Tetsuya Nagatani

Idiopathic Hypertrophic Cranial Pachymeningitis: Clinicoradiological Spectrum and Therapeutic Options

OBJECTIVE Idiopathic hypertrophic cranial pachymeningitis is a rare disease, of undetermined pathogenesis, that is characterized by inflammation and fibrosis of the dura mater. METHODS We encountered six patients with idiopathic hypertrophic cranial pachymeningitis and analyzed their clinical presentations, radiological findings, and treatment. RESULTS In the six patients, the main manifestations were cranial nerve palsies and headache. Three associations were present, namely optic neuropathy, Tolosa-Hunt syndrome, and diabetes insipidus. Gadolinium-enhanced magnetic resonance imaging was diagnostic, showing intense dural enhancement in a linear or nodular pattern. The responses to corticosteroid therapy were better for patients who exhibited linear, rather than nodular, dural enhancement. For one patient, surgical decompression of the superior orbital fissure provided lasting relief. The course of the disease followed one of three patterns, i.e., sustained remission, relapse with corticosteroid independence, or relapse with corticosteroid dependence. Pulse corticosteroid therapy provided significant relief, while reducing the daily corticosteroid requirement and avoiding side effects, for a corticosteroid-dependent relapsing patient. CONCLUSION Idiopathic hypertrophic cranial pachymeningitis exhibits varied clinical courses. It is important to prevent irreversible cranial neuropathy during the active phase of the disease, using daily administration of corticosteroids, pulse corticosteroid therapy, or surgical decompression.

Cerebellar stroke due to vertebral artery occlusion after cervical spine trauma. Two case reports.

The authors report two cases of cerebellar infarction due to vertebral artery (VA) occlusion resulting from cervical spine trauma. In one patient with dens and C2 body fracture, the left VA was occluded, resulting in a left cerebellar infarction. The second patient, with a subluxation of C4 on C5, presented with cerebellar swelling and infarction along with acute hydrocephalus secondary to bilateral vertebral artery occlusion. Because vertebral artery injuries with cervical trauma are rarely symptomatic, they can be easily overlooked. Bilateral or dominant vertebral artery occlusion, however, may cause rapid and fatal ischemic damage to the cerebellum and brain stem. Rapid recognition and optimal treatment for this injury depends on early vertebral artery angiography.

A perspective from magnetic resonance imaging findings of the inner ear: Relationships among cerebrospinal, ocular and inner ear fluids.

Visualization of endolymphatic hydrops has been performed using magnetic resonance imaging (MRI) after intratympanic or intravenous gadolinium (Gd) injection. Our recent findings indicate that just as the prevalence of asymptomatic glaucoma is greater than that of symptomatic glaucoma, there are also many cases of asymptomatic endolymphatic hydrops. It is assumed that the asymptomatic endolymphatic hydrops that precedes Ménières disease is found more frequently using MRI than with other techniques. Gd in the inner ear moves into the cerebrospinal fluid (CSF) via the internal auditory meatus. Gd enhancement is also recognized in the ocular fluid after the intravenous Gd administration. In this paper, the relationships between CSF, ocular fluid and inner ear fluid are reviewed. The central nervous system, eye and inner ear contain specialized extracellular fluids that are essential for maintaining their function: CSF, ocular fluid consisting of vitreous humor and aqueous humor, and inner ear fluid consisting of perilymph and endolymph. Abnormal accumulation of or pressure elevation in these fluids is associated with hydrocephalus, glaucoma and Ménières disease, respectively. The dura mater and the arachnoid membrane of the optic nerve canal and inner ear meatus are very close to the eye and the inner ear, respectively. It has been reported that low CSF pressure is associated with glaucoma and endolymphatic hydrops. In glaucoma and Ménières disease, nerve damage to ganglion cells rather than damage of the sensory cells is directly associated with progression of the disease. Retinal ganglion cells in glaucoma and spiral ganglion cells in Ménières disease are targets of the abnormal accumulation of, or increased pressure in, the extracellular fluid, just as neurons are damaged in hydrocephalus. Studies on hydrocephalus, glaucoma and Ménières disease as a group may deepen our understanding of each disease.

