Radiosurgery for symptomatic cavernous malformations in the brainstem

Purpose: Cavernous malformations are believed to be clinically silent and some are found just incidentally. However, the lesions once become symptomatic with hemorrhage or epilepsy, they are very troublesome because the repeated episodes may happen. Since the majority of symptomatic incidents of the brainstem lesions are hemorrhage, the prompt treatments are required. Microsurgery has a limited indication such as the lesions easy to access and located just beneath the brainstem surface. It is often difficult and risky to undergo surgery, which requires the skills of the microsurgeon to complete these tasks. Methods and cases: Radiosurgery is an alternative to microsurgery, which has been chosen for treating such symptomatic lesions. Because radiosurgery required no special techniques and can be performed by standard radio surgeons with sufficient knowledge. After the brainstem hemorrhage once or twice, radiosurgery was performed with a mean marginal dose of 12.8 Gy. After the radiosurgery, the follow-up studies were performed at the intervals of every 3 to 6 months. Results: Radiological studies with MRI demonstrated a lesion shrinkage approximately in half of the lesions, and the others showed no obvious change. A few lesions caused hemorrhage showing enlargement of the lesion in the association of clinical signs, even after the treatment. Hemorrhage rate before and after the treatment was considerably decreased from 30 %/year/case to 5 %/year/case after the treatment. Conclusion: Radiosurgery with gamma knife reduced the hemorrhage rate significantly and the lesions were smaller in half and the other half showed no remarkable changes. Since the indication for microsurgery is restricted, radiosurgery is the better treatment option for symptomatic CMs in the brainstem. Radiosurgery might be able to change the natural course of this peculiar disease. Abbreviation: CM: Cavernous malformation; CNS: Central nervous system; HR: Hemorrhage rate; PFS: Progression-free-survival. Introduction Cavernous malformations (CM) are one of the vascular anomalies similar to arteriovenous malformation, venous anomaly and capillary telangiectasia in the central nervous system (CNS). Different from the other three, CMs are a very peculiar disease. The majority of them are usually very silent, however, they become symptomatic all of the sudden in association with repeated hemorrhages and frequent epilepsy attacks. Once becoming symptomatic, they are so troublesome and may develop frequent episodes and neurological deterioration. This is true especially when the brainstem lesions become symptomatic, exclusively with hemorrhage. Motor dysfunction, ataxia, or disturbed ocular movement are the main and popular symptoms of brainstem hemorrhages. Since they may often appear repeatedly, the patients require prompt treatment procedures to stop the bleeding. A waitand-see strategy may be taken into account when the microsurgery is difficult because of the location and the patient’s condition. We, Gamma Knife Teams in Japan, have currently treated these symptomatic CMs in the brainstem with gamma knife radiosurgery in the past 30 years. Here in this paper, our treatment results are summarized and consider the strategy of this serious disease. Cases and methods For this retrospective study, cases were collected from nation-wide Gamma Knife Institutes in Japan. There were 139 cases, 85 males and *Correspondence to: Yoshihisa Kida, Scientific Committee of Japanese Gamma Knife Society, Gamma Knife Center in Okuma Hospital, Nagoya, Japan, E-mail: yoshihisa_kida@mac.com