Mitsunobu Ide

Long-term results of radiosurgery for arteriovenous malformation: Neurodiagnostic imaging and histological studies of angiographically confirmed nidus obliteration

Detailed follow-up results for 25 patients treated for cerebral arteriovenous malformation (AVM) with a gamma unit are presented. Complete nidus obliteration was angiographically confirmed in 16 (73%) of 22 cases receiving full-dose irradiation. There were no radiation- or AVM-related mortalities. However, we did experience one case of radiation-related morbidity and one of angiography-related mortality, the autopsy findings of which are discussed. Computed tomography scan and magnetic resonance imaging follow-up studies of radiosurgically treated AVMs indicated that increased enhancement of the nidus after contrast or gadolinium administration could persist even after obliteration of the AVM was angiographically confirmed.

Gamma knife radiosurgery for numerous brain metastases: Is this a safe treatment?

PURPOSE Gamma Knife (GK) radiosurgery has recently been employed in patients with numerous brain metastases (METs), even those with 10 or more lesions. However, cumulative irradiation doses to the whole brain (WB), with such treatment, have not been determined. METHODS AND MATERIALS Since the GammaPlan ver. 5.10 (ver. 5.31 is presently available, Leksell GammaPlan) became available in November 1998, 92 GK procedures have been performed for 80 patients with 10 or more brain METs at our facility. The median lesion number was 17 (range: 10-43) and the median cumulative volume of all tumors was 8.02 cc (range: 0.46-81.41 cc). The median selected dose at the lesion periphery was 20 Gy (range: 12-25 Gy). Based on these treatment protocols, the cumulative irradiation dose was computed. RESULTS The median cumulative irradiation dose to the WB was 4.71 (range: 2.16-8.51) Gy. The median brain volumes receiving >2 Gy, >5 Gy, >10 Gy, >15 Gy, and >20 Gy were 1105 (range 410-1501) cc, 309 (46-1247) cc, 64 (13-282) cc, 24 (2-77) cc, and 8 (0-40) cc, respectively. CONCLUSION The cumulative WB irradiation doses for patients with numerous radiosurgical targets were not considered to exceed the threshold level of normal brain necrosis.

MIB‐1 staining index and peritumoral brain edema of meningiomas

Growth rates and tumor aggressiveness of meningiomas are thought to be closely related to brain edema development. However, histopathologic data alone are not consistently accurate predictors of the behavior and clinical course of a meningioma.

Middle cerebral artery stenosis caused by relatively low-dose irradiation with stereotactic radiosurgery for cerebral arteriovenous malformations: case report.

OBJECTIVE AND IMPORTANCE There have been occasional reports of stenosis or occlusion of major cerebral arteries occurring several years after stereotactic radiosurgery for cerebral arteriovenous malformations. Nevertheless, little information is available regarding the actual irradiation dose to which the affected artery had been exposed. CLINICAL PRESENTATION We present a patient with arteriovenous malformations who, although asymptomatic, developed remarkable stenosis of the middle cerebral artery trunk (M1) 3 years after gamma knife radiosurgery. The nidus was covered with a 50% isodose volume. A central dose of 36 Gy was used. A gradual decrease in nidus volume had been suggested by 1- and 2-year postradiosurgical neuroimaging examinations. Three-year postradiosurgical angiography revealed severe segmental stenosis of the M1, as well as remarkable nidus shrinkage. INTERVENTION The actual irradiation dose delivered to the affected portion of the artery, as retrospectively determined using a highly accurate three-dimensional analysis technique, was estimated to be 5.1 to 9.8 Gy. CONCLUSION This case suggests that a normal major artery, if located close to the target volume, may be affected by low-dose irradiation (10 Gy or even slightly less) delivered with radiosurgery, although a decrease in blood flow through the M1 because of nidus shrinkage or associated stenosis of the distal middle cerebral artery, as well as other unknown factors, may also contribute to proximal M1 stenosis.

Long-term follow-up of radiosurgically treated arteriovenous malformations in children: Report of nine cases

Long-term follow-up results of nine children treated for cerebral arteriovenous malformation with a gamma unit are presented. Complete nidus obliteration was angiographically confirmed in six cases and significant decreases in arteriovenous malformation size were observed in the other three. There were no radiation-related deteriorations in physical or mental development. In seven patients who underwent endocrinological examination more than 3 years after irradiation, five were normal and the other two showed only low serum adrenocorticotropic hormone levels, which, however, did not necessitate replacement therapy. Neurodiagnostic imaging follow-up studies revealed no radiation-induced lesions in any of the nine cases.

Gamma knife radiosurgery for cerebral arteriovenous malformations: An autopsy report focusing on irradiation-induced changes observed in nidus-unrelated arteries☆

BACKGROUND In radiosurgical treatment for an arteriovenous malformation (AVM), the effects of irradiation on the intranidal and perinidal angioarchitectures have seldom been analyzed histologically. An autopsy case is reported, studying an AVM treated by gamma knife radiosurgery. Postmortem studies following AVM-unrelated death were performed after a 2-year angiography had demonstrated complete nidus obliteration. Irradiation-induced changes were also observed in surrounding nidus-unrelated arteries and the choroid plexus, both of which were within the irradiation target. METHODS Microscopic studies were performed using a coronal section of the brain including the center of the AVM, on which the percent isodose volume gradient, corrected with a magnification rate, was superimposed. RESULTS This study disclosed that intimal hypertrophy can occur in a normal, AVM-unrelated pial artery due to irradiation of 10 Gy or more and that more remarkable intimal hypertrophy with fragmentation of the elastic laminae, or even complete occlusion, can occur in these arteries with 25 Gy. Similarly, irradiation-induced degeneration was present in the choroid plexus, which had been exposed to doses varying from 10 Gy to 25 Gy. CONCLUSIONS A normal surrounding blood vessel may also be affected by high-dose, single-fraction irradiation though the abnormal vessels have been reported to be more susceptible.

