Introduction: Adult spinal deformity (ASD) surgery carries risk of spinal cord injury. Spinal cord ischemia is often implicated but has not been directly investigated. Here we present our index case as a proof of concept study for evaluating the role of spinal cord perfusion (SCP) in ASD correction.
Methods: ASD surgery was performed in the usual fashion with the addition of: 1) SCP monitoring, using laser Doppler probe fixated to the dura at the level of the pedicle subtraction osteotomy (PSO), 2) intrathecal pressure monitoring with lumbar drain. Somatosensory evoked- (SSEP) and motor evoked potentials (MEP) were monitored throughout the case.
Results: An 84-year-old male with kyphoscoliosis and progressive myelopathy was treated with T4 PSO and long segment reconstruction. At baseline, SSEP demonstrated normal signals in all four extremities, MEP signals were present in the right foot only, intrathecal pressure was 4 mmHg, and mean SCP was 21.2 perfusion units. The osteotomy was performed and reduced in two steps. After the first step of reduction, MEP signals appeared in the left leg and increased in amplitude in the right leg, and SCP simultaneously increased to 205.6. Further reduction lead to MEP signal loss in both legs and decrease in SCP to 39.2. With partial reversal of the reduction, and MEP signals returned in both legs and SCP improved to 76.0. The reduction was then completed in a delayed fashion, with stable MEP signals and final SCP of 42.9. SSEP signals, vital signs, and intrathecal pressure were stable throughout the case. Postoperatively the patient was neurologically stable.
Conclusions: Fluctuations in SCP likely contribute to neurologic changes during ASD surgery. The presented case provides the first direct evidence supporting this theory. Further investigation is under way with the ultimate goal of developing targeted strategies for spinal cord protection during these high-risk cases.
Patient Care: Spinal cord injury during adult spinal deformity correction can cause devastating neurological deficits. Understanding the physiology of spinal cord perfusion changes during these complex surgeries will ultimately allow for the development of targeted strategies for protection against ischemic injury. The next phase of this study involves investigating the ability of induced systemic hypertension and CSF diversion to augment spinal cord perfusion and provide neuroprotection during these cases.
Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the concept of spinal cord perfusion changes in adult spinal deformity (ASD) correction and the utility of laser Doppler flowmetry to monitor spinal cord perfusion, 2) Discuss, in small groups, potential applications in ASD patients, 3) Identify treatment strategies that can be used to augment SC perfusion in at risk patients.