Acute Motor Axonal Neuropathy presenting as Person-in-a-Barrel syndrome

ABSTRACT

Background and aims: Person-in-a-barrel syndrome (PIBS) is clinically characterized by brachial diparesis, with preserved cranial and crural muscle strength. It is a rare neurological syndrome most commonly caused by bilateral and symmetric injury of the motor neurons that control the upper limb movements, including bilateral injury to the brain hemispheres, brainstem, cervical spinal cord, brachial plexus, or peripheral nerves. Methods: N/A Results: A 70-year-old male patient with a history of hypertension, dyslipidaemia and hyperuricemia was admitted with an acute and rapidly progressive (10 days of evolution) bilateral upper limb weakness. The patient denied respiratory or gastrointestinal symptoms, fever or recent cervical trauma/pain. Two weeks earlier he was given the first dose of the Pfizer-BioNTech™ vaccine for COVID- 19. The neurological examination revealed severe brachial diparesis and generalized hyporeflexia. Ancillary testing revealed positive serum anti-GM1 and GD1b antibodies. The PCR for SARS-CoV-2 was negative (with positive serum T-Spike antibodies). CSF analysis and Brain/Spinal MRI were normal. The electromyography and nerve conduction studies disclosed diffuse motor conduction blocks in the upper extremities, ultimately fulfilling criteria for Acute Motor Axonal Neuropathy (AMAN) with reversible conduction failure. Intravenous human immunoglobulin (0.4g/kg/day, 5 days) and rehabilitation were started, with subsequent motor improvement. Conclusion: To our knowledge this is the first case of AMAN presenting as PIBS. We intend to highlight that AMAN should be added to the list of causes of this syndrome. The role of the COVID-19 vaccine in this case remains uncertain, and it is not possible, at this moment, to infer causality.