Functional Brain Mapping Using Depth Electrodes.

OBJECTIVE: This study investigated the neurologic symptoms and stimulus intensities in the stimulation of deep structures and subcortical fibers with the depth electrodes. METHODS: Seventeen patients with drug-refractory epilepsy who underwent functional brain mapping with the depth electrodes were enrolled. The 50 Hz electrical stimulation was applied, and the diffusion tensor image was used to identify subcortical fibers. The responsible structures and stimulus intensities for the induced neurologic symptoms were evaluated. RESULTS: Neurologic symptoms were induced in 11 of 17 patients. The opercular stimulation elicited the neurologic symptoms in 6 patients at the median threshold of 4.0 mA (visceral/face/hand sensory, hand/throat motor, negative motor and auditory symptoms). The insular stimulation induced the neurologic symptoms in 4 patients at the median threshold of 4.0 mA (auditory, negative motor, and sensory symptoms). The stimulation of subcortical fibers was induced in 5 of 9 patients at the median threshold of 4.5 mA. The thresholds of depth electrodes were significantly lower than those of subdural electrodes in 8 patients who used both subdural and depth electrodes and induced symptoms with both electrodes. CONCLUSIONS: The stimulation of depth electrodes can identify the function of deep structures and subcortical fibers with lower intensities than subdural electrodes.

Mechanical Thrombectomy Using a Large Dual-Layer Stent Retriever for Near-Occlusion of the Common Carotid Bifurcation Caused by a Giant Free-Floating Thrombus.

Objective: We report a case of near-occlusion of the common carotid bifurcation caused by a giant free-floating thrombus (FFT) successfully treated with mechanical thrombectomy using a large dual-layer stent retriever. Case Presentation: A 51-year-old man presented to our hospital with dysarthria, right hemiparalysis, and paresthesia. MRI revealed an acute infarction of the left cortical watershed zone, and MRA revealed decreased signals in the left common carotid bifurcation. Carotid ultrasonography demonstrated a giant FFT in the left common carotid bifurcation. Angiography revealed a giant thrombus extending from the left common carotid artery (CCA) to the internal carotid artery (ICA) and the external carotid artery. As direct aspiration from both a balloon-guided catheter (BGC) and an aspiration catheter (AC) was ineffective, we deployed a large dual-layer stent retriever from the ICA to the CCA with an AC-connected aspiration pump and retrieved it under manual aspiration through the BGC. The giant thrombus was successfully removed, and complete recanalization was achieved without distal embolisms. Conclusion: Although there is no established treatment for giant thrombi in the carotid artery, mechanical thrombectomy using a large dual-layer stent retriever may be an effective treatment option.

Comparison of Thresholds between Bipolar and Monopolar Electrical Cortical Stimulation.

Electrical cortical stimulation is widely performed and is the gold standard for functional mapping in intractable epilepsy patients; however, a standard protocol has not yet been established. With respect to stimulation methods, two techniques can be applied: monopolar and bipolar stimulation. We compared the threshold to induce clinical symptoms between these two stimulation techniques. Twenty patients with intractable epilepsy who underwent electrical cortical stimulation for functional mapping were retrospectively investigated. We evaluated the stimulation intensity thresholds required to induce motor, sensory, and language symptoms. A total of 114 electrodes in 20 patients were used to investigate motor, sensory, and language symptoms. The thresholds required to induce motor (median value, bipolar: 4 mA, monopolar: 5 mA, p < 0.05) and language symptoms (bipolar: 8 mA, monopolar: 10 mA, p < 0.0005) were significantly higher for monopolar stimulation than those for bipolar stimulation. However, for sensory symptoms, no significant differences were found in the required thresholds between monopolar and bipolar stimulation (bipolar: 4 mA, monopolar: 4 mA, p = 0.474). Bipolar cortical stimulation required lower intensities to produce clinical motor and language symptoms and thus would be safe and suitable for screening of the eloquent area in functional mapping.

Motor Mapping with Functional Magnetic Resonance Imaging: Comparison with Electrical Cortical Stimulation.

The aim of the present study was to evaluate motor area mapping using functional magnetic resonance imaging (fMRI) compared with electrical cortical stimulation (ECS). Motor mapping with fMRI and ECS were retrospectively compared in seven patients with refractory epilepsy in which the primary motor (M1) areas were identified by fMRI and ECS mapping between 2012 and 2019. A right finger tapping task was used for fMRI motor mapping. Blood oxygen level-dependent activation was detected in the left precentral gyrus (PreCG)/postcentral gyrus (PostCG) along the "hand knob" of the central sulcus in all seven patients. Bilateral supplementary motor areas (SMAs) were also activated (n = 6), and the cerebellar hemisphere showed activation on the right side (n = 3) and bilateral side (n = 4). Furthermore, the premotor area (PM) and posterior parietal cortex (PPC) were also activated on the left side (n = 1) and bilateral sides (n = 2). The M1 and sensory area (S1) detected by ECS included fMRI-activated PreCG/PostCG areas with broader extent. This study showed that fMRI motor mapping was locationally well correlated to the activation of M1/S1 by ECS, but the spatial extent was not concordant. In addition, the involvement of SMA, PM/PPC, and the cerebellum in simple voluntary movement was also suggested. Combination analysis of fMRI and ECS motor mapping contributes to precise localization of M1/S1.

Transdural Propagation of Glioblastoma Through Foramen Rotundum.

BACKGROUND: Glioblastoma, also known as glioblastoma multiforme, is the most common primary malignant cerebral tumor in adults. Although glioblastoma multiforme is one of the most aggressive tumors in the brain, propagation through the dura mater is rare. CASE DESCRIPTION: A 59-year-old man presented with progressive headache and aphasia. Magnetic resonance imaging identified an abnormal mass extending transcranially through the widened foramen rotundum into the infratemporal fossa and cavernous sinus. Emergency surgery was performed because of the patient's disturbed consciousness and uncal herniation. The pathologic diagnosis was glioblastoma with isocitrate dehydrogenase 1 (IDH-1) wild type arising in the left temporal region of the brain, penetrating the dura mater and propagating to the middle fossa with enlargement of the foramen rotundum. The tumor was resected, and radiochemotherapy with temozolomide was administered. CONCLUSION: Although the mechanism of tumor spread is unknown, we hypothesized that originally there may have been spontaneous dural defects or thinning, such as a meningoencephalocele in the middle fossa, and the tumor coincidentally occurred there.