Masahiko Ioku

Functional Changes in Thalamic Relay Neurons After Focal Cerebral Infarct: A Study of Unit Recordings from VPL Neurons After MCA Occlusion in Rats

We evaluated neuronal and histological changes of thalamic neurons 1, 4, 7, and 14 days after middle cerebral artery (MCA) occlusion in rats. After the somatosensory evoked potentials (SEPs) were measured from the cerebral cortex, the thalamic relay neuronal activities were recorded with a glass microelectrode following repetitive electrical stimulation of the contralateral forepaw at frequencies ranging from 1 to 50 Hz. In ∼95% of the occluded rats, the ipsilateral somatosensory cortex and/or the subcortical somatosensory pathway developed infarct, resulting in SEP loss. We evaluated unit data from rats with abolished SEPs. The average firing rate of the nucleus ventralis posterolateralis (VPL) neurons in response to 25 stimulations at 30 Hz was significantly reduced to 0.1 spike/stimulus 1 day after MCA occlusion. In sham-operated rats, the same stimulation produced 0.7 spike/stimulus. The firing rate recovered to 0.4 spike/stimulus at 30-Hz stimulation 4 and 7 days after occlusion. This was followed by resuppression (0.1 spike/stimulus) 14 days after occlusion. Histological study revealed some abnormal neurons in the ipsilateral thalamus 7 days after occlusion. We were unable to find normal-shaped neurons in the VPL 14 days after occlusion. The present study demonstrates that cortical infarct produces functional and morphologic changes that gradually and progressively affect the ipsilateral thalamus, although incomplete transient recovery of somatosensory transmission may occur.

Interstitial Chemotherapy with Biodegradable ACNU Pellet for Glioblastoma

For patients with nonresectable glioblastoma (GB) or recurrent GB, we have recently been using an interstitial chemotherapy with biodegradable polylactic acid pellets containing nimustine chloride (ACNU), in combination with superselective arterial ACNU injection, routine irradiation and chemotherapy. The ACNU pellets are prepared by mixing polylactic acid powder and ACNU, and then melting the mixture at low temperature and moulding it into a thin pellet. Pharmacological anticancer activity was experimentally demonstrated by the finding that a region of suppression was present surrounding an ACNU pellet placed in a B6 melanoma cell culture disc, but that no such suppression was present around a control pellet. In order to determine the spatial and temporal distribution of ACNU, a small pellet (ACNU: 0.6 mg) was implanted in the frontal lobe of rats. ACNU concentration determined by HPLC was 61.0 micrograms/g brain tissue on day 1. 22.5 on day 3, and 5.5 on day 7; small amounts of ACNU were in fact released for at least 4 weeks after implantation. This pellet was used for the clinical treatment of 11 GB patients. Four patients had several pieces of pellets implanted immediately after CT-guided stereotactic biopsy, and the other 7 had pellets placed in residual tumor after partial removal at craniotomy. No ACNU was detectable in serum. CT studies obtained at subsequent appropriate intervals disclosed gas formation around the pellets, a slight increase in edema, and necrosis or decrease in CT enhancement of tumor beginning around day 12 after implantation. Bone marrow suppression did not occur, since ACNU was administered interstitially and in the range of 50-200 mg (average: 126 mg) per patient.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of dopamine on cerebral blood flow, and metabolism for oxygen and glucose under barbiturate administration in cats

SummaryThe effect of dopamine during barbiturate therapy was investigated in 29 cats including 5 sham-operated cats. According to Kierseys classification of electro-encephalographic patterns, physiological variables, cerebral metabolic rates for oxygen and glucose, cerebral blood flow (CBF), and intracranial pressure (ICP), etc. were evaluated in each electro-encephalographic pattern. Oxygen-glucose index was calculated and used as an indicator for aerobic or anaerobic metabolism of glucose.Group 1 (12 cats), to which only thiamylal was administered, maintained aerobic glycolysis due to a parallel reduction of cerebral metabolic rates for oxygen and glucose (about half of the initial value at Kierseys fifth pattern) in spite of reduction of CBF and mean arterial blood pressure (MABP).Group 2 (12 cats), to which dopamine was administered in addition to thiamylal due to a reduction of MABP, showed anaerobic glycolysis though MABP and CBF were maintained.These findings are ascribed to an increase of cerebral metabolic rate for glucose up to 130% of the initial value though cerebral metabolic rate for oxygen decreased down to half of the initial value: The beneficial effect of barbiturate on cerebral metabolism was reduced by use of dopamine. ICP was reduced in both groups. Our result indicates that administration of extracellular fluid may be preferable for treatment of hypotension during barbiturate therapy than dopamine medication.

Clinicoanatomical Study of Thalamic Stimulation for Pain Relief

Our small experiences with electrical stimulation in the VPL and VPM for dysesthetic pain show that it provoked only paresthesia and induced some relief of pain. It does not increase the beta-endorphin level in CSF. To clarify the anatomical substrata in VPL stimulation, neuroanatomical studies were done about the inputs to VPL in man, monkey and cat by the Fink-Heimer method. The spinothalamic tract terminates in VPL in a patchy fashion in the monkey. The corticothalamic fibers from SI and SII cortex project to VPL and VPM in somatotopical organization in the cat. SI and SII cortices have reciprocal connections, in addition to projections to area 5 or SIII cortex. The corticofugal fibers to the magnocellular and gigantocellular tegmental fields are suggested in addition to the dorsal column nuclei, spinal trigeminal nuclei and spinal posterior horn in cat. The medial lemniscus input to VPL and the above neural circuits are thought to be associated with VPL stimulation.

