Yasuo Nii

Does the central sulcus divide motor and sensory functions ? Cortical mapping of human hand areas as revealed by electrical stimulation through subdural grid electrodes

To clarify the exact anatomic relationship of electrically identified hand areas to the central sulcus, we constructed cortical surface renderings of magnetic resonance images (MRI) to locate the central sulcus accurately and measured the distances of stimulated points from, the central sulcus and the Sylvian fissure.We obtained hand responses in 33 patients who underwent implantation of subdural grid electrodes for evaluation and surgical treatment of intractable epilepsy and analyzed these responses according to the presence of motor, sensory, mixed motor and sensory, and arrest responses. Hand motor responses occurred not only in the precentral gyrus but also in the postcentral gyrus, with great variability in superior-to-inferior distribution. Sensory responses also occurred in both the precentral and postcentral gyri with a distribution more ventral than that of motor responses. Mixed motor and sensory responses tended to be limited to the middle part of the central sulcus. Sites where electrical stimulation arrested simple hand repetitive voluntary movements occurred widely throughout the premotor and primary sensorimotor cortices. These data indicate a marked variability in the location of the human cortical hand area, and suggest that motor and sensory hand cortices overlap and are not divided in a simple manner by the central sulcus. NEUROLOGY 1996,46 360-367

Efficacy and toxicity of thromboxane synthetase inhibitor for cerebral vasospasm after subarachnoid hemorrhage

The efficacy and possible side effects of thromboxane A2 (TXA2) synthetase inhibitor in the treatment of cerebral vasospasm after subarachnoid hemorrhage (SAH) were assessed for 24 patients who presented with grades I to IV of the Hunt and Hess classification. All patients underwent aneurysmal clipping within 48 hours after SAH. Postoperatively, TXA2 synthetase inhibitor, Cataclot [sodium (E)-3-[p-(1H-imidazol-1-ylmethyl)phenyl]-2-propenoate] was administered to 13 patients by continuous drip infusion at a dose of 1 microgram/kg/min for 8 to 14 days (group A). The remaining 11 patients did not receive this drug (group B). Of the 13 patients in group A, seven patients (54%) showed no symptomatic vasospasm after SAH. Four patients (31%) developed a transient deterioration of consciousness and/or motor disturbance. Three of these patients fully recovered, while one of them showed a mild neurological deficit on discharge. One patient (8%) developed permanent dysphasia and hemiparesis as a result of ischemic brain damage due to vasospasm. One patient (8%) died of the side effect. On the other hand, of the 11 patients in group B, only three (27%) showed no symptomatic vasospasm. One (9%) patient presented a transient neurological deficit but fully recovered upon discharge. Four patients (36%) showed permanent neurological deficits, although they all could lead an independent life after discharge. The three remaining patients developed a severe disturbance of consciousness caused by ischemia due to vasospasm, and two of them died within 1 month after the onset of SAH. In the group treated with Cataclot, two patients developed an epidural hematoma late during the administration of the drug. Of these two, one patient died of increased intracranial pressure that was accelerated by the complication. These results indicate that TXA2 synthetase inhibitor is effective in not only decreasing the occurrence of symptomatic vasospasm but also reducing the neurological deterioration due to vasospasm after SAH. However, this drug has a hazardous side effect in that it may promote a tendency to bleed, which caused death in one of our patients.

Landau–Kleffner Syndrome: Localization of Epileptogenic Lesion Using Wavelet– Cross-Correlation Analysis

Magnetoencephalographic findings in a 6-year-old patient suffering from acquired aphasia with convulsive disorder (Landau-Kleffner Syndrome, LKS) are presented. The data were analyzed using wavelet-cross-correlation analysis, a nonstationary analysis method developed to analyze the localization of an epileptogenic lesion and the propagation of epileptiform discharges. The results indicate that LKS might be a disorder of the primary temporal cortex, and that the auditory neural network may function as the circuit for the epileptic discharge propagation.

