Yoshihiro Kuga

Microsurgical anatomy of the lower cervical spine and cord.

The authors dissected the cervical spine and its surrounding structures from 40 adult cadavers under a surgical microscope. The anterior part of the spine and spinal cord was examined after vertebrectomy. The posterior longitudinal ligament (PLL) consists of two layers; the anterior one is termed the deep layer, and the posterior one is termed the superficial layer. These two layers adhered together loosely. In the lateral portion of the spinal canal, the superficial layer joined the periradicular sheath at the level of the intervertebral disc spaces and joined the dura mater at the level of the vertebral bodies. After the removal of the deep layer, the anterior internal vertebral venous plexus was seen on top of the lateral part of the superficial layer. The venous plexus was embedded between the double-layered PLLs, was not located in the epidural space, and was not seen in the medial part of the PLL. The PLL without venous channels on top of it was about 10 mm in width at the levels of the intervertebral disc and about 5 mm at the levels of the vertebral body. The anterior root exit zone (AREZ) was an elliptical shape; the transverse length of the AREZ was about 2 mm, and the longitudinal length was 10 to 15 mm. The average number of anterior rootlets on the AREZ was 17 to 25 and tended to decrease in the lower cervical spinal cord. The posterior structures were examined after en bloc laminectomy.(ABSTRACT TRUNCATED AT 250 WORDS)

Classification of the Superior Petrosal Veins and Sinus Based on Drainage Pattern

BACKGROUND: The increasing number of reports of complications after sacrificing the superior petrosal veins, the largest veins in the posterior fossa, has led to a need for an increased understanding of the anatomy of these veins and the superior petrosal sinus into which they empty. OBJECTIVE: To examine the anatomy of the superior petrosal veins and their size, draining area, and tributaries, as well as the anatomic variations of the superior petrosal sinus. METHOD: Injected cadaveric cerebellopontine angles and 3-dimensional multifusion angiography images were examined. RESULTS: The 4 groups of the superior petrosal veins based on their tributaries, course, and draining areas are the petrosal, posterior mesencephalic, anterior pontomesencephalic, and tentorial groups. The largest group was the petrosal group. Its largest tributary, the vein of the cerebellopontine fissure, was usually identifiable in the suprafloccular cistern located above the flocculus on the lateral surface of the middle cerebellar peduncle. The medial or lateral segment of the superior petrosal sinus was absent in 40% of cerebellopontine angles studied with venography. CONCLUSION: The superior petrosal veins and their largest tributaries, especially the vein of the cerebellopontine fissure, should be preserved if possible. Obliteration of superior petrosal sinuses in which either the lateral or medial portion is absent may result in loss of the drainage pathway of the superior petrosal veins. Preoperative assessment of the superior petrosal sinus should be considered before transpetrosal surgery in which the superior petrosal sinus may be obliterated. ABBREVIATION: CPA, cerebellopontine angle

Cortical connections of the motor thalamic nuclei in the Japanese monkey, Macaca fuscata.

Our findings revealed the nucleus ventralis lateralis pars oralis (VLo) projection to motor area, and the nucleus ventralis anterior pars principalis (VApc) projections to the premotor and supplementary motor areas (SMA). The VLo gave rise to thalamocortical projections terminating in the superficial half of layer I, mainly in the forelimb motor area. The VApc gave rise to the superficial projections to the post-arcuate premotor area around the arcuate genu and arcuate spur as well as SMA. We suggested that the medial pallidal segment projects to the motor area via VLo, and to the premotor area and SMA via VApc. We also proposed that the premotor area and SMA receive cerebellar afferents via nucleus ventralis lateralis pars caudalis and area X.

Direct projections from the globus pallidus to the inferior colliculus in the rat.

A retrograde and anterograde wheat germ agglutinin-horseradish peroxidase (WGA-HRP) study in the rat indicated that some neurons in the globus pallidus (GP) sent their axons ipsilaterally to the inferior colliculus (IC). These neuronal cell bodies were located in the ventrolateral portions of the caudal part of the GP, and their axons were distributed mainly in the peripheral region of the external cortex of the IC.

Platelet Function and Spontaneous Thrombolytic Activity of Patients with Cerebral Infarction Assessed by the Global Thrombosis Test

Measurements of platelet reactivity and assessment of the efficacy of antiplatelet drugs are widely recognized as pre-requisite for the diagnosis and treatment of stroke patients. A recently established shear-induced platelet reactivity test using non-anticoagulated blood (the Global Thrombosis Test) has facilitated measurements of physiologically relevant platelet function and thrombolytic activity. 195 healthy volunteers, not taking antiplatelet drugs or anticoagulants, and 185 patients with acute cerebrovascular diseases were enrolled. The effect of antiplatelet drugs on platelet function and thrombolytic activity was assessed using the Global Thrombosis Test after 14 days of medication. The occlusion time (OT), an index of platelet reactivity, in healthy controls was 284.9 ± 92.2 s. The lysis time (LT), an index of thrombolytic activity, in healthy controls was 2,231 ± 1,223 s. Both times had no significant difference between males and females. The OT of all stroke patients was 210.3 ± 140.8 s and was shorter than that of the healthy controls (284.9 ± 92.2, p < 0.0001). The LT of all stroke patients was 3,159 ± 1,549 s and was longer than that of the controls (2,231 ± 1,223, p < 0.0001). Medication significantly prolonged the OT from 184.5 ± 150.6 s (before) to 295.3 ± 208.1 s (after) in all patients, indicating a reversal of the hyper-platelet reactivity. In addition, medication shortened the LT from 3,924 ± 1,718 s (before) to 3,107 ± 1,794 s (after) in all patients. A prothrombotic state exists in stroke patients due to enhanced platelet function and suppressed thrombolytic activity. Medication improved these physiological parameters of haemostasis.

