DC potentials of temporal lobe seizures in the monkey.

In 8 monkeys, made epileptic by alum or penicillin injection into temporal lobe structures, 40 seizures were studied by both DC cortical potential and subcortical EEG recordings. Eighteen seizures of lateral temporal origin had an abrupt negative DC potential shift of 0.5 to 2.0 mV in and around the focus. The frontal, parietal and occipital cortices did not develop DC potential changes, perhaps due to the limited propagation of the neocortical seizures. Twenty-two seizures of medial temporal origin showed a negative shift of the anterior, inferior or lateral temporal cortex in 85% of seizures. The other 15% had a positive or no shift. In hippocampal seizures, a positive displacement was sometimes seen prior to the main negative shift in the lateral temporal cortex. The remote cortex developed only a minimal positive shift in 30% of the mediotemporal seizures. A marked negative shift in the frontocentral cortex was the first sign of impending generalization, which may result from a series of chain reactions with seizure propagation, involving more and more structures of the brain. Registration of DC potentials in temporal lobe seizures may give insight into the nature of abnormal EEG activities and to some extent into the origin of seizures.

Non-invasive assessment of language dominance with near-infrared spectroscopic mapping.

Hemispheric dominance for language is usually assessed by means of the Wada test where amobarbital is injected into the carotid artery. Recently, positron emission tomography and functional MRI have been used as non-invasive alternatives to this method. We have applied 24-channel near-infrared spectroscopic topography (NIRS) as another non-invasive method to detect the unilateral cerebral activation during a language task. We used 11 healthy volunteers and six patients with intractable epilepsy. A word-generation task was applied for 17 s, followed by an extinction/resting period of 60 s. In healthy volunteers, the inferior frontal region was activated on the side opposite to the subject's handedness in infancy. In the epilepsy cases, the activated side agreed with the dominance determined by the Wada test. Our results demonstrate that NIRS is a feasible non-invasive alternative to the Wada test.

Noninvasive cerebral blood volume measurement during seizures using multichannel near infrared spectroscopic topography.

Near infrared spectroscopic topography (NIRS) is widely recognized as a noninvasive method to measure the regional cerebral blood volume (rCBV) dynamics coupled with neuronal activities. We analyzed the rCBV change in the early phase of epileptic seizures in 12 consecutive patients with medically intractable epilepsy. Seizure was induced by bemegride injection. We used eight-channel NIRS in nine cases and 24 channel in three cases. In all of the cases, rCBV increased rapidly after the seizure onset on the focus side. The increased rCBV was observed for about 30-60 s. The NIRS method can be applied to monitor the rCBV change continuously during seizures. Therefore, this method may be combined with ictal SPECT as one of the most reliable noninvasive methods of focus diagnosis.

Spatial and temporal analysis of human motor activity using noninvasive NIR topography.

The effect of motor activity on the left fronto-central region of the human brain was analyzed spatially and temporally by using noninvasive near-infrared light (NIR) topography. The changes in oxygenation states caused by motor activity were measured using intensity-modulated NIR spectroscopy at ten measurement positions on the head surface. The subject randomly performed unilateral finger opposition for 30 s as motor stimulation. When the subject performed contralateral (right) finger movement, significant increases in both oxygenated hemoglobin (oxy-Hb) and total hemoglobin (total-Hb) and decreases in deoxygenated hemoglobin (deoxy-Hb) were observed in a particular area. By mapping the static topograms of the changes of each Hb and comparing them with an anatomical image of MRI, it was found that the particular area was located on the motor cortex along the central sulcus. By mapping the dynamic topograms of the changes of total-Hb, which reflect the cerebral blood volume, and analyzing the spatiotemporal hemodynamic changes associated with the brain activity, it was found that the regional change in cerebral blood volume in the primary motor area overlaps the global change around the motor cortex. These results demonstrate that NIR topography can be used to effectively observe the human brain activity.

Open surgery assisted by the neuronavigator, a stereotactic, articulated, sensitive arm.

