We report 3 cases of cavernous angioma in the brain stem that were operated on.
Case 1 was a 25-year-old female who had a history of 4 episodes of a pontine hemorrhage. MRI demonstrated a cavernous angioma in the dorsal pons. A suboccipital craniectomy was performed and a transfourth ventricular approach was used to expose the cavernous angioma. No abnormal findings, such as staining of hemosiderin, were observed at the floor of the 4th ventricle. The facial colliculus and the median sulcus of the floor were considered to be useful landmarks in approaching the cavernous angioma. But the facial colliculus could not be identified on the surface of the 4th ventricle floor. Therefore EMGs of the m. orbi. oris. were monitored to find the location of the facial colliculus by electrical stimulation of the 4th ventricular floor. After confirming the facial colliculus, the angioma was removed successfully and safely. Postoperatively, no additional neurological deficits were seen.
Case 2 was a 37-year-old male who experienced a pontine hemorrhage 2 times. MRI demonstrated a cavernous angioma in the dorsal pons. Although the cavernous angioma was totally excised, the patient exhibited facial palsy and truncal ataxia.
Case 3 was a 27-year-old male who experienced a brain stem hemorrhage. MRI demonstrated a cavernous angioma in the medulla oblongata. A suboccipital craniectomy and C1 laminectomy were performed. A small incision was made along the median sulcus at just rostral to the obex and the angioma was removed successfully. During manipulation near the obex, transient hypotension and bradycardia were observed transiently. Postoperatively, the patient was discharged without having any additional dificits and followed a satisfactory postoperative course.
Because of the risk of repeated hemorrhage, symptomatic brain stem cavernous angiomas should be removed surgically. In operations, it is important to take a safe pathway to the lesion. However, it is difficult to find landmarks to the lesion on the surface of the 4th ventricular floor. We used EMG monitoring of the m. orbi. oris. by stimulating the 4th ventricular floor to find the location of the facial colliculus. The facial colliculus was a good landmark to approach the lesion in the dorsal pons.
