Search PubMed⌕ Search

Biomedical subjects

W J Nowack

Publications and source records attributed to W J Nowack.

At least 19 recordsLinked to original sources
PubMed1992

Triphasic waves and spike wave stupor.

Triphasic waves are usually thought of as indicating a metabolic encephalopathy. Recent investigations have added nonmetabolic etiologies to the differential diagnosis of triphasic waves. Seizures are not generally thought of as associated with triphasic waves. Similarities in the appearance of records with encephalopathies and continuous triphasic waves and those of some patients with the Lennox-Gastaut syndrome have been noted. We presented a case which suggests that the presence of TW in a patient with a metabolic encephalopathy might suggest petit mal status epilepticus.

Aged↗
PubMed1991

The thalamocortical contribution to epilepsy.

The experimental literature has dealt intensively with the cortical contribution to epilepsy. Possibly because of the direction of technological advance, much less attention has been paid to the role of other structures. A model which emphasizes the role of some of those non-cortical structures, specifically that of thalamocortical modulation of cortical excitability, is developed. Some aspects of the petit mal seizure, a seizure type considered by some investigators to involve thalamocortical mechanisms, are predicted by the model. Although the thalamocortical mechanisms under study are not the only mechanisms underlying seizures, a full understanding of the phenomenology of epilepsy needs to take into account the role of subcortical modification of cortical activities in addition to other mechanisms. Gloor has described two types of epileptogenesis: type I characteristic of non-convulsive seizures and type II characteristics of convulsions. There is disagreement as to whether or not the two mechanisms represent qualitatively different phenomena. Utilizing the thalamocortical model, it can be shown that the two types of epileptogenesis are qualitatively different. Furthermore, the thalamocortical model leads to a possible explanation of clinically different profiles of antiepileptic efficacy of medications.

Animals↗
PubMed1989

Cryptococcal meningoencephalitis presenting transient focal cerebral symptoms.

Cryptococcal meningoencephalitis (CM) is a fatal disease if untreated. We have presented an unusual case of CM clinically diagnosed as transient ischemic attacks. Therapy with amphotericin B and flucytosine cured the infection and the patient had no further episodes of transient focal cerebral dysfunction. In patients with transient focal cerebral symptoms, study of the cerebrospinal fluid may prove helpful.

Amphotericin B↗
PubMed1989

Positive temporal sharp waves in neonatal EEG.

The clinical correlates and EEG characteristics of rolandic positive sharp waves in neonatal EEG have been studied systematically. Morphologically similar positive sharp waves have been reported to occur in the temporal areas (PTS). Their significance is, however, unclear. We reviewed fifty-two EEGs on patients from the Neonatal Intensive Care Unit of the University of Arkansas for Medical Sciences. Twenty-one of the EEGs which were reviewed had PTS. We correlated the PTS with the results of ultrasound of the head and with clinical evaluations. PTS are more strongly correlated with the occurrence of non-hemorrhagic than of hemorrhagic intracranial pathology.

Cerebral Hemorrhage↗
PubMed1988

Effect of stimulation in three subcortical sites on the thalamocortical augmenting response in the cat.

The thalamocortical augmenting response is a complex multineuronal response which can be elicited by repetitive stimulation of the ventrolateral thalamus. A major function of the ventrolateral thalamus is known to be a result of its participation in central nervous system activity related to motor behaviour. The significance of the thalamocortical augmenting response itself is not known. Since it would be reasonable to relate that response to motor behaviour, we evaluated the effect on the thalamocortical augmenting response of the stimulation of two other central nervous system structures which are also thought to participate in motor control, the cerebellum and the red nucleus. We conclude that at least part of the effect of red nucleus stimulation on the thalamocortical augmenting response is exerted through a rubro-olivo-cerebellar pathway. We then compared the effects of red nucleus and of cerebellar stimulation to the effect of stimulating a non-motor mesencephalic site, the periaqueductal gray. The changes induced in the thalamocortical augmenting response appear not to be fully explicable solely in terms of changes in motor behaviour.

Animals↗
PubMed1988

Unilateral alpha rhythm and Cheyne-Stokes respirations.

A case of unilateral basal ganglion hemorrhage with Cheyne-Stokes respirations is presented. During the hyperpneic periods there was rhythmic alpha activity in the hemisphere contralateral to the basal ganglion hemorrhage. We postulate that the hemorrhage interrupted the thalamocortical fibers on the involved side. The implications of this clinical evidence are discussed in the light of the theory of cerebral autorhythmicity.

Alpha Rhythm↗
PubMed1988

The anterior temporal electrode in the EEG of the adult.

The anterior temporal cerebral region is not well covered, electroencephalographically, by the usual EEG electrodes. Numerous attempts have been made to add anterior temporal electrodes. There has been discussion regarding the amount of additional information actually attributable to those electrodes. We systematically evaluated the abnormalities revealed by one such noninvasive set of anterior temporal electrodes, D. Silverman's T1 and T2. A total of 624 consecutive EEGs were reviewed. We conclude that, in the adult, anterior temporal electrodes can add significantly to the information contained in the routine interictal EEG.

