Rapid Recovery From Cortical Blindness Caused by an Old Cerebral Infarction.

When the primary visual cortex (V1) is damaged, cortical blindness results. However, visual information obtained from the superior colliculus (SC) or direct thalamic afferents to higher visual cortices produces unconscious visual functions called blindsight. Alarming visual stimuli suggesting the approach of a predator are known to trigger escape behaviors via visual information mediated by the SC and amygdala in small animals, and salient and dynamic visual stimuli also produce some conscious visual experience even in patients with blindsight. Fresh cortical blindness sometimes recovers spontaneously in patients with fresh cerebral damages, and recovery can be accelerated by early rehabilitation. However, the mechanisms underlying recovery are not well-known. We analyzed a patient with cortical blindness caused by an old cerebral infarction. After repeated presentation of alarming visual stimuli, the ability to detect visual stimuli in the impaired visual field showed behavioral short-term improvement (STI) within a few minutes. Repeated behavioral STI induction was followed by behavioral long-term improvement (LTI) lasting more than several days. After behavioral LTI, the patient partially recovered the ability to read letters presented in the impaired visual field. The behavioral STI experiment, which can be performed within 10 min, may serve as a clinical screening test for anticipating recovery from cortical blindness.

Oligodendroglioma (WHO grade I) in a young epilepsy patient: a specific entity lying within the spectrum of dysembryoplastic neuroepithelial tumor?

We studied a frontal lobe subcortical cystic tumor that had been resected from a 13-year-old girl with a 3-year history of intractable partial seizure. Currently, more than 13 years after surgery, the patient remains recurrence-free and has no neurological deficits. Histological examination showed that the tumor was non-infiltrating and paucicellular with a mucinous matrix, and consisted of fairly uniform small cells with round to oval nuclei. Within the mucinous matrix, the tumor cells were often arranged in pseudorosettes around small blood vessels. Mitotic activity and necrosis were absent, with a Ki-67 labeling index of <1%. Based on the immunohistochemical and ultrastructural findings, the constituent tumor cells were considered to be those of oligodendroglioma, including mini-gemistocytes and gliofibrillary oligodendrocytes. No neuronal elements were identified. Features of cortical dysplasia (FCD Type 1) were evident in the cortex covering the lesion. The surrounding white matter also contained a significant number of ectopic neurons. The entire pathological picture appeared to differ somewhat from that of ordinary oligodendroglioma (WHO grade II). Considering the clinical and pathological features, the present unusual oligodendroglioma appeared to represent a previously undescribed form of oligodendroglioma (WHO grade I) lying within the spectrum of dysembryoplastic neuroepithelial tumor (DNT; WHO grade I). Simultaneously, the present oligodendroglioma also raises the question of whether or not oligodendrocyte-like cells of DNTs truly show neurocytic differentiation.

Unstable stenosis of the internal carotid artery caused by a craniofacial nail-gun injury-case report-.

A 30-year-old carpenter suffered accidental piercing of his jaw by a 3-inch nail from a nail gun. No neurological deficits were found on admission. Computed tomography showed that the tip of the nail had reached the foramen lacerum. Cerebral angiography revealed severe stenosis at the C(4) portion of the left internal carotid artery (ICA) and marked decrease in the flow of the distal ICA. He had developed right hemiparesis and sensory aphasia by the following morning. T(2)-weighted and fluid-attenuated inversion recovery magnetic resonance imaging showed a focal hyperintense signal in the left central region indicating cerebral infarction. Repeat angiography demonstrated that the antegrade blood flow from the occluded point on the admission day had partially resumed, and endovascular trapping of the ICA was successfully carried out. The nail was then removed safely without problematic bleeding. The patient suffered no additional deficit, and his sensory aphasia and right hemiparesis gradually improved. The fluctuating blood flow through the unstable stenosis of the ICA related to nail movement possibly caused the delayed cerebral infarction. To avoid the occurrence of such events, rapid treatment after necessary investigations is recommended in patients with craniofacial penetrating injuries that affect the ICA.

