Three-dimensional morphology of the superior cerebellar artery running in trigeminal neuralgia.

The superior cerebellar artery (SCA) is the most frequent offending vessel in trigeminal neuralgia. This study aims to elucidate the patterns of the SCA running in 34 patients with typical trigeminal neuralgia using three-dimensional computer graphics. The SCA which runs in the medial aspect of the trigeminal nerve compressed predominantly the root entry zone at the distal segment of the caudal loop. Meanwhile, the SCA which runs in the cranial or lateral aspect of the trigeminal nerve compressed predominantly the mid-third portion at the proximal segment of the caudal loop. The site of neurovascular compression differed depending on the shape of the initial segment of SCA. Transposition methods could not be performed in several patients with arch-shaped SCA. Three-dimensional computer graphics revealed different characteristics of the SCA running in trigeminal neuralgia depending on the site of neurovascular compression and shape of the SCA. These differences might affect procedures for microvascular decompression.

Dural Laceration Resulting in the Formation of Syringomyelia Caused by a Loosened Hydroxyapatite Intraspinous Spacer after Spinous Process-splitting Laminoplasty.

A 63-year-old man was admitted in our hospital with the chief complaint of upper limb numbness 3 years after undergoing spinous process-splitting laminoplasty (C3-C7) in another hospital. The hydroxyapatite spacers used for the laminoplasty had dislocated, resulting sensory disorders of the upper extremities. Additionally, loosened hydroxyapatite intraspinous spacers and syringomyelia were confirmed. A revision operation was performed, during which the C5 spacer was observed to have dislodged into the spinal canal, and a dural membrane defect, arachnoid membrane tear, cerebrospinal fluid leakage, and marked adhesion change were observed. The adhesion was exfoliated as far as possible; moreover, to prevent the reflux of syringomyelia, a syrinx-subarachnoid shunt (SS shunt) was placed. Although there was concern of further adhesion by putting foreign matter, SS shunt indwelling was chosen to obtain sure disappearance of syringomyelia. The postoperative course was uneventful. A gradual improvement in the upper limb numbness was observed without a recurrence of syringomyelia at 9 years of follow-up.

Optogenetic Activation of the Sensorimotor Cortex Reveals "Local Inhibitory and Global Excitatory" Inputs to the Basal Ganglia.

To understand how information from different cortical areas is integrated and processed through the cortico-basal ganglia pathways, we used optogenetics to systematically stimulate the sensorimotor cortex and examined basal ganglia activity. We utilized Thy1-ChR2-YFP transgenic mice, in which channelrhodopsin 2 is robustly expressed in layer V pyramidal neurons. We applied light spots to the sensorimotor cortex in a grid pattern and examined neuronal responses in the globus pallidus (GP) and entopeduncular nucleus (EPN), which are the relay and output nuclei of the basal ganglia, respectively. Light stimulation typically induced a triphasic response composed of early excitation, inhibition, and late excitation in GP/EPN neurons. Other response patterns lacking 1 or 2 of the components were also observed. The distribution of the cortical sites whose stimulation induced a triphasic response was confined, whereas stimulation of the large surrounding areas induced early and late excitation without inhibition. Our results suggest that cortical inputs to the GP/EPN are organized in a "local inhibitory and global excitatory" manner. Such organization seems to be the neuronal basis for information processing through the cortico-basal ganglia pathways, that is, releasing and terminating necessary information at an appropriate timing, while simultaneously suppressing other unnecessary information.

Management of non-benign meningiomas with Gamma Knife radiosurgery.