Adult↗
PubMed1987

Coexisting alpha pattern coma, theta pattern coma and spindle coma.

Abnormal ectopic rhythms, such as alpha-theta activities and spindles, occur in comatose patients. A case is presented in which the EEG of a comatose patient showed coexisting alpha-theta pattern activities and spindles. It is concluded that the coexistence of these rhythmic patterns in the EEG of a comatose patient implies continued physiologic functioning of a thalamocortical system deafferented by brainstem dysfunction and a lesser degree of cortical dysfunction.

Alpha Rhythm↗
PubMed1986

Adult onset stuttering and seizures.

A case is presented in which adult onset stuttering and focal seizures appear to be linked. The EEG showed left anterior and mid-temporal sharp waves. The patient responded well to combined therapy with phenytoin, fluency exercises, and stress reduction. The association between stuttering and seizures in adults and children, as well as treatment with anticonvulsants, are discussed.

Adult↗
PubMed1986

Episodic anterior drowsy theta in adults.

The present study included 1300 adults with various clinical problems. We prospectively studied the EEG's of this population over an 18-month period. Ninety-two patients showed episodic generalized or frontal-central bursts of theta activity, occurring synchronously over both hemispheres in drowsiness (episodic anterior drowsy theta or EADT). We found no interaction between the parameters involving the above theta rhythms (amplitude, rhythmicity, topography and presence or absence in the waking EEG), demographic variables (age, sex), and clinical presentation. Our data, however, did suggest that the incidence of the EADT may be higher in young females. We also found a tendency for the EADT in otherwise abnormal EEGs to be rhythmic and present awake. Our data indicated that the presence of EADT is non-specific as to etiology.

Electroencephalography↗
PubMed1983

Effect of hyperthermia on a thalamocortical system in the kitten and the cat: a preliminary study.

Hyperthermia produces many changes in the ongoing electrical activity of the brain. One of the responses which fever can induce is seizure activity. The thalamocortical augmenting response, a complex neurophysiological response, has been related to seizure discharges. The changes in that complex neurophysiological response induced by experimental hyperthermia were assessed in adult cats and in kittens, using analytical methodology first developed in adult cats. The effect of two anticonvulsants (phenytoin and valproate) on those hyperthermia-induced changes in the thalamocortical augmenting response were compared in kittens. The differences between the effects of the two anticonvulsants on the thalamocortical augmenting response can be related to the reported clinical differences between the two anticonvulsants in patients with febrile seizures.

Animals↗
PubMed1979

Cerebellar stimulation: regional effects on a thalamocortical system.

Regional effects of electrical stimulation of the cerebellar surface were quantitatively analyzed. Computer controlled stimulus sequences were delivered to ventrolateral thalamus and evoked responses recorded from ipsilateral sensorimotor cortex in the cat. Threshold and excitability profiles were produced with an on-line computer, and their modification by cerebellar stimulation was determined. The results of electrical stimulation of the cerebellar surface were: (1) depressed excitability from paramedian lobule and lobulus simplex; (2) uniquely elevated thresholds from paramedian lobule; and (3) a profound and long-lasting depression of excitability following termination of lobulus simplex stimulation. In comparison with our anticonvulsant drug studies, these data suggest that cerebellar surface stimulation has a far greater capacity to control excitability and threshold responsiveness of thalamocortical systems. Cerebellar electrode placement and temporal pattern of stimulation appear to be important factors in the production of antiepileptic effects.

Animals↗
PubMed1979

Effects of valproate and ethosuximide on thalamocortical excitability.

Sodium valproate and ethosuximide are anticonvulsants employed in the treatment of petit mal epilepsy; both drugs are considered to be thalamically active. Valproate and ethosuximide both decreased the average evoked response following the second of two stimuli delivered to the ventrolateral thalamus at stimulus frequencies in the region of 3 Hz. Ethosuximide, but not valproate, enhanced the average evoked response at high stimulus frequencies an action shared with several convulsant treatments having different modes of action. The clinical effects of valproate and ethosuximide can be related to this differential modulation of thalamocortical excitability.

Animals↗
PubMed1970

Brain norepinephrine: enhanced turnover after rubidium treatment.

After biosynthesis of norepinephrine was inhibited, treatment of rats for 10 days with rubidium chloride (0.6 milliequivalent per kilogram of body weight) caused an increase in the rate of disappearance of norepinephrine in the brainstem but not in the telencephalon. Also the utilization of intracisternally injected tritiated norepinephrine was increased and was accompanied by a shift in the pattern of norepinephrine metabolism to normetanephrine. These data suggest that greater amounts of neuronally stored norepinephrine were released to central adrenergic receptors.

Animals↗