PMC9947498_01
Preoperative physical examination. Bilateral thenar muscle atrophy, and the right thenar muscle was significantly atrophied compared to the contralateral side.
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F1
On examination, he had noticeable wasting of the thenar muscle in his right hand compared with the contralateral side, and the muscle strength of abductor pollicis brevis muscle and opponens pollicis muscle were slightly reduced to 5-/5 (MRC) (Figure 1). As shown in Figure 2 and Table 1, high-resolution ultrasonography of both wrists was performed and showed that the right median diameter becomes significantly thinner after entering the carpal tunnel, and the left median nerve is split into two branches by PMA, which are compressed and flattened as they pass through the carpal tunnel. Magnetic resonance imaging (MRI) of the wrist revealed that bilateral adductor pollicis extended to carpal tunnel causing compression of the median nerve, and axial fat-suppressed PD-weighted images at level of hook of hamate showed segmental swelling of median nerve, while PMA was missed on MRI (Figure 3, Supplementary Videos S1, S2). As shown in Supplementary Table S1 and Supplementary Figure S1, the median nerves cross-sectional area(CSA) at different axial MRI levels showed that the right median CSA became smaller after entering the carpal tunnel, while the left median CSA became larger.
Preoperative high-resolution ultrasonography of both wrists. (A) Axial ultrasonography of left wrist shows bifid median nerve (N) with persistent median artery (A,B) Sagittal ultrasonography of left carpal tunnel shows the left median nerve (Yellow arrow) becomes significantly thinner after entering the carpal tunnel. (C,D) Axial and Sagittal ultrasonography of right carpal tunnel also shows the right median nerve (Yellow arrow) becomes significantly thinner after entering the carpal tunnel.
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F2
As shown in Figure 2 and Table 1, high-resolution ultrasonography of both wrists was performed and showed that the right median diameter becomes significantly thinner after entering the carpal tunnel, and the left median nerve is split into two branches by PMA, which are compressed and flattened as they pass through the carpal tunnel. Magnetic resonance imaging (MRI) of the wrist revealed that bilateral adductor pollicis extended to carpal tunnel causing compression of the median nerve, and axial fat-suppressed PD-weighted images at level of hook of hamate showed segmental swelling of median nerve, while PMA was missed on MRI (Figure 3, Supplementary Videos S1, S2). Physical examination showed that bilateral thenar muscles still atrophied, but the atrophy was not further aggravated compared with two years ago (Supplementary Figure S2).
Preoperative MRI imaging of the bilateral hands and wrists. (A,C) Coronal sections of the left and right hand show an anomalous lumbrical muscle in carpal tunnel. (B) Axial section at left hamate hook level showing anomalous lumbrical muscle, bifid median nerve with persistent median artery. (D) Axial section at right hamate hook level showing anomalous lumbrical muscle and compressed median nerve. ALM, anomalous lumbrical muscle; RT, radial trunk of the median nerve; UT, ulnar trunk of the median nerve; PMA, persistant median artery; MN, median nerve.
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F3
Magnetic resonance imaging (MRI) of the wrist revealed that bilateral adductor pollicis extended to carpal tunnel causing compression of the median nerve, and axial fat-suppressed PD-weighted images at level of hook of hamate showed segmental swelling of median nerve, while PMA was missed on MRI (Figure 3, Supplementary Videos S1, S2).
Intraoperative photographs. (A,B) Intraoperative photographs of the left wrist show bifid median nerve, persistent median artery and anomalou lumbrical muscle. (C,D) Intraoperative photographs of the right wrist show compressed median nerve and anomalou lumbrical muscle. ALM, anomalous lumbrical muscle; RT, radial trunk of the median nerve; UT, ulnar trunk of the median nerve; PMA, persistant median artery; MN, median nerve.
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F4
Operative exploration was shown in Figure 4, the right median nerve was obviously compressed at the carpal tunnel, a thickened epineurium and a thinner nerve were seen, and the recurrent thenar branch of the median nerve was compressed by fibrous connective tissue.