1518 - A Rare Case of Acute Motor Axonal Neuropathy (AMAN): Electrodiagnostic Findings and Functional Recovery with IVIG and Rehabilitation.

A 59-year-old female presented to the electrodiagnostic lab with one month of bilateral leg weakness, followed by bilateral hand weakness with difficulty opening jars and urinary retention. Upper extremities were 3/5, and she was unable to perform lower extremity testing due to weakness. She denied any infectious symptoms or recent vaccinations. At an outside facility, lumbar puncture revealed albuminocytologic dissociation, and MRI showed enhancement of the ventral roots. EMG was concerning for an AMAN variant of acute inflammatory demyelinating polyradiculoneuropathy (AIDP), and she was treated with IVIG for 5 days.
 

Case Description:

The most pertinent electrodiagnostic findings included markedly attenuated bilateral tibial distal motor latencies with absent F waves. Bilateral fibular motor evoked responses were absent. Left ulnar distal motor latency was normal but with markedly reduced amplitudes. The left ulnar sensory evoked response was normal. Bilateral superficial peroneal and left sural responses were normal. EMG showed a predominance of denervation involving proximal muscles. The electrodiagnostic study was suggestive of AMAN. She completed inpatient rehabilitation and outpatient robotic therapy, physical therapy (PT), and occupational therapy (OT), which significantly improved her function, enabling her to ambulate without assistive devices.
 

Discussions:

Acute Motor Axonal Neuropathy is a rare variant of Guillain-Barré Syndrome characterized by rapid-onset muscle weakness due to motor nerve axon damage. It is often triggered by infections, particularly Campylobacter jejuni. Unlike other GBS types, AMAN typically lacks sensory loss and is more common in Asia and Central America. Diagnosis involves nerve conduction studies showing motor axonal degeneration. Recovery varies, with some improving quickly and others requiring extended rehabilitation.
 

Conclusions:

This case underscores the importance of early diagnosis and intervention. Electrodiagnostic findings, along with timely IVIG treatment and a comprehensive rehabilitation program, led to substantial functional recovery. It highlights the potential for positive outcomes with prompt management of AMAN.