1613 - Atypical Guillain-Barré Syndrome Masquerading as Cauda Equina Syndrome: A Case Report

We describe a case of a 22-year-old female who presented with low back pain accompanied by bowel and bladder incontinence. Neurological examination demonstrated left greater than right lower extremity weakness, left ankle clonus, sensory loss in the saddle region and bilateral lower extremities, with preserved tendon reflexes. MRI revealed minimal enhancement of the left cauda equina nerve roots from L1–L4, while cerebrospinal fluid (CSF) studies were unremarkable. She was treated for suspected cauda equina syndrome.

Electrodiagnostic testing showed conduction block in the left peroneal motor nerve, slowed left tibial conduction velocity, bilaterally reduced tibial CMAP amplitudes, absent bilateral peroneal F-waves, and early denervation changes, consistent with an acute inflammatory demyelinating polyradiculoneuropathic (AIDP) variant of GBS.

Two weeks later, the patient developed worsening right leg weakness and new right-hand grip weakness. Repeat EMG/NCS findings were consistent with the initial study, with additional mild denervation in select muscles. 

Discussions:

This case highlights the diagnostic challenge of atypical GBS when CSF studies are negative. EMG/NCS was pivotal in guiding management. Electrodiagnostic testing can reveal early demyelination or axonal involvement, even when the CSF remains normal. In this patient, serial EMG allowed clinicians to pursue IVIG therapy, underscoring the value of EMG as a diagnostic adjunct in atypical GBS

Conclusions:

Atypical GBS may present with inconclusive CSF findings. EMG/NCS is a valuable diagnostic tool in such cases, and repeat testing should be considered when symptoms evolve. Its use can guide timely therapy, and prevent further neurological decline.