Biomedical subjects
Publications and source records attributed to D M Psatta.
A new type of visual field perimeter, equipped with conic light emitting diodes (LEDs) located at 10 degrees intervals automatically programmable is described. The device is meant for visual field analysis by mapping of the evoked responses derived from the retina and specific cortical projection areas.
Visual field projection maps were obtained using retinal and cortical EP amplitude values. Single meridian investigations were also performed. Stimulation was done with punctual photic stimuli delivered by the LED perimeter built for the purpose. Schedule with 28 stimulation loci was adopted. The B wave of the average ERG and P100 component of the cortical VEP were measured. The maps were obtained by interpolation of amplitude values on a grid of 21 x 21 characters. By comparing the retinal and cortical visual field maps, conclusions regarding the normality of visual structures (peripheral or central) can be drawn. Our procedure adds to the previous data on visual field investigation (cynetic or static) important elements concerning vision electrophysiology.
Twenty schizophrenia-like psychotic patients suspected of epilepsy were explored using EEG techniques (recordings in the 10-20 International System, source derivation, EEG mapping and EEG spectral reaction mapping by photic and somesthetic stimulation). In 16 of them, latent epileptic disorders were found. EEG spiking foci could be located either: (a) in temporal, (b) fronto-basal, or (3) in the sagittal-line leads. A corresponding associated dysrhythmia was clearly revealed by EEG mapping. On EEG spectral reaction mapping a suggestive aberrant displacement of the area of maximal sensory response was found. These EEG disorders were in significant relation with the psychotic syndrome observed in the respective group of patients: (a) patients with fronto-basal (temporal anterior) foci were prevalently paranoid; (b) patients with temporal lobe foci were prevalently depressive; (c) patients with sagittal line (singular) foci presented a predominantly expansive, hypomanic behaviour. The study shows the importance of normal fronto-limbic circuits for the preservation of mental health.
EEG investigations (using source-derivation) were performed in 15 mentally retarded children, before, during (at 1 and 6 months) and after three months of pineal hormone treatment (AVT, 10(-6) mg/day, intranasally). Power spectral analysis, maturation lines and EEG mapping were used to ascertain the functional changes induced by AVT. A rapid increase in maturation EEG coefficients was found. It resulted from a significant reduction in the percent amount of theta and delta activity and from the increase in alpha activity. A significant increase in alpha peak frequency occurred after 6 months of treatment as well as a better separation of the EEG patterns between the anterior and posterior halves of the hemispheres. These favourable effects were clearly evidenced by EEG mapping. They are in good relation with cognitive function (attention, intelligence) improvement induced by AVT therapy.
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Forty neurologic patients were investigated in order to disclose the diagnostic advantages by power ratio EEG mapping. Typical examples of EEG maps in brain tumours, cerebral infarction, encephalitis and epilepsy are given. In spite of obvious limitations, the necessity of EEG mapping utilization in the neurological clinic is supported.
The influence of head down (HD) tilting on brain-stem auditory evoked responses (BAER) was studied in hypertensives with supine brain-stem disorders (occipital headache, vertigo, nausea, diplopia, blurred vision occurring after night recumbency), in hypertensives without such phenomena and in normotensives. In the latter two categories of subjects HD tilting had no effect on BAER. On the contrary, in hypertensives with supine brain-stem disorders the manoeuvre induced a constant prolongation of I-V and III-V intervals and a depression in the amplitude of wave V; the alterations of BAER produced by HD tilting reveal probably a dysfunction of the superior brain-stem area and might be due to the impaired cerebral venous draining subsequent to the manoeuvre. The study of BAER after HD tilting seems to be a proper means to attest the supine brain-stem disorders displayed by some hypertensives.
A 53-year-old man developed spastic ataxia associated with diabetes insipidus. The patient experienced frequent attacks of stiffness and numbness of the four limbs accompanied by difficulty of speech. During an eight years' follow-up a progressive deterioration of the motor function was observed but no extracerebral manifestations were noticed. The association of spastic ataxia is generally considered as diagnostic of histiocytosis X. In the present case, however, multiple sclerosis seems a more likely diagnosis in view of the late onset and the highly characteristic brain stem seizures.
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The purpose of the study was to reconsider the somatosensory evoked potential (SEP) morphology in case of thermalgic versus proprioceptive sensory loss. The study was carried out on 70 inpatients affected by uni- or bilateral dissociated sensory disorders and on 45 normal controls. The median or tibial nerves were stimulated (at wrist or ankle), the stimulus intensity being adjusted to elicit a visible muscle response with liminal pain. SEPs were measured with regard to 7 negative components parameters (latency, amplitude) and statistically compared in the three groups. Results show that the initial SEP components (N18, N30, N70) are specifically affected in case of proprioceptive and the late components (N150, N220, N340) in case of thermalgic sensory disorders (N150 having an intermediate position). The intergroup differences were statistically significant. The results are thought to be used in clinical diagnosis.
Simultaneous ERG and VEP investigations were performed in 42 patients presenting reduced visual acuity and characteristic signs of retinopathy on direct ophthalmoscopic inspection: 1) primary retinal pigmentary degeneration - 15 cases; 2) secondary retinopathy - 11 cases; 3) infantile retinal degeneration - 16 cases. Reciprocal relations of ERG--VEP component latency/amplitude in the three types of retinal disorder are described.
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Explore the source record for details and available documents.