Implementation of bedside and intraoperative neurophysiological monitoring in the diagnosis of functional neurological symptom disorder following spinal surgery: illustrative case.

BACKGROUND: Intraoperative somatosensory evoked potentials (SSEPs) are routinely used during spine surgery to assess the integrity of white matter pathways and identify potential neurological injury. Their use as a bedside diagnostic adjunct for unexplained postoperative neurological deficits, particularly when functional neurological disorder (FND) is suspected, has not been well described. OBSERVATIONS: A 53-year-old woman developed profound lower extremity weakness and sensory loss after L3-5 decompression and fusion despite stable intraoperative neuromonitoring and imaging findings that did not explain her deficits. Bedside SSEPs remained normal and comparable to intraoperative recordings. Subsequent revision surgery also demonstrated stable SSEPs and robust transcranial motor evoked potentials. Together with inconsistent examination findings and preserved movement when distracted, these results supported a multidisciplinary diagnosis of FND. LESSONS: Bedside SSEPs may provide objective evidence of preserved sensory pathway function in patients with unexplained postoperative neurological deficits and may assist in distinguishing functional symptoms from structural injury. https://thejns.org/doi/10.3171/CASE251006.