Intraoperative assessment of cerebral ischemia during carotid surgery

One of the problems in carotid surgery is the intraoperative detection of brain ischemia. None of the methods (EEG; stump pressure) applied so far have been successful. Branston et al. (1974) found a threshold relationship between cortical cerebral blood flow and cortical somatosensory evoked potential (SEP). As the local blood flow fell below about 16 ml/100 g/min a progressive reduction occurred in the amplitude of the cortical evoked potential (N20/P25), implying a fundamental failure of neuronal function in the somatosensory cortex. We have monitored cortical SEP (somatosensory evoked potential) during 734 CEA's (carotid endarterectomies) in order to find an index of risk of incipient cerebral ischemia during carotid cross-clamping, to determine the need for shunting and the causes of early irreversible neurologic deficits. In 59 cases evaluation of SEP was not possible because of technical difficulties. During 586 CEA's no alteration of SEP occurred. However, 4 patients had an immediate postoperative neurologic deficit, while the SEP remained normal. Abnormal SEP occurred in 89 cases and in 6 of these an irreversible loss of SEP was seen. These patients awoke with a new neurologic deficit. We found a reversible abnormal SEP in 83 cases. Reversible changes of SEP occurred mainly during carotid clamping. The diagnostic sensitivity of intraoperative SEP monitoring in predicting neurologic outcome was 60% with a specificity of 100%.     

Intraoperative somatosensory evoked potential monitoring in scoliosis

During surgical correction of scoliosis, 63 patients had somatosensory evoked potential (SEP) monitoring of the spinal cord. Tibial nerves were unilaterally stimulated, and the potentials were recorded from the midcervical spine with surface and epidural needle electrodes. Over 85% had no significant change in their SEP and no postoperative neurologic deficits. Eleven percent had a significant change in their potential (amplitude decrease of greater than 60% and/or latency increase of greater than 2.5 msec) with no neurologic complications. One patient had a significant potential change and temporary postoperative sensory deficits did occur. One additional patient experienced postoperative neurologic complications but had no SEP change. This single false negative case, however, was clinically significant only for motor dysfunction, which is not monitored by the SEP. When changes in patient core temperature were compared to changes in SEP amplitude and latency, an intraoperative decrease in core temperature increased SEP latency and decreased amplitude, which may explain in part the false positive rate of the procedure.     

Pure motor hemiparesis with stable somatosensory evoked potential monitoring during aneurysm surgery: case report.

We report a patient who sought treatment for an acute subarachnoid hemorrhage as a result of an intracranial aneurysm. Management included early surgical repair and intraoperative monitoring of evoked potentials. Pan-angiography revealed berry aneurysms of the communicating anterior artery and right middle cerebral artery. Surgery was uneventful, and the somatosensory evoked potential monitoring did not show any abnormalities. Nevertheless, the patient showed a neurological deficit due to a clip-related infarct in the right middle cerebral artery territory characterized by a right hemiparesis with no sensory deficit. This case report supports the possibility of false-negative results in single-mode intraoperative monitoring during aneurysm surgery.     

Monitoring of somatosensory evoked potentials during surgical procedures on the thoracoabdominal aorta. IV. Clinical observations and results

Thirty-three patients undergoing operations on the descending thoracic or thoracoabdominal aorta were monitored to evaluate causes and effects of spinal cord ischemia as manifested by changes in somatosensory evoked potentials. Maintenance of distal aortic perfusion pressure (greater than 60 mm Hg) by either shunt or bypass techniques in 17 patients resulted in preservation of somatosensory evoked potentials and a normal postoperative neurologic status, irrespective of the interval of thoracic cross-clamping (range 23 to 105 minutes). In 16 other patients in whom cross-clamp time ranged from 16 to 124 minutes, evoked potential loss was observed because of failure to provide distal perfusion (n = 8), inadequate maintenance of distal perfusion pressure (less than 60 mm Hg) despite shunt/bypass (n = 6), or interruption of critical intercostal arteries (n = 2). Incidence of paraplegia in the entire group was 15.1% (5/33) and was limited to only those patients in whom evoked potential loss occurred (5/16, 31.2%) (p = 0.02). Loss of somatosensory evoked potentials for more than 30 minutes resulted in a 71.2% (5/7) incidence of paraplegia, whereas no neurologic deficit was noted in patients (0/26) in whom evoked potential loss was either prevented or limited in duration to 30 minutes (p less than 0.001 versus loss for more than 30 minutes). Intraoperative monitoring of somatosensory evoked potentials is a sensitive indicator of spinal cord ischemia. Simple aortic cross-clamping, failure to maintain distal perfusion pressure above 60 mm Hg, and inability to reimplant critical intercostals in a timely fashion result in a high rate of paraplegia if duration of spinal cord ischemia as measured by somatosensory evoked potentials exceeds 30 minutes. Routine evoked potential monitoring during thoracoabdominal procedures appears useful in assessing the adequacy of spinal cord perfusion. Furthermore, it can alert the surgeon to the necessity for critical intercostal artery reimplantation as well as the need for adjustment or regulation of distal aortic perfusion.     

