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H Kuyama

Publications and source records attributed to H Kuyama.

At least 37 records · Page 2Linked to original sources
PubMed1988

The effect of intravenous lidocaine on experimental brain edema and neural activities.

A series of experiments was conducted to clarify the effect of intravenous administration of lidocaine on brain water content, local cerebral blood flow (lCBF), and neural recovery in brain injury induced by exposure of the cat's cerebral surface to the air. The injury produced ischemia and edema in the cortex and white matter without direct damage of the cortex. Lidocaine (3.0 mg/kg) was given intravenously for 30 minutes immediately after air exposure and thereafter at the rate of 2 mg/kg/hour. Twelve hours after exposure, lidocaine significantly suppressed cortical ischemia and edema; however, it had no effects in the white matter. The electrophysiologic activities of the cortex and white matter which were assessed by the direct cortical response and somatosensory evoked response were significantly preserved by lidocaine compared with nontreated animals. The results of this experiment demonstrate that intravenous lidocaine has a significant beneficial effect on cortical ischemia and electrophysiologic activities of the cortex and white matter in injured brain.

Animals↗
PubMed1988

[Unruptured cerebral aneurysms in two siblings screened by cerebral computed angiotomography].

The authors report two siblings, both of whom had unruptured cerebral aneurysms found by screening examination of noninvasive cerebral computed angiotomography. Other authors have reported unruptured cerebral aneurysms detected by conventional cerebral angiography in asymptomatic relatives of families in which two or more individuals had cerebral aneurysmal rupture. It is of interest that, in our cases, the unruptured cerebral aneurysms were detected by noninvasive cerebral computed angiography in two asymptomatic siblings in a family with no history of ruptured aneurysm. To the best of our knowledge, this is the first report of detection of unruptured familial aneurysm by cerebral computed angiotomography. Case 1 is a 67-year-old female who had been complaining of dullness in the head. Cerebral computed angiotomography showed a small high density nodule, suggesting an unruptured aneurysm of the right middle cerebral artery. An aneurysm with a diameter of 4 mm was found in the right middle cerebral artery. A 72-year-old male, who was a brother of case 1, had been afraid of having cerebrovascular disease, and wanted to have a neurological examination check-up. Computed angiotomography revealed a high-density nodule in the anterior communicating artery. Conventional cerebral angiogram showed a 6 X 7 mm aneurysm. However, both of the patients refused surgical treatment. Lozano et al reviewed the previously reported familial aneurysm cases. According to them, familial aneurysm tends to rupture at a younger age and at a smaller size than non-familial aneurysm. It is well known that asymptomatic members of familial aneurysm have a risk of developing aneurysm.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1987

Prediction and evaluation of brainstem function by auditory brainstem responses in patients with uncal herniation.

Serial measurements of auditory brainstem-evoked responses (BERs) were conducted in 15 patients with supratentorial mass lesions. Significant prolongation of the latency of wave V BERs, which originates in the inferior colliculus, occurred when the intracranial pressure (ICP) approached 30 mmHg. In four of five patients whose BERs were measured before pupillary changes, a significant lengthening of wave V latency was observed prior to clinical manifestation of uncal herniation. These results suggest that immediate medical or surgical decompression of ICP should be performed when ICP approaches 30 mmHg with significant prolongation of wave V latency.

Adult↗
PubMed1987

Artificial embolization with isobutyl-2-cyanoacrylate for the treatment of carotid-ophthalmic aneurysm.

A large carotid-ophthalmic aneurysm was successfully obliterated by the combined treatment of clipping the aneurysmal neck and intraaneurysmal injection of isobutyl-2-cyanoacrylate. Reflux of the glue into the artery was prevented by temporary trapping of the carotid artery. The obliteration of an aneurysm with isobutyl-2-cyanoacrylate is an effective procedure in cases where clipping of the aneurysmal neck is not completed due to technical difficulties.

Bucrylate↗
PubMed1987

Effect of stimulation of the medullary reticular formation on cerebral vasomotor tonus and intracranial pressure.

The authors report the results of a study to evaluate the effect of stimulation of the medullary reticular formation on cerebral vasomotor tonus and intracranial pressure (ICP) after the hypothalamic dorsomedial nucleus and midbrain reticular formation were destroyed. Systemic arterial pressure (BP), ICP, and local cerebral blood volume (CBV) were continuously recorded in 32 cats. To assess the changes in the cerebral vasomotor tonus, the vasomotor index defined by the increase in ICP per unit change in BP was calculated. In 29 of the 32 animals, BP, ICP, and CBV increased simultaneously immediately after stimulation. The increase in ICP was not secondary to the increase in BP, because the vasomotor index during stimulation was significantly higher than the vasomotor index after administration of angiotensin II. The vasomotor index was high during stimulation of the area around the nucleus reticularis parvocellularis. In animals with the spinal cord transected at the C-2 vertebral level, ICP increased without a change in BP. These findings indicate that the areas stimulated in the medullary reticular formation play an important role in decreasing cerebral vasomotor tonus. This effect was not influenced by bilateral superior cervical ganglionectomy, indicating that there is an intrinsic neural pathway that regulates cerebral vasomotor tonus directly. In three animals, marked biphasic or progressive increases in ICP up to 100 mm Hg were evoked by stimulation. The reduction of cerebral vasomotor tonus and concomitant vasopressor response induced by stimulation of the medullary reticular formation may be one of the causes of acute brain swelling.

