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Background Cryptococcal meningoencephalitis (CM) causes cerebral infarction, typically, lacunar infarction in the basal ganglia. However, massive cerebral infarction leading to death is rare and its pathophysiology is unclear. We report a case of CM causing massive cerebellar infarction, which led to cerebral herniation and death. Case presentation A 56-year-old man who suffered from dizziness and gait disturbance for one month was admitted to our hospital and subsequently diagnosed with a cerebellar infarction. He had a past medical history of hepatitis type B virus infection and hepatic failure. Although the findings on magnetic resonance imaging (MRI) imitated an arterial infarction of the posterior inferior cerebellar artery, an accompanying irregular peripheral edema was observed. The ischemic lesion progressed, subsequently exerting a mass effect and leading to impaired consciousness. External and internal decompression surgeries were performed. Cryptococcus neoformans was confirmed in the surgical specimen, and the patient was diagnosed with CM. In addition, venule congestion in the parenchyma was observed with extensive fibrosis and compressed veins in the subarachnoid space. The patient died 26 days after admission. Autopsy revealed that pathological changes were localized in the cerebellum. Conclusion C. neoformans can induce extensive fibrosis of the subarachnoid space, which may compress small veins mechanically inducing venule congestion and massive cerebral infarction. In such cases, the clinical course can be severe and even rapidly fatal. An atypical pattern of infarction on MRI should alert clinicians to the possibility of C. neoformans infection.

A 14-year-old boy suffered from daily epileptic seizures originating from the left polymicrogyric occipital cortex. Visual activation positron emission tomography (PET) was used to map the function of the occipital cortex presurgically. Loss of visual function in the left occipital cortex was suggested by both visual activation PET and electrical cortical stimulation. Left occipital lobectomy resulted in a completely seizure-free status without deterioration in the visual function. Preoperative evaluation of the visual function in the epileptogenic occipital cortex by activation studies using PET or functional magnetic resonance imaging is the key to the successful surgical treatment of occipital lobe epilepsy.

Objective: Temporo-parietal theta activity (TPTA), often detected in hemispheres with internal carotid (ICA) or middle cerebral artery (MCA) occlusive lesions, is more clearly separated from occipital alpha activity by magnetoencephalography (MEG) than electroencephalography. The present study investigated whether TPTA is correlated with misery perfusion, a surgically correctable type of hemodynamic impairment. Methods: Awake MEG was measured in 56 patients with ICA or MCA occlusive lesions. Regional cerebral blood flow (rCBF) and regional cerebrovascular reactivity (rCVR) to acetazolamide were measured in the MCA territory by xenon-133 single-photon emission computed tomography. MEG was repeated in 10 patients after vascular reconstruction surgery. Results: Fourteen patients showed TPTA in the lesion hemisphere (n = 13) or bilaterally (n = 1). The presence of TPTA was significantly correlated with both reduced rCBF and reduced rCVR (P = 0.0009). After surgery, TPTA disappeared in 7 of the 10 studied patients. Conclusions: The presence of TPTA suggests misery perfusion, which is characterized by reduced rCBF and reduced rCVR. Significance: MEG can detect the presence of reversible and surgically remediable cerebral ischemia before the development of complete infarction.

A 16-year-old girl suffering from intractable temporal lobe epilepsy presented with a pilocytic astrocytoma, which occurred in an area of nodular heterotopia located in the white matter of the temporal lobe. The pilocytic astrocytoma appeared to be covered by an area of gliosis, which contained numerous Rosenthal fibers, while in the lesion the pilocytic astrocytoma occupied a small area. The gliosis eventually became a tumor-like lesion. The white matter around the mass was composed of gliosis with nodular heterotopia. Temporal developmental malformation, which was a basic lesion of the patient, might therefore be a precursor lesion of pilocytic astrocytomas.

Due to excellent spatio temporal resolution and noninvasive nature of the measurements, magnetoencephalography (MEG) becomes a powerful tool for clinical application. This is especially the case in evoked MEG applied for presurgical diagnosis of the patients who suffered brain diseases. However, in spontaneous activity such as epileptic discharges, applicability is not so simple. This is because, for spontaneous waves, several brain activities or noises were superimposed on the detected signal, and separation for target activity is generally difficult. Small array of sensing coils also restricted the spatial resolution and sometimes brought erroneous results simply because they could not cover the entire brain at once. The appearance of whole-head MEG directly linked to magnetic resonance imaging (MRI) reduces data acquisition time, patient fatigue and localization error. It also provides objective information about patients which is essential for correct diagnosis. Spontaneous MEG studies used to be concentrated to epileptic spike activity. However, slow wave activity, typically observed by electroencephalography (EEG), is quite common in stroke, tumor, epilepsy, cerebrovascular disease, or head injury. Earlier investigations of slow wave activity with MEG [1–3] were restricted to small (1 to 37) channel system. Here we present the results of whole head MEG and source analysis of a slow wave activity.

It is critical to preserve eloquent cortices during surgery of cerebral arteriovenous malformations (AVMs). Although MRI scans may identify “anatomical” central suclus, it is controversial whether the “functional” central sulcus can be shifted due to AVMs. Cortical recording of somatosensory evoked potentials (SEPs) can be used to recognize the central sulcus during open surgery. However, the cortical SEPs are not available during surgery for large AVMs, intravascular surgery, or stereotaxic radiosurgery. In the present study, somatosensory evoked fields (SEFs) were measured to localize the “functional” central sulcus non-invasively in cases with AVM adjacent to the central sulcus.

The “cruciform model” of the visual cortex suggests that the P100 generators of the visual evoked responses to pattern reversal (PR) stimuli are located throughout the entire striate cortex, including the interhemisphere surface and calcarine fissures. Our recent studies of visual evoked fields (VEFs) to PR stimuli [1–3] have localized the P100m sources near the lateral end of the calcarine fissures. We suggested that a smaller part of the striate cortex contributes to the P100m response than in the cruciform model. In the present study, we measured PR-VEFs in patients with homonymous hemianopsia due to unilateral occipital lobe lesions, to demonstrate the correlation between PI00m patterns and occipital lesions.

✓ The N100m wave response of the auditory evoked magnetic field originates in the posterior part of the bilateral superior temporal planes for either contra- or ipsilateral ear stimulus. Cortical auditory function was evaluated in 14 patients with temporal lobe tumors using a magnetic resonance (MR) imaging—linked whole-head magnetoencephalography (MEG) system. Before surgery, seven patients had normal N100m latency (within the range of the mean ± 2 standard deviations of 37 normal volunteers) in both normal hemispheres and in those with lesions, and MR imaging indicated no tumor invasion or edema in the posterior one-third of the superior temporal planes, even when the sylvian fissure was shifted upward due to the mass effect. Seven patients had prolonged N100m latency or absence of N100m in the hemisphere containing the lesion, and the posterior portion of the superior temporal plane was involved by the tumor or perifocal edema. Prolonged N100m latency recovered to the normal range after removal of tumors in two of four patients investigated postoperatively. The MEG system can be used to evaluate cortical auditory function noninvasively before and after surgical treatment of temporal lobe tumors.