Spinal cord monitoring in patients with nonidiopathic spinal deformities using somatosensory evoked potentials.

Seventy-nine somatosensory evoked potentials were intraoperatively recorded in 52 patients undergoing spinal surgery for nonidiopathic spinal deformities. There were 37 true-negative, 28 true-positive (a significant change in the somatosensory evoked potential related to the surgical process), and 14 false-positive (a significant change in the somatosensory evoked potential not related to a surgical event) readings. There were, however, no postoperative neurologic deficits with any of the true-positive readings and no false negatives. Spinal and subcortical somatosensory evoked potentials gave few false-positive readings. True-positive somatosensory evoked potentials occurred in 44% of the patients with neuromuscular deformities, 17% with congenital deformities, 45% with Luque instrumentation, 22% with Harrington instrumentation, and none with fusion in situ. Fifty percent of the true positives occurred while the sublaminar wires were tightened. The predictive accuracy of intraoperative spinal cord monitoring in this patient population is not high, but the sensitivity to potentially harmful surgical events is high.     

Intradural lumbar disc herniation—Is it predictable preoperatively? A report of two cases

BACKGROUND CONTEXT: Intradural disc herniations are thought to be rare events, and there have been relatively few literature reports of intradural disc herniations available with regard to magnetic resonance imaging findings. PURPOSE: The authors describe two patients with intradural lumbar disc herniations, one with and one without preoperative diagnosis, who had different postoperative outcomes. STUDY DESIGN: Case study METHODS: The first patient underwent an extended L3 subtotal laminectomy followed by bilateral medial facetectomy and foraminotomy at L3-L4. A durotomy uncovered large disc fragments comprised of friable disc materials and end plates, after no clear disc herniation was found in the epidural space. The second patient underwent anterior lumbar interbody fusion after a preoperative diagnosis of intradural disc herniation. RESULTS: The first patient experienced a marked reduction of pain and progressive recovery of sensory disturbance, but neurologic examination showed right foot drop postoperatively. Two years after surgery, she can not walk without a cane because the neurologic deficit of the right ankle has shown no improvement. Two days after surgery, the second patient was allowed to ambulate with a lumbar orthosis. Neurologic examination showed no motor deficit. Twenty-one months after surgery, the patient reports minimal back pain when sitting on a chair for prolonged periods of time. CONCLUSION: Our cases highlight the importance of preoperative diagnosis in the treatment of intradural lumbar disc herniations. The potential presence of an intradural disc herniation must always be considered preoperatively on a patient whose magnetic resonance imaging study demonstrates the "hawk-beak sign" on axial imaging as well as abrupt loss of continuity of the posterior longitudinal ligament (PLL). This association results in an adequate surgical approach, thereby reducing the chance of postoperative neurologic deficit. Finally, anterior lumbar interbody fusion can be a reasonable alternative in the treatment of intradural lumbar disc herniations.     

Comparison of transcranial electric motor and somatosensory evoked potential monitoring during cervical spine surgery

