|IMAGING FOR RESIDENTS – ANSWER
|Year : 2019 | Volume
| Issue : 1 | Page : 56-57
A man with numbness in the hands
Siam Tongprasert, Montana Buntragulpoontawee
Department of Rehabilitation Medicine, Chiang Mai University, Chiang Mai, Thailand
|Date of Submission||02-May-2018|
|Date of Acceptance||07-Jun-2018|
|Date of Web Publication||21-Feb-2019|
Dr. Montana Buntragulpoontawee
Department of Rehabilitation Medicine, Chiang Mai University, Chiang Mai
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Tongprasert S, Buntragulpoontawee M. A man with numbness in the hands. J Med Ultrasound 2019;27:56-7
| Section 2 – Answer|| |
A 38-year-old man had a 4-month history of numbness in both hands. The numbness was triggered by riding a motorcycle. Examination showed no wasting of both thenar eminences. A Phalen's maneuver elicited tingling in the right middle finger after 30 s. Tinel's sign could not be induced on percussion of the median nerves at the wrist. Neither weakness nor sensory loss was found. Electrodiagnostic examination was performed and there is neurophysiologic evidence of moderate median nerve dysfunction at both wrists. Ultrasound imaging was done at both wrists for guiding steroid injection. [Figure 1] shows left and right median nerves at the wrists. What is your diagnosis?
In [Figure 1], a linear 5–18 MHz transducer was placed transversely on both wrists at the level of distal wrist creases with the wrists fully supinated on a stable surface, demonstrating left and right median nerves. The left median nerve was enlarged with a cross-sectional area (CSA) of 0.13 cm2. [Figure 2] shows right median nerve, separating to two parts at the carpal tunnel inlet with the larger lateral part, CSA of 0.1 cm2 and a smaller medial part, CSA of 0.05 cm2 compatible with a bifid median nerve.
|Figure 2: Bifid median nerve at right wrist with a larger lateral part than medial part|
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| Discussion|| |
Carpal tunnel syndrome (CTS) is the most common reported nerve compression syndrome. In recent years, high frequency ultrasound (US) has become increasingly used by physiatrists for diagnostic and therapeutic purposes. Ultrasound is now a potential adjunctive tool in evaluation of neuromuscular disease that is an ideal complement to electrodiagnosis (EDx); the latter typically provides functional information, whereas ultrasound provides structural and in some cases additional functional information. The American Association of Neuromuscular and Electrodiagnostic Medicine evidence-based guideline in 2012 recommended that neuromuscular ultrasound measurement of median nerve cross-sectional area (CSA) at the wrist is accurate and may be offered as a diagnostic test for CTS (level A) and neuromuscular ultrasound probable adds value to electrodiagnostic studies when diagnosing CTS and should be considered in screening for structural abnormalities at the wrist in those with CTS (level B).
In the present case, the CSA of the median nerves on the short axis scan of both sides was increased and right bifid median nerve was found. Result from a recent retrospective study performed in 2017, bifid median nerves were found in 66 (4.6%) of the 1425 patients studied with US in screening for EDX abnormalities in patients with CTS symptoms. Another study found the prevalence of bifid median nerve and/or persistent median artery of 8.6% and 3.7%, respectively. The knowledge of the existence of bifid median nerve is an important factor in planning surgical decompression of median nerve to avoid nerve and persistent median artery injuries and/or potential relapse if decompression of both branches is not carried out. Although a bifid median nerve is not an independent factor for the development of CTS.
In conclusion, ultrasound provides high-resolution neural imaging that is easily accessible, noninvasive, low cost, fast tool which has novel diagnostic values that might modify the management of CTS by meticulous preoperative evaluation.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
The authors would like to thank Ms. Tarinee Prakobkhong, for technical support.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]