Intradural cranial chordoma

BACKGROUND Intradural chordomas are rare and have been considered benign owing to the feasibility of complete resection and the display of lesser aggressive biologic behavior than typical chordomas. CASE DESCRIPTION We herein reported 2 cases of intradural cranial chordoma with aggressive biologic behavior. A tumor (anti-Ki-67 monoclonal antibody [MIB-1], 13.9%) in a 59-year-old woman was strongly adherent to the brainstem and involved the basilar artery and its branches. After subtotal removal, the remnant tumor was treated with stereotactic radiotherapy. A tumor (MIB-1, 6.2%) in a 75-year-old woman repeatedly recurred even after initial gross total removal. The recurrent chordomas were treated with γ-knife radiosurgery. CONCLUSION The cases presented in this study indicate that intradural chordomas can also be aggressive such as typical chordomas. Long-term follow-ups with a large number of patients with this condition are essential for elucidating the prognosis of intradural chordomas.

Perforating branches from offending arteries in hemifacial spasm: anatomical correlation with vertebrobasilar configuration

OBJECTIVE In microvascular decompression for hemifacial spasm, the perforating branches around the facial nerve root exit zone occasionally complicate facial nerve decompression. In this context, the vertebrobasilar configuration was retrospectively correlated with the perforating branches. METHODS Based on vertebral angiography, magnetic resonance angiography, and three dimensional computed tomographic angiography, 69 patients were divided into three groups, according to the anatomy of the vertebrobasilar system. In patients with the type I configuration, the vertebral artery on the affected side was dominant and had a sigmoidal course. The type II patients had the basilar artery curving mainly towards the affected side. The type III patients showed the basilar artery either running straight or curving toward the unaffected side. The relation of the anatomical configuration of these vessels with the perforating branches around the facial nerve exit zone was investigated. RESULTS The posterior inferior cerebellar artery in type I patients (n=33) and the anterior inferior cerebellar artery in type II (n=5) and type III (n=31) patients were the most common offending arteries. More than half of the type I patients (n=20) showed no perforating branches around the facial nerve exit zone. However, the type II (n=3) and III patients (n=23) often showed one or more perforating branches around that region. CONCLUSIONS The configuration of the vertebrobasilar system has a significant correlation with the presence of perforating branches near the site of microvascular decompression. These perforating vessels are often responsible for the difficulty encountered in mobilising the offending artery during the procedure.

A novel method of intracranial injection via the postglenoid foramen for brain tumor mouse models

OBJECT Mouse models have been widely used in developing therapies for human brain tumors. However, surgical techniques such as bone drilling and skin suturing to create brain tumors in adult mice are still complicated. The aim of this study was to establish a simple and accurate method for intracranial injection of cells or other materials into mice. METHODS The authors performed micro CT scans and skull dissection to assess the anatomical characteristics of the mouse postglenoid foramen. They then used xenograft and genetically engineered mouse models to evaluate a novel technique of percutaneous intracranial injection via the postglenoid foramen. They injected green fluorescent protein-labeled U87MG cells or virus-producing cells into adult mouse brains via the postglenoid foramen and identified the location of the created tumors by using bioluminescence imaging and histological analysis. RESULTS The postglenoid foramen was found to be a well-conserved anatomical structure that allows percutaneous injection into the cerebrum, cerebellum, brainstem, and basal cistern in mice. The mean (± SD) time for the postglenoid foramen injection technique was 88 ± 15 seconds. The incidence of in-target tumor formation in the xenograft model ranged from 80% to 100%, depending on the target site. High-grade gliomas were successfully developed by postglenoid foramen injection in the adult genetically engineered mouse using virus-mediated platelet-derived growth factor B gene transfer. There were no procedure-related complications. CONCLUSIONS The postglenoid foramen can be used as a needle entry site into the brain of the adult mouse. Postglenoid foramen injection is a less invasive, safe, precise, and rapid method of implanting cells into the adult mouse brain. This method can be applied to both orthotopic xenograft and genetically engineered mouse models and may have further applications in mice for the development of therapies for human brain tumors.

Magnetically guided 3-dimensional virtual neuronavigation for neuroendoscopic surgery: technique and clinical experience.