OBJECTIVE: Results of Gamma Knife radiosurgery (GKS) were retrospectively evaluated in 16 patients with histologically confirmed atypical and anaplastic intracranial meningiomas. MATERIALS AND METHODS: There were nine men and seven women (mean age 61.0 years). Atypical meningiomas were diagnosed in nine cases and anaplastic meningiomas in seven. In nine patients there was malignant transformation of a tumor that had initially proved to be benign. In total, 21 radiosurgical procedures were performed. The mean tumor volume at the time of GKS was 7.1 cm3. The mean marginal and maximum irradiation doses were 18.8 and 37.0 Gy, respectively. The mean length of follow-up after treatment was 37.1 months. FINDINGS: Of 21 radiosurgical procedures, 6 (29 %) led to stabilization of tumor growth during the mean follow-up of 40.5 months. It was significantly associated with small lesion volume (P = 0.02), and greater marginal (P = 0.04) and maximum (P = 0.02) irradiation doses. Seven patients underwent eight surgical resections of a progressing tumor during the mean period of 26.1 months after irradiation. Five patients (31 %) died because of tumor progression within the average time period of 16.8 months after GKS. Overall, at the time of the last follow-up just two patients (13 %) had no evidence of tumor regrowth, and only three patients (19 %) maintained good activities of daily living during 12, 59, and 69 months, respectively, after radiosurgery. CONCLUSION: GKS has limited efficacy in cases of non-benign meningioma. Better tumor control rates can be attained for small neoplasms treated with greater marginal and maximum irradiation doses.

Reduced pallidal output causes dystonia.

Dystonia is a neurological disorder characterized by sustained or repetitive involuntary muscle contractions and abnormal postures. In the present article, we will introduce our recent electrophysiological studies in hyperkinetic transgenic mice generated as a model of DYT1 dystonia and in a human cervical dystonia patient, and discuss the pathophysiology of dystonia on the basis of these electrophysiological findings. Recording of neuronal activity in the awake state of DYT1 dystonia model mice revealed reduced spontaneous activity with bursts and pauses in both internal (GPi) and external (GPe) segments of the globus pallidus. Electrical stimulation of the primary motor cortex evoked responses composed of excitation and subsequent long-lasting inhibition, the latter of which was never observed in normal mice. In addition, somatotopic arrangements were disorganized in the GPi and GPe of dystonia model mice. In a human cervical dystonia patient, electrical stimulation of the primary motor cortex evoked similar long-lasting inhibition in the GPi and GPe. Thus, reduced GPi output may cause increased thalamic and cortical activity, resulting in the involuntary movements observed in dystonia.

Analysis of factors affecting the long-term functional outcome of patients with skull base meningioma.

We analyzed the factors that affect the long-term clinical outcome of a series of patients with skull base meningiomas. Clinical records of 73 patients with cranial base meningiomas were reviewed retrospectively, of whom 13 patients experienced a recurrence at various times following the initial surgery. The mean follow-up time was 90.4 ± 21.2 months (range=60-124 months). Based on the location of the recurrence, patients with recurrence were divided into peripheral (n=6) and central (n=7) skull base groups. Of several variables analyzed using a multivariate logistic regression model, "high MIB-1 (Ki-67 proliferation antigen) labeling index" was an independent variable predicting poor long-term functional outcomes. Recurrence of the tumor at the central skull base was also a strong predictor of poor long-term outcomes. An increased proliferative potential, as indicated by a high MIB-1 labeling index, may induce repeated recurrences, eventually leading to worse functional outcomes, particularly for patients with central skull base meningiomas.

Cortically evoked responses of human pallidal neurons recorded during stereotactic neurosurgery.