Animals↗
PubMed1987

[Interaction between neurogenic and metabolic factors upon deterioration in cerebrovascular tonus--experimental study on the etiology of cerebral vasoparesis].

It is widely accepted that a tremendous increase in cerebral blood volume (CBV) due to progressive cerebral vasoparesis is an essential to the development of acute brain swelling. This study was designed to determine whether neurogenic and/or metabolic factors are predominant and how these interact with each other in producing cerebral vasoparesis. Fifty-one awake cats immobilized with pancuronium bromide were divided into 4 groups: group I, control; group II, normocapnic hypoxia (PaO2 = 50 mmHg); group III, normoxic hypercapnia (Pa-CO2 = 70 mmHg), and group IV, increased intracranial pressure (ICP = 40 mmHg) by brain compression. Systemic arterial pressure (BP), CBV (photoelectric method), and ICP (epidural pressure) were continuously recorded. The dorsomedial hypothalamic nucleus (DM) and the reticular formation of the midbrain (MB-RF) were bilaterally coagulated by a stereotaxic technique (3mA, 1 min). Therefore alterations in cerebrovascular tonus created by destruction of the cerebral vasomotor centers were examined in the animals with metabolically induced cerebral vasodilatation to various degree's. In group I, vasomotor center destruction resulted in an immediate and transient decrease in BP (DM; -14.1 +/- 6.7 mmHg, MB-RF; -10.2 +/- 4.8 mmHg) and simultaneous increase in CBV and ICP (DM; 7.6 +/- 7.0 mmHg, MB-RF; 6.0 +/- 5.6 mmHg) for 3 to 4 minutes. Increase in ICP by destruction of vasomotor centers reduced significantly in group II (DM; 2.3 +/- 2.6 mmHg, MB-RF; 1.6 +/- 1.2 mmHg) and reduced slightly in group IV (DM; 7.5 +/- 4.0 mmHg, MB-RF; 4.8 +/- 3.2 mmHg). In these 3 groups, autoregulation of cerebral blood flow and CO2 vasoreactivity were not changed by destruction of vasomotor centers.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

[The role of brain-stem vasomotor centers on the neurogenic control of cerebrovascular tonus. Part 2: The effect of stimulation of the medullary reticular formation on cerebrovascular tonus].

Acute brain swelling has been proposed to be caused by vasomotor paralysis secondary to disruption of metabolic and/or neurogenic control of cerebrovascular tone. In previous experiments, acute brain swelling was produced by stimulation of the reticular formation of the medulla oblongata (MORF) with destruction of the dorsomedial nucleus of the hypothalamus (DM) and the reticular formation of the midbrain (MBRF) in 2 (out of 56) animals. The purpose of the present study is to clarify the effect of stimulation of the MORF on cerebrovascular tone. Using 32 cats, blood pressure (BP), intracranial pressure (ICP) and cerebral blood volume (CBV) were continuously measured. The animals were divided into 4 groups: those in which the ICP was normal (Group A), those in which the ICP increased after subarachnoid hemorrhage (Group B), those which underwent superior cervical ganglionectomy (Group C) and those in which the spinal cord was transected at the C2 level (Group D). In all animals, the MORF was stimulated after the DM and MBRF were destroyed. Thirty minutes after cessation of stimulation, the BP was increased again by injection of angiotensin II until it reached the same level as with MORF stimulation. The vasomotor index (VI), defined by delta ICP/delta BP, was calculated and compared between the two situations. BP, ICP and CBV increased simultaneously immediately after MORF stimulation. In 29 out of the 32 animals, ICP increased abruptly from 2 to 48 mmHg and after ten seconds or more decreased gradually. The BP rose about 50 mmHg more slowly than the ICP. After cessation of MORF stimulation, BP, ICP and CBV returned to the control value.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II↗
PubMed1986

[The effect of brain-stem vasomotor centers on the neurogenic control of cerebrovascular tonus--Part 3. The effects of destruction and stimulation of the brain-stem on intracranial pressure in acute subarachnoid hemorrhage].

