200 Section - Preserved sacral sensation in anterior cord syndrome: A rare case demonstrating the diagnostic specificity of a novel point-of-care electrosacrogram

Case Diagnosis: Thoracolumbar medullary ischemic stroke presenting with acute anterior cord syndrome and preserved sacral sensory perception on electrosacrogram (ESG)-based electrical perceptual threshold (EPT) testing.

Case Description: A 69-year-old woman with hypertension, dyslipidemia, and mild cognitive impairment presented with sudden-onset bilateral lower extremity paresthesia and flaccid paralysis. MRI confirmed an acute thoracolumbar medullary ischemic stroke. Thoracoabdominal and pelvic CT angiography revealed only mild large-vessel atherosclerosis without evidence of thrombosis or embolic occlusion. Neurological examination demonstrated flaccid paraplegia with an ISNCSCI neurological level of injury at T6 and AIS grade B. Light touch sensation was preserved below the neurological level, whereas pinprick sensation was absent, confirming an anterior cord syndrome.
 
Sacral sensory function was further evaluated using EPT testing delivered through a novel point-of-care electrosacrogram (ESG) device. Pulsed biphasic symmetrical stimulation (200 µs pulse width, 10 Hz frequency, 5 s rest cycles, 1 mA incremental increases beginning at 1 mA) was applied at S4–S5 using surface electrodes. The patient consistently detected stimulation at amplitudes within the normal range, indicating preserved sacral sensation.

Discussions: In this patient with acute anterior cord ischemia, sacral EPT responses were intact despite the absence of pinprick sensation. Given that EPT primarily stimulates Aβ fibers and may recruit deeper pathways at higher amplitudes, these findings support the interpretation that ESG-based EPT is mediated through spinothalamic pathways irrigated by the anterior spinal artery. The preserved sacral perception also suggests that EPT may detect sensory integrity in cases where standard pinprick testing is inconclusive or discordant with the clinical picture.

Conclusions: This case highlights the potential utility of ESG-based EPT testing in differentiating sensory pathway involvement in acute spinal cord ischemia. Preserved sacral EPT responses in anterior cord syndrome may provide additional diagnostic clarity and support its use as an adjunct to ISNCSCI examination in acute SCI evaluation.