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Biomedical subjects

V J Iragui

Publications and source records attributed to V J Iragui.

26 records · Page 2Linked to original sources
PubMed1985

Periodic lateralized epileptiform discharges in asphyxiated neonates.

Electrographic seizures (EGS) were detected in 13 of 16 asphyxiated neonates who were undergoing continuous electroencephalographic monitoring for detection of evidence of central nervous system injury. Five of the 13 neonates with EGS also had periodic lateralized epileptiform discharges (PLEDs). The electrographic characteristics of PLEDs in these infants were similar to those reported in neonatal herpes simplex encephalitis and in older children and adults. Of the 5 neonates with PLEDs, 2 died, 2 are developmentally delayed and only 1 is normal at 12 months. This is in contrast to the normal outcome for 8 of the 11 infants who did not have PLEDs. One other was neurologically normal but died of pulmonary disease at 3 months and the other two were developmentally delayed. PLEDs in neonates, as in other age groups, lack diagnostic specificity, but when associated with neonatal asphyxia, may indicate a poor prognosis. Continuous EEG monitoring is helpful in identifying PLEDs in these cases.

Asphyxia Neonatorum↗
PubMed1984

The cervical somatosensory evoked potential in man: far-field, conducted and segmental components.

Somatosensory evoked potentials (SEPs) to median nerve stimulation were recorded from neck and scalp electrodes in 23 normal adults using cephalic and non-cephalic (knee) references simultaneously. With a cephalic reference, the neck SEP consisted of several 'negative' potentials that had the same latency at all recording locations. Simultaneous recordings from neck-scalp, neck-knee and scalp-knee derivations demonstrated that scalp far-field potentials significantly contributed to neck-to-scalp recordings and obscured the cervical SEPs. With a non-cephalic reference, the neck SEP consisted of a prominent positive wave (P9) followed by a large negative component (N13). A small positive potential, P10, seen in the lower neck, gradually increased in latency and amplitude from lower to upper neck and appeared as a P11 potential at upper cervical levels. In lower neck recordings, a negative wave, N11, was also present and in some subjects exhibited a latency shift from lower to upper neck. P9, P11 and N11 had a short refractory period suggesting a presynaptic origin whereas N13 had a longer refractory period indicating a postsynaptic generator. The consensus that P9 originates in the peripheral nervous system is consistent with its rapid recovery cycle. The bipolar characteristics of N11 and P11 as well as their latency shift and their short recovery cycle suggest that they reflect activity in the cervical dorsal columns. N13, that displayed no latency shift and had a longer recovery cycle, may originate in spinal cord dorsal horn interneurons.

Adult↗
PubMed1984

Clinically useful applications of evoked potentials in adult neurology.

Recent advances in the field of sensory evoked potentials (EPs) have allowed assessment of function in regions of the nervous system that were previously inaccessible to noninvasive electrophysiologic study. Pattern visual and brainstem auditory EPs, respectively, are more sensitive to certain optic nerve or posterior fossa lesions than either clinical or laboratory tests. Short-latency somatosensory EPs from the upper and lower extremities are sensitive to pathology at cervicomedullary and thoracolumbar levels of the neuraxis as well as to suprasegmental lesions. This article reviews the development of these tests as clinically useful tools and the applications in which they have contributed most to the practice of adult neurology.

Arm↗
PubMed1983

Physiologic and prognostic significance of "alpha coma".

A patient with posthypoxic "alpha coma" is described whose EEGs were recorded before coma, within two hours following the onset of coma and after recovery. The differences observed between the alpha activity during coma and that seen before and after suggest that the alpha activity during coma and the physiologic alpha rhythm are different phenomena. This case, as well as others reported, also suggests that "alpha coma" resolving in the first 24 hours following hypoxia may have a better prognosis than "alpha coma" detected after the first day, and stresses the need for EEG monitoring begun in the immediate period following hypoxia in order to assess accurately the prognostic significance of this EEG pattern in the early stages of postanoxic encephalopathy. The aetiology of "alpha coma" also affects outcome. The survival rate appears higher in patients with respiratory arrest than in those with combined cardiopulmonary arrest.

Alpha Rhythm↗
PubMed1982

Capsular ataxic hemiparesis.

Left hemiparesis and left-sided ataxia developed in a 67-year-old man. Computed tomography (CT) showed an area of decreased attenuation in the anterior part of the rostral posterior limb of the right internal capsule that enhanced with contrast. As the patient's condition improved, the contrast enhancement resolved. The clinical course combined with the changes in CT scans indicates that the responsible lesion was an infarct. This report suggests that ataxic hemiparesis can result from an infarct of the posterior limb of the internal capsule.

Aged↗
PubMedDate not supplied

Differential antiepileptic sensitivity between cortical sites in the rat.

The relative efficacies of phenobarbital (PB), phenytoin (PHT), carbamazepine (CBZ), and valproic acid (VPA) in the suppression of focal and generalized seizures produced by electrical stimulation of two different cortical sites (areas 3 and 10) were evaluated in the rat. The two cortical sites were distinguished by significantly different dose-response curve slopes for the suppression of afterdischarge duration by PHT, CBZ and VPA, which suggests more than one mechanism of action for these drugs. The dose-response curve slopes for PB, on the contrary, were not significantly different, although its potency was significantly greater in area 10. For suppression of generalized convulsions, dose-response curve slopes were not significantly different for any of the drugs. Potencies of PHT, CBZ and VPA were equivalent in the two areas, but PB was significantly more potent in the suppression of generalized convulsions triggered from area 10. It is concluded that focal seizures elicited by the stimulation of different cortical sites are differentially refractory to antiepileptic drugs.

Animals↗