This is a pilot study designed to acquire data on the added value of hydrodissection when using a corticosteroid injection as a treatment for patients with carpal tunnel syndrome. Hydrodissection is part of a standard clinical care injection under ultrasound guidance in which the fluid is used to separate the nerve from surrounding structures.

Inclusion Criteria:

• Clinical CTS diagnosis with indication for steroid injection as determined by attending physician (if both hands are involved, only the side with the most severe CTS as indicated by electromyography (EMG) will be included) AND
• adult men and women between age 21 and 80 AND
• no more than moderate severity as indicated by EMG AND
• symptoms of numbness or tingling for at least 4 weeks in the median nerve distribution area AND
• classic or probable carpal tunnel syndrome on Katz-Stirrat hand diagram AND
• ability to complete English-language questionnaires and clinical evaluations AND
• is reachable by phone for the follow up contact

Exclusion Criteria:

Exclusion criteria are largely based on the premises of only including patients with idiopathic carpal tunnel syndrome without expected interferences of the acquisition of the ultrasound images or corticosteroid treatment.

• Previous Carpal Tunnel Release (CTR) or other volar wrist surgery on the study hand OR known tumor/mass OR deformity of the study hand/wrist OR
• previous history of steroid injection into carpal tunnel OR
• currently taking a steroid medication either regularly or on an as needed basis OR
• any of the following clinical diagnoses or conditions: Cervical radiculopathy; rheumatoid or other inflammatory arthritis, including gout; osteoarthritis in the wrist; renal failure; sarcoidosis; peripheral nerve disease; diabetes, thyroid disease or other metabolic disorder; pregnancy; amyloidosis; or major trauma (fractures or complete ligamentous tears) to the ipsilateral arm OR
• prisoners, institutionalized individuals, or others who may be considered vulnerable populations, such as individuals with dementia