Disclosures: Jordan M. Stumph, MD: No financial relationships or conflicts of interest

Case Description: A 65-year-old man presented with acute pain in the left shoulder, radiating to the left lateral elbow and posterior forearm. Over two months, he additionally developed left hand weakness and numbness of the medial forearm. Exam was pertinent for weakness of left hand intrinsic muscles with left first dorsal interosseous and hypothenar muscle atrophy. MRI cervical spine demonstrated mild-moderate left foraminal stenosis at each level from C5- T1. MRI brachial plexus did not reveal a focal brachial plexus lesion or abnormal enhancement. MRI left elbow demonstrated a thickened, high-signal ulnar nerve within the cubital tunnel. Electrodiagnostic studies showed a mild-moderate ulnar neuropathy across the left elbow and denervation of radial-innervated left arm muscles, suggestive of a brachial plexopathy or mononeuritis multiplex. Patient was referred for diagnostic ultrasound of the left brachial plexus after evaluation by a peripheral neurosurgeon.

Setting: Outpatient rehabilitation medicine practice at a tertiary academic institution.

Patient: 65-year-old man with well-controlled diabetes, diagnosed with Parsonage-Turner syndrome affecting the left radial and ulnar nerves. Assessment/

Results: Ultrasound evaluation revealed diffuse enlargement of the radial, median, and ulnar nerves with superimposed focal compression of the radial nerve within the Arcade of Fröhse, median nerve at the carpal tunnel, and ulnar nerve beneath the flexor carpi ulnaris.

Discussion: Based on the aforementioned results, the patient underwent left ulnar nerve decompression surgery. Radial nerve decompression was considered but deferred due to clinical improvement in that distribution.

Conclusion: This case demonstrates neuromuscular ultrasound’s emerging importance in evaluating focal entrapments superimposed upon diffuse nerve enlargement seen in Parsonage-Turner syndrome. While electrodiagnostics demonstrated ulnar neuropathy across the elbow, it did not reveal median and radial nerve entrapment seen on ultrasound. High-frequency ultrasound additionally aids in pre-surgical planning of decompression, thus improving prognosis and function in a syndrome otherwise considered to be self-limiting.

Level of Evidence: Level V

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/ultrasound-evaluation-and-diagnosis-of-superimposed-median-radial-and-ulnar-entrapment-neuropathies-in-parsonage-turner-syndrome-a-case-report/