Responses of neurons in the globus pallidus (GP) to cortical stimulation were recorded for the first time in humans. We performed microelectrode recordings of GP neurons in 10 Parkinson's disease (PD) patients and 1 cervical dystonia (CD) patient during surgeries to implant bilateral deep brain stimulation electrodes in the GP. To identify the motor territories in the external (GPe) and internal (GPi) segments of the GP, unitary responses evoked by stimulation of the primary motor cortex were observed by constructing peristimulus time histograms. Neurons in the motor territories of the GPe and GPi responded to cortical stimulation. Response patterns observed in the PD patients were combinations of an early excitation, an inhibition, and a late excitation. In addition, in the CD patient, a long-lasting inhibition was prominent, suggesting increased activity along the cortico-striato-GPe/GPi pathways. The firing rates of GPe and GPi neurons in the CD patient were lower than those in the PD patients. Many GPe and GPi neurons of the PD and CD patients showed burst or oscillatory burst activity. Effective cathodal contacts tended to be located close to the responding neurons. Such unitary responses induced by cortical stimulation may be of use to target motor territories of the GP for stereotactic functional neurosurgery. Future findings utilizing this method may give us new insights into understanding the pathophysiology of movement disorders.

Ictal asomatognosia due to dominant superior parietal cortical dysplasia.

We report a 23-year-old man with left dominant parietal cortical dysplasia manifesting as ictal asomatognosia. The man had experienced seizures, during which he underwent ictal asomatognosia as a feeling of loss of his right extremities. Scalp electroencephalography (EEG) showed interictal discharges in the left parietal region of his brain. Magnetic resonance fluid-attenuated inversion recovery (FLAIR) imaging revealed a hyperintense lesion in the left superior parietal lobule. A [(123)I]-iomazenil (IMZ) single-photon-emission CT scan demonstrated an area of low IMZ binding coincident with the lesion observed in the MRI scan. Invasive EEG monitoring showed ictal discharges in the cortex posterior to the postcentral sulcus. High-frequency electrical stimulation of the same area of the cortex also induced asomatognosia of the patient's right forearm. We performed a corticectomy of the anterior part of the superior parietal lobule, which resulted in no new neurological deficits. The seizures disappeared after surgery with the maintenance of preoperative medication. Therefore, the anterior part of the superior parietal lobule may be a symptomatogenic zone for ictal asomatognosia.

Surgical treatment and outcome of skull base meningiomas with extracranial extensions.

OBJECTIVE: Recurrent cranial base meningiomas occasionally extend into craniofacial structures, and are one of the most difficult tumors to surgically manage. We reviewed our experience of surgical treatment in a series of patients with meningiomas showing extensive extracranial extensions. METHODS: We surgically treated a total of 10 patients with recurrent cranial base meningiomas with large extension to multiple craniofacial structures. All patients underwent orbitozygomatic or zygomatic frontotemporal craniotomy for surgical resection of the tumor. An endoscopic endonasal technique was also employed, if necessary, as an adjunct to the transcranial approach. RESULTS: Eight patients were treated solely with a frontotemporal approach associated with an extended resection of the floor of the middle fossa. In 2 patients, an endoscopic endonasal approach was additionally required for resection of tumors located in the nasal cavity and ethmoid sinus. A gross total resection was achieved without serious surgical complications in 9 out of the 10 patients. In all patients, the tumors were found to invade the surrounding tissue such as the bone and skeletal muscle to varying degrees. CONCLUSION: Our data indicate that recurrent craniofacial meningiomas can usually be managed by using a lateral cranial base approach. Whereas it would be expected that a radical resection may prevent further recurrence with an acceptable quality of life, a long-term follow-up would be required for confirming the benefit of this treatment strategy.

Nondominant parietotemporal cortical dysplasia manifesting as hypermotor seizures.

We describe the case of a 33-year-old man with nondominant right parietotemporal cortical dysplasia. Habitual seizures were violent, ballistic movements of the extremities with pelvic thrusting, resembling complex gestural automatisms or "hypermotor seizures." Scalp electroencephalography (EEG) and interictal [(123)I]iomazenil single-photon-emission computed tomography revealed an epileptogenic zone including a lesion observed on magnetic resonance imaging. Corticectomy of the inferior parietal lobule was performed via invasive EEG monitoring, but resulted in failed seizure control. The middle and posterior temporal cortices were additionally resected in the second surgery. The patient experienced contralateral hemianopsia postoperatively, but no hemispatial neglect. Hypermotor seizures have not been seen for 1.5years since surgery. This is the first description of a patient with a parietal lobe lesion experiencing hypermotor seizures. The middle and posterior temporal cortices were considered epileptogenic together with the inferior parietal lobule in the present case.

