• Endoscopic Carpal Tunnel Release Surgery for Carpal Tunnel Syndrome

    Case Presentation

    • A 71-year-old woman presented to our service with a painful right hand and paresthesia for the past 1 year.
    • Her symptoms affected her the most in digits 3 and 4, while her numbness with gripping activities was primarily in digits 1-3.
    • Aggravating activities included gripping, kayaking, and lying down.
    • She had low Oswestry Disability Index and percentage scores, indicating that the symptoms significantly interfered with her life.
    • She had no history of trauma or degenerative diseases of the wrist.
    • The patient demonstrated decreased sensitivity to Semmes-Weinstein monofilament testing in a median nerve pattern.
    • Tinels and Phalens tests were positive.
    • Electrodiagnostic studies demonstrated reduced amplitude, prolonged latency, and reduced conduction velocity of the right median nerve.
    • Ultrasound of the right hand showed swelling of the median nerve proximal to the transverse carpal ligament.
    • Cross-sectional area = 25 mm2, where 13 mm2 is two standard deviations from asymptomatic mean cross-sectional area.
    • Loss of fascicular echogenicity is detected within the nerve.

    Alternatives

    • Alternative options to surgery:
    • Conservative medical management, e.g., splinting
    • It is the primary treatment option.
    • However, the patient had already failed conservative management.
    • Steroid injection
    • Anticipated outcomes, including timing and likely degree of neurologic improvement, should be explained to the patient in detail.
    • Severity of carpal tunnel syndrome on EMG/ultrasound should be explained.
    • Thenar atrophy is infrequently fully reversed.
    • Expectations following surgery include temporary reduction in grip strength, decreased hand use, and wrist pain from the shift in the carpal bone anatomy.
    • Possible complications include persistent incisional pain, persistent pillar pain, infection, wound healing issues, nerve injury, need for revision surgery, etc.

    Approach

    • Right-sided endoscopic carpal tunnel release surgery was used to divide the transverse carpal ligament and decompress the median nerve with the goal of ameliorating the patients symptoms.

    Positioning

    • Select from one of the following, if appropriate:
    • Supine/Flat
    • The patient is placed supine with the arm abducted and forearm supinated and draped on a hand table or an arm board.
    • The patient remains awake throughout the procedure, with only local anesthetics and sedation needed.
    • A tourniquet with Bier block is essential.
    • Most hand endoscopes are not irrigating.
    • The Bier block reduces sensitivity associated with introducing the endoscope into the canal.
    • I set the tourniquet to 50 mm Hg greater than resting systolic blood pressure.
    • Turning
    • No turning
    • Not turned

    Anatomy

    • The median nerve lies deep to the flexor retinaculum (transverse carpal ligament).
    • The carpal tunnels floor and lateral walls are formed by the carpal bones, while the roof is formed by the transverse carpal ligament.
    • The transverse carpal ligament begins 1 cm proximal to the distal wrist crease and extends 3 cm distal to the crease and is 4 cm in length.
    • The palmar cutaneous branch of the median nerve comes off before the nerve crosses below the flexor retinaculum and travels above it.
    • Upon exiting the tunnel, the recurrent motor branch takes off from the median nerve from the underside of the carpal tunnel.
    • The flexor retinaculum should be cut completely to release the pressure on the median nerve.
    • Anatomical studies have suggested a variation, with reports of trans-ligamentous recurrent and palmar cutaneous branches, in which these nerves may pierce through the transverse carpal ligament.
    • Anatomical studies have also suggested a rare variation in which the recurrent branch emerges from the ulnar side of the median nerve.