Subjective visual symptoms and electroencephalographic analysis before and after removal of occipital falx meningioma

A 41-year-old patient underwent surgery for the partial removal of a posterior falx meningioma, which invaded deeply into both occipital lobes. After surgery, the patient complained of marked metamorphopsia, colored photopsia, afterimage and loss of stereopsia. The relationships between these symptoms and features of the VEP and EEG power spectra (both under resting and photic driving conditions) were investigated. Marked photopsia on the 4th postoperative day was accompanied by EEG features indicating asynchronous excitation of injured cortical cells, while the presence of a strong afterimage on days 17 through 24 coincided with indications of an apparent refractoriness in cortical activation.

Neurofunctional Changes in Thalamic Neurons After Cortical Ablation in Adult Rats: Effect of Basic Fibroblast Growth Factor upon Thalamic Neurons

Traumatic damage to cortex results in progressive degeneration in the ipsilateral thalamus. It has recently been suggested that this degeneration is attributable to neurotrophic mechanisms. We studied the functional and morphological changes in thalamic relay neurons that occurred following traumatic cortical ablation, and also studied the effects of basic fibroblast growth factor (b-FGF), one of neurotrophic factors, on these changes.

Experimental study on the indications for Barbiturate therapy : change in haemodynamics and the influence of dopamine

SummaryThe effect of barbiturates on the cerebral haemodynamics and the influence of dopamine on barbiturates were investigated using 20 cats, and clinical indication of barbiturate therapy is discussed. Cerebral blood flow, oxygen extraction fraction, and cerebro-vascular resistance as well as physiological variables were evaluated at various concentrations of barbiturates in the blood.Thiamylal caused simultaneous reduction of mean arterial blood pressure and cerebral blood flow. As the disruption of autoregulation proceeded, cerebro-vascular resistance and oxygen extraction fraction increased till the barbiturate-induced coma stage. Furthermore, cerebro-vascular resistance increased much more markedly by the combined use of dopamine. Clinically, our results indicate barbiturates would increase cerebral circulatory disturbances caused by vasospasm following subarachnoid haemorrhage because barbiturates further increase cerebro-vascular resistance. Then again, the combined use of dopamine is not preferable because of deterioration in vasospasm.

NMR Images of Non-communicating Hydrocephalus Associated with Dandy-Walker Variant and Achondroplasia

Two cases of non-communicating hydrocephalus caused by a relatively rare etiology were reported. The causes of hydrocephalus in these 2 cases were associated with congenital anomaly in the posterior fossa. Previously these lesions were very difficult to make diagnoses using CT scan due to the complicated structure in the narrow posterior fossa, and artefact by the bony structure. After the advent of nuclear magnetic resonance (NMR), NMR became an effective tool for the diagnosis of the posterior fossa lesion, as was presented in this paper. The first patient, a 4-month-old boy, had Dandy-Walker variant, manifesting enlargement of the torcular Herophilii, straight sinus, and vein of Galen, hypoplasia of the inferior vermis and corpus callosum, and a large cyst behind the vermis as well as hydrocephalus. The longitudinal length of the floor of the fourth ventricle was short, possibly associated with hypoplasia of the inferior vermis, but the shape of the fourth ventricle was essentially reserved. Communication of cerebro-spinal fluid between the cyst and subarachnoid space was demonstrated by CT cisternography.

Postoperative Course of the Size of Arachnoid Cyst in the Middle Fossa

Postoperative courses of arachnoid cysts in the middle fossa were evaluated in 12 patients. This paper focussed on the postoperative changes of the volume of arachnoid cysts, and the interesting phenomena during reduction of the cysts. The ages ranged from 6 months to 49 years. The postoperative courses observed ranged from 41 days to 7 years. They were classified by the morphological classification of Galassii 4 cases of Galassi type 1 (Case 2, 3, 7, and 11), 5 cases of type 2 (Case 1, 4, 5, 6, and 12), and 3 cases of type 3 (Case 8, 9, and 10). The sizes of the cysts (cubic centimeter) were arbitrarily defined by the product of the maximal length of the cyst, the maximal length crossing at right angles to the above, and the vertical length of the cyst, using horizontal sections of CT images. The patients were treated by several different operative methods individually: resection of the external wall of the cyst, cyst-peritoneal shunt, intermittent puncture of the Ommaya’s reservoir where the fluid drained from the cyst was collect, and making communication between the basal cistern and cyst. In 11 cases the operation was done combining these methods.

Clinical Experiences of Non-destructive Transcutaneous Afferent Electrical Stimulation Therapy for Pain Relief

Clinical experiences of the transcutaneous afferent electrical stimulation therapy for various types of intractable pain are reported. A total of 29 pain patients included 9 residual or recurrent chronic pain patients who had had various destructive pain treatment, 15 non-malignant chronic pain patients and 5 patients with pain due to malignant tumors. In 93% of the patients complete or partial relief of pain was observed. After the subsequent successive stimulation therapy from a week to two years and ten months 86% of the 22 patients who could use the stimulator by themselves in free of charge got pain relief in more or less degree. Only 42% of these patients, however, wished to continue this therapy for their pain relief. All the malignant tumor patients and many posttraumatic chronic headache patients with Barre-Lieou syndrome discontinued electrical stimulation. Good benefits are to be expected from this non-destructive treatment for chronic pain in combination with medication and/or destructive treatment.