Neuralgic amyotrophy and COVID-19 infection: 2 cases of spinal accessory nerve palsy.

OBJECTIVE: Neuralgic amyotrophy (NA), also known as Parsonage-Turner syndrome is often triggered by mechanical stress or viral infections. We reported 2 cases of shoulder weakness and amyotrophy related to spinal accessory nerve (SAN) palsy due to neuralgic amyotrophy occurring after COVID-19 infection. METHODS: For both patients, clinical history, clinical examination, electrodiagnostic (EDX), and imaging examinations invalidated other diagnoses but confirmed NA diagnosis. RESULTS: The NA involved only the SAN in both cases. EDX revealed a characteristic axonal lesion found in NA. SAN conduction study revealed normal latencies and low compound motor action potential amplitude for trapezius muscle when needle examination demonstrated a neurogenic pattern and denervation signs in the trapezius muscle. Both patient's MRI revealed denervation T2 hyper signal in impaired muscles, without any mass, cyst, injury, fibrous band, or tearing signs along SAN course. CONCLUSIONS: The COVID-19 infection could be the trigger for NA as many other viruses, and as it is a possible trigger for Guillain-Barré syndrome.