BACKGROUND: There has been little enthusiasm for somatosensory evoked potential monitoring in cervical spine surgery as a result, in part, of the increased risk of motor tract injury at this level, to which somatosensory monitoring may be insensitive. Transcranial electric motor evoked potential monitoring allows assessment of the motor tracts; therefore, we compared transcranial electric motor evoked potential and somatosensory evoked potential monitoring during cervical spine surgery to determine the temporal relationship between the changes in the potentials demonstrated by each type of monitoring and neurological sequelae and to identify patient-related and surgical factors associated with intraoperative neurophysiological changes. METHODS: Somatosensory evoked potential and transcranial electric motor evoked potential data recorded for 427 patients undergoing anterior or posterior cervical spine surgery between January 1999 and March 2001 were analyzed. All patients who showed substantial (at least 60%) or complete unilateral or bilateral amplitude loss, for at least ten minutes, during the transcranial electric motor evoked potential and/or somatosensory evoked potential monitoring were identified. RESULTS: Twelve of the 427 patients demonstrated substantial or complete loss of amplitude of the transcranial electric motor evoked potentials. Ten of those patients had complete reversal of the loss following prompt intraoperative intervention, whereas two awoke with a new motor deficit. Somatosensory evoked potential monitoring failed to identify any change in one of the two patients, and the change in the somatosensory evoked potentials lagged behind the change in the transcranial electric motor evoked potentials by thirty-three minutes in the other. No patient showed loss of amplitude of the somatosensory evoked potentials in the absence of changes in the transcranial electric motor evoked potentials. Transcranial electric motor evoked potential monitoring was 100% sensitive and 100% specific, whereas somatosensory evoked potential monitoring was only 25% sensitive; it was, however, 100% specific. CONCLUSIONS: Transcranial electric motor evoked potential monitoring appears to be superior to conventional somatosensory evoked potential monitoring for identifying evolving motor tract injury during cervical spine surgery. Surgeons should strongly consider using this modality when operating on patients with cervical spondylotic myelopathy in general and on those with ossification of the posterior longitudinal ligament in particular.     

Intraoperative somatosensory evoked potential monitoring of the sciatic nerve: an animal model.

Sciatic, peroneal, and tibial nerves were isolated in 18 hind limbs in 10 adult mongrel cats. A pair of needle electrodes was used to stimulate both divisions of the sciatic nerve individually at the level of the popliteal fossa. The sciatic nerve was injured by complete or partial transection, crush, and controlled compression. Motor function was correlated with intraoperative cortical somatosensory evoked potential and spinal somatosensory evoked potential tracings. We observed that significant changes in the waveforms of cortical somatosensory evoked potential and spinal somatosensory evoked potential tracings immediately precede postoperative peripheral nerve deficits, and that loss of motor function may be avoided by immediate response to significant spinal somatosensory evoked potential and cortical somatosensory evoked potential waveform changes. A complete motor palsy can be created in one division of the sciatic nerve while normal tracings are being obtained in the other division of the nerve. Stimulating both divisions may result in a spinal somatosensory-evoked potential/cortical somatosensory evoked potential tracing that masks the deficit that is present in only one nerve division.     

Bilateral giant intracavernous aneurysms. Technique of unilateral operation

We report a case of bilateral intracavernous giant aneurysms of which the right side was clipped by direct surgery. Our case was a 74-year-old woman who developed bilateral abducens palsy. Computed tomography and angiography showed bilateral intracavernous giant aneurysms. This patient was followed up in the outpatient clinic. She developed headache and right trigeminal neuralgia 2 years later. The trigeminal pain was quite severe and very disturbing to her. Repeat angiography showed an increase in the size of the aneurysms. An operation was carried out after a balloon Matus test monitoring electroencephalogram, somatosensory evoked potential, and clinical symptoms. The cavernous sinus was opened and the aneurysm was clipped. There was no postoperative complication except right ophthalmoplegia which resolved after 3 months. Headache and trigeminal neuralgia also disappeared.     

Monitoring of somatosensory and motor evoked potentials during open reduction and internal fixation of pelvis and acetabular fractures

Monitoring of motor and somatosensory evoked potentials provides instantaneous intraoperative assessment of a patient's neurologic status. Monitoring of the sciatic nerve through motor and somatosensory evoked potentials can be used during open reduction and internal fixation of pelvic and acetabular fractures. A review of 12 pelvic and acetabular fractures treated with open reduction and internal fixation was conducted and assessed with a combination of intraoperative motor and somatosensory evoked potential monitoring. Results revealed intraoperative motor evoked potential monitoring was 100% sensitive and 100% specific in predicting postoperative sciatic nerve deficits, whereas somatosensory evoked potentials were not accurate in predicting postoperative sciatic nerve deficits. Combined monitoring of the sciatic nerve with motor and somatosensory evoked potentials is beneficial at predicting postoperative sciatic nerve deficits during open reduction and internal fixation of pelvic and acetabular fractures.     