Late Cyst Convolution after Gamma Knife Radiosurgery for Cerebral Arteriovenous Malformations

Although many series of patients with cerebral arteriovenous malformations (AVMs) treated radiosurgically have been published, there has been little information on cysts appearing several years after irradiation. Herein, we discuss the incidence, mechanisms and predictability of late cyst formation based on our personal experiences, as well as reported patients. The incidence of this complication, though generally considered to be 0.5% or less, may be higher than assumed. Although a breakdown of the blood-brain barrier is likely to play a major role in the formation process, the hematoma cavity itself may have the potential to become a cyst. A radiation-induced lesion appearing several years after irradiation and persisting for several years thereafter may be a warning sign of late cyst formation. Long-term follow-up, particularly using neuroimaging techniques, is necessary even after the ‘treatment goal’ has been achieved.

Neuroimaging studies of postobliteration nidus changes in cerebral arteriovenous malformations treated by gamma knife radiosurgery

BACKGROUND Following radiosurgical treatment, the majority of patients with arteriovenous malformations (AVMs) are periodically examined by means of computed tomography (CT) and magnetic resonance imaging (MRI) to assess the attainment of nidus obliterations, as well as adverse radiation effects in the surrounding brain. However, few neuroimaging studies of the long-term results following complete obliterations, confirmed by angiography, have been published to date. METHODS CT, MRI, magnetic resonance (MR) angiographic and angiographic images, obtained after angiographic confirmation of complete nidus obliteration, were reviewed in 11 AVM patients treated with gamma knife radiosurgery. The period between angiographic confirmation of nidus obliteration and these most recent examinations was 12-84 months (mean, 29 months). RESULTS In ten patients who were assessed by CT, the obliterated nidus was shown to be isodense (eight cases). A significant time-related decrease in contrast enhancement was observed within 1 to 2 postobliteration years (five/seven cases). Eight patients were evaluated by MRI. On T1-weighted imaging, the nidus was shown to be hypointense (six cases) or a mixture of hypointense and isointense areas (two cases). On T2-weighted imaging, nidus intensity varied more than than observed on T1-weighted imaging, and time-related intensity increases were observed (two/seven cases). No flow-signal void was demonstrated in any of these cases. In four of the seven cases, in which serial postobliteration follow-up MRI studies were conducted, significant gadolinium enhancement persisted 3 years or more after obliteration (maximum of 7 years). No vascular abnormalities were demonstrated in seven patients who were assessed by conventional angiography and/or MR angiography. CONCLUSIONS Radiosurgery-induced changes in a nidus may continue for several years after angiography has shown complete AVM obliteration.

Postradiation volume changes in gamma unit-treated cerebral arteriovenous malformations ☆

Postradiation changes in angiographically determined nidus volume were quantitatively studied in 22 arteriovenous malformation (AVM) cases treated by gamma unit radiosurgery. The postradiosurgical decrease was statistically significant by post-treatment year 2 (p < .05). In children, AVMs tended to be obliterated more quickly than in adults. Volume reduction was more rapid in nidi receiving 25 Gy or more than in those receiving less than 25 Gy (p < .01). However, there were no significant differences in nidus volume decrease between these two dose groups at the second or third postradiosurgical year. Dose response curves were obtained 1, 2, and 3 years following treatment.

Penetration of intravenous antibiotics into brain abscesses.

INTRA-ABSCESS CONCENTRATIONS OF the intravenously administered latamoxef (LMOX, moxalactam in the United States) and cefotetan (CTT), were studied in 11 patients with intracranial abscess. None of these patients underwent surgical ablation of the abscess. In all cases, the abscess was aspirated, and multiple aspirations were required in five patients. Antibiotic concentrations in 18 aspirates were, therefore, determined by the agar well method. LMOX concentrations in 16 aspirates drawn from nine brain abscess cases ranged from 0 to 10.9 micrograms/ml, with a mean (standard deviation) of 4.18 (3.04) micrograms/ml. The CTT concentration in one patient with a brain abscess was 8.51 micrograms/ml, and the LMOX concentration in the one remaining patient with subdural empyema was 5.20 micrograms/ml. In one patient, the serum-to-pus penetration rate of LMOX was estimated to be 0.11 against the peak value of the concentration in serum or 0.44 against the simultaneously obtained level in serum. Significantly higher concentrations of LMOX were produced in abscess cavities with multiple-dose administration or by prior drainage of pus. More-advanced stages of local inflammation, as demonstrated by computed tomography, correlated with higher concentrations. However, the routine indexes of systemic inflammation, such as body temperature, white blood cell count, and level of C-reactive protein in serum, cannot be used to predict the concentration present in intracerebral pus. A tendency for LMOX concentrations in pus obtained after single dose-administration to decrease with increasing duration from symptom onset to sampling was observed but was not statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)