Yukimasa Yasumoto

The Virchow-Robin spaces: delineation by magnetic resonance imaging with considerations on anatomofunctional implications

IntroductionThe Virchow-Robin spaces (V-R spaces) are well-known, but not systematically understood fluid-filled perivascular spaces that allow the convexity and basal perforating vessels to penetrate deep into the cerebral parenchyma.ObjectiveThis study aims to delineate anatomical characteristics of the normal V-R spaces by MR imaging with considerations on clinical and anatomofunctional implications of the V-R spaces.MethodsIn this prospective study with 3T magnetic resonance (MR) imaging, the whole extent of the intracranial V-R spaces was classified into basal, cortical, subcortical, paraventricular, and brainstem segments, on the basis of the topological difference in 105 control subjects. Morphological characteristics in each segment of the V-R spaces are described. For comparison with the neuroimaging appearance, V-R spaces were histologically examined in cadaveric human brains. The physiological functions of the V-R spaces and pathognomonic implications of unusually dilated, but asymptomatic, V-R spaces encountered in five subjects are discussed.ResultsThe V-R spaces were found to form a complicated, while anatomically highly consistent, intraparenchymal canal network distributed over the whole cerebral hemispheres and connect the cerebral convexity, basal cistern, and ventricular system.ConclusionThe V-R spaces may be essential for drainage routes of cerebral metabolites, additional buoyancy for the brain, and maintenance of homogenous intracranial pressure. MR imaging may be more advantageous in depicting the V-R spaces than histological examination.

Cervical spondylosis: Evaluation of microstructural changes in spinal cord white matter and gray matter by diffusional kurtosis imaging

INTRODUCTION We investigated microstructural changes in the spinal cord, separately for white matter and gray matter, in patients with cervical spondylosis by using diffusional kurtosis imaging (DKI). METHODS We studied 13 consecutive patients with cervical myelopathy (15 affected sides and 11 unaffected sides). After conventional magnetic resonance (MR) imaging, DKI data were acquired by using a 3T MR imaging scanner. Values for fractional anisotropy (FA), apparent diffusion coefficient (ADC), and mean diffusional kurtosis (MK) were calculated and compared between unaffected and affected spinal cords, separately for white matter and gray matter. RESULTS Tract-specific analysis of white matter in the lateral funiculus showed no statistical differences between the affected and unaffected sides. In gray matter, only MK was significantly lower in the affected spinal cords than in unaffected spinal cords (0.60±0.18 vs. 0.73±0.13, P=0.0005, Wilcoxons signed rank test). CONCLUSIONS MK values in the spinal cord may reflect microstructural changes and gray matter damage and can potentially provide more information beyond that obtained with conventional diffusion metrics.

Metabolic alterations in fiber layers of the CA 1 region of the gerbil hippocampus following short-term ischemia: high-energy phosphates, glucose-related metabolites, and amino acids.

The CA 1 neurons of the gerbil hippocampus die at 4 days following 5 min of bilateral ischemia. The fiber and somal layers of the CA 1 region of the gerbil hippocampus were analyzed for high-energy phosphates, glucose-related metabolites, and amino acids from 0.75 hr to 4 days of postischemia. The results were compared to those from two layers of the CA 3 region and the cerebral cortex. The metabolite changes in the fiber layers of the CA 1 region were qualitatively similar to those in the somal layer. The energy status of the tissues taken from the CA 1 region was never compromised for up to 2 days of recirculation, after which the ATP and P-creatine in the somal layer decreased to 43 and 56% of the control, respectively, whereas the average decreases in the CA 1 fiber layers were only 71 and 88% of the control, respectively. Thus, the high-energy phosphate response of the neuronal elements in the fiber layers was temporally similar to that found in the somal layer of the CA 1 region. The biphasic increases in glycogen, glucose, glucose-6-phosphate, and high-energy phosphates to values greater than the control indicated that the metabolic restoration following transient ischemia is a dynamic process which persists for up to 2 days of recirculation, even in resistant tissues. A similar pattern of delayed changes was observed in glutamate, γ-aminobutyric acid (GABA), and glutamine, but the change in each amino acid appeared to be independent of the others despite their close metabolic relationship. The delayed decreases in GABA would favor a loss of inhibition to the CA 1 neurons and may be related to the phenomenon of delayed neuronal death.

