 20:549.
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Katz, JN, Keller, RB, Simmons, BP, et al. Maine Carpal Tunnel Study: outcomes of
operative and nonoperative therapy for carpal tunnel syndrome in a community-basedcohort. J Hand Surg [Am]1998; 23:697.
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Jacobsen, MB, Rahme, H. A prospective, randomized study with an independent
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Macdermid, JC, Richards, RS, Roth, JH, et al. Endoscopic versus open carpal tunnel
release: a randomized trial. J Hand Surg [Am]2003; 28:475.
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Saw, NL, Jones, S, Shepstone, L, et al. Early outcome and cost-effectiveness of
endoscopic versus open carpal tunnel release: a randomized prospective trial. J HandSurg [Br]2003; 28:444.
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Atroshi, I, Larsson, GU, Ornstein, E, et al. Outcomes of endoscopic surgery compared
with open surgery for carpal tunnel syndrome among employed patients: randomisedcontrolled trial. BMJ 2006; 332:1473.
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GRAPHICS
Structures involved with carpal tunnel syndrome
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Cross-sectional anatomy of the wrist
Tendons and median nerve may be compressed by inflammation or infection because they
are encompassed by synovial sheath and flexor retinaculum.
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