Tooru Inoue

Surgical approaches to the cavernous sinus: a microsurgical study.

The surgical approaches to the cavernous sinus were examined in 50 adult cadaveric cavernous sinuses using magnification of X3 to X40. The following approaches were examined: 1) the superior intradural approach directed through a frontotemporal craniotomy and the roof of the cavernous sinus; 2) the superior intradural approach combined with an extradural approach for removing the anterior clinoid process and unroofing the optic canal and orbit; 3) the superomedial approach directed through a supraorbital craniotomy and subfrontal exposure to the wall of the sinus adjacent to the pituitary gland; 4) the lateral intradural approach directed below the temporal lobe to the lateral wall of the sinus; 5) the lateral extradural approach for exposure of the internal carotid artery in the floor of the middle cranial fossa proximal to the sinus; 6) the combined lateral and inferolateral approach, in which the infratemporal fossa was opened and the full course of the petrous carotid artery and the lateral wall of the sinus were exposed and; 7) the inferomedial approach, in which the medial wall of the sinus was exposed by the transnasal-transsphenoidal route. It was clear that a single approach was not capable of providing access to all parts of the sinus. The intracavernous structures best exposed by each route are reviewed. The osseous relationships in the region were examined in dry skulls. Anatomic variants important in exposing the cavernous sinus are reviewed.

Surgical treatment of moyamoya disease in pediatric patients--comparison between the results of indirect and direct revascularization procedures.

Either encephaloduroarteriosynangiosis (EDAS) or superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis combined with encephalomyosynangiosis (EMS) has been performed on most of the children with moyamoya disease in our department. EDAS alone was done in the parietal region of 13 sides in 10 patients, and STA-MCA anastomosis with EMS in the parietal region was done on 7 sides in 6 patients. The surgical results of these two different procedures were then compared. Postoperative collateral formation was observed on external carotid angiograms, and the improvement of clinical symptoms was monitored for 1 year after the bypass procedure. STA-MCA anastomosis with EMS was found to be superior to EDAS in both the development of collateral circulation (P less than 0.05) and postoperative clinical improvement (P less than 0.01). EDAS can be done easily and safely on small children with moyamoya disease, but STA-MCA anastomosis with EMS is considered to be more appropriate, whenever possible.

Antiplatelet therapy contributes to acute deterioration of intracerebral hemorrhage.

Objective: The purpose of this study was to examine the effect of antiplatelet therapy on the initial severity and the acute outcome of intracerebral hemorrhage (ICH). Methods: The authors reviewed records of 251 consecutive patients hospitalized in their cerebrovascular center within 24 hours after onset of ICH. Results: Fifty-seven patients (23%) had development of ICH during oral antiplatelet therapy. The major indication for antiplatelet therapy was the prevention of stroke recurrence (63%). As compared with patients without antiplatelet therapy, those who received antiplatelet therapy more frequently were aged 70 years or older (60% vs 35%; p < 0.001), had previous symptomatic ischemic stroke (54% vs 7%; p < 0.0001), had diabetes mellitus (26% vs 15%; p < 0.05), and had heart disease (32% vs 8%; p < 0.0001). Antiplatelet therapy was predictive of an increase in the hematoma volume by more than 40% on the second hospital day (hematoma enlargement, odds ratio [OR] 7.67, 95% CI 1.62 to 36.4) and the need for emergent surgical evacuation of the hematoma (OR 3.10, 95% CI 1.18 to 8.15). Antiplatelet therapy was an independent predictor for the occurrence of any of hematoma enlargement, emergent death, or evacuation surgery, which suggests that clinical deterioration occurs into the second hospital day (OR 7.45, 95% CI 2.46 to 22.5). Conclusions: Antiplatelet therapy seems to contribute to the acute clinical deterioration of intracerebral hemorrhage.

