Ultrasound-guided percutaneous injection, hydrodissection, and fenestration for carpal tunnel syndrome: description of a new technique

Objective: Carpal tunnel syndrome, caused by compression of the median nerve deep to the flexor retinaculum, is the most common entrapment neuropathy. Most patients are initially treated with conservative measures such as splinting. When conservative measures fail, interventional techniques are considered the next step. Many studies have appeared comparing open surgical flexor retinaculum release to blind injections of corticosteroids into the carpal tunnel, but neither technique has proven superior to the other. Advantages of injection are: lower level of invasiveness, faster recovery, and ease of the technique. Occasional failures and complications occur with all techniques. Method: We have been using an ultrasound-guided procedure of percutaneous hydrodissection of the median nerve away from the deep surface of the flexor retinaculum, followed by fenestration of the flexor retinaculum along a path parallel to the long axis of the arm, starting from the level of the distal part of the capitate bone and progressing proximally to the level of the radio-lunate joint, the intent being to lower the pressure exerted by the flexor retinaculum on the nerve. We have treated a series of 44 wrists in 34 patients who had electrically-proven carpal tunnel syndrome, using this technique of hydrodissection and fenestration, performed using standard injection equipment and an ultrasound system. All patients had typical carpal tunnel syndrome symptoms, and presented to us for interventional treatment after conservative measures have failed. No patient had had previous surgery, and two had had blind carpal tunnel steroid injections, without hydrodissection or fenestration. Outcomes were defined as: * Excellent-all symptoms resolved, * Fair-some residual symptoms, or return of symptoms, but improved compared to prior to procedure, * Failure-required open surgical release. First follow-up periods after procedure ranged from 3-60 weeks, averaging 32 weeks. Second follow up periods varied from 25-96 weeks, averaging 63 weeks. Patients were contacted by telephone, or seen in follow-up in clinic, to determine outcomes. Results: * Excellent at first followup, lost to second followup--two wrists, too little time to judge second followup--One wrist * Excellent at first followup and second followup--19 wrists * Excellent at first followup, fair at second followup--9 wrists * Fair at first followup and second followup--five wrists * Fair at first followup, lost to second followup--o