PMC7750753_01
Mild atrophy of the dorsal and palmar interosseous muscles was found in the left
hand.
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Atrophy of the dorsal and palmar interosseous muscles was found (Figure 1).
Axial view obtained using ultrasonography shows the occult ganglion (arrow) and the
ulnar nerve (arrowhead) at the level of the medial epicondyle.
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Axial view obtained using MRI shows the occult ganglion (arrow) inside the ulnar nerve
(arrowhead) at the level of the medial epicondyle.
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Netherlands; Figure 3) showed an occupied lesion inside the ulnar nerve at the medial epicondyle of the humerus. Nerve conduction study results indicated the motor nerve conduction velocity of the ulnar nerve on the affected side as 40.2 m/s between the upper elbow and the below elbow, compared to 54.4 m/s on the unaffected side.
(a) The ulnar nerve was compressed by the Osborn ligament over the flexor carpi ulnaris
(FCU) (arrow). (b) Decompression was performed by releasing the Osborn ligament and FCU
fascia. Neuroedema of the ulnar nerve (arrowhead) caused by compression was found at the
proximal position of the fibrous bundle. (c) We tried to resect the small ganglion as en
bloc. However, the ganglion was ruptured (arrowhead).
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The ulnar nerve was compressed by Osborn's ligament, which was apparently harder and thicker than normal (Figure 4(a)). Neuroedema of the ulnar nerve caused by compression was found at the proximal position of the fibrous bundle (Figure 4(b)). However, the ganglion was ruptured (Figure 4(c)).