Microvascular decompression for treatment of trigeminal neuralgia, hemifacial spasm, and glossopharyngeal neuralgia : three surgical approach variations : technical note

OBJECTIVEWe have used three different approaches, namely, the infratentorial lateral supracerebellar approach, the lateral suboccipital infrafloccular approach, and the transcondylar fossa approach, for microvascular decompression for treatment of trigeminal neuralgia, hemifacial spasm, and glossopharyngeal neuralgia, respectively. Each approach is a variation of the lateral suboccipital approach to the cerebellopontine angle (CPA); however, each has a different site of bony opening, a different surgical direction, and a different route along the cerebellar surface. METHODSThe infratentorial lateral supracerebellar approach is used to access the trigeminal nerve in the superior portion of the CPA through the lateral aspect of the cerebellar tentorial surface. The lateral suboccipital infrafloccular approach is directed through the inferior part of the cerebellar petrosal surface to reach the root exit zone of the facial nerve below the flocculus. The transcondylar fossa approach is used to access the glossopharyngeal nerve in the inferior portion of the CPA through the cerebellar suboccipital surface, after extradural removal of the jugular tubercle as necessary. RESULTSIn all three approaches, the cerebellar petrosal surface is never retracted transversely, that is, the cerebellar retraction is never directed parallel to the longitudinal axis of the VIIIth cranial nerve, dramatically reducing the risk of postoperative hearing loss. CONCLUSIONThe greatest advantage of the differential selection of the surgical approach is increased ability to reach the destination in the CPA accurately, with minimal risk of postoperative cranial nerve palsy.

Microsurgical and magnetic resonance imaging anatomy of the cerebello-medullary fissure and its application during fourth ventricle surgery.

The cerebellomedullary fissure, the only entrance or exit to the fourth ventricle, is surrounded rostrally by the cerebellar tonsils and the biventral lobules and caudally by the medulla oblongata, the tela choroidea, and the lateral recesses. This fissure is an important route in operations on the fourth ventricle. We studied the microsurgical and magnetic resonance imaging (MRI) anatomy of the fissure by using autopsied normal cerebellum. MRI revealed that the fissure is visible as a slit and is indicated by the enhanced choroid plexus and the flocculus. Oriented by the anatomical information thus obtained, we have surgically treated nine patients with a tumor either in or around the fourth ventricle. Preoperative MRI clearly demonstrated the tumors in relation to the cerebellomedullary fissure. It revealed the precise anatomical location and extension of the tumor, not only its inferior extension but also its lateral one. The MRI findings and microsurgical anatomy of the cerebellomedullary fissure were quite useful for the removal of the tumors in the fourth ventricle.

Correlation of microanatomical localization with postoperative survival in posterior fossa ependymomas.

Twenty-two surgically treated infratentorial ependymomas were analyzed according to their anatomical origins and characteristics of extension in conjunction with the microsurgical anatomy of the fourth ventricle. The correlation between tumor origin and postoperative survival of the patients was also assessed. The tumors were classified into three types according to their origins and extensions: 1) midfloor-type: tumors originating from the caudal half of the fourth ventricular floor beneath the striae medullares. After occupying the fourth ventricular cavity, they extended downward through the foramen Magendie to the upper cervical level. 2) Lateral type: tumors arising from the vestibular area and/or the lateral recess. They grew not only inferiorly but also laterally to the cerebellomedullary cistern through the cerebellomedullary fissure and the foramen of Luschka. 3) Roof type: tumors originating from the roof of the ventricle. The overall cumulative survival rates at 2, 5, and 10 years were 84, 62, and 47%, respectively. Interestingly, the lateral-type tumors showed a significantly lower 5-year cumulative survival rate and mean survival time (21% and 40 months) when compared with midfloor-type tumors (73% and 170 months). Because the tumor originates near the vital neural structures and because each type has characteristics of extension, a clear knowledge of the microanatomical relationship between the tumor and the surrounding structures would be of great benefit for improving the operative outcome of posterior fossa ependymomas.

Formalin fixed brains are useful for magnetic resonance imaging (MRI) study

We carried out magnetic resonance imaging (MRI) studies on human brains which had been fixed in formalin solution for over 2 years and had been proven neuropathologically to be cases of multiple sclerosis (MS), progressive multifocal leukoencephalopathy (PML), and Balos concentric sclerosis (Balo). Using spin echo (SE) and inversion recovery (IR) pulse sequences to detect demyelinated lesions in a living person with MS, the demyelinated lesions of the fixed brains in cases of MS, PML and Balo definitely re-appeared, although T1 and T2 in the gray and white matter were reduced following fixation. High signal areas on the SE images corresponded not only to the characteristic distribution of demyelinated lesions in the white matter but also to sparse myelin, gliosis and mild perivascular cuffing in the white matter around the demyelinated foci in cases of the fixed MS, PML and Balo brains. On the IR images, only MS plaques were evident. This MRI study of fixed brains proved useful to elucidate clinicopathological correlations.

