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Carpal Tunnel

  • Editor(s): Todd W Thomsen, MD, Gary S Setnik, MD, FACEP
  • Section Editor(s): Phillip M Harter, MD
  • Contributor(s): Carmie Chan, MD
PRE-PROCEDURE
INDICATIONS
  • Treatment can be nonoperative or operative, and should be based on the following:
    • Nonoperative treatment
      • Night splints and injection of cortisone preparations
      • Five important factors in determining success:
        • Age over 50 years
        • Duration longer than 10 months
        • Constant paresthesia
        • Stenosing flexor tenosynovitis
        • Positive Phalen test result in less than 30 seconds.
      • Cure rate with medical therapy:
        • 0 factors: 66%
        • 1 factor: 60%
        • 2 factors: 20%
        • 3 factors: 10%
        • 4-5 factors: 0%
    • If symptoms are mild and there is no thenar muscle atrophy, medical therapy can be attempted
  • Operative management
    • If signs and symptoms are persistent and progressive, especially if they include thenar atrophy, operative management is indicated.
CONTRAINDICATIONS
  • No specific contraindications to open release
  • Contraindications for endoscopic surgery include:
    • Need for neurolysis, tenosynovectomy, Z-plasty of the transverse carpal ligament, or decompression of Guyon's canal
    • Space-occupying lesion or other severe abnormality of the muscles, tendons, or vessels in the carpal tunnel.
    • Infection or severe hand edema
    • Tenuous vascular status of the upper extremities
    • Revision surgery for unresolved or recurrent carpal tunnel syndrome
    • Significant anatomical variation in the median nerve
      • This is suggested by clinical findings of wasting in the abductor pollicis brevis muscle without significant median sensory changes.
    • Previous tendon surgery or flexor injury
      • This causes scarring in the carpal tunnel, preventing the safe placement of the instruments for endoscopic carpal tunnel release.
EQUIPMENT
  • Standard hand set
  • Open procedure
    • Blunt dissector, such as a McDonald dissector
  • Agee single-portal technique
    • MicroAire Carpal Tunnel Release System
      • Includes synovial elevator and several hamate finders
    • Ragnell right-angle retractors
    • Tenotomy scissors
  • Chow two-portal technique
    • ECTRA System
      • 4.0 mm × 30± endoscope
      • Slotted cannula
      • Rigid obturator
      • Curved blunt dissector
      • Self-retaining retractor
      • Hand holder
      • Probe
      • Palmar arch suppressor ("Chow catcher")
    • ECTRA Disposable Kit
      • Probe knife
      • Retrograde knife
      • Triangle knife
      • Hand pad
ANATOMY
  • Boundaries of carpal tunnel:
    • Dorsal: transverse arch of the carpal bones
    • Ventral: flexor retinaculum, with three components: deep forearm fascia (most proximal), transverse carpal ligament (TCL) (over the wrist) and distal aponeurosis between thenar and hypothenar muscles (most distal)
      • Flexor retinaculum attachments:
        • Medial: pisiform and hook of hamate
        • Lateral: scaphoid tubercle and trapezium at the beak and body
    • Medial (ulnar): hook of hamate, triquetrum, pisiform
    • Lateral: scaphoid, trapezium, fibroosseous flexor carpi radialis (FCR) sheath
  • Once through the carpal tunnel, the median nerve divides into:
    • Lateral digital branch
      • Enters the thenar eminence and supplies abductor pollicis brevis, flexor pollicis brevis, opponens pollicis, and first lumbrical muscles
    • Medial digital branch
      • Divides into variable number of digital nerves; supplies second lumbrical muscle
  • Carpal tunnel pressures (mean):
    • Wrist in neutral position
      • 25 mm Hg, healthy
      • 32 mm Hg, CTS
    • 90 degrees of wrist flexion
      • 31 mm Hg, healthy
      • 99 mm Hg, CTS
    • 90 degrees of wrist extension
      • 30 mm Hg, healthy
      • 110 mm Hg, CTS

PROCEDURE
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Agee technique. <B>A</B>, U-shaped flap elevated in palmar direction. Synovium elevator prepares wrist for optimal endoscopic view by separating synovium from deep side of ligament. Redrawn from Agee JM, McCarroll HR, North ER: Endoscopic carpal tunnel release using the single proximal incision technique. Hand Clin 1994;10:647.
Figure 4 :  Agee technique. A, U-shaped flap elevated in palmar direction. Synovium elevator prepares wrist for optimal endoscopic view by separating synovium from deep side of ligament. Redrawn from Agee JM, McCarroll HR, North ER: Endoscopic carpal tunnel release using the single proximal incision technique. Hand Clin 1994;10:647.

Agee technique. <B>B</B>, Safe zone of blade elevation is triangle defined by a, ulnar half of distal edge of transverse carpal ligament; b, ulnar border of median nerve (i.e., its common digital branch to long/ring web space); and c, superficial palmar arch. Redrawn from Agee JM, McCarroll HR, North ER: Endoscopic carpal tunnel release using the single proximal incision technique. Hand Clin 1994;10:647.
Figure 4 :  Agee technique. B, Safe zone of blade elevation is triangle defined by a, ulnar half of distal edge of transverse carpal ligament; b, ulnar border of median nerve (i.e., its common digital branch to long/ring web space); and c, superficial palmar arch. Redrawn from Agee JM, McCarroll HR, North ER: Endoscopic carpal tunnel release using the single proximal incision technique. Hand Clin 1994;10:647.

