Plexiform Neurofibroma as a Cause of Carpal Tunnel Syndrome in a Radial Deficiency Patient
Kejia HU, MD1; Ziv Williams, MD2; Wendong Xu, MD, PhD3
1Huashan Hospital, Shanghai, China; 2MGH, Boston, MA, 3Fudan University, Shanghai, China
A 31-year-old female presented with a 5-year history of an enlarged mass in her right wrist with predominant nocturnal numbness in the right hand, including the palmar surface of the thumb, second, third, and lateral half of the fourth finger and over the thenar eminence. She also had a history of type IV deficiency of the thumb, suggesting a floating thumb. Physical examination revealed diffuse swelling of the wrist with positive Tinel's sign over the median nerve and a negative Phalen's test. X-rays revealed a right first metacarpus deficiency. MRI scans showed a nodule following the median nerve trajectory that was isointense to the muscle on T1-weighted images and hyperintense on T2-weighted images. Electrodiagnostic tests confirmed an impairment of the sensory conduction velocity of the median nerve of the wrist. Intra-operatively, the right flexor carpi radialis and palmaris longus tendons were absent. The median nerve had expanded spindle-shaped (2 cm [length] × 1 cm [width] × 1 cm [depth]) at the carpal tunnel, with transverse carpal ligament thickening. The nerve tracts were stiff, thickened, and circuitous. We released the compression with an incision in the distal part of the transverse carpal ligament and performed interfascicular neurolysis. The floating thumb was also removed, as the patient's request. The pathologic diagnosis was plexiform neurofibroma. At one-year follow-up there was no evidence of local recurrence. Our case sheds light on anatomy and possible etiological association which may help clinical management.
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