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A4201
October 27, 2015
1:00:00 PM - 3:00:00 PM
Room Hall B2-Area D
Neuro-Monitoring Alerts and New Neurologic Deficits in Pediatric Spine Fusion Surgery
Victor M. Neira Aragon, M.D., Kamyar Ghaffari, M.D., Srinivas Bulusu, B.Sc., Mohamed Nassef, M.D., Paul Moroz, M.D., James Jarvis, M.D., Nicholas Barrowman, Ph.D., William M. Splinter, M.D.
Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
Disclosures: V.M. Neira Aragon: None. K. Ghaffari: None. S. Bulusu: None. M. Nassef: None. P. Moroz: None. J. Jarvis: None. N. Barrowman: None. W.M. Splinter: None.
Purpose: Intraoperative neuro-monitoring (IONM) is used to detect an impending new neurologic deficit (NND) during pediatric spinal fusion surgery (SFS) and has greatly replaced wake up test.1 Our objective was to measure the sensitivity and specificity of Motor Evoked Potentials (MEPs) and Somatosensory Evoked Potentials (SSEPs) and their combination during pediatric SFS.

Methods: Ethics Board approval was obtained for this retrospective chart review of all patients undergoing SFS at a single academic institution from April 2007 to October 2014. We included all subjects younger than 21 years old who underwent SFS for correction of scoliosis and/or kyphosis. Subjects excluded did not receive IONM, had uninterpretable baseline signals or had incomplete data records. IONM was performed in all cases including MEPs and SSEPs simultaneously. Definitions of significant IONM alerts have been described. 1,2

Results: Of the potential 318 subjects, 27 cases (25 neuromuscular) were excluded as shown in Fig 1. In the remaining 291 subjects, the baseline signals were good in at least one modality, of which 282 and 273 had good baseline MEPs and SSEPs respectively. Distribution of cases was 192 females (66%), etiology of deformity was idiopathic (n=200, 69%), neuromuscular (n=45, 15%) and others (n=46, 17%). The incidence of a new neurologic deficit was 3% (n=11). The classifications of deficits were: total spinal (n=2 (18%)), partial spinal (n=6 (55%)), plexopathy (n=2 (18%)) and peripheral nerve (n=1 (9%)), before analysis, this last case was excluded because the defect was in the myo/dermatome not being monitored by the IONM. Forty-six cases had MEP alerts with 7 of them had NND (true positives), 2 cases had persistent MEP alert and no NND (2 false positives) and 1 false negative case. Sensitivity and specificity of MEPs were estimated in 88% and 86 % respectively. Ten cases had SSEPs alerts, 2 of them developed NND (true positives), 1 case had persistent SSEP alert and did not develop NND (false positive), and 5 cases had false negative results. Sensitivity and specificity of SSEPs were estimated in 28% and 97% respectively. Analysing both modalities, 51 cases had an alert in either or both modalities, of which 7 cases had NND (true positives), 2 cases were false negatives and 3 false positive cases. Sensitivity and specificity for both modalities was estimated in 78% and 84 % respectively.

Conclusion: Of the modalities studied here, MEPs are the most sensitive modality to detect an impending new neurologic deficit. SSEPs may add information to identify impending spinal cord injury because it is monitoring different neural structures; however we found its sensitivity inferior to MEPs. The low sensitivity of SSEPs can be explained by the low incidence of NNDs and monitoring only selected neural structures. Due to the pre-existing neurologic defects, baseline signals are often uninterpretable among neuromuscular patients. Although IONM is considered the “standard of care” during SFS in several countries, our results contrast with previous reports and highlight the shortcomings of these tests.3 Larger studies with a multi-centric design and larger number of patients are required to establish the role of the IONM modalities in SFS.

References

1. Schwartz DM, et al. J Bone Joint Surg Am. 2007;89(11):2440-9.

2. Kundnani VK, et al. Indian J Orthop. 2010;44(1):64-72.

3. Vitale MG, et al. J Bone Joint Surg Am. 2010;92(1):64-71.





Figure 1

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