Monitoring of somatosensory evoked potentials during surgical procedures on the thoracoabdominal aorta. I. Relationship of aortic cross-clamp duration, changes in somatosensory evoked potentials, and incidence of neurologic dysfunction

To determine if intraoperative monitoring of somatosensory evoked potentials detects spinal cord ischemia, we subjected 21 dogs to aortic cross-clamping distal to the left subclavian artery. Group I animals (short-term studies, n = 6) demonstrated decay and loss of somatosensory evoked potentials at 8.5 +/- 1.1 minutes after aortic cross-clamping. During loss of somatosensory evoked potentials, significant decreases in spinal cord blood flow occurred in cord segments below T6. Significant reactive hyperemia occurred without normalization of somatosensory evoked potentials after reperfusion. Fifteen Group II animals (long-term studies) were studied to determine the relationship between duration of spinal cord ischemia (evoked potential loss) and subsequent incidence of paraplegia. Extension of aortic cross-clamping for 5 minutes after loss of somatosensory evoked potentials in six dogs resulted in no paraplegia (mean cross-clamp time 12.7 +/- 0.6 minutes). Prolongation of aortic cross-clamping for 10 minutes after evoked potential loss in nine dogs (mean cross-clamp time 17.6 +/- 0.6 minutes) resulted in a 67% (6/9) incidence of paraplegia 7 days postoperatively (p = 0.02 versus 10 minutes of aortic cross-clamping). These findings demonstrate that simple aortic cross-clamping uniformly results in spinal cord ischemia and that such ischemia is detectable by monitoring of somatosensory evoked potentials. Duration of ischemia, as measured by the time of evoked potential loss during the cross-clamp interval, is related to the incidence of postoperative neurologic injury.     

Neurophysiological monitoring of lumbar spinal nerve roots: A case report of postoperative deficit and literature review

IntroductionIntraoperative neurophysiological monitoring (IONM) has proven to help reduce the probability of postoperative neurological deficit for spinal deformity correctional surgeries. However, in rare cases new deficits may still happen. We report a surgical case in which the patient had postoperative paralysis. We would like to call for more case reports with postoperative neurological deficits as they present difficult clinical cases.Presentation of caseA 61-year-old male patient with severe thoracolumbar kyphoscoliosis underwent posterior spinal correction and fusion with segmental T10-L5 pedicle screws and rods instrumentation with IONM. The only intraoperative event was a pedicle breach at left L3 which was detected by triggered electromyography (EMG) testing, and the pedicle screw was repositioned. Left lower extremity paralysis was observed upon patient awakening. He received rehabilitation treatment and had limited recovery of muscle strength. Partial lumbar nerve root injury was likely the cause of the paralysis.DiscussionThis is a case with new lumbar nerve root deficit, with positive EMG signal change, but negative somatosensory evoked potential (SSEP) and motor evoked potential (MEP) findings. We discuss the different neurophysiological modalities for monitoring lumbar spinal nerve root function. We review journal articles from the past two decades which reported lumbar root deficits, and list neuromonitoring events during the surgeries.ConclusionMultimodality monitoring with spontaneous and electrically triggered EMG combined with SSEP and MEP may provide the best chance to detect lumbar nerve root injuries.     

Monitoring of somatosensory evoked potentials in carotid surgery: Results,usefulness and limitations of the method

We have monitored cortical somatosensory evoked potentials (SEP) during 177 carotid operations (167 carotid endarterectomies). An intraluminal shunt was always used for endarterectomy of the internal carotid artery (CEA). SEP was not readable in 21 operations. During 126 carotid operations, no alteration of SEP occurred. However, three patients had an immediate postoperative neurologic deficit while the SEP remained normal. Abnormal SEP occurred in 30 patients. In two cases irreversible loss of SEP was seen. Both patients awoke with a new neurologic deficit after the operation. We found reversible abnormal SEP in 28 cases. In 63 cases with contralateral stenosis, abnormal SEP caused by carotid clamping was observed in 15 (24%). The diagnostic sensitivity of intraoperative SEP monitoring in predicting neurologic outcome following carotid operation was 100% with a specificity of 40%. Monitoring of SEP during carotid surgery is a reliable and useful method to detect incipient cerebral ischemia and to determine the need for shunting. The prognostic value of SEP monitoring to predict postoperative neurologic deficits is limited by the low specificity of the method.     

