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Biomedical subjects

W J Nowack

Publications and source records attributed to W J Nowack.

At least 19 recordsLinked to original sources
PubMed2001

An artificial neural network approach to diagnosing epilepsy using lateralized bursts of theta EEGs.

Determining the cause of seizures is a significant medical problem, as misdiagnosis can result in increased morbidity and even mortality of patients. The reported research evaluates the efficacy of using an artificial neural network (ANN) for determining epileptic seizure occurrences for patients with lateralized bursts of theta (LBT) EEGs. Training and test cases are acquired from examining records of 1,500 consecutive adult seizure patients. The small resulting pool of 92 patients with LBT EEGs requires using a jack-knife procedure for developing the ANN categorization models. The ANNs are evaluated for accuracy, specificity, and sensitivity on classification of each patient into the correct two-group categorization: epileptic seizure or non-epileptic seizure. The original ANN model using eight variables produces a categorization accuracy of 62%. Following a modified factor analysis, an ANN model utilizing just four of the original variables achieves a categorization accuracy of 68%.

Diagnosis, Computer-Assisted↗
PubMed1999

Progression of electroclinical changes in complex partial status epilepticus: filling in the blanks.

Treiman has described five electroclinical stages through which the EEG progresses during generalized convulsive status epilepticus (GCSE). The EEG can show similar patterns in patients with complex partial status epilepticus (CPSE), but there is no agreement as to whether the different patterns seen in the human EEG result from a similar orderly progression through similar stages. We report the case of a patient in CPSE whose EEG passed progressively through two of the earlier stages described by Treiman. This case of EEG progression in a single patient suggests that CPSE can progress through stages analogous to those in GCSE.

Aged↗
PubMed1998

Diagnostic problems in multiple sclerosis: overreliance on neuroimaging.

Atypical manifestations of multiple sclerosis (MS) can mislead the physician into misdiagnosis. The correct diagnosis of MS depends on a combination of clinical and laboratory evidence. The introduction of newer neuroimaging studies has decreased the proportion of overdiagnoses of MS. Overreliance on either clinical or laboratory (currently neuroimaging) data can lead to underdiagnosis. The physician should consider the possibility of an atypical clinical presentation of MS in the differential diagnosis of patients with disease of the central nervous system.

Adult↗
PubMed1997

Epilepsy: a costly misdiagnosis.

Nonepileptic events misdiagnosed as manifestations of epilepsy are a significant problem. Five representative cases suggest that a diagnosis of epilepsy should be based on a careful history and analysis of the clinical event. The clinician should make a diagnosis of epilepsy only when there is definite positive support and not on the basis of poorly characterized paroxysmal episodes and a few minor and nonspecific EEG findings. Effective treatment presupposes correct diagnosis and early diagnosis appears to be correlated with better prognosis. The annual cost of nonepileptic spells misdiagnosed as epileptic can be estimated at between $650,000,000 and $4,000,000,000. Aggressive efforts to establish a definite diagnosis of spells not clearly epileptic is both medically and economically indicated.

Adult↗
PubMed1996

Dyshormia revisited: generalized seizures and arousal.

Niedermeyer has described dyshormia, or deviant arousal, and related this EEG pattern to generalized seizures. We describe a patient with generalized seizures who in the same EEG had spindles transforming into generalized epileptiform discharges and generalized epileptiform discharges transforming into spindles. This suggests that similar neural circuitry may underlie both spindles and generalized epileptiform discharges, and that the mechanism described by Gloor for feline generalized penicillin induced epilepsy may also apply to some humans with generalized epilepsies.

Adult↗
PubMed1996

Transitory cognitive impairment with brief generalized spike-wave paroxysm: a clinical counterexample to the three-second rule.

The topic of transitory impairment of consciousness with spike wave bursts has been of interest to neurologists for years. Based on some early experiments, a 3-second rule was formulated and has found its way into the conventional wisdom of neurology. It states that, in order to result in impairment of consciousness, a spike-wave burst must be of at least 3 seconds' duration. We discuss a case which poses a clinical counterexample to that rule.

Adult↗
PubMed1994

Propofol, seizures and generalized paroxysmal fast activity in the EEG.

Propofol is a relatively new anesthetic agent used in outpatient surgery. Some investigators use it in the treatment of status epilepticus and in epilepsy surgery and have concluded that propofol has an anticonvulsant effect. Cases of seizure-like behaviors, myoclonus and opisthotonus following propofol anesthesia have been reported. Although rare, official warnings about this association have been issued. Different EEG abnormalities, and no abnormality, have been associated with propofol. We report a case of a healthy man who developed nonconvulsive seizures and generalized paroxysmal fast activity in his EEG following use of propofol for anesthesia.

Adult↗
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↗