Calvarial diploic venous channels: an anatomic study using high-resolution magnetic resonance imaging

BackgroundThe calvarial diploic venous channels (CDVCs) are well-known intraosseous structures, but their distribution and anatomofunctional implications are not fully understood.ObjectiveTo investigate the architecture of CDVCs using high-resolution magnetic resonance (MR) imaging.MethodThis prospective study enrolled 43 male and 37 female outpatients who underwent a 3.0-T MR imaging equipped by a 32-channel head coil. T1-weighted imaging covering the whole cranial vault was performed after gadolinium injection. In addition, one-piece orbitozygomatic craniotomy was performed in three cadaveric heads to observe the interruption of the CDVCs.ResultsThe CDVCs showed irregular contours and peculiar branching patterns with four common major pathways: the pteriofrontparietal (PFP), frontoorbital (FO), occipitoparietal (OP), and occipitocervical (OC) routes. The proximal PFP coursed as a single trunk and divided into several branches at the level of the frontal eminence. The orbital part of the FO continued to the subcutaneous vein via the supraorbital rim. The PFP and the pterional part of the FO fused proximally with the sphenoparietal sinus and descended as the middle meningeal vein. The OP coursed in the superoinferior direction and connected the junction part of the transverse-sigmoid sinus to the parietal superior sagittal sinus. The OC occurred as a single trunk in the median occipital bone, drained extracranially, and joined the suboccipital venous channels.ConclusionsThe CDVCs seem to be a relatively consistent network functioning not only as conduits connecting the intracranial dural sinuses but also as pathways to the extracranial venous systems. High-resolution MR imaging is useful for investigating the CDVCs.

Spinal angiolipoma in a pregnant woman presenting with acute epidural hemorrhage

A 26-year-old woman in week 31 of pregnancy presented to the emergency room with acute onset of paraplegia. Her medical history was unremarkable. Neurological examination revealed complete paraplegia, total sensory loss below the T7 dermatome, and significant vesicorectal dysfunction. MRI revealed an intraspinal mass from T3 to T4, which was hyperintense on both T1-weighted and T2-weighted images. Blood examination found no abnormality. She underwent emergent hemilaminectomy and removal of the hematoma. Intraoperatively, unusually ectatic venous vessels were found adhered to the lower surface of the epidural clot. No concurrent vascular malformations were identified and the dura mater was intact. The histological diagnosis was angiolipoma. Postoperatively her neurological deficits showed remarkable improvement, and she gave birth to a healthy baby. Spinal angiolipoma in a pregnant woman may be complicated with acute epidural hemorrhage. Emergent surgical evacuation can be performed safely with a good functional prognosis.

Genomic causes of multiple cerebral cavernous malformations in a Japanese population

Cerebral cavernous malformation (CCM) is a hamartomatous vascular disease affecting the central nervous system. A fraction of CCM are thought to arise in association with genomic mutations in the cerebral cavernous malformation 1 (CCM1) (KRIT1), CCM2 (MGC4607), and CCM3 (PDCD10) genes. In the present study, 18 Japanese patients with multiple CCM (10 with familial type and eight with sporadic type), underwent genomic analysis for CCM1, CCM2 and CCM3 mutations with blood samples and surgical specimens. MRI showed CCM in the cerebral hemisphere in 17 patients, the cerebellum in 10, the brainstem in 10 and the spinal cord in eight. CCM2 mutations were the most prominent, followed by CCM1 and CCM3. CCM1, CCM2 and CCM3 mutations were not identified in seven patients. Among the 10 patients with familial CCM, CCM1, CCM2 and CCM3 mutations were found in two, three and one patient, respectively, whereas four patients lacked these mutations. Among the eight patients with sporadic CCM, these mutations were found in one, three, and one patients, respectively, whereas three patients lacked these mutations. Most of the patients had a stable course during the follow-up period. Genomic mutations other than CCM1, CCM2 and CCM3 may be frequent in patients with multiple CCM in the Japanese population.

