Disclosures: Paul N. Andrews, MD: No financial relationships or conflicts of interest

Case Diagnosis: Anterior Interosseous Nerve (AIN) Syndrome following COVID-19 infection.

Case Description: A 59-year-old right hand dominant female with recent mild COVID-19 infection presented with 2 days of paresthesia and weakness in the right upper extremity.

Setting: Outpatient electrodiagnostic clinic.Assessment/

Results: Examination was notable for 4/5 strength in right wrist pronation and 1/5 strength in the right thumb and index finger flexion at the interphalangeal and distal interphalangeal joints, respectively. Froment’s sign was positive, and sensation was intact. Four weeks later electromyography (EMG) and nerve conduction studies (NCS) were performed. NCS were normal, while EMG demonstrated active denervation and early reinnervation in the flexor digitorum profundus (FDP) and flexor pollicis longus (FPL). The pronator quadratus (PQ) was deferred. EMG of the abductor pollicis brevis, pronator teres, flexor carpi radialis, first dorsal interosseus, extensor indicis proprius, biceps, triceps, deltoid, infraspinatus, and supraspinatus was normal.

Discussion: The AIN is a pure motor branch of the median nerve involved in 1 percent of upper extremity palsies. AIN syndrome classically presents with painless loss of function of the FDP, FPL and PQ. It is most frequently observed after trauma from penetrating injury, hematoma, or fracture; but also seen in neuralgic amyotrophy, which is commonly precipitated by an immunological stressor. In the absence of trauma, the patient’s presentation is most consistent with neuralgic amyotrophy after COVID-19, adding to the growing body of evidence associating the two. This is the first reported case, to our knowledge, of AIN syndrome following COVID-19 infection.

Conclusion: COVID-19 has been implicated in a variety of direct and indirect neurological sequalae. There is a growing association between the disease and neurogenic amyotrophy, highlighting the importance of accurate and timely neurological screening in this population.

Level of Evidence: Level V

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/post-covid-19-anterior-interosseous-nerve-syndrome-a-case-study/