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Background Arachnoid cysts (ACs) are congenital anomalies of the central nervous system and arise in virtually all locations where the arachnoid membrane exists. Posterior fossa ACs are considered to develop in the posterior aspect of the rhombencephalic roof plate and do not communicate freely with the fourth ventricle or perimedullary subarachnoid space. Although posterior fossa ACs have been reported a number of times, ACs arising from the foramen of Magendie are very rare. Case description We report here on a 76-year-old female who presented with progressive gait disturbance. Magnetic resonance imaging of the head showed a large AC in the foramen of Magendie that was compressing the inferior vermis and medial aspects of the cerebellar hemisphere without causing hydrocephalus. Neurological examination revealed cerebellar ataxia without Romberg's sign. A nearly total excision of the cyst was safely performed via a median suboccipital approach. The patient's postoperative course was excellent and her neurological recovery was remarkable. Conclusion Most cases of ACs located in the foramen of Magendie are reported in children, and it is extremely rare to observe such ACs in the elderly. In fact, to our knowledge, a symptomatic foramen Magendie AC has never been reported previously in an elderly person. Our results indicate that proper surgical intervention can yield highly positive outcomes in such cases.

Background: Patients with Chiari malformation type I (CM-I) can manifest neurological symptoms, such as headache, neck pain, dysesthesia, swallowing disturbance, and paresis, which are usually stable or slowly progressive even if syringomyelia is coexistent. In some instances, however, acute onset of neurological symptoms has been reported but the pathogenetic mechanism and subsequent clinical course have not been explained. In those cases, it was reported that urgent treatment of foramen magnum decompression (FMD) was very effective. This work reports that an 11-year-old girl with CM-I subacutely developed unique symptoms and that urgent treatment of FMD was very effective. Case Description: We present here an 11-year-old girl with CM-I who subacutely developed dysphagia, left upper extremity monoparesis and sensory dysesthesia, with the limb assuming a peculiar posture at rest, with the wrist in extension and the elbow joint in flexion. Although her symptoms were assumed to be due to previously diagnosed CM-I without syringomyelia, no differences on magnetic resonance imaging (MRI) could be found except for slight change in the shape of tonsils compared with the previous ones. FMD and C1 removal with duraplasty was performed and resulted in an excellent neurological recovery. Conclusion: This case is a reminder that the presence of a new neurological deficit referable to nuclei within, or tracts that traverse, the cerebromedullary junction is a firm surgical indication for FMD in a patient with CM-I. MRI was nearly identical during the asymptomatic and symptomatic periods in this case, and did not explain the timing of symptom onset.

Background: We developed a new 6-Fr guiding catheter (Slim Guide®) that features a large lumen (0.072 inch) for performing advanced techniques as are required in patients with wide-necked aneurysms whose treatment with a single microcatheter is difficult. Methods: The Slim Guide was used to address 30 saccular and 20 dissecting aneurysms. All 50 patients presented with subarachnoid hemorrhage. To perform the advanced techniques we used SL-10® or Excel 14® and Hyperform® balloon microcatheters. Results: Of the 30 patients with saccular aneurysms, 20 were treated with the double microcatheter- and the other 10 with the balloon assist technique. All 20 patients with dissecting aneurysms were treated with the double microcatheter technique. We encountered slight interference during the treatment of one saccular aneurysm with the balloon assist technique using the Slim Guide guiding catheter; another patient with a saccular aneurysm treated with the balloon assist technique suffered a minor transient ischemic complication. Conclusions: With the Slim Guide, the risks inherent in the application of advanced techniques may be decreased. Its use facilitates the coil embolization of aneurysms that pose treatment challenges.

Background: To evaluate the effectiveness of cilostazol in patients with intracranial arterial stenosis, we used magnetic resonance angiography (MRA). The drug's effect on the cerebral blood flow (CBF) was examined by single photon emission computed tomography (SPECT). Methods: In this retrospective study, we evaluated the clinical outcomes of 20 patients with stenosis in the M1 segment of the middle cerebral artery (MCA) who had suffered ischemic stroke within 12 weeks or manifested asymptomatic stenosis exceeding 50%. All patients received cilostazol (100 mg twice daily). MRA and SPECT (at rest and after acetazolamide challenge) studies were performed before and 6 and 12 months after the start of cilostazol treatment. Results: In 5 patients the stenotic lesion showed improvement on MRA. Mean stenosis before cilostazol therapy was 71.7 ± 4.9%, which improved to 39.0 ± 3.2% at 6 months and to 27.2 ± 2.8% at 12 months. SPECT study showed that CBF was improved in 3 patients; in one there was improvement at rest and the other 2 manifested improvement upon acetazolamide challenge. Conclusions: Cilostazol had a remodeling effect on stenotic lesions due to arteriosclerotic changes and improved CBF in some patients.

Background: Posterior fossa arachnoid cysts, including quadrigeminal cistern arachnoid cysts, can occasionally cause compression of the quadrigeminal plate, leading to Sylvian aqueduct stenosis and induction of cerebellar tonsillar descent into the foramen magnum. This, in turn, can result in obstructive hydrocephalus. In such cases, the characteristic of hydrocephalus is generally considered to be hypertensive. Case Description: We present the case of a 28-year-old female complaining of chronic and progressively worsening headaches following the delivery of her first child. Magnetic resonance imaging revealed marked tri-ventriculomegaly, the arachnoid cyst located in the quadrigeminal cistern, and cerebellar tonsillar descent. Ophthalmoscopy revealed bilateral papilledema indicating a long-standing elevation of intracranial pressure. Endoscopic third ventriculostomy (ETV) was performed successfully and resulted in complete recovery from her headaches and papilledema. Postoperative MRI revealed resolution of ventriculomegaly and cerebellar tonsillar descent, suggesting that the fourth ventricle outlet obstruction was associated with the development of the hydrocephalus in this patient. Conclusion: Our case is the first report that a quadrigeminal arachnoid cyst associated with both cerebellar tonsillar descent and hydrocephalus was well treated with ETV. It was indicated that the patient's hydrocephalus and cerebellar tonsillar descent were secondary and synergistic events, caused by the arachnoid cyst located in the quadrigeminal cistern.

Background: Because extra-axial cavernous malformations (CMs) are rare, the common clinical course remains unclear. We report the case of a patient with progressive CM originating from the cerebellar tentorium. Case Description: A 64-year-old woman was admitted to our hospital with the complaint of diplopia. Magnetic resonance (MR) imaging revealed a lesion attached to the left cerebellar tentorium, close to the cerebral peduncle. This well-demarcated lesion rapidly enlarged for 3 months and eroded into the midbrain. Cerebral angiography showed a branch of the middle meningeal artery supplying the lesion and pooling of the contrast medium in the venous phase. A dark reddish and mulberry-like mass of the tentorium was observed intraoperatively, allowing the diagnosis of a tentorial CM. The feeding artery was identified in the tentorium and was coagulated. Postoperative MR imaging showed remarkable mass reduction and central necrosis of the lesion. However, the lesion recurred in 3 months; consequently, gamma knife radiosurgery was performed. After an additional 2 months, the lesion shrank in response to the radiosurgery. Conclusions: We report an extremely rare case of tentorial CM which showed rapid growth in a short period. Coagulation of the feeding artery was not sufficient to control the lesion. Gamma knife radiosurgery may prove highly effective for recurrent lesions. Copyright: © 2012 Furuta T.