OBJECTIVE The authors have developed a novel intraoperative neuronavigation with 3-dimensional (3D) virtual images, a 3D virtual navigation system, for neuroendoscopic surgery. The present study describes this technique and clinical experience with the system. METHODS Preoperative imaging data sets were transferred to a personal computer to construct virtual endoscopic views with image segmentation software. An electromagnetic tracker was used to acquire the position and orientation of the tip of the neuroendo-scope. Virtual endoscopic images were interlinked to an electromagnetic tracking system and demonstrated on the navigation display in real time. Accuracy and efficacy of the 3D virtual navigation system were evaluated in a phantom test and on 5 consecutive patients undergoing neuroendoscopic surgery. RESULTS Virtual navigation views were consistent with actual endoscopic views and trajectory in both phantom testing and clinical neuroendoscopic surgery. Anatomic structures that can affect surgical approaches were adequately predicted with the virtual navigation system. The virtual semitransparent view contributed to a clear understanding of spatial relationships between surgical targets and surrounding structures. Surgical procedures in all patients were performed while confirming with virtual navigation. In neurosurgery with a flexible neuroscope, virtual navigation also demonstrated anatomic structures in real time. CONCLUSION The interactive method of intraoperative visualization influenced the decision-making process during surgery and provided useful assistance in identifying safe approaches for neuroendoscopic surgery. The magnetically guided navigation system enabled navigation of surgical targets in both rigid and flexible endoscopic surgeries.

Normalisation of plasma growth hormone levels improved cardiac dysfunction due to acromegalic cardiomyopathy with severe fibrosis

A 51-year-old man was referred to the Department of Cardiology in our hospital due to severe congestive heart failure and ventricular arrhythmias in March 2008. He had repeated ventricular tachycardia for years and the left ventricular ejection fraction (EF) was 11% on admission. A myocardial biopsy revealed that over 50% cardiomyocytes were replaced by fibrosis. Due to the typical acromegalic features, he was referred to the endocrinology department and diagnosed as acromegaly. He was treated with octreotide for 8 months followed by trans-sphenoidal surgery. The plasma levels of growth hormone (GH) and insulin-like growth factor-1 (IGF-1) decreased by octreotide and normalised by surgery after which the cardiac function improved drastically. The current case demonstrates that cardiac dysfunction in acromegaly could be recovered by normalisation of GH and IGF-1 even in the presence of severe fibrosis in the myocardium.

Altered sympathetic thermoregulation in patients with hypothalamic dysfunction following resection of suprasellar tumors

In patients with suprasellar tumors, both the tumor and its surgical resection may produce hypothalamic dysfunction including thermoregulatory disturbances. We quantitated skin sympathetic nerve activity using microneurography in eight patients with hypothalamic dysfunction following resection. Skin sympathetic nerve activity, skin blood flow (by laser Doppler flowmetry), sweating, blood pressure, and pulse rate were monitored during changes of core (tympanic) temperature in the patients and seven healthy controls. Core temperature was decreased by 0.3 degrees C and increased by 0.5 degrees C relative to baseline using a cooling/heating blanket. The increase in sympathetic nerve activity in response to cooling did not differ between controls and patients (41.0+/-13.1 vs. 38.1+/-7.7 bursts [min degrees C](-1)), but an increase upon heating in controls (45.1+/-5.4 bursts [min degrees C](-1)) was absent in the patients (-26.0+/-17.5 bursts [(min degrees C](-1)). Skin blood flow during heating increased significantly in controls but not in patients (35.6+/-14.6 vs. 15.8+/-5.8 ml [min 100 g tissue degrees C](-1)). The patients thus showed impaired heat loss during body temperature elevation. Microneurography proved to be a sensitive measure of hypothalamic autonomic function.

Endoscopic resection of cystic pontine tumour: three case reports and a proposal for minimally invasive dual-endoscopic surgery.

Objective and importanceWe describe a new endoscopic technique, the dual-endoscopic method, in which two independent endoscopic systems are simultaneously used in the subtemporal space and intraparenchymal field for patients with pontine cystic tumours. Tumours were successfully removed through a sheath placed in the brainstem via the subtemporal keyhole approach, with safety ensured by the second subtemporal endoscope.Clinical presentationA purely endoscopic subtemporal approach was performed in three cases of pontine cystic tumour, including two low-grade gliomas and a recurrent chordoma. The gliomas showed nodules. Recurrent chordoma consisted of a mucinous component.TechniqueUsing a keyhole subtemporal approach and a 4.0-mm rigid endoscope with a high-definition camera, a transparent puncture needle containing a 2.7-mm rigid endoscope was inserted into the cyst. The tumour was removed using suction, biopsy forceps, and scissors simultaneously placed with the 2.7-mm endoscope in a transparent sheath.ConclusionSince the 4.0-mm endoscope placed in the subtemporal space monitored all procedures of the 2.7-mm endoscope, tumour removal was performed safely without damaging the pons, cranial nerves, or vessels. We safely and successfully removed a cystic pontine tumour using a dual-endoscopic method. This new method ensures the safety of deep-seated endoscopic procedures via a minimally invasive transcranial approach.