The purpose of the present study is to clarify the effects of destruction and stimulation of the brain-stem on intracranial pressure (ICP) in experimentally induced subarachnoid hemorrhage (SAH). Using 23 cats, blood pressure (BP), ICP and local cerebral blood volume (CBV) were continuously measured. Acute SAH was produced by injection of autogenous blood (3 to 7 ml) into the cisterna magna. The animals were divided into two groups. Group A: those in which hypothalamic dorsomedial nucleus (DM) and reticular formation of the midbrain (MBRF) were coagulated bilaterally one hour after SAH and Group B: in addition to the procedure of Group A, reticular formation of the medulla oblongata (MORF) was electrically stimulated bilaterally. In 19 out of 23 cats of both groups, transient small increases in ICP and CBV were observed during coagulation and/or stimulation of DM, MBRF and MORF respectively in the animals whose ICP remained approximately 20 mmHg or below and progressive increase in ICP was never evoked. In 3 animals of Group A whose ICPs remained high at more than 20 mmHg, sequential destruction of DM and MBRF induced stepwise increase in ICP to 40 to 80 mmHg and consequently resulted in acute brain swelling. In 1 animal of Group B whose ICP fluctuated around 20 to 40 mmHg, biphasic increase in ICP to 100 mmHg was repeatedly evoked by stimulation of MORF. It is concluded that in the condition of increased ICP produced by SAH, lesions in the DM and MBRF and stimulating condition of MBRF may result in acute brain swelling.

Acute Disease↗
PubMed1984

An experimental study of acute subarachnoid haemorrhage in baboons: changes in cerebral blood volume, blood flow, electrical activity and water content.

Subarachnoid haemorrhage following transection of the posterior artery was produced in 10 baboons. Cerebral blood volume (CBV) decreased transiently after subarachnoid haemorrhage. Two basic patterns of intracranial pressure (ICP) were observed; in one ICP returned to normal but in the other it remained elevated. In this latter group four out of five animals showed an increase in CBV above the original level. There were delays in sensory conduction (measured using somatosensory evoked potentials) bilaterally; those on the contralateral side to the bleed were correlated with ICP whereas other factors are implicated on the ipsilateral side. Initial flow reduction and restoration of cerebral blood flow were both correlated with water content.

Animals↗
PubMed1984

Dural arteriovenous malformations of the spine. Clinical features and surgical results in 55 cases.

The clinical and angiographic findings of 55 patients with a spinal dural arteriovenous malformation (AVM) are reviewed, and the results of surgery assessed. The symptoms of dural AVM are usually gradual in onset, and hemorrhage from this type of AVM is less common than in true spinal cord angiomas. Other clinical features and the myelographic findings are similar to those of spinal cord angiomas. On angiography, the nidus of dural AVM's usually projected lateral to the spinal cord. Clipping of communicating vessels between the AVM and the coronal plexus was carried out in 50 patients, and decompressive laminectomy only in five cases. Surgery led to improvement of disturbed gait or arrest of a previously progressive course in 85% of those managed by clipping communicating vessels. The pathophysiology and surgical treatment of dural AVM's are discussed.

Adult↗
PubMed1983

An experimental study of the acute stage of subarachnoid hemorrhage.

A baboon model of subarachnoid hemorrhage (SAH) has been developed to study the changes in cerebral blood flow (CBF), intracranial pressure (ICP), and cerebral edema associated with the acute stage of SAH. In this model, hemorrhage was caused by avulsion of the posterior communicating artery via a periorbital approach, with the orbit sealed and ICP restored to normal before SAH was produced. Local CBF was measured in six sites in the two hemispheres, and ICP monitored by an implanted extradural transducer. Following sacrifice of the animal, the effect of the induced SAH on ICP, CBF, autoregulation, and CO2 reactivity in the two hemispheres was assessed. Brain water measurements were also made in areas of gray and white matter corresponding to areas of blood flow measurements, and also in the deep nuclei. Two principal patterns of ICP change were found following SAH; one group of animals showed a return to baseline ICP quite quickly and the other maintained high ICP for over an hour. The CBF was reduced after SAH to nearly 20% of control values in all areas, and all areas showed impaired autoregulation. Variable changes in CO2 reactivity were evident, but on the side of the hemorrhage CO2 reactivity was predominantly reduced. Differential increase in pressure lasting for over 7 minutes was evident soon after SAH on the side of the ruptured vessel. There was a significant increase of water in all areas, and in cortex and deep nuclei as compared to control animals.

Acute Disease↗
PubMed1983

Myxopapillary ependymoma of the lateral ventricle. A study on the mechanism of its stromal myxoid change.

Reported was the first case of myxopapillary ependymoma arising from the right lateral ventricle of a 29-year-old Japanese male. The histological and ultrastructural findings were identical to those from the filum terminale. It was suggested that insudation of plasma proteins found within hyaline-thickened blood vessels in the tumor stroma represented the presence of previous long-standing anoxia and thus, circulatory disturbance would be closely related to the formation of the stromal myxoid change.

Adult↗