Supracerebellar Infratentorial Approach to Cavernous Malformations of the Brainstem

Abstract

In Brief OBJECTIVE The supracerebellar infratentorial (SCIT) approach can be performed at the midline (median variant), lateral to the midline (paramedian variant), or at the level of the angle formed by the transverse and sigmoid sinuses (extreme lateral variant). We analyzed our experience with SCIT approaches for the surgical treatment of cavernous malformations of the brainstem (CMBs). METHODS Demographic, clinical, radiologic, and surgical data from 45 patients (20 males and 25 females; mean age, 36.2 years) with CMBs surgically removed through SCIT approaches were reviewed retrospectively. Anatomic information was explored using cadaver head dissection. RESULTS Twenty-three lesions were in the midbrain, 3 were at the midbrain and extended to the thalamus, 9 were at the pontomesencephalic junction, and 10 were in the upper pons. All patients presented with hemorrhage. The median variant was used in 13 patients, the paramedian variant in 9, and the extreme lateral variant in 23. Intraoperatively, all CMBs were associated with a developmental venous anomaly. At last follow-up, 88% of the patients were the same or better. After a mean follow-up of 20 months, their mean Glasgow Outcome Scale score was 4.1. CONCLUSION SCIT approaches provide excellent exposure to CMBs located at the posterior incisural space, not only in the midline but also in the posterolateral surface of the upper pons and midbrain. Careful preoperative planning and neuronavigational assistance are needed to determine the best angle of attack and trajectory for SCIT approaches. Refined microsurgical techniques are paramount to achieve safe surgical removal of CMBs with good outcomes. Cavernous malformations of the brainstem located on the posterolateral surface of the upper pons and midbrain can be reached through the supracerebellar infratentorial approach, at the midline (median variant) and the posterolateral surface of the upper pons and midbrain (paramedian and extreme lateral variants). The choice depends on the best trajectory between the most superficial point of the lesion and the surface of the skull. We analyzed our clinical experience with these three variants for the treatment of cavernous malformations of the brainstem. Use of these variants avoids other complex and time-consuming approaches to the same region. Refined microsurgical techniques associated with neuronavigational assistance should be used to ensure the safe surgical resection of cavernous malformations of the brainstem.