Principles and Practice of Stereotactic Radiosurgery by Lawrence S. Chin & William F. Regine

Author:Lawrence S. Chin & William F. Regine
Language: eng
Format: epub
Publisher: Springer New York, New York, NY

Fig. 31.8The patient remains without residual tumor following surgical resection and chemotherapy at last follow-up

Vascular Malformations: Arteriovenous Malformation

The most dangerous congenital vascular malformations are arteriovenous malformations (AVMs). Prevalence in adults is about 18 per 100,000 and AVMs account for between 1 and 2 % of all strokes, 3 % of strokes in young adults, and 9 % of subarachnoid hemorrhages [103]. AVMs usually present between ages 10 and 40 with the most common symptoms being headache, seizures, focal neurologic deficits, and intracranial hemorrhage; however, at least 15 % of people affected by AVMs are asymptomatic [103]. The long-term crude annual case fatality rates are between 1 and 1.5 % [103]. After a hemorrhage, the annual mortality can be as high as 18 % [104]. Ninety percent of AVMs in the brain are located supratentorially, while the rest are located in the posterior fossa. The Spetzler-Martin Intracranial AVM grading scale [105] was devised based upon size, location, and deep venous drainage. The lesion grade (I–V) is derived by summing assigned points in each category. Complete surgical excision of a grade I lesion (small <3 cm, located in a non-eloquent region such as the anterior frontal lobe, and with solely superficial drainage) would have very little risk of any resulting morbidity or mortality. On the other hand, a grade V lesion (larger than 6 cm, located within or adjacent to eloquent brain areas and with some drainage into the deep venous system) would have significant morbidity and mortality [105]. Surgical resection is the treatment of choice for grade I–III AVMs, due to its high cure rate (reported from 89 to 98.4 %) and low morbidity and mortality [106, 107]. In children, AVMs are most frequently located in the basal ganglia, thalamus, corpus callosum, brainstem, or within the motor, speech, or visual cortex [108, 109] and are the most frequent cause of intracranial hemorrhage in children [110–112]. Mortality from AVM hemorrhage in the pediatric population is much greater for cerebellar AVM than for AVM in the cerebral hemisphere (57 % to 4.5 %, respectively, p < 0.0001) [113]. While surgery is the mainstay of treatment for AVMs, endovascular embolization has become a useful additional technique along with radiosurgery as an alternative for high-risk lesions. After primary stereotactic radiosurgery, Pan et al. [114] reported a pediatric AVM obliteration rate of 65 % at 48 months following the procedure. When needed, additional SRS led to a total obliteration rate of 81 % [114]. Kano et al. [110] showed an even higher total obliteration with SRS of 70 % with at least 4 years of follow-up. Similar obliteration rates were obtained with Gamma knife radiosurgery, as Dinca et al. [115] reported 71.3 % for a one time treatment and 82.7 % overall. Thus, GKS is considered to be a valid active management option for pediatric AVM, though limitations include delayed effect with persistence of bleeding risk for 2–4 years posttreatment [115] (Case Study 31.4, Figs. 31.9 and 31.10).

Fig. 31.9An axial contrast-enhanced T2-weighted MRI shows the appearance of a

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