Hirotsune Kawamura

A New Approach to Control Central Deafferentation Pain: Spinal Intrathecal Baclofen

We investigated the short-term effects of an intrathecal bolus injection of baclofen on central pain due to stroke or spinal cord injury. Pain relief was obtained in 64% of the patients. The effects developed 1-2 hours after the injection and continued for 10-24 hours. Both spinal segmental and supraspinal mechanisms may be involved in the production of baclofen-analgesia.

CT-guided stereotactic surgery for evacuation of hypertensive intracerebral hematoma

During the last 3 years, 46 cases of hypertensive intracerebral hemorrhage were treated by CT-guided stereotactic surgery. Our present report is concerned with the evaluation of this procedure in the treatment of hypertensive intracerebral hematoma, in terms of the rate of aspirated hematoma and follow-up study of patients. It is difficult to draw any definite conclusion about the operative indications. CT-guided stereotactic aspiration, however, can be evaluated as a less invasive and more definitive treatment of intracerebral hematoma in the basal ganglia and thalamus.

Single Neuron Analysis of the Human Midbrain Tegmentum

Rostral mesencephalic reticulotomy (RMR) has been performed since 1973 for relief of intractable pain. The target area is in the midbrain reticular formation (MRF) bordering the periaqueductal gray matter at the superior collicular level. The target of RMR is 13--16 mm posterior to the midpoint of the AC-PC line and 5--8 mm below the AC-PC line. The laterality of the target is measured from the center of the aqueduct, ranging 5 to 8 mm from the midline. The rationale for this procedure is based upon the previous findings that the brain stem reticular formation plays a more important role above the spinal cord level than the lateral spinothalamic tract in the central conduction of nociceptive impulse. In the present study, intraoperative single neuron recording was made with tungsten microelectrodes from the human midbrain tegmentum in response to peripheral pinprick stimulation. These nociceptive neurons were classified into three groups in regard to the unit latency from the peripheral pinprick stimulation.

An Image-Guided Stereotactic System for Neurosurgical Operations

A new simulation system utilizing digital images (CT/MRI/SPECT) and an ultrasound/laser navigation system has been developed for image-guided surgery. Preoperative CT/MRI imaging does not always indicate the actual location of the lesion during intracranial operation, because the lesion may be displaced or distorted by operative procedures or CSF flowout. The authors developed an image integration system including an intraoperative ultrasonogram, which provides accurate information not only on the location of the deep-seated lesions but also surrounding anatomical structures during operation. The rationale of the system is to coordinate the three-dimensional axes of each image with the aid of a stereotactic subframe. Our simulation system has two ways. One simulation system works on a SUN workstation. At the preoperative simulation study: the entry point on the brain surface and the access route to the lesion are decided on from the three-dimensional CT/MRI images on the computer display. Then the configuration of the lesion from the operative view is displayed as an expected ultrasound image by reconstructing the CT and/or SPECT image. Another simulation system (HyperCAS) works on the HyperCard of a MacIntosh. The target point, the entry point and the trajectory are decided on and the three-dimensional location of these points is measured from serial CT images on the LCD display. At the time of operation, stereotactic craniotomy is performed using the laser navigator. The extent of the lesion at every depth in the surgical process is predicted from these images, and the access route to the lesion is easily corrected with the intraoperative ultrasound navigator.(ABSTRACT TRUNCATED AT 250 WORDS)

Intracranial aneurysm in a child with klippel-trenaunay-weber syndrome: Case report

The authors report a case of cerebral aneurysm in an 8-year-old boy with Klippel-Trenaunay-Weber syndrome. This syndrome is a type of neurocutaneous disorder characterized by skin hemangiomas and hypertrophy of soft tissues and/or osseous structures in the involved region. Spinal hemangioma is occasionally found in this syndrome and may cause spinal subarachnoid hemorrhage. To our knowledge, however, no case of cerebral aneurysm in a child with this syndrome has been reported previously in the literature.

