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  • Author or Editor: Nobuhito Saito x
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Keisuke Maruyama, Masahiro Shin, Masao Tago, Hiroki Kurita, Nobutaka Kawahara, Akio Morita and Nobuhito Saito

Object

Appropriate management of hemorrhage after Gamma Knife surgery (GKS) for arteriovenous malformations (AVMs) of the brain is poorly understood, although a certain proportion of patients suffer from hemorrhage.

Methods

Among 500 patients observed for 1 to 183 months (median 70 months) after GKS, 32 patients (6.4%) suffered a hemorrhage. Hemorrhage developed even after angiographically documented obliteration of the AVM in five (2%) of 250 patients followed for 1 to 133 months (median 75 months) post-GKS. These patients had been treated according to their pathological condition. Treatment of these patients and their outcomes were retrospectively reviewed. As a management strategy in patients with preobliteration hemorrhage, the intracerebral hematoma and the AVM nidus were removed in four patients, and chronic encapsulated hematoma was removed in three. Among 11 patients who were conservatively treated, AVMs were ultimately obliterated in five, including three patients who underwent repeated GKS. Intracerebral hematoma from angiographically documented obliterated AVMs was radically resected in two patients, including one who also underwent aspiration of an accompanying symptomatic cyst. Intraoperative bleeding was easily controlled in these patients. Outcomes after hemorrhage, measured with the modified Rankin Scale, were significantly better in patients with postobliteration hemorrhage than in those with preobliteration hemorrhage (p < 0.05).

Conclusions

Various types of hemorrhagic complications after GKS for AVMs can be properly managed based on an understanding of each pathological condition. Although a small risk of bleeding remains after angiographically demonstrated obliteration, surgery for such AVMs is safe, and the patient outcomes are more favorable. Radical resection to prevent further hemorrhage is recommended for ruptured AVMs after obliteration because such AVMs can cause repeated hemorrhages.

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Keisuke Maruyama, Tomoyuki Koga, Masahiro Shin, Hiroshi Igaki, Masao Tago and Nobuhito Saito

Object

Optimal timing of Gamma Knife surgery (GKS) after hemorrhage from brain arteriovenous malformations (AVMs) is unclear and of concern to neurosurgeons because GKS is usually performed after absorption of the hematoma. The authors investigated whether waiting for hematoma absorption is beneficial and aimed to clarify the optimal treatment timing.

Methods

The authors retrospectively studied 211 patients with AVMs who presented with hemorrhage and underwent GKS as the initial treatment. Patients were categorized into 3 groups according to the interval between the time of first hemorrhage and GKS, as follows: Group 1, 0–3 months (70 patients); Group 2, 3–6 months (62 patients); and Group 3, > 6 months (79 patients). The obliteration rates, number of hemorrhages before and after GKS, and complication rates were compared between these 3 groups. The authors also analyzed a subgroup of 127 patients who presented with intracerebral hemorrhage (ICH) to identify the influence of ICH on outcome.

Results

After a median follow-up of 6.3 years, the rates of obliteration, hemorrhage after treatment, and complication were not significantly different between the 3 groups even though the patients with a longer interval before GKS (Group 3) had more AVMs in eloquent areas and neurological deficits. However, the numbers of patients with preoperative hemorrhage in the interval before GKS was significantly higher in Group 3 (1, 3, and 20 patients in Group 1, 2, and 3, respectively). These results were similar in the analyses of 127 patients presenting with ICH.

Conclusions

No benefit was detected in waiting for hematoma absorption until GKS after hemorrhage from AVM. Because of higher hemorrhagic risk until GKS > 6 months after hemorrhage, the authors recommend GKS within 6 months after hemorrhage.

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Keisuke Maruyama, Kyousuke Kamada, Masahiro Shin, Daisuke Itoh, Yoshitaka Masutani, Kenji Ino, Masao Tago and Nobuhito Saito

Object

No definitive method of preventing visual field deficits after stereotactic radiosurgery for lesions near the optic radiation (OR) has been available so far. The authors report the results of integrating OR tractography based on diffusion tensor (DT) magnetic resonance imaging into simulated treatment planning for Gamma Knife surgery (GKS).

Methods

Data from imaging studies performed in 10 patients who underwent GKS for treatment of arteriovenous malformations (AVMs) located adjacent to the OR were used for the simulated treatment planning. Diffusion tensor images performed without the patient's head being secured by a stereotactic frame were used for DT tractography, and the OR was visualized by means of software developed by the authors. Data from stereotactic 3D imaging studies performed after frame fixation were coregistered with the data from DT tractography. The combined images were transferred to a GKS treatment-planning workstation. Delivered doses and distances between the treated lesions and the OR were analyzed and correlated with posttreatment neurological changes.

Results

In patients presenting with migraine with visual aura or occipital lobe epilepsy, the OR was located within 11 mm from AVMs. In a patient who developed new quadrantanopia after GKS, the OR had received 32 Gy. A maximum dose to the OR of less than 12 Gy did not cause new visual field deficits. A maximum dose to the OR of 8 Gy or more was significantly related to neurological change (p < 0.05), including visual field deficits and development or improvement of migraine.

Conclusions

Integration of OR tractography into GKS represents a promising tool for preventing GKS-induced visual disturbances and headaches. Single-session irradiation at a dose of 8 Gy or more was associated with neurological change.

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Keisuke Maruyama, Tomoyuki Koga, Kyousuke Kamada, Takahiro Ota, Daisuke Itoh, Kenji Ino, Hiroshi Igaki, Shigeki Aoki, Yoshitaka Masutani, Masahiro Shin and Nobuhito Saito

Object

To prevent speech disturbances after Gamma Knife surgery (GKS), the authors integrated arcuate fasciculus (AF) tractography based on diffusion tensor (DT) MR imaging into treatment planning for GKS.

Methods

Arcuate fasciculus tractography was retrospectively integrated into planning that had been previously performed by neurosurgeons and radiation oncologists. This technique was retrospectively applied to 12 patients with arteriovenous malformations adjacent to the AF. Diffusion tensor images were acquired before the frame was affixed to the patient's head and DT tractography images of the AF were created using the authors' original software. The data from DT tractography and stereotactic 3D imaging studies obtained after frame fixation were transported to a treatment planning workstation for GKS and coregistered so that the delivered doses and incidence of posttreatment aphasia could be assessed.

Results

The AF could not be depicted in 2 patients who initially presented with motor aphasia caused by hemorrhaging from arteriovenous malformations. During the median follow-up period of 29 months after GKS, aphasia developed in 2 patients: 30 Gy delivered to the frontal portion of the AF caused conduction aphasia in 1 patient, and 9.6 Gy to the temporal portion led to motor aphasia in the other. Speech dysfunction was not observed after a maximum radiation dose of 10.0–16.8 Gy was delivered to the frontal fibers in 4 patients, and 3.6–5.2 Gy to the temporal fibers in 3.

Conclusions

The authors found that administration of a 10-Gy radiation dose during GKS was tolerated in the frontal but not the temporal fibers of the AF. The authors recommend confirmation of the dose by integration of AF tractography with GKS, especially in lesions located near the temporal language fibers.