Joonho Byun M.D., Jae Sung Ahn M.D., Ph.D., Wonhyoung Park M.D., Seok Ho Hong M.D., Ph.D., Young-Hoon Kim M.D., Ph.D., Chang Jin Kim M.D., Ph.D., Jeong Hoon Kim M.D., Ph.D., Seungjoo Lee M.D., Ph.D.
Abstract
Objectives
Controversies regarding effectiveness of intraoperative neurophysiologic monitoring (IONM) in resection of brainstem cavernous malformations (CMs) have been argued. Immediate postoperative surgical outcomes, long term functional outcomes including cranial nerve deficits prognosis and modified Rankin Scale (mRS) were investigated.
Methods
Total 47 patients of brainstem CMs who underwent surgery from January 2000 to November 2016 were identified and analyzed. All patients' clinical, radiological and surgical records were obtained and reviewed.
Results
The incidence of aggravation of immediate postoperative pre-existing neurological deficits in surgery without IONM and with IONM group were 41.7% and 20%, respectively (p = 0.04). The incidence of newly developing postoperative neurological deficits in surgery without IONM and with IONM were 50% and 20%, respectively (p = 0.06). The postoperative surgical complications such as intracerebral hemorrhage/intraventricular hemorrhage, subdural hemorrhage, cerebrospinal fluid leakage, hydrocephalus were occurred 16.6% vs 8.7% in surgery without IONM and with IONM group, respectively (p = 0.06). The functional outcomes of each cranial nerve were not statistically significant. There was no statistically significant factor affecting immediate postoperative neurological deterioration in univariate analysis. The mRS after 1-year in surgery with IONM group showed statistically significant improvement compared to preoperative and 1-month postoperative period (from 3.4 to 1.87, p < 0.01).
Conclusions
The application of IONM during brainstem CM surgery might prevent postoperative deterioration of pre-existing neurological deficits and the development of additional deficits. Further, it might be associated with better functional outcomes.
Fig. 1. Radiologic and intraoperative findings of brainstem CM in the pons. (A) Brain CT scan showed a high-density lesion on the pontine tegmentum. (B) Preoperative T2-weighted MRI, mainly low signal intensity lesion contained in focal high signal intensity area was observed, and there was minimal perilesional edema. (C) Postoperative T2-weighted MRI, total removal of CM, with no evidence of adjacent brainstem tissue. (D) The pontine CM was approached using the telovelar approach; the lesion was dark-red and yellowish, and contained hemorrhagic foci. (E) Baseline electrophysiological findings were obtained; the stimulating probe was used to verify the location of the cranial nerve nuclei. (F) IONM helps in minimizing adjacent neural tissue damage; lesion removed safely. CM: cavernous malformation, CT: computed tomography, MRI: magnetic resonance imaging, IONM: intraoperative neurophysiologic monitoring. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
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