651 - Forearm and Hand Pain and Weakness after Motor Vehicle Accident

Left dorsal forearm pain consistent with radial neuritis in the setting of a space-occupying ganglion cyst of the elbow. Progressive left-hand weakness in a predominantly ulnar/C8-T1 distribution.

Case Description:

38-year-old female with no significant medical history who presented for evaluation of left upper extremity numbness and weakness 49 days after a motor vehicle collision. Patient reports difficulty lifting her arms overhead and weakness in her grasp and fine motor activities.

Physical exam demonstrated 4/5 strength in the left first dorsal interosseous, abductor digiti minimi, abductor pollicis brevis, and extensor indicis proprius. Otherwise, 5/5 strength. Pain in the dorsal aspect of the forearm with numbness and pain over the dorsum of the thumb, 2^nd, and 3^rd fingers. Tenderness to palpation over ulnar aspect of distal forearm and cubital tunnel.

Magnetic resonance imaging of the cervical spine showed mild flattening of the ventral cord at left C5-C6 and right C6-C7. No electrodiagnostic or sonographic evidence of median neuropathy, ulnar neuropathy, or cervical radiculopathy. Ultrasound showed a ganglion cyst against the radial nerve proximal to the branch of the posterior interosseous nerve.

Discussions:

Radial neuritis is an uncommon peripheral neuropathy. Additionally, the sensory distribution of the radial nerve is known to be variable, and therefore the symptoms may mimic more common etiologies, such as cervical radiculopathy. Additionally, this case demonstrates radial neuritis prior to the posterior interosseous nerve branching off, illustrating why the patient has both sensory and motor symptoms. This case also illustrates the importance of dynamic ultrasound when trying to diagnose peripheral neuropathies.

Conclusions:

Radial neuritis in the setting of a space-occupying ganglion cyst of the elbow can present as forearm and hand pain and weakness.