A new computed tomographic-stereotactic device that translates the operating point onto preoperative computed tomographic (CT) images, the Neuronavigator, has been developed. We have applied this system to various neurosurgical procedures to examine its usefulness. The system consists of a 6-joint sensing arm and a 16-bit personal computer. It projects the location of the arm tip onto a corresponding CT slice with a cursor that guides the surgeon toward the intracranial target during open surgery. The system also projects the location of the tip onto angiograms, and when used in conjunction with echography or a transcranial Doppler (TCD) flow meter, the surgeon's ability to navigate is enhanced. Sixty-eight patients underwent operation with the Neuronavigator. The navigation system worked as the core of a multimodal three-dimensional data base that proved to be useful during surgery. The maximum detection error was 2.5 mm, which was considered sufficient for open microsurgery. It also proved useful in designing the position of a craniotomy, in targeting deep-seated mass lesions, and in tracing the tumor edge, which had been identified on a CT scan. When the angiogram was combined with the navigator, it became easy to identify key vessels within a small operating field. The system was also combined with a TCD flow meter. This combination makes it possible to translate the measuring point of the TCD directly into CT coordinates, improving the precision of location of the TCD probe. The Neuronavigator combines various diagnostic images into one database and effectively guides the surgeon during surgery.

Extracranial-intracranial bypass to the proximal posterior cerebral artery and to the proximal middle cerebral artery for multiple occlusive cerebrovascular disease.

A 48-year-old man with a multiple occlusive cerebrovascular disease involving both the carotid and the vertebrobasilar systems is reported. Faced with noneffective conservative treatment, a surgical approach was carried out. As the patient had poorly developed posterior communicating arteries, two extracranial-intracranial bypasses were performed for both the carotid and the vertebrobasilar circulations; extracranial-intracranial bypasses with interposed saphenous vein grafts between the left external carotid artery and the proximal segment of the left middle cerebral artery, and between the right external carotid artery and the proximal segment of the right posterior cerebral artery. Advantages, precautions, and techniques of this kind of bypass procedure are discussed.

Three-dimensional digitizer (neuronavigator): new equipment for computed tomography-guided stereotaxic surgery.

A new device was invented as an adjunct for computed tomography (CT)-guided stereotaxic or open neurosurgery. It is composed of a multijoint three-dimensional digitizer (sensor arm) and a microcomputer, which indicates the place of the sensor arm tip on preoperative CT images. Computed tomography scan is performed preoperatively with three markers placed on the nasion and ears. At surgery, after fixing the patient's head and the sensor arm, sampling of the standard points was done to translate the position of the tip of the sensor arm onto the CT images displayed on a computer screen. In this way positional data from conventional preoperative CT scan can be directly transferred into the surgical field. This system has the unique feature of introducing CT-guided stereotaxis into conventional open neurosurgery.

Effect of lower body negative pressure on cerebral circulation.

This experiment was performed to study the effects of lower body negative pressure (LBNP) on cerebral circulation. Cerebral hemodynamics were monitored continuously and noninvasively in eight subjects at 30 mmHg of LBNP for 25 minutes by following items: 1) the carotid Doppler flowmeter which measures the carotid blood flow, 2) the transcranial Doppler sonography which measures the flow velocity of the middle cerebral artery, 3) the near infrared spectrophotometer which measures the oxygenated and deoxygenated hemoglobin in the brain. The mean flow velocity of the middle cerebral artery and the blood flow of the common carotid artery significantly decreased during LBNP, even though the mean arterial blood pressure was well maintained. The oxygenated hemoglobin was significantly increased during LBNP, while the deoxygenated hemoglobin was not changed significantly. Our results suggest that exposure to moderate LBNP (30 mmHg) decreased the cerebral blood flow with the vasodilation on the arterial side of the brain.

[Epilepsy surgery--advances in presurgical evaluations and operative techniques].