Cortical evoked potential monitoring. A system for intraoperative monitoring of spinal cord function

This report describes the intraoperative use of a somatosensory cortical evoked potential system to monitor spinal cord function during 300 orthopedic surgical procedures. This system requires sophisticated equipment and the establishment of normative data but has performed well with no false negatives noted. The most frequent technical problem encountered was the effect of medications and anesthetic agents, some of which impair the evoked response significantly. In this series of 300 cases, three neurologic deficits were documented intraoperatively and confirmed postoperatively. There were four cases in which changes in evoked potentials led to change in operative procedure, with no subsequent neurologic deficit. In the remaining cases, the monitoring indicated no neurologic problems during surgery, and none were noted postoperatively.     

Role of intraoperative neurophysiologic monitoring in lumbosacral spine fusion and instrumentation: a retrospective study

BackgroundThis study was carried out to determine the efficacy of IONM in detecting iatrogenic neural injury during pedicle screw insertion, in comparison to the efficacy of computerized tomography (CT) and direct visual inspection of adjacent nerve roots.MethodsWe reviewed the records of 86 patients, who had had 414 titanium pedicle screws inserted for posterior lumbar instrumentation. A standardized multimodality technique under total intravenous anesthesia was used. A relevant neurophysiologic change (surgical alert) was defined as a reduction in amplitude of at least 50% for somatosensory evoked potentials or at least 65% for transcranial electric motor evoked potentials (tcMEPs) compared with baseline. A stimulation threshold of 8 mA or less indicated that the screw was too close to the nerve root.ResultsImmediate feedback via evoked electromyography (EMG) using stimulating pedicle probes in appropriate muscle groups was suggestive of pedicle cortical bone compromise in 28 screws (6.7%). Twenty-one screws were removed and redirected. Four false-positive evoked EMGs in 4 patients were detected by direct visual inspection of the nerve roots and the pedicles, and the surgeon elected not to reposition the screws. None of those patients had postoperative neurologic deficit, and the postoperative CT confirmed the integrity of pedicles. Three false-negative EMGs in 3 patients were detected postoperatively by new neurologic deficits and abnormal CT (3.48%).ConclusionIntraoperative neurophysiologic monitoring is a valuable tool to add to the surgical skill and intraoperative fluoroscopy to protect neural tissue during pedicle screw instrumentation. However, postoperative CT is the ultimate test to determine the accuracy of positioning of the titanium screws. We propose a wake-up test in the operating room after extubation and urgent CT if the patient develops a new neurologic deficit to determine whether to reposition the screws in the same setting.     

Two cases reports of neurologic complications after aortic aneurysm operation

Two cases with dissecting aortic aneurysm of DeBakey type IIIb were treated by graft replacement of the descending thoracic aorta under temporary bypass (Heparinized Hydrophilic Polymer shunt tube) with concurrent somatosensory evoked potential (SEP) monitoring. The SEP was unchanged during operation in both cases, and three sets of intercostal or lumbar arteries were reattached in case 2. In case 1 anterior spinal artery syndrome occurred below the fourth thoracic level (T-4) and right side hemiplegia immediately after the operation. Case 2 had normal neurological function initially after recovering from anesthesia but showed Brown-Séquard syndrome below the first lumbar level (L-1) two days later. In both cases, neurologic disturbance gradually recovered, 19 months postoperatively, case 1 can walk with assistance, and case 2 is able to resume his former activity. The probability of the prevention of neurologic deficits is discussed.     

Monitoring of somatosensory evoked potentials during surgery for middle cerebral artery aneurysms

Somatosensory evoked potentials (SEPs) were monitored during 53 procedures for aneurysms of the middle cerebral artery (MCA). "Significant" changes were reported to the surgeon, who took corrective action when possible. Changes in the SEPs were categorized as follows: Type I, no change; Type II, significant change with complete return to baseline; Type III, significant change with incomplete return to baseline; Type IV, complete loss with no return; and Type V, no response at baseline. Only 1 of 37 patients with a Type I SEP had a new neurological deficit, and this was a patient who could not be examined for several days after surgery because he was in a pentobarbital coma. All 4 patients with Type III and IV changes had new postoperative neurological deficits. Perhaps of greater importance, 4 of 5 patients with Type II changes had no new deficit. These patients all had changes in SEPs that were completely reversible by clip adjustment (2), prompt removal of temporary clips (1), and inducing hypertension after aneurysm trapping (1). These cases may, therefore, represent instances in which SEP monitoring allowed the clinicians to prevent a neurological deficit. The MCA supplies the area of the somatosensory cortex that controls the hand. Median nerve SEPs are, therefore, a theoretically ideal monitor during surgery for MCA aneurysms. This study suggests that the results of MCA aneurysm surgery may be accurately predicted and improved with SEP monitoring.     