Pediatric multicentric glioma occurring after cranial irradiation

An 8-year-old girl with no family history of neoplasia underwent biopsy and chemoradiation therapy for a suprasellar mixed germ cell tumor, which resulted in complete remission. A surveillance MRI taken 37 months after irradiation detected a non-enhancing mass in the genu of the corpus callosum. MRI taken 42 months after irradiation revealed significant growth of the mass and a new enhancing lesion in the temporal lobe, which showed rapid growth over 3 weeks. Subtotal resection and biopsy were performed on the lesions in the temporal lobe and the corpus callosum, respectively. Histological examination revealed that the temporal tumor was a glioblastoma multiforme and the frontal lesion was a diffuse astrocytoma. These tumors had newly developed within the irradiated field, but were separated in both location and time. Radiation-induced gliomas may develop within a shorter time interval than previously considered.

Magnetic resonance imaging appearance of primary spinal extradural Ewing's sarcoma: case report and literature review.

PurposePrimary spinal extradural Ewing’s sarcoma (PSEES) or primitive neuroectodermal tumor (PNET) is uncommon. The present study summarizes the magnetic resonance (MR) imaging appearance of PSEES.MethodsLiterature search from 1994 to 2012 with our representative case presentation.ResultsTwenty-one patients, 12 males and 9 females, aged 3 weeks to 44 years, were identified. The thoracic spine was most frequently affected, followed by the cervical, cervicothoracic, and thoracolumbar spine. Superior–inferior extension of lesions was three vertebral levels in 7, two in 7, five in 4, four in 1, one in 1 and unknown in 1. PSEESs appeared isointense in 9 cases, hypointense in 2, hyperintense in 1, and no description in 9 on T1-weighted imaging, while hyperintense in 6, hypointense in 3, heterogeneous in 1, and no description in 11 on T2-weighted imaging. Varying enhancement was noted in 13 cases (62 %), with no description of contrast study in the other 8 cases. Dumbbell-shaped configuration of PSEES was found in 5 cases, foraminal widening in 4, and erosions or scalloping of the adjacent vertebral bodies in 4.ConclusionThe MR imaging appearance of PSEESs is indistinguishable from other tumors. PSEES should be assumed as the differential diagnosis of spinal extradural tumors in pediatric, adolescent, and young adult patients, and prompt surgical exploration should be performed.

Peduncular hallucinosis following microvascular decompression for trigeminal neuralgia without direct brainstem injury: case report

We report a 68-year-old woman who experienced visual hallucinations diagnosed as peduncular hallucinosis (PH) following microvascular decompression for trigeminal neuralgia. Postoperative MRI showed only ischemic oedema of the left cerebellar hemisphere due to retraction. Our case first reveals that PH can be induced without direct brainstem injury, instead possibly by a cerebellar lesion.

Cranial Arachnoid Protrusions and Contiguous Diploic Veins in CSF Drainage

BACKGROUND AND PURPOSE: Studies have suggested that arachnoid villi or granulations found in the walls of the cranial dural sinuses, olfactory mucosa, and cranial nerve sheaths function as outlets for intracranial CSF. However, their role as CSF outlets has not yet been verified. Here we show that arachnoid protrusions and contiguous diploic veins provide an alternative drainage route for intracranial CSF. MATERIALS AND METHODS: Four hundred patients with intact skull, dura mater, and dural sinuses underwent MR imaging to explore arachnoids protruding into the skull and diploic veins. Patients with symptoms of increased intracranial pressure or intracranial hypotension were excluded. For 15 patients undergoing craniotomy, both peripheral and diploic venous blood was collected. Albumin and the CSF-specific biomarkers were measured by enzyme-linked immunosorbent assay. RESULTS: With MR imaging, arachnoid protrusions into the skull and contiguous diploic veins were consistently identified throughout the cranium with their characteristic appearance depending on the cranial region. In addition, elevated amounts of prostaglandin D synthase and cystatin C were confirmed in diploic veins compared with peripheral venous blood. CONCLUSIONS: Diploic veins are distributed ubiquitously throughout the cranium. A portion of the intracranial CSF may be drained through arachnoid protrusions and contiguous diploic veins.