In 1886, Victor Horsley realized the possibility of surgical treatment of epilepsy, which had been suggested by John H. Jackson. However, it is only recently that surgery has been widely accepted as an important method of comprehensive management of epilepsies. In general, the presurgical evaluation is carried out in two phases: first phase of noninvasive studies (EEG and videomonitoring, brain imaging, psychometrics) and second phase using surgical techniques (videomonitoring with intracranial electrodes, angiography, Wada test, functional mapping). EEG-videomonitoring to record habitual seizures of patients contributed significantly. Although in about 25% of cases, phase 1 monitoring with scalp and sphenoid electrodes may be sufficient in determining surgical indication, depth electrode exploration is still necessary in the rest of cases. Among brain imaging tests, SPECT and PET showed better correlation with EEG abnormality, PET studies in ictal stage is the most reliable methods. The classical operative techniques, such as focal resection, temporal lobectomy and callosotomy are still in use. Application of microsurgical techniques enhanced the reliability of surgical outcome. The complex partial seizures of temporal origin are the most promising candidates for surgery. Careful presurgical evaluation may warrant more than a 90% postoperative improvement.

[The migration of cefotiam to cerebrospinal fluid].

The concentration of cefotiam (CTM), a newly synthesized cephem derivative antibiotic in serum and cerebrospinal fluid after single intravenous treatment was determined and its utility in the field of cerebral neurosurgery was studied. 1. One gram or 2 g of CTM was intravenously administered for 1 time to 10 patients admitted to our department. Dose dependency was observed in the progress of the mean serum concentration. There was no difference in the specific rate of constant, and the ratio of AUC between the group treated with 1 g and the one with 2 g was 1:1.9. The biological half-lives of the elimination phase for both dose levels were about 1.1 hours. 2. Disparity was recognized in the cerebrospinal fluid concentration in spite of the dose dependency. Although a case with comparatively high value of 1.37 micrograms/ml at 60 minutes after administration were seen in the 1 g treatment group, generally the migration concentration was low. Good cerebrospinal fluid concentration was attained in all of the cases in the 2 g treatment group, and the peak values ranged from 0.59 to 10.16 micrograms/ml. 3. The concentration ratio of cerebrospinal fluid to serum in the 2 g treatment group elevated till 360 minutes after administration, and the maximum values ranged from 15.8 to 89.8%. 4. The migration to the cerebrospinal fluid was faster in cases with slight inflammation than those without inflammation in the 2 g treatment group. 5. It was assumed that the prophylactic effect of CTM 2 g administration against staphylococci, streptococci and Klebsiella pneumoniae which are the major causative organisms can be expected in postoperative infection in the field of cerebral neurosurgery.

[Extra-intracranial bypass and internal carotid artery ligation in one-stage operation for intracavernous and giant carotid aneurysm].

The combined one-stage operations, STA-MCA anastomosis and internal carotid artery (ICA) ligation (or trapping) were carried out in 11 cases (Age): 18-79 yrs, Av.: 45.8 yrs) of ICA aneurysms which were inaccessible for a direct operation because of their locations and sizes. First the STA-MCA anastomosis was performed under general anesthesia. Then the patient was awaken and thereafter under local anesthesia the ICA was temporarily clamped for 30 min. under induced hypotension to check whether any ischemic signs appeared. This was followed by proximal ICA ligation when no ischemic signs were observed. In all 11 cases, the anastomosis was patent. The aneurysms disappeared. Neither cerebral ischemia nor rebleeding from the aneurysms was seen during the long follow-up. The mean value of the bypass flow was 119 m/min which was twice as much as that in the cases of other occlusive cerebrovascular diseases and which was about one third of the blood flow of the ICA. Cerebral blood flow measurements through 133Xe inhalation method revealed that there was no difference in rCBF values between the operated and non-operated sides and that their values were within normal limits. The postoperative blood pressure was unchanged in 42% of our 11 cases, temporarily elevated and thereafter normalized in 33% and persistently elevated in 25%. Ophthalmodynamometry showed that the pressure of the central retinal artery decreased postoperatively in a degree of 5-10% in comparison to the non-operated side. No visual impairment was observed postoperatively (except case 3, see the text). These combined operations, STA-MCA anastomosis and ICA ligation were beneficial in preventing the potential postoperative cerebral ischemia. Intra-arterial pressure measurements of the STA and MCA suggested that the one-stage operations of these two procedures are better than the two-stage operations for the patency of the anastomosis because the pressure gradient between the donor and recipient vessels is increased (from 10.3 mmHg to 49.3 mmHg) by this technique. Temporary ICA clamp for 30 min. under induced hypotension in local anesthesia is useful to check whether the one-stage operations can be tolerated or not. EC/IC bypass with an interposed saphenous vein graft is a more beneficial surgical technique than a routine STA-MCA anastomosis, because an immediate and larger amount of bypass flow can be obtained.

