Microvascular Brainstem Ischemia After Vestibular Schwannoma Surgery: A Clinical and Microanatomic Study

World Neurosurg. 2018 Apr:112:e415-e424. doi: 10.1016/j.wneu.2018.01.056. Epub 2018 Jan 31.

Abstract

Objective: To identify a potential microvascular etiology in patients who underwent vestibular schwannoma surgery (VSS) complicated by postoperative microvascular brainstem ischemia.

Methods: Charts were retrospectively reviewed of all patients who had an MRI within 14 days of VSS in years 2005-2016. Patient characteristics, preoperative and postoperative imaging features, clinical course and potential predictors of brainstem ischemia were recorded. Cadaveric dissections of 4 cerebellopontine angle (CPA) cisterns with focus on the anterior inferior cerebellar artery (AICA) microvascular were also performed to identify candidate vessels and potential etiology.

Results: Fifty-four of 258 patients had an MRI within 14 days of VSS. Retrosigmoid approach was used in 61.1% of patients, translabyrinthine approach in 25.9%, and middle fossa approach in 13.0%. Four patients (7.4%) had acute microvascular ischemia involving the middle cerebellar peduncle (MCP) adjacent to the cranial nerve (CN) VII-VIII complex demonstrated on postoperative MRI. A statistically significant association was found between the translabyrinthine approach and acute brainstem ischemia (odds ratio, 10.6; 95% confidence interval, 1.004-112.7). Dissection of CPAs revealed 10-20 perforating arteries per specimen originating from the lateral pontine and the flocculopeduncular segments of the AICA. Most microvessels travelled in retrograde fashion along the anteroinferior surface of the CN VII-VIII complex to perforate the cisternal surface of the MCP. No patient had residual or delayed neurologic deficits related to brainstem ischemia at final follow-up.

Conclusions: While effort should be made to preserve perforating vessels, microvascular brainstem ischemia is often asymptomatic and did not lead to permanent neurologic deficits in our series.

Keywords: Anterior inferior cerebellar artery; Brainstem; Cerebellopontine angle cistern; Middle cerebellar peduncle; Vestibular schwannoma surgery.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Brain Ischemia / diagnostic imaging
  • Brain Ischemia / etiology*
  • Brain Stem / blood supply*
  • Brain Stem / diagnostic imaging
  • Cerebellopontine Angle / diagnostic imaging
  • Cerebellopontine Angle / surgery*
  • Female
  • Humans
  • Magnetic Resonance Imaging
  • Male
  • Middle Aged
  • Neuroma, Acoustic / diagnostic imaging
  • Neuroma, Acoustic / surgery*
  • Neurosurgical Procedures / adverse effects*
  • Postoperative Complications / diagnostic imaging
  • Retrospective Studies
  • Young Adult