Intraoperative neurophysiological monitoring of T9-T10 fracture in a patient with morbid obesity and ankylosing spondylitis: A case report with literature review

INTRODUCTION: As the prevalence of obesity continues to rise, there is a growing need to identify practices that protect overweight patients from injury during spine surgery. Intraoperative neurophysiological monitoring (IONM) has been recommended for complex spine surgery, but its use in obese and morbidly obese patients is understudied. CASE REPORT: This case report describes a patient with morbid obesity and ankylosing spondylitis who was treated for a T9-T10 3-column fracture with a planned, minimally invasive approach. Forty minutes after positioning the patient to prone, the IONM team identified a positive change in the patient’s motor responses in the bilateral lower extremities and alerted the surgical team in a timely manner. It turned out that the pressure exerted by gravity on the patient’s large pannus resulted in further dislocation of the fracture and narrowing of the spinal canal. The surgical team acknowledged the serious risk of spinal cord compression and, hence, immediately changed the surgical plan to an urgent, open approach for decompression and reduction of the fracture. The patient’s lower extremities’ motor responses improved after decompression. The patient was ambulatory on post-operative day 2 and pain-free at six-weeks with no other neurologic symptoms. SIGNIFICANCE: The use of IONM in this planned minimally invasive spine surgery for a patient with morbid obesity prevented potentially serious iatrogenic injury. The authors include a literature review that situates this case study in the existing literature and highlights a gap in current knowledge. There are few studies that have examined the use of IONM during spine surgery for morbidly obese patients. More research is needed to elucidate best practices for the use of IONM in spine surgery for morbidly obese patients.