[Three dimensional CT reconstruction system on a personal computer].

A new computer system to produce three dimensional surface image from CT scan has been invented. Although many similar systems have been already developed and reported, they are too expensive to be set up in routine clinical services because most of these systems are based on high power mini-computer systems. According to the opinion that a practical 3D-CT system should be used in daily clinical activities using only a personal computer, we have transplanted the 3D program into a personal computer working in MS-DOS (16-bit, 12 MHz). We added to the program a routine which simulates surgical dissection on the surface image. The time required to produce the surface image ranges from 40 to 90 seconds. To facilitate the simulation, we connected a 3D system with the neuronavigator. The navigator gives the position of the surgical simulation when the surgeon places the navigator tip on the patient's head thus simulating the surgical excision before the real dissection.

[A case of growth hormone-producing adenoma presenting as a non-functioning tumor at recurrence].

The authors report a case of recurrent pituitary adenoma, which changed its endocrinological function from GH producing to non-functioning. A 37-year-old woman was admitted to our hospital complaining of headaches, amenorrhea and acromegalic features. Skull X-rays showed marked ballooning of the sella turcica and mild thickening of the calvarium. X-rays of the hands and feet revealed moderate acromegalic changes. On pneumoventriculography, the tumor elevated the floor of the third ventricle. The serum GH level was 29.3 ng/ml, which did not respond to insulin induced hypoglycemia. Radical removal of the tumor was performed through a right frontal craniotomy. Histologically, it was diagnosed as a pituitary eosinophilic adenoma. Immunostains revealed the presence of many GH positive cells in the adenoma. Since the post-operative GH levels were still high (12-16 ng/ml), irradiation to the sellar region was carried out. The serum GH concentration gradually decreased to the normal level in one year after the irradiation. At that time no sellar tumor could be found on CT scans. The patient had been well for six years until she noticed hearing impairment of her right ear. She was re-admitted about seven years after the first admission because of cerebellar ataxia and hearing loss. CT scans revealed a recurrent tumor extending from the sellar region to the right cerebello-pontine angle. Serum GH levels on admission were within normal range (3-4 ng/ml). The tumor was partially removed by suboccipital craniectomy. Pathologically, the tumor was reported as a pituitary chromophobe adenoma. With immunostains, no GH positive cells could be found in the adenoma.(ABSTRACT TRUNCATED AT 250 WORDS)

[Diffuse ventricular enlargement outlines the late outcome of diffuse axonal brain injury].

Clinical significance of ventriculomegaly after severe head trauma has not been fully explored yet. We analyzed hospital records of 53 cases of diffuse axonal injury and 7 cases of brain concussion together. The follow-up periods ranged from 6 months to 8 years (average 25 months). Four patients underwent CSF shunting without noticeable effect. We classified their outcome according to our modification of the Glasgow outcome scale: vegetated, severe, moderate, mild, fair, and good. We reviewed initial (within 12 hours after injury) CT scans and late (3 to 6 months after injury) CT scans or MRI's. We measured the ratio of the third ventricular width to the inner diameter of the skull on the axial view. We computed the lateral ventricular volume by our newly-devised method which took the partial volume phenomenon into account. Temporary extracerebral fluid accumulation was noted mostly within 3 months after injury in 25 of 39 cases in the mild level or above, and 2 of the 9 fair or good level cases. Ventriculomegaly occurred early and stabilized around the 3 month period. We found the differences between the late and the initial values of the third ventricular width (%) and the lateral ventricular volume (cc) highly correlated with our outcome scale (Spearman's correlation coefficient rs = 0.531, 0.676, respectively with p < 0.001 unanimously). We found the late values themselves of the third ventricular width and the lateral ventricular volume highly correlated with our outcome scale (rs = 0.575, 0.650, respectively with p < 0.001 unanimously). These 4 parameters were also highly correlated with the duration of the initial unconsciousness (LOC). Thus, posttraumatic diffuse ventriculomegaly affecting the third ventricle as well should outline the late outcome of diffuse axonal injury. Both the ventriculomegaly and the late outcome should be roughly predicted by the duration of the initial unconsciousness.