    Operation

    • Endoscopic carpal tunnel release surgery:
    • The proximal wrist crease is selected.
    • Selecting the distal wrist crease may leave some fibers of the transverse carpal ligament intact.
    • Approximately 1-cm skin incision is planned.
    • Endoscopic carpal tunnel release surgery:
    • 2 mL of a 0.5% bupivacaine hydrochloride (Marcaine) with epinephrine is injected in the skin and subcutaneous tissues at the planned procedural site for post-procedural anesthesia and hemostasis.
    • Endoscopic carpal tunnel release surgery:
    • The subcutaneous tissues are dissected to visualize the antebrachial fascia.
    • Any cutaneous nerves in the subcutaneous fat are mobilized and not divided.
    • The antebrachial fascia is then opened transversely.
    • The antebrachial fascia is confluent with the transverse carpal ligament, entering the carpal tunnel.
    • The median nerve can be visualized here, to a limited extent.
    • Endoscopic carpal tunnel release surgery:
    • A synovial elevator is used to free the undersurface of the transverse carpal ligament.
    • The transverse carpal ligament has a distinct ridge or washboard feel.
    • Complete dissection of the undersurface of the transverse carpal ligament is necessary for the endoscope to visualize the undersurface.
    • Sequential dilators can be passed into the carpal tunnel.
    • Endoscopic carpal tunnel release surgery:
    • The endoscope is used to enter the carpal tunnel with good visualization of the horizontal fibers, confirming the identity of the transverse carpal ligament.
    • Endoscopic carpal tunnel release surgery:
    • Downward pressure on the transverse carpal ligament improves visualization.
    • To ensure distal enough decompression, the endoscope is palpated in the subcutaneous space.
    • The transverse carpal ligament should be divided completely through multiple passes of the endoscopic knife, using the nose of the endoscope to widen the division of the transverse carpal ligament, with visualization of the underside of the palmaris brevis muscle and palmar aponeurosis.
    • The fibers of the palmar aponeurosis are vertical, not horizontal like the transverse carpal ligament.
    • Once the endoscope is removed, pressure should be applied to the wrist for hemostasis as the tourniquet is released and hyperemia ensues.
    • The operative field is finally copiously lavaged with normal saline and bacitracin.
    • Endoscopic carpal tunnel release surgery:
    • The skin incision should be closed in the standard fashion with a 4-0 nylon in horizontal mattress fashion.

    Post Op

    • The wrist is bandaged with an adhesive bandage, and patients are encouraged to begin wrist mobilization as soon as possible.
    • Patients are typically discharged home shortly after surgery.
    • Most of my carpal tunnel releases are performed on Friday to allow the weekend for recovery.
    • My postoperative recommendations are as follows:
    • Ice and elevation for 72 hours postoperatively is recommended.
    • In the absence of contraindications, 400 mg ibuprofen q 6hrs and 1,000 mg acetaminophen q 6 hours for 72 hours postoperatively is recommended.
    • A short prescription of tramadol is recommended for some patients (only if they are narcotic-nave). Patients rarely use tramadol when taking anti-inflammatories as above.

    Outcome

    • No complications were observed.
    • In a phone call 2 days after surgery, the patient reported significant improvement in her pain and numbness.
    • The patient returned to her usual activities without limitations or complaints.
    • Sutures are usually removed 2 weeks after surgery.

    Pearls and Pitfalls

    • This case demonstrates a patient with carpal tunnel syndrome that was managed successfully with endoscopic carpal tunnel release surgery.
    • Identifying the transverse carpal ligament and cutting it completely is essential to relieving the patients complaints.
    • Detailed knowledge of the anatomy and anatomical variations of the median nerve along with meticulous dissection are essential in carpal tunnel surgery.
    • Preoperative imaging of the median nerve is essential prior to endoscopic release as the procedure is blind to nerve pathology. Either MRI or ultrasound can be used.

    Discussion

    • The endoscopic approach is associated with a small incision and less an incidence of scar tenderness and pillar pain compared to the open approach.
    • The endoscopic approach is associated with a quicker return to work.
    • However, the major disadvantage of the endoscopic approach is the potentially higher rate of or shorter duration until recurrence/reoperation. Additionally, there is a learning curve for endoscopic surgery.

    References

    • Vasiliadis HS, Georgoulas P, Shrier I, Salanti G, Scholten RJ. Endoscopic release for carpal tunnel syndrome. Cochrane Database Syst Rev. 2014(1):CD008265.
    • Atroshi I, Hofer M, Larsson GU, Ranstam J. Extended follow-up of a randomized clinical trial of open vs endoscopic release surgery for carpal tunnel syndrome. JAMA. 2015;314(13):1399-401.
    • Thoma A, Veltri K, Haines T, Duku E. A meta-analysis of randomized controlled trials comparing endoscopic and open carpal tunnel decompression. Plast Reconstr Surg. 2004;114(5):1137-46.
    • Keiner D, Gaab MR, Schroeder HW, Oertel J. Long-term follow-up of dual-portal endoscopic release of the transverse ligament in carpal tunnel syndrome: an analysis of 94 cases. Neurosurgery. 2009;64(1):131-7; discussion 7-8.

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