Agee technique. <B>C</B>, Longitudinal cross section through carpal tunnel depicting blade elevation in triangular safe zone. Redrawn from Agee JM, McCarroll HR, North ER: Endoscopic carpal tunnel release using the single proximal incision technique. Hand Clin 1994;10:647
Figure 4 :  Agee technique. C, Longitudinal cross section through carpal tunnel depicting blade elevation in triangular safe zone. Redrawn from Agee JM, McCarroll HR, North ER: Endoscopic carpal tunnel release using the single proximal incision technique. Hand Clin 1994;10:647

Agee technique. <B>D</B>, Initial release facilitates accurate viewing and division of ligament. Redrawn from Agee JM, McCarroll HR, North ER: Endoscopic carpal tunnel release using the single proximal incision technique. Hand Clin 1994;10:647
Figure 4 :  Agee technique. D, Initial release facilitates accurate viewing and division of ligament. Redrawn from Agee JM, McCarroll HR, North ER: Endoscopic carpal tunnel release using the single proximal incision technique. Hand Clin 1994;10:647

Agee technique. <B>E</B>, Inspection of incised transverse carpal ligament in which left view depicts incomplete release as V-shaped defect, with superficial fibers of transverse carpal ligament remaining intact. Center view depicts complete release of ligament after reinsertion of blade assembly. Fat and transverse fibers of palmar fascia that remain palmar to divided ligament can be noted. View on right demonstrates that rotating blade assembly approximately 20 degrees in either direction causes separated cut edges of ligament to fall into window. Redrawn from Agee JM, McCarroll HR, North ER: Endoscopic carpal tunnel release using the single proximal incision technique. Hand Clin 1994;10:647
Figure 4 :  Agee technique. E, Inspection of incised transverse carpal ligament in which left view depicts incomplete release as V-shaped defect, with superficial fibers of transverse carpal ligament remaining intact. Center view depicts complete release of ligament after reinsertion of blade assembly. Fat and transverse fibers of palmar fascia that remain palmar to divided ligament can be noted. View on right demonstrates that rotating blade assembly approximately 20 degrees in either direction causes separated cut edges of ligament to fall into window. Redrawn from Agee JM, McCarroll HR, North ER: Endoscopic carpal tunnel release using the single proximal incision technique. Hand Clin 1994;10:647

Agee technique. <B>F</B>, Tenotomy scissors used to release forearm fascia proximal to skin incision. Redrawn from Agee JM, McCarroll HR, North ER: Endoscopic carpal tunnel release using the single proximal incision technique. Hand Clin 1994;10:647.
Figure 4 :  Agee technique. F, Tenotomy scissors used to release forearm fascia proximal to skin incision. Redrawn from Agee JM, McCarroll HR, North ER: Endoscopic carpal tunnel release using the single proximal incision technique. Hand Clin 1994;10:647.

Chow technique. <B>A</B>, Incision for entry portal. Redrawn from Chow JC: Endoscopic carpal tunnel release. Two-portal technique. Hand Clin 1994;10:673.
Figure 5 :  Chow technique. A, Incision for entry portal. Redrawn from Chow JC: Endoscopic carpal tunnel release. Two-portal technique. Hand Clin 1994;10:673.

<b>B</b>, Incision for exit portal. Redrawn from Chow JC: Endoscopic carpal tunnel release. Two-portal technique. Hand Clin 1994;10:673.
Figure 5 :  B, Incision for exit portal. Redrawn from Chow JC: Endoscopic carpal tunnel release. Two-portal technique. Hand Clin 1994;10:673.

<B>C</B>, Carpal ligament is identified by transverse fibers. Redrawn from Chow JC: Endoscopic carpal tunnel release. Two-portal technique. Hand Clin 1994;10:673.
Figure 5 :  C, Carpal ligament is identified by transverse fibers. Redrawn from Chow JC: Endoscopic carpal tunnel release. Two-portal technique. Hand Clin 1994;10:673.

<B>D</B>, First cut made with probe knife, cutting distal to proximal, to release distal edge of carpal ligament. Redrawn from Chow JC: Endoscopic carpal tunnel release. Two-portal technique. Hand Clin 1994;10:673.
Figure 5 :  D, First cut made with probe knife, cutting distal to proximal, to release distal edge of carpal ligament. Redrawn from Chow JC: Endoscopic carpal tunnel release. Two-portal technique. Hand Clin 1994;10:673.

<B>E</B>, Second cut made with triangle knife, with cut made in midsection of carpal ligament. Redrawn from Chow JC: Endoscopic carpal tunnel release. Two-portal technique. Hand Clin 1994;10:673.
Figure 5 :  E, Second cut made with triangle knife, with cut made in midsection of carpal ligament. Redrawn from Chow JC: Endoscopic carpal tunnel release. Two-portal technique. Hand Clin 1994;10:673.

<B>F</B>, Third cut made by placing retrograde knife in second cut and drawing it distally to join first cut. Redrawn from Chow JC: Endoscopic carpal tunnel release. Two-portal technique. Hand Clin 1994;10:673.
Figure 5 :  F, Third cut made by placing retrograde knife in second cut and drawing it distally to join first cut. Redrawn from Chow JC: Endoscopic carpal tunnel release. Two-portal technique. Hand Clin 1994;10:673.

<B>G</B>, Proximal section of carpal ligament is identified, and proximal edge is released; probe knife is used to make fourth cut. Redrawn from Chow JC: Endoscopic carpal tunnel release. Two-portal technique. Hand Clin 1994;10:673.
Figure 5 :  G, Proximal section of carpal ligament is identified, and proximal edge is released; probe knife is used to make fourth cut. Redrawn from Chow JC: Endoscopic carpal tunnel release. Two-portal technique. Hand Clin 1994;10:673.