Diagnostic Impact of Transcranial Color-Coded Real-Time Sonography With Echo Contrast Agents for Hyperperfusion Syndrome After Carotid Endarterectomy

Background and Purpose— The purpose of the present study was to evaluate availability of transcranial color-coded real-time sonography (TCCS) to detect hyperperfusion after carotid endarterectomy (CEA). Methods— This prospective study included 105 consecutive patients who underwent CEA for severe carotid stenosis. TCCS with echo contrast agents was performed serially to evaluate flow velocity of the middle cerebral artery (MCA). Regional cerebral blood flow (rCBF) and vasodilatory capacity of the MCA territory were evaluated using single-photon emission computed tomography. We compared the changes in MCA flow velocity with rCBF. Results— Using echo contrast agents, we could evaluate the MCA flow in 95 (90%) of 105 patients. Twelve patients showed hyperperfusion syndrome. Changes in the MCA mean flow velocity (MFV) before and 4 days after CEA were significantly correlated with those in rCBF (r =.48; P <.0001). An increase of >50% in MCA MFV was observed within 4 days after CEA in all 12 patients with hyperperfusion syndrome. Multivariate analysis revealed that reduced vasodilatory capacity (odds ratio, 0.14; 95% CI, 0.04 to 0.46) was an independent risk factor for a 1.5-fold increase in the MFV of MCA ipsilateral to CEA. Conclusions— Findings of a 1.5-fold increase in the MCA MFV can accurately identify those patients with high risk of developing post-CEA hyperperfusion syndrome. TCCS with echo contrast agents is available for the evaluation of hyperperfusion after CEA.

Spontaneous disappearance of a middle fossa arachnoid cyst associated with subdural hematoma

The case of a 7-year-old boy with a middle fossa arachnoid cyst that spontaneously disappeared is presented. Computed tomography (CT) scan revealed an arachnoid cyst in the right middle fossa with a thin subdural hematoma on the same side. As the subdural hematoma spontaneously resolved, the cyst became smaller and finally disappeared without surgical intervention after 18 months on the follow-up CT scans. Possible mechanisms of the spontaneous disappearance of an arachnoid cyst are discussed.

Effects of carotid endarterectomy on cerebral blood flow and neuropsychological test performance in patients with high-grade carotid stenosis

We examined the changes in cognitive function following carotid endarterectomy (CEA) in relation to the cerebral blood flow (CBF) in patients with high-grade carotid stenosis. The subjects consisted of 23 patients who underwent CEA and 17 controls matched by age and education. Single photon emission computed tomography (SPECT) and neuropsychological tests were performed 2 weeks before and 4 weeks after CEA in all patients. The preoperative CBF tests revealed a decreased vasodilatory reserve in the ipsilateral cerebral hemisphere in nine patients, which was increased after CEA. In these patients, the grade of carotid stenosis was significantly higher than in those with a normal perfusion reserve (90.2+/-8.1% vs. 78.6+/-11.3%, respectively, p<0.05). In the patient group, the postoperative scores (27.2+/-2.9) of the mini-mental state examination (MMSE) improved significantly over the preoperative ones (26.1+/-3.2, p<0.05). Moreover, the scores in the block-design test after CEA (86.8+/-19.8) were significantly higher than those before the operation (81.8+/-22.3, p<0.01). The error score in immediate retention improved from 9.0+/-3.1 to 7.7+/-4.0 following CEA (p<0.05). In the control group, none of the test scores showed significant improvement between the first and second tests. In the patients with an impaired vasodilatory reserve, the mean score of the block-design test significantly improved from 65.6+/-22.1 to 74.0+/-19.2 after CEA compared with those in patients without impairment (p<0.05). High-grade carotid stenosis was thus concluded to cause cognitive impairment due to cerebral hemodynamic failure, which is presumably reversed by CEA.