False Negative in Spinal Cord Monitoring Using Spinal Cord–Evoked Potentials Following Spinal Cord Stimulation During Surgery for Thoracic OPLL and OLF

Abstract

Several electrophysiologic methods have been used for intraoperative monitoring of spinal cord functions. Recently, muscle responses following transcranial electric stimulation have also been widely used. However, in patients with severe myelopathy, only the spinal cord responses following spinal cord stimulation can be recorded. We report a false-negative case in monitoring using spinal cord responses following spinal cord stimulation. The patient presented with severe thoracic myelopathy due to ossification of the posterior longitudinal ligament (OPLL) and ligamentum flavum. Spinal cord responses following spinal cord stimulation were recorded during laminectomy and partial removal of the OPLL. Although the amplitude of those responses decreased transiently to within 50% of control data during decompression, it had recovered to the control level by the end of surgery. Just after surgery, the patient showed complete motor paralysis with preserved sensory function. Spinal cord responses following spinal cord stimulation can be recorded in patients with severe myelopathy. However, motor problems may occur when surgery is continued in the false belief that responses are accurate.

Clinical characteristics and surgical outcome of thoracic myelopathy caused by ossification of the ligamentum flavum: a retrospective analysis of 85 cases

“…73,74 Another serious surgical complication in thoracic OLF surgery is spinal cord injury. 62,75,76 Several procedures were followed with the aim of minimizing the risk of spinal cord injury. To avoid injury to the blood supply to the spinal cord, the microcirculation around the intervertebral foramen should be protected when ligating the vertebral segmental vessels.…”

Thoracic Myelopathy in Ossified Ligamentum Flavum: Surgical Management and Long-Term Outcome Following 2 Different Techniques of Surgical Decompression

“…Younger age and shorter duration of symptoms have been purported to be major positive predictive variables. 25,26,30 In our study, 75% of patients with excellent recovery presented with symptoms of less than 1 month duration (which was significant on both uniand multi-variate analyses). In our study, there was statistically significant correlation between intra-medullary T2-weighted signal change and surgical outcome on both uni-and multivariate analyses.…”

Iatrogenic Spinal Cord Injury during Removal of the Inferior Articular Process in the Presence of Ossification of the Ligamentum Flavum

“…While several case series cite higher rates of nerve root and spinal cord injury (30%) during deformity correction surgery [ 14 – 16 ], most of these papers were published prior to the development of modern techniques [ 17 – 19 ]. Similarly, although outcomes after decompressive procedures for myelopathic OLF patients are mixed (10–30% of patients experience neurological deficits after decompression for ossification of the posterior longitudinal ligament) [ 20 – 23 ], no cases of iatrogenic injury due to asymptomatic OLF have been previously reported. The preceding case reflects a mechanism by which an incidental OLF facilitated iatrogenic injury secondary to correction of a different degenerative condition, which to our knowledge has not been previously reported.…”