Takekazu Akiyama

Evaluating the roles of the inferior frontal gyrus and superior parietal lobule in deductive reasoning: An rTMS study

This study used off-line repetitive transcranial magnetic stimulation (rTMS) to examine the roles of the superior parietal lobule (SPL) and inferior frontal gyrus (IFG) in a deductive reasoning task. Subjects performed a categorical syllogistic reasoning task involving congruent, incongruent, and abstract trials. Twenty four subjects received magnetic stimulation to the SPL region prior to the task. In the other 24 subjects, TMS was administered to the IFG region before the task. Stimulation lasted for 10min, with an inter-pulse frequency of 1Hz. We found that bilateral SPL (Brodmann area (BA) 7) stimulation disrupted performance on abstract and incongruent reasoning. Left IFG (BA 45) stimulation impaired congruent reasoning performance while paradoxically facilitating incongruent reasoning performance. This resulted in the elimination of the belief-bias. In contrast, right IFG stimulation only impaired incongruent reasoning performance, thus enhancing the belief-bias effect. These findings are largely consistent with the dual-process theory of reasoning, which proposes the existence of two different human reasoning systems: a belief-based heuristic system; and a logic-based analytic system. The present findings suggest that the left language-related IFG (BA 45) may correspond to the heuristic system, while bilateral SPL may underlie the analytic system. The right IFG may play a role in blocking the belief-based heuristic system for solving incongruent reasoning trials. This study could offer an insight about functional roles of distributed brain systems in human deductive reasoning by utilizing the rTMS approach.

The role of inferior frontal cortex in belief-bias reasoning: An rTMS study

The belief-bias effect in syllogistic reasoning refers to the tendency for subjects to be erroneously biased when logical conclusions are incongruent with belief about the world. This study examined the role of inferior frontal cortex (IFC) in belief-bias reasoning using repetitive transcranial magnetic stimulation (rTMS). We used an off-line rTMS method to disrupt IFC activity transiently. Right IFC stimulation significantly impaired incongruent reasoning performance, enhancing the belief-bias effect. Subjects whose right IFC was impaired by rTMS may not be able to inhibit irrelevant semantic processing in incongruent trials. Although left IFC stimulation impaired congruent reasoning, it paradoxically facilitated incongruent reasoning performance, eliminating the belief-bias effect. Subjects whose left IFC was impaired by rTMS may not suffer from interference by irrelevant semantic processing. This study demonstrates for the first time the roles of left and right IFC in belief-bias reasoning using an rTMS approach.

Cavernous angioma of the vestibular nerve: case report and literature review

BACKGROUND To date, 50 cases of cavernous angioma in the CPA have been reported, and previous reports did not describe the tumors site of origin. We describe a case of a small, extraaxial cavernous angioma of the vestibular nerve. We also propose a reclassification system for cavernous angioma of the CPA based on the tumors site of origin. CASE DESCRIPTION A 39-year-old female patient had recurrent deteriorating vertigo and a right hearing disturbance. Magnetic resonance imaging revealed a cavernous angioma of the right CPA. Surgery was performed through a right lateral suboccipital approach. In the present case, the mass was attached to and covered the cisternal portion of the vestibular nerve, and it contained microvessels that were fed from the vascular plexus of the vestibular nerve. The tumor was resected en bloc, and the microvessels feeding it were cauterized. CONCLUSIONS On the basis of our review of 50 cases of cavernous angioma of the CPA, we propose that these tumors can be classified according to whether they develop from the venous plexus of the dura matter or of a cranial nerve. We also suggest that the site of origin affects the postoperative symptoms.

Case reportLipomatous meningioma

We present a case of intracranial lipomatous meningioma in the parietal convexity in a 64-year-old woman. The mass showed low density on computed tomography, was hyper-intense on T1-weighted magnetic resonance images, and had decreased intensity upon imaging with fat-suppressed sequences. Gross total removal of the tumor was performed. Histopathologically, the tumor was a meningioma with mixed transitional and lipomatous patterns. Immunohistochemically, the meningothelial foci were positive for epithelial membrane antigen (EMA) and vimentin, and negative for S-100 protein. The lipomatous foci were positive for EMA, vimentin, and S-100 protein. The Ki-67 index values of the meningothelial and lipomatous foci were 1.0% and 1.8%, respectively. We review previous reports of lipomatous meningioma and discuss its clinical presentations and pathology.

Intrasellar Salivary Gland-Like Pleomorphic Adenoma: Case Report

BACKGROUND AND IMPORTANCE: We present a rare case of a patient with intrasellar salivary gland-like pleomorphic adenoma and review the 2 previously reported cases of the clinical entity to identify their common clinical features. CLINICAL PRESENTATION: A 56-year-old Asian man visited our hospital with a chief complaint of visual disturbance caused by brain tumor that filled up the sella turcica with suprasellar extension. The patient underwent craniotomy via a left pterional approach, and the subdural, intracranial portion of the tumor was totally removed, with every artery and nerve preserved. Pathological diagnosis of the tumor was intrasellar salivary gland-like pleomorphic adenoma. Three years after the operation, the patient remains free from tumor recurrence. CONCLUSION: Tumors in all 3 reported cases of intrasellar salivary gland-like pleomorphic adenoma, including the present case, showed suprasellar extension and compressed optic chiasm that resulted in visual disturbance of the patients. A calcified region inside the tumor on computed tomographic scanning was also a common finding. Differential diagnosis of intrasellar salivary gland-like pleomorphic adenomas should be considered in patients with calcified intrasellar tumors with suprasellar extension. The clinical entity seems to show good prognosis if surgically removed.

Chronic Encapsulated Intracerebral Hematoma: Endoscopic Removal as Minimally Invasive Surgery for a Patient with Alcoholic Cirrhosis

Chronic encapsulated intracerebral hematoma (CEIH) is a rare cerebrovascular disease. Here, we describe a case of a patient with alcoholic cirrhosis and an abnormal coagulation state that was treated with minimally invasive endoscopic hematoma removal. A 54-year-old man presented with a 2-week history of incoherent speech, incontinence, and repeated stumbling. Laboratory analysis showed thrombocytopenia and the prolongation of prothrombin time due to alcoholic cirrhosis. Computed tomography and magnetic resonance imaging showed a large mass in the left parieto-occipital lobe suggesting a hematoma. Minimally invasive endoscopic hematoma removal was then performed. CEIH was diagnosed from the intraoperative findings of serous hematoma, a thin yellowish capsule, and old clots. The postoperative course was uneventful and there was no hematoma recurrence. In conclusion, endoscopic hematoma removal may be one of the options for the treatment of CEIH in patients with cirrhosis and an abnormal coagulation state.