53. 脳動静脈奇形に対する放射線治療の問題点:-Conventional RadiotherapyとRadiosurgeryを比較して-

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The options for the management of cerebral arteriovenous malformations (AVMs) must be balanced against the risk-effectiveness of various therapies while considering the natural course of these lesions. The use of conventional radiotherapy has been advocated in the treatment of inoperable AVMs (such as deep-seated and/or large ones) in the past, but in spite of some occasional successes, this technique has generally been considered ineffective and has been abandoned. Recently, Drake emphasized the value of radiation therapy for such lesions. We have treated one patient with stereotactic radiosurgery and two with conventional radiotherapy and will report the follow-up results. We will also discuss the problems of radiation treatment for AVMs as compared with conventional radiotherapy with radiosurgery. Case 1 was a 10-year-old girl who had a small AVM (about 15×15×10mm) fed by the anterior choroidal and lateral branches of the posterior cerebral artery and drained through the basal vein situated in the right medial temporal lobe extending into the internal capsule She had only homonymous hemianopsia one month after hemorrhage. An operation was not performed because of the risk of sacrificing the internal capsule and problems in the patient's family, Radiosurgery was undertaken four months after onset; two radiation fields with 14-mm collimetors were used and 25 Gy each were given to the nidus of her AVM (total dose was 50 Gy) The follow-up angiography revealed gradual reduction in size, and, 14 months after the irradiation, complete obliteration was detected. Twenty months after the treatment, CT showed minimal contrast effect in the previous site, but she is doing well except for only homonymous hemianopsia. Case 2 was a 21-year-old male who had a medium-sized (about 25×25×20mm) AVM fed by perforators from the anterior cerebral, middle cerebral and posterior communicating arteries and drained into the basal and middle cerebral veins located in the right temporal lobe adjacent to the temporal horn of the lateral ventricle. An operation was not performed because of the location of the AVM and the fact that there was no neurological deficit. He was irradiated using 10 MV X-rays through two 40×30mm and four 30×30mm portals with a total of 21 Gy in 16 treatments over 27 days, 0.5-3 Gy per taertment. The nidus of his AVM was encompassed by a 90%isodose level of the maximum dose on the dose reconstruction plan. The follow-up angiography showed a slight reduction in size and hemodynamic changes 16 months after initial treatment, so that he received an additional 30 Gy through a 20×20mm portal with the horizontal arc rotation method in 20 fractions over 29 days. He has no neurological deficit three months after the second treatment. Case 3 was a 19-year-old female who had a medium-sized (30×25×20mm) AVM fed by perforators of the anterior, middle and posterior cerebral arteries and drained into the thalamostriate vein situated in the right caudate head. We did not perform surgery because of the risk of sacrificing the internal capsule and the fact that she had no neurological deficit. The irradiation was given with a total dose of 40 Gy in 20 fractions over 29 days through four 40×40mm portals with 10 MV X-rays. The nidus was encompassed accurately by a 90%isodose curve on the dose reconstruction plan. She has no neurological deficit six months after the treatment. With regard to the literature dealing with radiation treatment for AVMs and also considering our experiences, the following problems may exist: 1) size of the AVM (especially in the nidus), 2) accurate determination of the irradiation field and dosimetry, 3) systematic and careful planning of the follow-up, 4) appropriate choice of radiation method and determination of the total dose to the target, 5) the risk of rebleeding during the latent period before the obliteration,
The Japanese Society on Surgery for Cerebral Strokeの論文

53. 脳動静脈奇形に対する放射線治療の問題点:-Conventional RadiotherapyとRadiosurgeryを比較して-

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