Usefulness of Ultrasound for Detecting Suspected Peripheral Nerve Lesions in Diagnosis of Peripheral Neuropathy : Case Report and Brief Review of the Literature
A 50-year-old female presented with one week of numbness and tingling over the ulnar side of her right wrist, hand, and fourth and fifth fingers. There was no known history of trauma or injury to her head, neck, or right upper extremity. There was no evidence of muscle atrophy or skin changes in the affected extremity on physical examination. The hypothenar aspect of the right hand and the palmar side of the fourth and fifth fingers showed decreased sensation to light touch. Tinel's sign over the right ulnar nerve at the elbow and wrist and the median nerve and Phalen's test were all negative. Squeezing power of the fourth and fifth fingers of the right hand was decreased. Froment's sign was positive. Under the impression of right ulnar neuropathy, electromyogram (EMG) and nerve conduction velosity (NCV) were performed. Surprisingly, the electrophysiologic studies showed only mild median nerve abnormalities, and there were no abnormal findings on the right ulnar nerve. We had little confidence in these findings because of the short duration of the patient's symptoms, and ultrasound scanning of the right ulnar nerve along its expected course from the level of the elbow level distally was performed, revealing a mucoid cystic mass compressing the ulnar nerve at the proximal portion of Guyon's tunnel ().