Alterations of Immunoreactive beta-Endorphin in the Third Ventricular Fluid in Response to Electrical Stimulation of the Human Periaqueductal Gray Matter

Immunoreactive beta-endorphin in the third ventricular fluid was measured in response to electrical stimulation of the periaqueductal gray matter in 8 patients with intractable pain during rostral mesencephalic reticulotomy for pain relief. In all patients, marked increase of immunoreactive beta-endorphin was observed. On the other hand, in cases of electrical stimulation of the zona incerta performed during stereoencephalotomy, in 5 patients with involuntary movement, immunoreactive beta-endorphin in the third ventricular fluid did not show any significant change. The authors conclude that the increase of immunoreactive beta-endorphin on electrical stimulation of the periaqueductal gray matter is not a nonspecific response to brain stimulation but a specific response in regard to cerebral localization of endorphins. Direct correlation between pain relief and periaqueductal gray stimulation is also questioned.

A New Apparatus for CT-Guided Stereotactic Surgery

Combining whole-body CT scan with a stereotactic system, the authors have developed and applied clinically an apparatus which readily provides intraoperative CT images, making it possible to confirm the location of the target point and ascertain the intraoperative environment. It takes about 9 s to obtain a CT image. Our purpose is to make stereotactic surgery, a kind of blind surgery, as safe and reliable as a visualized procedure by intraoperative CT scanning. By the method, in which there is very little invasion under local anesthesia, evacuation of deep-seated intracerebral hematomas as well as brain abscesses and also biopsy or brachytherapy of brain tumors in the brain can be done with safety and reliability.

Stereotactic Mesencephalotomy for Pain Relief

Rostral mesencephalic reticulotomy (RMR) for pain relief was performed in 34 patients with intractable pain. Most of these patients have been followed for a long period of time postoperatively, the longest follow-up period being 11 years. Contrary to the commonly prevailed bias in the past that mesencephalotomy may be a surgical intervention with potential risk, these patients of RMR have continued to substantial improvement postoperatively in terms of their preoperative intractable painful dysesthesia after a long period of time. The results of pain relief for denervation pain as well as for nondenervation pain are surprisingly good even after unilateral procedures. There was no operative mortality. Postoperative disturbance of ocular motility has been reduced. RMR has its scientific basis in that the medial part of the reticular formation rather than the classical lateral spinothalamic tract has more significance in the central conduction of nociceptive impulses through the midbrain level, which was verified by intraoperative neuronal recording with a tungsten microelectrode. The present report emphasizes that stereotactic mesencephalotomy, if performed meticulously and precisely, is a safe surgical procedure for pain relief. Results of MRI and sensory manifestations of a patient 11 years after RMR are also presented.

A new apparatus and stereotactic method for percutaneous high cervical cordotomy

In order to elucidate pathogenesis of perifocal edema in the human brain tumors, we observed the alteration of capillary permeability between the glioblastomas with remarkable edema (4 cases) and astrocytoma with slight edema (3 cases). Specimens were studied by conventional ultrathin section and freeze-fracture replica technique. In ultrathin sections of capillaries in glioblastomas, some of these cell junctions were tortuous, elongated, in fact, open. Other capillary abnormalities included endothelial hyperplasia with extensive vesicular formation, surface infolding of endothelial cells, irregularity of the basal lamina and the presence of a large collagen filled extracellular space. In freeze-fracture replicas of capillary endothelium, pinocytotic vesicles markedly increased and were an average fo 52 per micron. Tight junction in one area was seen as network of 6 strands composed of about 100A particles, but in the other areas as one or two strands. In ultrathin sections of astrocytoma, yet there were blood vessels appeared relatively normal. In freeze-fracture replicas, pinocytotic vesicles markedly increased and were an average of 34 per micron. Tight junction was seen as network of 7 strands. We concluded that fewer strands of the tight junction play an important role in increasing the permeability in the vessels of glioblastomas with severe perifocal edema, in addition to increasing the pinocytotic vesicles.

Cerebral-Evoked Responses Elicited by Direct Stimulation of the Lateral Spinothalamic Tract in the Human

The authors recorded cerebral-evoked responses elicited by direct stimulation of the human lateral spinothalamic tract (LST) during percutaneous cordotomy to investigate central conduction of noxious stimuli. These responses consisted of four negative potentials, peak latency being 3.8 (N1), 8.4 (N2), 12.2 (N3) and 21.9 (N4) ms respectively. N1 showed wide distribution over the scalp and was considered to be of subcortical origin. N2-N4 were distributed in both the temporal and central area. The different distribution pattern of N2-N4 from conventional somatosensory-evoked potential suggested a different projection of LST from the medial lemniscus system.