Surgical removal of pontomesencephalic cavernous hemangiomas

Abstract

Cavernous hemangiomas of the brain stem are usually discovered accidentally during evacuation of a hematoma, and successful surgical treatment of these lesions is seldom achieved. With the increasing use of magnetic resonance imaging, the presence of a cavernous hemangioma can be detected before surgery, allowing an elective surgical approach. We successfully removed pontomesencephalic cavernous hemangiomas from 2 patients and pontomedullary hemangiomas from 2 others. Elective surgery was performed with perioperative bimodal monitoring of somatosensory and auditory evoked potentials. Performing surgery soon after the hemorrhage minimizes the risk of additional postoperative neurological deficit, since surgical excision is facilitated when the hematoma is not completely organized. Pontine hemangiomas are approached via the 4th ventricle. Mesencephalic hemangiomas are removed by a midline supracerebellar approach when they are lateralized by using a subtemporal approach. The lesion can be removed through a small incision in the brain stem at the site of the lesion. The favorable results, which include marked improvement of preoperative neurological deficits and documentation of complete removal of the lesion by magnetic resonance imaging, support a more aggressive approach to the treatment of symptomatic cavernous hemangiomas of the brain stem. Further investigation of the natural history of these lesions is mandatory.

Brain stem cavernous malformations

“…Type II is the most common form, and it appears as a nodular lesion with relatively short T1-weighted and long T2-weighted signals, circumscribed by a hypointense ring giving the classic ''popcorn" appearance of the cavernoma. 5,11,14 Venous malformations are associated with 8% to 100% of BSCM. 9,11 These venous anomalies may induce the formation of cavernous malformations and have a role in their recurrence.…”

“…1,2 Brain stem cavernous malformation (BSCM) is rare, affecting only 0.4% to 0.9% of the population, 3,4 and representing 9% to 35% of all cavernous malformations. [5][6][7] With the advent of MRI, BSCM have been diagnosed more frequently. These lesions have a propensity to hemorrhage and rehemorrhage; they have a 20-fold increased incidence of hemorrhage and rehemorrhage compared to their supratentorial counterparts.…”

Cavernous Malformation of the Ventral Midbrain Successfully Removed Via a Transsylvian-Transpeduncular Approach -Case Report-

“…Relatively early surgery -within 4 to 6 weeks of the hemorrhage -has been recommended because the procedure will be easier if the hematoma is still unorganized and no significant amount of fibrous perilesional gliotic tissue has developed. 4,7) Most previous reports used a cortical incision at the focal bulge and/or discolored part of the cortical surface. Cavernous malformation in the cerebral peduncle required a minimal 3-to-5 mm incision parallel to the fiber tracts initially.…”

Brainstem cavernomas: a surgical challenge

“…Before the era of magnetic resonance imaging (MRI), brainstem CM was only diagnosed at autopsy or in surgery (6) . The MRI appearance consists of a reticulated core of high and low signal intensities surrounded by a hypointense rim of hemosiderin (7) . Digital subtraction angiography (DSA) is considered an unnecessary tool for diagnosis but it is important in deciding the strategy and approach to surgery (subtemporal, combined petrosal, or interhemispheric) (8) .…”

“…The first neurosurgeon to operate a pontine cavernoma was Dandy, in 1928, and the indication for this surgical procedure was a pontine bleeding. Apparently the diagnosis was established only after surgery (7) . Presence or absence of bleeding, acuteness, localization, and mass effect dictate the timing of the surgery.…”