Carpal Tunnel Diagnosis: Can Ultrasound Streamline Patient Care?

Carpal tunnel syndrome is thought to affect anywhere from 4 to 10 million Americans. Yet the electrodiagnostic testing used for carpal tunnel syndrome diagnosis can be painful, costly and require multiple visits, so your patients may be hesitant to take next steps in their treatment.

Surgeons across the country are continuing to prescribe these electrodiagnostic testing procedures yet  research that found that ultrasound (US) can be a feasible alternative to electromyography (EMG) and nerve conduction studies (NCS) as a first-line confirmatory test.

In their recent study published in The Journal of Hand Surgery, Charles et al. sought to determine whether replacing EMG and nerve conduction studies with ultrasound to diagnose carpal tunnel syndrome would decrease patients’ time to surgery and the number of office visits required.

Comparing the Efficiency of Electrodiagnostic Testing and Ultrasound

For their study, Charles et al. selected 132 participants who had presented to the University of Pittsburgh Medical Center with numbness and tingling in the hand between 2013 and 2018, excluding any that had a history of carpal tunnel release surgery.

The treating surgeon used ultrasound to confirm carpal tunnel diagnosis in 34 patients, and EMG and nerve conduction studies for diagnosing carpal tunnel syndrome in 98 patients. The study authors found that the overall time to surgery for all participants was 41 days. The average number of medical visits, which included office visits to the surgeon and EMG/NCS physician prior to surgery, was 2.6 days.

But when the EMG/NCS and US groups were compared, the average time to surgery was much shorter in the US group—24 days vs. 47 days respectively, or nearly three weeks difference.

However, the average number of medical visits prior to surgery was still less for the US group compared to the EMG/NCS group at 1.2 vs. 3.1 visits respectively. The additional medical visits for the EMG/NCS group were found to largely consist of additional testing visits related to diagnostic testing and follow-up visits to review test results.

The study authors also noted that using US could be more cost-effective as well in diagnosing carpal tunnel syndrome. The 1.8 fewer medical visits in the ultrasound group, they found, would correlate with a $144 reduction in health care spending per patient.

However, Charles et al. acknowledge that there are some limitations to their study.

The patients studied were not randomly assigned to a diagnostic method, and therefore they may not be generalizable to all patients with symptoms of carpal tunnel syndrome. Patients were given a certain diagnostic method based solely on surgeon’s preference.

Additionally, ultrasound was conducted by a surgical specialist, and non-specialists may face different challenges. Also, they note, some physicians may choose to call patients with test results rather than have them come to the office, which would save an additional visit and possibly time to surgery as well.

However, they believe that overall, their study demonstrates that surgeon-conducted ultrasound for the confirmatory diagnosis of carpal tunnel syndrome may impact the efficiency of patient care.

Uncovering the Cause: Using Ultrasound to Determine Acute Carpal Tunnel Etiology

While Charles et al. found that using ultrasound can help to streamline patient care, a 2021 study published in Clinical Neurology and Neurosurgery determined that ultrasound is also able to detect the underlying causes of acute carpal tunnel syndrome that may not be discerned from electrodiagnostic testing alone.

In this 10-year retrospective analysis of 25 patients referred to an Electrodiagnostic Center with acute carpal tunnel syndrome, all patients had undergone EMG/NCS studies followed by high-resolution ultrasonography and color Doppler of the median nerve.

After examining the patient cases, Shields et al. considered the use of ultrasound in combination with the Doppler to be an “urgent test” needed to detect the cause of acute carpal tunnel syndrome. Ultrasound, they found, can detect many abnormalities such as decreased diameter of the nerve within the carpal tunnel and an increase in the cross-sectional area at the carpal tunnel inlet. It is also able to determine the specific cause of median nerve compression.

Additionally, according to a set of guidelines currently being developed at the Neurodiagnostic Center in Louisville, KY, ultrasound is able to provide accurate localizations where electrodiagnostic testing cannot, such as in determining the precise localization of retrograde and anterograde demyelination in patients with longstanding entrapment.

Using ultrasound to detect the persistent median artery, the study author found, was also helpful for preoperative planning especially when the vessel was found to be large. They believe that the use of ultrasound with Doppler of the median nerve as a complement to electrodiagnostic testing can help determine the best method of managing acute carpal tunnel syndrome and help to prevent permanent nerve damage.

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