Intra‐Operative Neurophysiological Monitoring in Patients with Intraspinal Abnormalities Undergoing Posterior Spinal Fusion

Abstract

Objective To analyze the intraoperative neurophysiological monitoring (IONM) data of patients with intraspinal abnormalities undergoing posterior spinal fusion and to determine how intraspinal abnormalities influence IONM results. Methods Patients with severe kyphoscoliosis and intraspinal abnormalities who underwent posterior spinal correction and fusion between September 2015 and January 2019 were retrospectively reviewed. Candidate intraspinal abnormalities included Chiari malformation, syringomyelia, split cord malformation, and tethered cord syndrome. Total intravenous anesthesia was administered, and no muscle relaxant or inhalation anesthesia was used for maintenance. IONM data, including somatosensory evoked potentials (SSEP) and motor evoked potentials (MEP), were recorded. The P37 and N50 latencies and amplitude were recorded for SSEP, whereas only the amplitude was recorded for MEP. The possible high‐risk factors for abnormal IONM results were analyzed. Results The current study included 87 patients (40 men, 47 women) with an average age of 20.2 ± 10.4 years. The etiologies were neuromuscular in 45 patients, idiopathic in four, and congenital in 38. A total of 136 intraspinal abnormalities were detected, including Chiari malformation in 33 patients, syringomyelia in 55, split‐cord malformation in 25, and tethered cord syndrome in 23. Forty patients had one intraspinal abnormality, whereas 47 patients had two or three intraspinal abnormalities. The monitorabilities were 87.4% and 97.7% for the SSEP and MEP, respectively. SSEP alerts were reported in five patients and MEP alerts in four patients, and new neurological deficits were observed in three patients postoperatively. The sensitivity and specificity were 100% and 97.3% for SSEP, and 100% and 98.8% for MEP, respectively. A significant difference in MEP amplitude between the concave and convex sides was observed, while significantly higher SSEP latency was observed on the concave side in patients with preoperative neurological deficits. There were 52 (59.8%) patients with abnormal IONM data. Preoperative neurological deficits (χ 2 = 7.715, p = 0.005) and more than one intraspinal abnormality (χ 2 = 9.186, p = 0.004) indicated a higher risk of abnormal IONM data. Conclusions IONM can be effectively used in patients with intraspinal abnormalities who undergo posterior spinal fusion. Patients with preoperative neurological deficits and more than one intraspinal abnormality have a higher risk of abnormal IONM monitoring.

Intra‐operative Neurophysiological Monitoring in Patients Undergoing Posterior Spinal Correction Surgery with Pre‐operative Neurological Deficit: Its Feasibility and High‐risk Factors for Failed Monitoring

“…According to previous studies, the sensitivity and specificity of IONM in patients with neurological deficit seemed to be inclusive 14 . Clark et al 15 .…”

“…According to previous studies, the sensitivity and specificity of IONM in patients with neurological deficit seemed to be inclusive. 14 Clark et al 15 reported the sensitivity was 75% and the specificity was 98% for intraoperative MEP monitoring in patients undergoing surgery for cervical and cervicothoracic myelopathy. Eggspuehler et al 12 showed a sensitivity of 75% and a specificity of 97% in 36 patients undergoing surgical decompression of thoracic spinal stenosis.…”

“…Nowadays, the somatosensory evoked potentials (SEP) and motor evoked potentials (MEP) have been widely regarded as basic and non‐invasive intra‐operative neurophysiological monitoring (IONM) techniques for various spine surgeries 5–8 . With the help of IONM, most iatrogenic neurological deficit could be promptly detected and proper management indicated reversible neurological recoveries for those unfortunate patients.…”

“…1,3,4 Nowadays, the somatosensory evoked potentials (SEP) and motor evoked potentials (MEP) have been widely regarded as basic and non-invasive intra-operative neurophysiological monitoring (IONM) techniques for various spine surgeries. [5][6][7][8] With the help of IONM, most iatrogenic neurological deficit could be promptly detected and proper management indicated reversible neurological recoveries for those unfortunate patients. It should be mentioned that patients with preoperative neurological deficit do suffer from a higher incidence of unreliable/failed IONM monitoring results (the monitoring success rate was as low as 39.1%), leaving patients facing a significantly dangerous dilemma.…”

Assessing Neurologic Complications in Thoracic Three-Column Osteotomy

“…Currently, several preoperative indicators are used to evaluate the risk of IONM alerts and postoperative neurologic deficits, such as severe or angular kyphoscoliosis, pre-existing neurologic deficits, vertebral rotational subluxation, and intraspinal abnormalities. [12][13][14][15] Recently, an MRI-based classification of spinal cord shape and CSF presence at the curve apex was proposed. 9 We sought to conduct a comprehensive analysis of intraoperative and postoperative neurological complications in patients with different spinal cord types undergoing 3CO to assess the predictive value of this MRI-based system for postoperative neurological deficits.…”