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Kazuhiko Nishino, Hitoshi Hasegawa, Kenichi Morita, Masafumi Fukuda, Yasushi Ito, Yukihiko Fujii and Mitsuya Sato

OBJECTIVE

Arteriovenous malformations (AVMs) in the cerebellopontine angle cistern (CPAC) are specific lesions that can cause neurovascular compression syndromes as well as intracranial hemorrhage. Although case reports describing the CPAC AVMs, especially those presenting with trigeminal neuralgia (TN), have been accumulating by degrees, the pathophysiology of CPAC AVMs remains obscure. The authors' purpose in the present study was to evaluate the clinical and radiographic features of CPAC AVMs as well as the treatment options.

METHODS

This study defined a CPAC AVM as a small AVM predominantly located in the CPAC with minimal extension into the pial surface of the brainstem and closely associated with cranial nerves. All patients with CPAC AVMs treated in the authors' affiliated hospitals over a 16-year period were retrospectively identified. Clinical charts, imaging studies, and treatment options were evaluated.

RESULTS

Ten patients (6 men and 4 women), ranging in age from 56 to 77 years (mean 65.6 years), were diagnosed with CPAC AVMs according to the authors' definition. Six patients presented with hemorrhage, 3 with TN, and the remaining patient developed a hemorrhage subsequent to TN. Seven AVMs were associated with the trigeminal nerve (Group V), and 3 with the facial-vestibulocochlear nerve complex (Group VII–VIII). All patients in Group VII–VIII presented with the hemorrhage instead of hemifacial spasm. Regarding angioarchitecture, the intrinsic pontine arteries provided the blood supply for all CPAC AVMs in Group V. In addition, 5 of 7 AVMs with hemorrhagic episodes accompanied flow-related aneurysms, although no aneurysm was detected in patients with TN alone. With respect to treatment, all patients with hemorrhagic presentation underwent Gamma Knife surgery (GKS), resulting in favorable outcomes except for 1 patient who experienced rebleeding after GKS, which was caused by the repeated rupture of a feeder aneurysm. The AVMs causing TN were managed with surgery, GKS, or a combination, according to the nidus-nerve relationship. All patients eventually obtained pain relief.

CONCLUSIONS

Clinical symptoms caused by CPAC AVMs occur at an older age compared with AVMs in other locations; CPAC AVMs also have distinctive angioarchitectures according to their location in the CPAC. Although GKS is likely to be an effective treatment option for the CPAC AVMs with hemorrhagic presentations, it seems ideal to obliterate the flow-related aneurysms before performing GKS, although this is frequently challenging. For CPAC AVMs with TN, it is important to evaluate the nidus-nerve relationship before treatment, and GKS is especially useful for patients who do not require urgent pain relief.

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Ayumi Narisawa, Toshiki Endo, Kenichi Sato, Mika Watanabe, Akira Takahashi and Teiji Tominaga

The authors report on a 49-year-old man with a thoracic spinal dural arteriovenous shunt (dAVS) in which rupture of a varix caused intramedullary hemorrhage. In the literature, patients with a thoracic dAVS predominantly present with congestive myelopathy; however, the patient featured in this report presented without increased deep tendon reflexes or muscle weakness, but instead with intermittent stabbing chest pain and paresthesia. Magnetic resonance images and angiograms demonstrated tortuous enlargement and the formation of a varix-like structure of the draining veins, features compatible with those of high-flow angiopathy. Recognition of this phenomenon is important in thoracic dAVS because intramedullary hemorrhage dramatically degrades outcome. A high index of clinical suspicion can prevent a similar case of thoracic dAVS from progressing to intramedullary hemorrhage.

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Alaa Elkordy, Hidenori Endo, Kenichi Sato, Yasushi Matsumoto, Ryushi Kondo, Kuniyasu Niizuma, Toshiki Endo, Miki Fujimura and Teiji Tominaga

OBJECTIVE

The anterior and posterior choroidal arteries are often recruited to supply arteriovenous malformations (AVMs) involving important paraventricular structures, such as the basal ganglia, internal capsule, optic radiation, lateral geniculate body, and medial temporal lobe. Endovascular embolization through these arteries is theoretically dangerous because they supply eloquent territories, are of small caliber, and lack collaterals. This study aimed to investigate the safety and efficacy of embolization through these arteries.

METHODS

This study retrospectively reviewed 13 patients with cerebral AVMs who underwent endovascular embolization through the choroidal arteries between 2006 and 2014. Embolization was performed as a palliative procedure before open surgery or Gamma Knife radiosurgery. Computed tomography and MRI were performed the day after embolization to assess any surgical complications. The incidence and type of complications and their association with clinical outcomes were analyzed.

RESULTS

Decreased blood flow was achieved in all patients after embolization. Postoperative CT detected no hemorrhagic complications. In contrast, postoperative MRI detected that 4 of the 13 patients (30.7%) developed infarctions: 3 patients after embolization through the anterior choroidal artery, and 1 patient after embolization through the lateral posterior choroidal artery. Two of the 4 patients in whom embolization was from the cisternal segment of the anterior choroidal artery (proximal to the plexal point) developed symptomatic infarction of the posterior limb of the internal capsule, 1 of whom developed morbidity (7.7%). The treatment-related mortality rate was 0%. Additional treatment was performed in 12 patients: open surgery in 9 and Gamma Knife radiosurgery in 3 patients. Complete obliteration was confirmed by angiography at the last follow-up in 10 patients. Recurrent bleeding from the AVMs did not occur in any of the cases during the follow-up period.

CONCLUSIONS

Ischemic complications are possible following the embolization of cerebral AVMs through the choroidal artery, even with modern neurointerventional devices and techniques. Although further study is needed, embolization through the choroidal artery may be an appropriate treatment option when the risk of surgery or radiosurgery is considered to outweigh the risk of embolization.