Cerebral and spinal cord tanycytic ependymomas in a young adult with a mutation in the NF2 gene

We studied one frontal lobe tumor and multiple spinal cord tumors (one in an extramedullary location) that had been resected from a 24‐year‐old man. The frontal lobe tumor was well demarcated and non‐infiltrating, and consisted of eosinophilic, elongated fibrillary cells arranged in a fascicular pattern. A similar histology was reproduced in the spinal cord tumors, with additional areas showing standard features of ependymoma. Immunohistochemical and ultrastructural observations revealed that all the tumors were ependymal in nature with positivity for GFAP and epithelial membrane antigen and negativity for oligodendrocyte transcription factor 2, showing intra‐ and intercellular microrosettes, leading us to a diagnosis of tanycytic ependymoma for the frontal lobe tumor and tanycytic ependymoma with ordinary ependymomatous component for the spinal cord tumors. The spinal extramedullary tumor was a schwannoma. Importantly, a heterozygous truncating mutation in the NF2 gene was identified in the blood lymphocytes from the patient. It is known that multiple nervous system tumors can occur in neurofibromatosis type 2 (NF2), which is caused by mutation in the NF2 gene, and that occurrence of ependymoma, including the tanycytic variant, can be associated with this genetic condition. The present case provides further information about the clinicopathology of tanycytic ependymoma with details of the immunohistochemical, ultrastructural and genetic features.

Topographical Organization of the Thalamostriatal Projection in the Japanese Monkey, Macaca Fuscata, with Special Reference to the Centromedian-Parafascicular and Motor Thalamic Nuclei

Thalamostriatal projection was studied in monkeys (Macaca fuscata) using the axonal transport techniques of WGA-HRP and autoradiography to clarify the topographical organization. Major findings were as follows: The dorsomedial part of the centromedian nucleus (CM) projects to the dorsolateral strip in the leg territory of the putamen (Put); the ventromedial CM projects to the ventromedial strip in the face area; and the lateral CM projects to the intermediate strip in the arm region of the Put. The lateral part of the parafascicular nucleus (Pf) and nucleus ventralis anterior pars parvicellularis project to the lateral part of the head of the caudate nucleus (CN) and to the dorsolateral part of the rostral Put. Whereas the medial Pf and nucleus ventralis anterior pars magnocellularis project to the medial and ventral parts of the CN and to the ventromedial part of the rostral Put. The nucleus ventralis lateralis pars oralis projects to the Put. The medial part of the nucleus subthalamicus (STN) projects to the head of CN and rostral Put, while the lateral STN projects to the remaining whole part of the Put.

Carotid Endarterectomy for Patients over 80 Years Old

Objective: Carotid endarterectomy (CEA) is one of the surgical treatments for carotid artery stenosis. While a large clinical trial showed that advanced age is a risk factor for CEA, other studies reported contradictory results. The aim of this study was to evaluate the outcomes of CEA in patients aged over 80. Methods: Patients who underwent CEA between January 2012 and June 2015 in our hospital were included, and were divided into either the high age group (>80 years old) or standard group (<80 years old). CEA was the firstline surgical treatment, instead of carotid artery stenting (CAS), for all eligible cases, except where patients were not deemed amenable to general anesthesia or at patients’ request not to undergo CEA. Patient background and perioperative complications were assessed and compared statistically between the high age group and standard group. Results: Of a total of 127 patients, 20 (15.7%) were in the high age group. No significant differences in patient background were obtained between the high age group and standard group. Four (20%) cases in the high age group had perioperative complications which were all transient. No significant differences in perioperative complications were obtained between the high age group and standard group. Conclusions: It is possible for CEA to be performed safely in the elderly, provided adequate preoperative assessment of the general condition and perioperative management of patients are carried out. We recommend that CEA should not be avoided as a treatment option in the elderly, based solely on patient age.

Relationship between dyslipidemia and vascular repair after cervical artery dissection

In some cases of cervical artery dissection, vascular repair subsequently occurs at the stenotic or occluded sites. The factors responsible for this type of vascular repair remain unknown, but some reports from in vitro and animal models suggest that it is related to lipid metabolism.

Penetration of the Optic Nerve by an Unruptured Internal Carotid Artery- Ophthalmic Artery Aneurysm: Case Report

Internal Carotid Artery (ICA)-ophthalmic artery aneurysms are relatively rare aneurysms, constitute 0.3% to 1% of intracranial aneurysms and 0.9% to 6.5% of aneurysms of the ICA. Including them, large and giant aneurysms developing around the optic nerve sometimes press it and make it thin, but rarely penetrate it. There have been very few reports that they could predict the ICA-ophthalmic artery aneurysm penetrated the optic nerve with preoperative Magnetic Resonance Imaging (MRI), and it is very useful. We present a case that we could predict penetration of the optic nerve by an ICA-ophthalmic artery aneurysm before the operation, and could confirm it in the operation.