Late-onset tumefactive multiple sclerosis.

A patient with tumefactive multiple sclerosis (MS) initially presented at the age of 87 years; the revised diagnostic criteria from the International Panel on MS (2001) were fulfilled. Late-onset MS and tumefactive demyelinating lesions are discussed. This case suggests that MS can occur at any age. MS should be borne in mind for differential diagnosis if a brain tumor-like lesion with little mass effect and edema is found in an elderly patient.

Successful recanalization by in-stent percutaneous transluminal angioplasty with distal protection for acute carotid stent thrombosis.

A 71-year-old male presented with severe left cervical internal carotid artery stenosis manifesting as repeated transient ischemic attacks consisting of right hemiparesis and motor aphasia. Carotid artery stenting (CAS) under distal protection was performed to prevent further ischemic events. This procedure was uneventful. However, the patient exhibited progressive right hemiparesis and motor aphasia 3 days after CAS. Emergent angiography revealed carotid artery occlusion due to in-stent thrombosis. In-stent percutaneous transluminal angioplasty (PTA) was performed under distal protection. The carotid artery was recanalized with small residual thrombus. The neurological deficits almost completely disappeared after PTA. Follow-up angiography 9 months after stenting showed restenosis but no in-stent thrombosis. Carotid thrombosis after CAS can be resolved by in-stent PTA under distal protection and subsequent treatment with antithrombotic agents.

[Craniotomy for organized subdural hematoma].

We reported 3 cases of organized chronic subdural hematoma (CSDH), which required radical treatment by craniotomy. All patients were in the 70s (male, two; female, one). Two cases had previously received craniotomy and neck clipping for intracranial aneurysm. All of them received trephine evacuation of hematoma more than two times, although the hematoma was not removed due to organization. Because of this, we performed craniotomy and removal of the hematoma with its thick outer membrane. In order to obliterate the subdural space completely, we stripped the dura mater from the skull and attached it to the inner membrane with fibrine glue. After a period of more than two years of followed-up, no recurrences had been discovered.

The mechanism and effect of chronic electrical stimulation of the globus pallidus for treatment of Parkinson disease.

OBJECT: Although chronic electrical stimulation of the globus pallidus (GP) has been shown to ameliorate motor disabilities in Parkinson disease (PD), the underlying mechanism remains to be clarified. In this study the authors explored the mechanism for the effects of deep brain stimulation of the GP by investigating the changes in neurotransmitter levels in the cerebrospinal fluid (CSF) during the stimulation. METHODS: Thirty patients received chronic electrical stimulation of the GP internus (GPi). Clinical effects were assessed using the Unified PD Rating Scale (UPDRS) and the Hoehn and Yahr Staging Scale at 1 week before surgery and at 6 and 12 months after surgery. One day after surgery, CSF samples were collected through a ventricular tube before and 1 hour after GPi stimulation. The concentration of neurotransmitters such as gamma-aminobutyric acid (GABA), noradrenaline, dopamine, and homovanillic acid (HVA) in the CSF was measured using high-performance liquid chromatography. The treatment was effective for tremors, rigidity, and drug-induced dyskinesia. The concentration of GABA in the CSF increased significantly during stimulation, although there were no significant changes in the level of noradrenaline, dopamine, and HVA. A comparison between an increased rate of GABA concentration and a lower UPDRS score 6 months postimplantation revealed that the increase in the GABA level correlated with the stimulation-induced clinical effects. CONCLUSIONS: Stimulation of the GPi substantially benefits patients with PD. The underlying mechanism of the treatment may involve activation of GABAergic afferents in the GP.