Individual differences of cerebrovascular responses to gravitational stress--prediction of orthostatic intolerance.

This experiment was designed to investigate the individual differences in the cerebrovascular responses to orthostatic stress. Seven male volunteers were exposed to head-up tilt (HUT) at 60 degrees for 15 min and to lower body negative pressure (LBNP) at 30 mmHg for 25 min. We measured the flow velocity of the middle cerebral artery and the quantity of the oxygenated and deoxygenated hemoglobin (oxy-Hb and deoxy-Hb) in the brain. Based upon oxy-Hb change during exposure to HUT, we classified the subjects into two groups: 1) the "good responder" group in which the oxy-Hb gradually increased from the 5th to 10th minute of HUT; 2) the "bad responder" group in which the oxy-Hb stabilized at lower levels after the initial decrease. The oxy-Hb changes between the two groups were significantly different during exposure to LBNP. During exposure to HUT and LBNP, no significant difference was observed in blood pressure and heart rate between the two groups. Our results suggest that there might be an individual difference in the cerebrovascular responses to orthostatic stress.

Effect of head up tilt on cerebral circulation.

This study was performed to study the effect of the head up tilt (HUT) on cerebral circulation across the time course (60 degrees HUT for 15 minutes) and across the different angles of HUT (15, 30, 45, 60 degrees HUT for 15 minutes). Cerebral circulation was continuously monitored during 15 minutes of HUT by the carotid Doppler flow meter, the transcranial Doppler flow meter, and the near infra-red spectrophotometer. The results show that the cerebral blood flow decreased during HUT and that the cerebral blood volume decreased initially and then gradually increased. And the magnitude of the effect may have the relationship with the angles of the HUT.

[Identification of the central sulcus using magnetoencephalography and neuronavigator].

The brain-generated currents that produce potentials measured by the electroencephalogram also produce magnetic fields which can be measured by the magnetoencephalogram (MEG), N 20 compatible evoked field after median nerve stimulation is known to be generated in primary sensory cortex. Using MEG with 37 channel SQUIDs, a current dipole is back traced which corresponds to the sensory cortex. When the dipole is projected onto the MRI of the same patient, the primary sensory cortex is precisely identified in the MRI images. These data were used as the key images for navigator enabling a surgeon identify the central cortex in the surgical field. Seven patients with peri-central mass lesion (3 meningiomas, 1 metastatic tumors, 1 angiomas, 2 gliomas) underwent surgery under MEG-navigator method. In every case, the central sulcus and motor cortex were easily identified on the cortex and the tumor was removed as far as possible preserving the motor strip. There were no postoperative worsening of the motor paresis and no other complications were noticed. The method which combines the MEG functional mapping and navigator was considered to be a powerful tool in surgery of the pericentral mass lesions.

[Mechanism of deafferentation pain--experimental research using spinal root resection model].

In rats, autotomy of the digits following dorsal root resection has been observed by many researchers and is considered as an animal model of deafferentation pain. Using C5-Th 1 root resection model of rats, we investigated the role of the ventral roots and pain experience given before deafferentation in the development of autotomy. Male Sprague-Dawley rats of eight weeks old, weighing about 200 g, were used. Animals were divided into two major groups; dorsal root resection group and total (both ventral and dorsal) root resection group. Each group was further divided into several sub-groups, according to the use of formalin injection, before or after surgery, and to the side of formalin injection, the forearm of the affected (root resection) side or unaffected side or of both sides. In pre-injection groups, 0.1 ml of 5% formalin was given subcutaneously on the forearm one hour before surgery. In the postinjection groups, formalin was given within one hour after surgery. Dorsal root resection group without formalin injection was used as control. Under anesthesia with intraperitoneal injection of nembutal, left C 5-Th 1 dorsal root resection was performed by C 4-Th 1 laminectomy and left C5-Th 1 total root resection by opening of the corresponding vertebral foramen. After surgery, we checked neurological findings, systemic condition and local changes of all the extremities everyday during the first week and once a week thereafter for at least three months. In control groups, autotomy was not observed at all during the observation period of three months.(ABSTRACT TRUNCATED AT 250 WORDS)