Abstract 036: Diagnostic Accuracy of IONM for Perioperative Strokes during Endovascular Treatment of Ruptured Intracranial Aneurysms
Authors: Qudah Abdullah M Al , Bata Ammar , Anetakis Katherine , Crammond Donald J , Shandal Varun , Gross Bradley A , Lang Michael R , Al‐Bayati Alhamza R , Bhatt Nirav R , Nogueira Raul G , Thirumala Parthasarathy D , Balzer Jeffery R 
Published: March 2024

Introduction
Ruptured aneurysmal SAH accounts up to 80% of nontraumatic SAH, with more than 80% located in the anterior circulation and a mortality rate upwards of 50%.1‐3 Endovascular treatment (EVT) of ruptured intracranial aneurysms (rIA) is increasingly being recognized as a standard treatment that may result in better early outcomes and independency when compared with open neurosurgical clipping in cases of appropriate equipoise.1,2,4–6 Despite this, EVT of intracranial aneurysms has its own risk of complications including intraoperative rupture and thromboembolic events.7 The complication rate is found to be higher in cases of rIA than that seen in cases of unruptured intracranial aneurysms.8 The use of somatosensory evoked potentials (SSEP) and electroencephalography (EEG) intraoperative neuromonitoring (IONM) have proven their efficacy in identifying iatrogenic neurological complications in vascular surgeries including carotid endarterectomy 9–11, EVT and microsurgical treatment of intracranial aneurysms. 11,12 rIA have their own unique challenges due to preoperative neurological deficits and perioperative vasospasm making it more difficult to identify new neurological deficits after the procedure. They are also associated with decreased vasoreactivity secondary to bleeding, and a higher rate of procedural complications that can alter the IONM signals.13,14 IONM in the form of SSEP and EEG can be utilized in anesthetized patients to indirectly monitor intraoperative cerebral perfusion as well as central and peripheral neuronal integrity.15,16 Changes in one or both modalities indicate a change in cerebral perfusion that can be related to EVT directly, for example, aneurysm perforation or coil herniation and embolism, or indirectly secondary to anesthesia and hemodynamic changes.17 (Figure1)

Methods
We reviewed the medical records of 323 patients who underwent EVT of ruptured aneurysms with IONM utilizing SSEP and EEG. We included all patients who had endovascular management of ruptured aneurysm and completed IONM records until the end of the procedure and excluded those with no IONM records or incomplete records. Patients were divided into 2 groups, one group with postprocedural neurological deficits (PPND) and one group without PPND.

Results
Total of 323 patients undergoing EVT, significant IONM changes were noted in 71 patients (21.98%) and 46 (14.24%) who experienced PPND. 22 out of 71 (30.98%) patients who had significant IONM changes experienced PPND. Univariable analysis demonstrated that persistent changes in SSEP and EEG were associated with PPND (p‐values: <0.001 and <0.001). Multivariable analysis showed that persistent IONM changes were significantly associated with PPND (OR: 8.28 (95%CI:2.92‐24.66, p‐value: <0.001). Simultaneous changes in both modalities had a specificity of 95% (95% CI: 0.92, 0.97%) and sensitivity of 48% (95% CI: 0.33, 0.63) to predict PPND when either modality had a change. Out of 46 patients with PPND, 29 (63.04%) experienced periprocedural complications. PPND was associated with periprocedural complications with a p‐value <0.001. Also, multivariable analysis showed an association between IONM changes and persistent IONM changes with PPND with OR of 7.35 (95% CI; 3.68, 15.03) and 7.25 (95% CI; 3.58, 15.00), respectively.

Conclusion
Significant IONM changes during EVT for rIA are associated with an increased risk of PPND.