Outcome of Therapies for Cavernous Malformations in Children
Outcome After Surgery
Rehemorrhage: The risk of rehemorrhage ranges from 7–15% (15, 39).
Better outcome with early intervention for seizures: Most studies report poor rates of postoperative seizure control for patients who, preoperatively, had a long duration of epilepsy or experienced generalized seizures. The chance of being seizure free postoperatively in patients without chronic seizures is approximately 80%. With chronic seizures, the chance is approximately 60% (7, 12, 31). To avoid the development of chronic seizures, Broggi et al. recommend surgery after the first seizure by lesionectomy, leaving a real epilepsy surgery to the second stage in which sophisticated investigations for epileptogenic focus localization are needed (7).
Removal of hemosiderin controversial: It remains controversial whether the additional resection of hemosiderin deposits will give better seizure control as compared with pure lesionectomy. Some studies have demonstrated the elimination of seizures with pure lesionectomy (that is, without the removal of perilesional hemosiderin) (10, 12). Others reported that the additional resection of hemosiderin deposits or secondary epileptogeneic foci provides a higher rate of seizure control (4, 60).
Duration of seizures, resection of hemosiderin, and size of cavernous malformation related to outcome: In a recent review, Kim and colleagues suggest that four factors are related to a seizure-free postoperative outcome: (i) extent of resection of the cavernous malformation and its surrounding hemosiderin rim; (ii) single or sporadic seizures compared to chronic epilepsy; (iii) illness duration less than 1 or 2 years; and (iv) size of cavernous malformation less than 1.5 cm (28).
Outcome after Radiosurgery
2-year delay in treatment effect: In a report from a single institute, the annual risk bleeding dropped to 1% after the first two years following SRS, which is favorable as compared with the natural history of the disease (37, 42). Interpretation of the bleeding rate outcome remains controversial (62).
Modification of technique affects tolerance: Modification of technique (treatment volume within the T2-weighted MRI-defined margin, use of MRI, and dose reduction for cavernous malformations in critical brainstem locations) contributed to reduced risks after SRS.
>50% seizure free at 2 years: 53% of those treated were seizure free, and 20% had a highly significant decrease in the number of seizures over a mean follow up period of 2 years (35).
Radiosurgery option: Radiosurgery may be an alternative treatment for selected cases of cavernous malformation-related epilepsy only, for example, when lesions are located in eloquent cortex (55).