Spinal cord monitoring using intraoperative somatosensory evoked potentials for spinal trauma

BACKGROUND: Intraoperative spinal cord monitoring is commonplace in scoliosis surgery as an adjunct to evaluate functional integrity of the cord; however, limited information is available on its applicability in spinal trauma. METHODS: We investigated the efficacy of somatosensory evoked potential (SEP) recording during reconstructive procedures in 82 patients who sustained 20 cervical, 8 thoracic, 6 thoracolumbar, and 48 lumbar vertebral fractures or fractures-dislo-cations. Seventy-one patients underwent single anterior or posterior operations and 11 combined anterior-posterior procedures. Forty patients had incomplete injuries, and 42 had no preoperative neurologic deficit. SEP trace amplitude at insertion of electrode was considered as the baseline value and was compared with the lowest intraoperative signal amplitude and the amplitude at completion of operation. RESULTS: Fifty-nine patients had a depression in wave amplitude of >25% during surgery; in 25 patients, the trace fell by >50%, and in 7 cases, a >75% diminution was recorded. A loss of 50% in SEP signal amplitude showed 67% sensitivity and 71% specificity in predicting neurologic outcome. Increasing trace deterioration threshold from 50% to 60% improved specificity to 81% without compromising sensitivity. A loss of >50% in SEP amplitude occurred with significantly increased incidence during the anterior compared with the posterior spinal procedures. More than 20% recovery in signal amplitude at the conclusion of the procedure in patients with incomplete injuries was correlated with favorable neurologic function. CONCLUSION: Persistent intraoperative decrement in SEP amplitude and poor restitution at completion of surgery increase the risk for postoperative neurologic compromise.     

Neurophysiological criteria for intraoperative prediction of pure motor hemiplegia during aneurysm surgery. Case report

The value of motor evoked potentials (MEPs) as an intraoperative neurophysiological monitoring tool for detecting selective subcortical ischemia of the motor pathways during intracerebral aneurysm repair is described and the use of such measures to predict postoperative motor status is discussed. The authors present the case of a 64-year-old woman in whom there was an incidental finding of two right middle cerebral artery (MCA) aneurysms. During the aneurysm clipping procedure, an intraoperative MEP loss in the left abductor pollicis brevis and tibial anterior muscles occurred during an attempt at permanent clip placement. There were no concurrent changes in somatosensory evoked potentials. Postoperatively, the patient demonstrated a left hemiplegia with intact sensation. A computerized tomography scan revealed an infarct in the anterior division of the MCA territory, including the posterior limb of the internal capsule. In this patient, intraoperative neurophysiological monitoring with MEPs has been shown to be a sensitive tool for indicating subcortical ischemia affecting selective motor pathways in the internal capsule. Therefore, intraoperative loss of MEPs can be used to predict postoperative motor deficits.     

Delayed-onset neurological deficit following correction of severe thoracic kyphotic deformity

There are many potential risks associated with spinal deformity correction procedures including transient and/or permanent neurological deficits. Typically, neurological deficits caused by the surgical correction of spinal kyphosis occur acutely during surgery or immediately after surgery. Delayed postoperative neurological deficits are extremely rare. The authors report a case of delayed neurological deficit that occurred 48 hours after surgical correction of thoracic hyperkyphosis. An 18-year-old man with myotonic dystrophy presented with a 110 degrees T7-L1 kyphosis. The patient underwent an uneventful two-stage correction procedure of the hyperkyphotic deformity. First, anterior discectomies and fusion were performed from T-7 to L-1 using rib autograft, and all segmental vessels were preserved. Subsequently, on the same day, the patient underwent posterior Smith-Petersen osteotomies and T7-L2 pedicle screw fixation. Intact somatosensory and motor evoked potentials were maintained throughout both operations. Postoperatively, he remained neurologically intact without sequelae for nearly 48 hours. On postoperative Day 2, the patient developed delayed monoplegia of the left leg and sensory level loss below T-10. Medical management enabled complete reversal of the patient's monoplegia and sensory loss. At 2-year follow-up, the patient had no adverse neurological sequelae. In this case, a delayed postoperative neurological deficit occurred following spinal hyperkyphosis correction. The authors discuss the possible etiological mechanisms behind this complication and suggest strategies for its management.