[Delayed brain abscess after penetrating transorbital injury].

We report a case of brain abscess caused by a penetrating head injury that occurred 9 years earlier. A 14-year-old girl presenting with fever, headache, and stiff neck was admitted to our hospital. She was diagnosed with aseptic meningitis and treated conservatively. Seven days after admission she became stuporous and showed left hemiparesis. Computed tomography (CT) revealed two ring-enhancing masses with perifocal edema in the right frontal lobe. We diagnosed brain abscess and performed right fronto-temporal decompressive craniectomy and stereotactic aspiration, followed by systemic antibiotic therapy. Post-surgery bone window CT revealed a well-defined, low-density foreign body passing from the left orbita to the right frontal lobe through the ethmoid sinus. We learned that the patient had been struck with a plastic chopstick in the left medial eyelid at the age of 5 years. No particular symptoms developed during the following 9 years. After the cerebral edema had diminished over the next 10 days, a second surgery was performed to remove the residual chopstick, repair the fistula at the base of the skull, and perform cranioplasty. The patient was discharged with only slight hyposmia after a 4-week course of antibiotics. This case showed that it is necessary to remove a residual foreign body and to close the dural fistula if there is a possibility of recurrent central nervous system infection. When a child presents with brain abscess, previous penetrating head injury should be considered.

Fusiform gyrus epilepsy: the use of ictal magnetoencephalography. Case report.

The authors report successful presurgical identification of an epileptic focus in the fusiform gyrus by using ictal magnetoencephalography (MEG), which was performed with the aid of an advanced whole-brain neuromagnetometer. A 22-year-old man had suffered from medically refractory complex partial seizures since he was 10 years of age. Seizure symptoms, magnetic resonance imaging, and ictal single-photon emission computerized tomography examinations indicated right temporal lobe epilepsy; however, ictal electroencephalography, including sphenoidal recordings, failed even to lateralize the seizure focus. The MEG studies revealed that equivalent current dipoles of interictal activities were scattered bilaterally around the medial temporal structures, but those of ictal onset and postictal activities formed a cluster in the left fusiform gyrus. After confirmation of each ictal and interictal MEG finding by using long-term electrocorticography recordings, focal cortical resection of the left inferior temporal and fusiform gyri was performed. The histopathological diagnosis was cortical dysplasia, and the patient has achieved a good seizure outcome, now 15 months after the operation. Ictal and also postictal MEG may be more specific than interictal MEG for identifying the ictal onset zone.

[Presurgical functional mapping of the sensorimotor area using evoked magnetic fields].

In the present study, we evaluated the usefulness of magnetoencephalography (MEG) for presurgical identification of not only the central sulcus by somatosensory evoked magnetic fields (SEFs), which is a well-known, reliable technique, but also the primary hand motor area by movement-related cerebral magnetic fields (MRCFs). Subjects were 10 patients with brain tumor (6 glial tumors, 3 cavernous angiomas, and 1 metastatic tumor) around the sensorimotor area. Identification of the central sulcus by SEF responses to multiple sites of stimulation (median nerve, tibial nerve, thumb, and lower lip) was performed in all patients, and identification of the hand motor area by MRCF responses to the index finger extension task was made in 9. All MEG data were superimposed on sectional or three-dimensional magnetic resonance (MR) images. The central sulcus was clerAly identified by SEFs in all patients, even in 5 whose MR images showed severe distortion, and the primary hand motor area was identified by MRCFs in 6 of 9 patients. The central sulcus and primary motor area identified by MEG were confirmed by cortical recording of somatosensory evoked potentials in response to median nerve stimulation in 7 patients and motor evoked potentials in response to direct cortical stimulation in 5. All patients underwent tumor removal guided by functional mapping by MEG and experienced no surgical complications. In conclusion, MEG is a useful tool in presurgical functional mapping of the sensorimotor area. This is the first report of a case in which identification of the hand motor area by MRCFs was used in a clinical setting.