We report the case of a male 20 years old, previously healthy presented with numbness and pain along the little left finger.

He complained about diffculty in holding objects and reported a wrist trauma 2 months earlier.

On examination ,there was a pulsatile mass on the ulnar border of the wrist (figure 1) , a remarkable atrophy of the palmer and dorsal interosseous (figure 2) , abductor digiti minimi ,and abdcutor pollicis muscle.

Wartenberg and Tinel signs were positive in the left hand and Froment test was also positive.

Prolonged distal sensory latency of 2.56 ms (compared to 3.4 ms in the right hand) was showed in the conduction of velocity studies of the left ulnar nerve ,also a decreased sensory velocity , a lowered conduction velocity of the motor nerve at the wrist and reduced amplitude of the interosseous muscle.

These electrodiagnostic studies suggest compression of the ulnar nerve at the wrist.

Magnestic resonance imaging was not performed however doppler ultrasound showed an aneurysm of the ulnar artery comperssing the ulnar nerve at the guyon’s canal.