Bifrontal Epidural Hematoma after Transsphenoidal Operation: Report of a Case with a Rare Complication

We report a patient with a growth hormone-secreting adenoma who developed bifrontal epidural hematomas after a transsphenoidal operation. To our knowledge, this is the first report of such a complication.

TRANSLUCENCE STEREOSCOPY OF INTERICTAL MAGNETOENCEPHALOGRAPHIC EPILEPTIFORM DISCHARGE

We have developed a translucence stereoscopy method for displaying the distribution of multiple interictal epileptiform discharges within the intracranial space. The epileptiform discharges, measured using a whole-head magnetoencephalography system, were modeled by a least-squares method to obtain the equivalent current dipoles. The dipoles were located in the stereo pair of intracranial images composed of translucent brain slices at several selected levels. The technique demonstrated clearly the distribution of interictal dipoles within the brain in three patients. Three dimensional understanding of the intracranial distribution of multiple dipoles in one image is valuable in analyzing the intracerebral neurophysiological events in epileptic patients.

The application of SAM virtual sensor method for analysis of epileptic discharges: comparison with simultaneously recorded ECoG

Abstract The synthetic aperture magnetometry (SAM) enables to display the regional currentodensitogram (CDG) of the arbitrary selected brain tissue as if depth electrodes were inserted. The sensitivity and directivity of this SAM virtual sensor (SAM-VS) method were investigated. MEG and ECoG were simultaneously measured in a patient with refractory temporal seizure from cortical dysplasia. The regional currentodensitogram from SAM-VSs, which were placed three-dimensionally covering over the temporal lobe, were computed and compared with ECoG on the same time axis. The epileptic discharges detected simultaneously by both method accounted for 60% of those by SAM-VS method, and for 27% of those by ECoG method. Analyzing the coincident discharges detected by both methods, the spatial position difference between sensors disclosed maximum amplitude was less than several millimeters. Thus, high directivity of SAM-VS method, comparable to the subdural electrodes, was suggested. This new functional imaging might eliminate the need for invasive intracranial electrodes by disclosing abnormal functional process in epileptic brain noninvasively.

Somatosensory evoked potentials to median nerve stimulation after partial section of the corpus callosum.

SummaryCortical somatosensory evoked potentials (SEPs) to electrical stimulation of the median nerve were studied in four patients with intractable epilepsy who had undergone callosotomy and in a patient with infarction in the corpus callosum in order to determine whether the corpus callosum was involved in the generation of ipsilateral frontal components. Both pre- and postoperative SEPs were recorded in three of four epileptic patients. There were no significant differences in the latencies and amplitudes of the bilateral frontal components (P20, N26) between pre- and postoperative recordings. Furthermore, irrespective of the extent of the section or lesion in the corpus callosum, the nature of the impairment and the existence of the disconnection syndrome, the SEP findings showed no significant differences compared with those of normal subjects. It thus appears unlikely that the ipsilateral SEP responses are transmitted from the contralateral hemisphere through at least the anterior portion of the corpus callosum.

Hydrocephalus: Antenatal detection and neonatal neurosurgical management

In order to evaluate the structual brain reconstitution and functional recovery, clinical record of an infant presenting hydrocephalus in utero at 31 weeks of gestation and operated immediately after birth was reported. Before the advent of sonography, the diagnosis of fetal hydrocephalus was based on the radiologic demonstration of an enlarged fetal head. With the propagation of B-mode ultrasound imaging in the obstetrical field, pathological ventriculogram could be diagnosed antenatally. In this case, greatly distended hydrocephalic brain regressed completely by continuous cerebrospinal fluid drainage through a miniature Ommaya’s reservoir during early neonatal period and thereafter ventriculoperitoneal shunting at age of four weeks after birth. Also, electroencephalogram at age of 35 days showed improvement as disappearance of high-voltage slow wave on the frontal region and the normal pattern corresponding to his moon’s age. This paper reviewed the current understanding of diagnosis and prognosis of fetal hydrocephalus, and author’s opinions for neurosurgical management early after birth are stated.