Electrophysiologic testing aids early diagnosis of anterior spinal cord infarction

Anterior spinal artery syndrome (ASAS) presents with motor paralysis and dissociated sensory loss. Early diagnosis is difficult due to often normal initial MRI findings. Neurophysiological testing may offer critical diagnostic clues in the acute phase before imaging changes appear.

A 62-year-old man with vascular risk factors presented with acute-onset flaccid paraplegia and loss of pain and temperature sensation below the hips, with preserved vibration sense - suggestive of ASAS. MRI of the spine at presentation and at 72 h showed no abnormalities. However, nerve conduction studies revealed absent tibial F-waves, indicating anterior horn cell dysfunction, while tibial somatosensory evoked potentials (SSEPs) were preserved, suggesting intact dorsal columns. This "F-EP dissociation" aligned with the clinical picture of ASAS. Supportive therapy was initiated, and a repeat MRI after one week showed confirmed anterior spinal cord infarction.

This case highlights the utility of electrophysiological testing in the early diagnosis of MRI-negative ASAS. The combination of absent F-waves and preserved SSEPs serves as surrogate evidence of anterior cord involvement. Timely recognition through clinical and neurophysiological correlation enables early intervention and improved outcomes.