Ultrasound-Guided Nerve Hydrodissection for Peripheral Entrapment Neuropathies

Ultrasound-guided nerve hydrodissection is a technique whereby fluid is used to separate a nerve from surrounding tissue as a means to alleviate symptoms of peripheral entrapment neuropathies. Pre-procedure scans are necessary to plan a safe procedure. Typically, the operator will target the site of nerve entrapment, which is just distal to the point of maximum cross-sectional area enlargement. Possible mechanisms for improvement in symptoms include improvement in the function of the nervi nervorum and vasa nervorum. These procedures offer an option after conservative measures (such as splinting and activity modification) have failed but before surgical intervention is considered. They also can play a role in post-surgical entrapment (such as after a failed carpal tunnel release) when scar tissue contributes to the mononeuropathy. Anesthetic, normal saline, dextrose 5% in water (D5W), hyaluronic acid, platelet-rich plasma (PRP), and corticosteroid have all been reported as solutions used to hydrodissect nerves, and D5W may be the preferred injectate for injectate preparations not utilizing corticosteroid. This expert clinical perspective reviews the choice of injectate, needle tracking technique, and the state of the science with regard to hydrodissection in carpal tunnel syndrome. Ulnar neuropathy at the elbow, radial tunnel syndrome, saphenous neuropathy, sciatic neuropathy, and fibular neuropathy are other conditions that may be amenable to hydrodissection in select cases. Further research is needed to define the ideal volume of injectate for these procedures and to more accurately identify the patient populations who will benefit most from these procedures.