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Biomedical subjects

J Vajda

Publications and source records attributed to J Vajda.

96 records · Page 6Linked to original sources
PubMedDate not supplied

Changes in somatosensory evoked potentials following an experimental focal ischaemic lesion in thalamus.

Experiments have been performed to produce localized thalamic ischaemia in baboons anaesthetised with alpha-chloralose. Somatosensory evoked potentials to median nerve stimulation were recorded in the medial lemniscus, VPL of thalamus and the primary somatosensory cortex. Local blood flow was also recorded by the hydrogen clearance technique in these regions. The early potential recorded in thalamus has been shown to be generated from 3 sources: (i) a positivity generated outside the VPL, (ii) local wavelets, most likely from synaptic activity close to the recording electrode, and (iii) a local overall negativity. The first of these potentials alone remains after thalamic ischaemia. It arises below the level of the thalamus, being very likely generated by the afferent volley in the medial lemniscus, and is seen in the surface-recorded response as the early component P8 (corresponding to P15 in the human).

Animals↗
PubMedDate not supplied

A model of selective experimental ischaemia in the primate thalamus.

A model for studying changes in local CBF and evoked potentials in selective thalamic ischaemia has been developed. The arterial supply to the posterior thalamus (mainly from the posterior choroidal arteries) was occluded in the baboon using a transorbital approach to the region of prepontine and ambient cisterns. Local CBF was measured by the hydrogen clearance method using electrodes introduced into the nucleus ventralis posterior lateralis of thalamus as well as cortex on both sides. The production of focal ischaemia was demonstrated by a significant decrease in thalamic CBF and confirmed by examination of the brain perfused with carbon particles.

Animals↗
PubMedDate not supplied

Early surgery for ruptured cerebral aneurysm.

Preliminary experience with 150 consecutive cases of ruptured cerebral aneurysms operated on within 48 hours is reported. The rationale of this emergency procedure is to prevent early rerupture and also to prevent neurological ischaemic consequences of the subarachnoid haemorrhage likely to develop in the first week after a rupture. The acceptable outcome of the surgically treated cases (87% excellent and good outcome) has been favourably matched to those of a group of equal number of consecutive cases seen in suitable condition for surgery within 48 hours by medical personnel but that remained unoperated for various reasons. The incidence of delayed neurological ischaemia as the definite cause of death is lower in the group operated on in the acute stage than those with delayed surgery, although the overall incidence of clinical vasospasm does not seem significantly lower than in the delayed surgery group.

Adolescent↗