What is carpal tunnel syndrome?

The carpal tunnel is a canal on the palm side of the wrist/hand formed by the carpal bones (floor) and transverse carpal ligament (roof). Within the canal is the medial nerve and nine tendons: the flexor pollicis longus, the four flexor digitorum superficialis and the four flexor digitorum profundus.

Median nerve entrapment at the carpal tunnel leading to ”carpal tunnel syndrome” is the most common nerve entrapment syndrome in humans with an incidence of 3.5-6.2%. (49-51) 

How is it diagnosed?

The diagnosis of carpal tunnel syndrome is primarily clinical, with most patients complaining of numbness and tingling in the thumb, index, and ring fingers of the hand with or without weakness. Electro diagnostic testing may be obtained to assess the severity of injury to the median nerve and differentiate from other common diagnoses such as a multiple nerve issue (peripheral neuropathy) or a nerve pinched in the neck (cervical radiculopathy). (34,52)  

Recent studies have increasingly shown the use of ultrasound as effective to evaluate and manage patients with peripheral nerve entrapment. (33-37) Diagnostic ultrasound has been shown to be as accurate as EMG/NCS with the diagnosis of carpal tunnel syndrome. (33-37)  Furthermore, the dynamic nature of ultrasound allows the provider to identify impingement that is related to motion, that may otherwise go missed on imaging or nerve testing

How is it treated?

Ultrasound guided carpal tunnel release with the Sonex device. The primary goal of any carpal tunnel release is to cut the transverse carpal ligament while avoiding injury to other neurovascular structures, to provide relief to the pinched median nerve. (55,56,64,72,73) Although it has been reported that endoscopic release may promote a faster recovery compared to the mini-open release, there has been raising concerns regarding increased complications due to the inability to visualize surrounding at-risk structures during the procedure. (55,56,60,72)  ultrasound guided carpal tunnel release combines a single or dual incision (Manos procedure) with direct ultrasound visualization of at-risk structures.(61,65,66,68-71,74-83) More recently, disposable device (SX-One MicroKnife, Sonex Health LLC, Rochester, MN) with ability to protect at risk neurovascular structures.

USG Sonex device carpal tunnel release and setup for patient

The Sonex device is a minimally invasive, single use, disposable that allows the user to take advantage of the benefits of ultrasound guidance, while establishing and maintaining a safe treatment area, via the use of expandable protective balloons. The device is inserted through a single <5 mm distal forearm skin incision and into the carpal tunnel, with the use of ultrasound-guidance.  The protective balloons allow for a consistent treatment area release the carpal tunnel. 

The procedure itself is done in the office with use of ultrasound-guidance, local anesthesia, and typically in under 10 minutes. 

What is the recovery like?

Typically, patients will leave with a small incision on the distal forearm. Most patients will resume usual activities within 3-7 days. Few patients have reported palm pain (Pilar pain) up to 21 days. Initial studies on this device have shown promising results, with faster recovery, less use of pain medication, and faster return to normal function with no reported neurovascular injuries to date. (54,65,77-79) 

What are the risks/complications?

As with any invasive procedure, there is always an extremely low risk of infection, that the procedure will not work or not provide relief, or that there is neurovascular injury. The use of ultrasound for pre-procedure screening as well as for guidance during the procedure theoretically reduces these risks. 

Despite many different devices being used to perform USGCTR, current publications on USGCTR report > 98% clinical success rate without any documented neurovascular injuries. (54,61-63,65-67,69,70,74,77-79,82-85) Cadaveric investigation using the same device to perform USCTR on cadaveric specimens documented a 100% rate of TCL release and no neurovascular injury. (85)  To date over 5000 ultrasound-guided carpal tunnel releases  have been performed with the Sonex device without any reported neurovascular complications. 


Conservative treatment options for carpal tunnel syndrome typically includes activity modification, occupational therapy, bracing, steroid injections, ultrasound guided nerve hydrodissection, and alternative medicine. For patients that fail conservative treatment carpal tunnel release is considered the definitive treatment option.  

Approximately a half a million carpal tunnel releases are performed annually in the United states with a total cost of over 2 billion dollars. (49-51)  Approximately 90% of patients report clinical improvement following surgical release. (49-51,53)

Although initially performed via a large (3-5 cm), palm incision (“traditional open release”), with a goal of improved cosmesis, reduced pain, and faster recovery, less invasive techniques have evolved. (54-57) The goal of less invasive treatments is improving cosmesis, reducing post-operative pain, and promoting faster recovery.   The currently available surgical techniques include mini-open release, via a single, 1-3 cm palmar incision, endoscopic release, via one (wrist) or two (wrist and palm) 1-2 cm incisions, and more recently ultrasound-guided release via a single < 1 cm wrist or palmar incision. (54,58-71) Rojo-Maudate et al published their randomized clinical trial comparing mini-open carpal tunnel release compared to ultrasound guided carpal tunnel release demonstrating 5 x faster functional recovery, pain reduction, and pain medication discontinuation. (62)


See the full list of Dr. Pourcho's reference publications on this topic

Research articles

Minimally Invasive Ultrasound-Guided CarpalTunnel Release: Preliminary Clinical Results

Henning PT, Yang L, Awan T, Lueders D, Pourcho AM.J Ultrasound Med. 2018Nov;37(11):2699-2706. doi: 10.1002/jum.14618. Epub 2018 Apr 2.PMID: 29608024 

Sonographic Changes After Ultrasound-Guided Release of theTransverse Carpal Ligament: A Case Report.

Latzka EW, Henning PT, Pourcho AM.PM R. 2018Oct;10(10):1125-1129. doi: 10.1016/j.pmrj.2018.02.018. Epub 2018 Mar 6.PMID: 29518589

Evidence For Ultrasound-Guided Carpal Tunnel Release

Wise A., Pourcho AM, P.T. Henning, Latzka EW. - Review ­– Archives of PM R, 2020