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Biomedical subjects

T C van Woerkom

Publications and source records attributed to T C van Woerkom.

At least 19 recordsLinked to original sources
PubMed1994

Altered attentional processing of background stimuli in Gilles de la Tourette syndrome: a study in auditory event-related potentials evoked in an oddball paradigm.

In 24 adults and 29 children both with Gilles de la Tourette syndrome and in 24 control adults and 17 control children we studied auditory event-related potentials (ERP's) evoked in 2 different oddball paradigms: a passive listening paradigm (PLP) in which subjects had only to attend tones (260 standards, 40 deviants), followed by an active discrimination paradigm (ADP) in which subjects had to press a microswitch in response to the deviant tones. In the adult Tourette patients the PLP disclosed between 200-300 msec at all derivations (Fz, Cz, Pz, C3, C4, P3, P4) a significantly more negative activity than in the controls. In the Tourette children such a result was only found at Fz. In the ADP the differences between both adult groups disappeared, but the curves of the control children became now significantly more positive than those of the Tourette ones except at C3 and P3. Between 200-300 msec the curves of all 4 groups were significantly less negative in the ADP than in the PLP. This decrease in negativity was significantly larger in the adult Tourette patients than in the adult controls, but in the children groups the reverse occurred. It is hypothesized that the differences in amplitude between patients and controls and between both paradigms are due to differences in amplitude of an endogenous negative component overlapping the exogenous N100-N200 standard curve. Based on this hypothesis the results could suggest that one of the problems in Tourette syndrome is an increased attention to non-relevant stimuli.

Adolescent↗
PubMed1994

EEG changes during mental activation.

Desynchronization of the EEG in relation to mental activity can be demonstrated through various means. The acceleration spectrum entropy (ASE) is a method that quantifies the desynchronization of the EEG. It is a measure of the randomness or irregularity of a time series and ranges from 0 (straight line) to 100 (discrete random signal). The ASE was calculated for 20 EEGs under four conditions: "eyes closed," "eyes open," "eyes closed and mental arithmetic" and "eyes open and mental arithmetic." There was a significant increase between the conditions "eyes closed" and "eyes open" and a significant increase between the conditions "eyes closed" and "eyes closed and mental arithmetic." During eye opening the largest increase was seen in the occipital areas. Mental arithmetic showed an asymmetrical increase, namely in the left temporo-occipital region and in the right centro-temporal region. It is suggested that the ASE can be used to study cortical activation due to mental activity.

Algorithms↗
PubMed1992

Carbamyl phosphate synthetase-1 deficiency discovered after valproic acid-induced coma.

Valproic acid induced coma is presented in an adult patient without a history of metabolic disease. Liver biopsy revealed a reduction in activity of carbamyl phosphate synthetase-I, an enzyme obligated for transformation of ammonia to urea in the urea cycle. After recovery CT scan follow-up showed marked cerebral atrophy which did not exist prior to the state of coma. Risk factors are discussed.

Adult↗
PubMed1992

Mental play in Gilles de la Tourette's syndrome and obsessive-compulsive disorder.

A new phenomenon, found only in Gilles de la Tourette (GTS) patients, and which we have called 'mental play', is described. It was compared with the phenomenon of counting, which occurred in both GTS and obsessive-compulsive patients. In the GTS patients both mental play and counting were best characterised as playful impulsions. In contrast to the GTS patients, the counting of the obsessive-compulsive patients was in line with their obsessive-compulsive behaviour. These findings suggest that repetitive symptoms in GTS patients, even when they share superficial similarities with obsessive-compulsive symptoms, should not be diagnosed automatically as obsessive-compulsive.

Adolescent↗
PubMed1990

Subacute progressive sensory ataxic neuronopathy after Rickettsia conorii infection.

A case is presented in which sensory ataxic neuronopathy developed after serologically proven infection with Rickettsia conorii and continued to be progressive after appropriate antibiotic treatment. Electrophysiological studies showed decreasing sensory nerve conduction velocities ending with the absence of sensory nerve action potentials as well as peripheral and cortical somatosensory evoked potentials. Histological studies revealed a profound loss of myelinated fibres due to primarily axonal degeneration. The clinical course and the electrophysiological and histological findings suggest primary involvement of the dorsal root ganglion. Peripheral neuropathy due to infection with R. conorii is rare and usually of the mixed motor and sensory type. We believe this to be the first report of sensory ataxic neuronopathy associated with R. conorii infection.

Aged↗
PubMed1988

Contingent negative variation in adults with Gilles de la Tourette syndrome.

Three deflections or waves of the Contingent Negative Variation (CNV): the Slow Negative Wave (SNW), the Terminal CNV (TCNV) and the Post Imperative Negative Variation (PINV) were studied in 18 adults with Gilles de la Tourette syndrome and in 15 controls. The patients showed a reduced SNW, a normal TCNV and an increased PINV. Moreover, at the right parietal region the patients demonstrated a decreased SNW, TCNV and PINV. The results are discussed in relation to behavioral and neuropsychological disturbances found in Gilles de la Tourette syndrome.

Adolescent↗
PubMed1987

Disappearance of tardive dyskinesia during catatonic stupor.

A 61-year-old man diagnosed as having catatonic schizophrenia was treated with neuroleptics for many years. From 1983 he showed tardive dyskinesia on trunk and limbs as well as orofacial dyskinesia. In September 1985 he displayed a catatonic stupor several times. With the outbreak of the stupor the dyskinesia disappeared and vice varsa. This finding induces the hypothesis that the dopaminergic system is suppressed during catatonic stupor in such a way that tardive dyskinesia is no longer visible.

Catatonia↗
PubMed1985

Late components of the auditory evoked potentials in Gilles de la Tourette syndrome.

Late components (N1, P2, N2, P3) of the event-related potential (ERP) elicited by simple auditory discrimination tasks were investigated in 6 patients with Gilles de la Tourette syndrome. The ERP's were registrated in the patients before and during drug treatment as well as in 16 healthy controls. It appeared that in Tourette syndrome the N2 and P2 waveforms (target response) at Cz and Pz were remarkably less well identifiable. The results did not reveal P3 abnormalities in the patients. However, the patients demonstrated definite changes in the N1 and P2 components as compared to the controls. The N1 amplitudes were decreased in the patients. During drug treatment the N1 amplitudes increased although they remained smaller than in the controls. It is concluded that Tourette patients have no abnormalities in early and late components, but that specifically the components between 90-280 ms are affected. These abnormalities may reflect specific attention deficits which often occur in Tourette syndrome.

Adolescent↗
PubMed1985

Ocular dipping.

Explore the source record for details and available documents.

Arousal↗
PubMed1984

Persistence of the blink reflex to sudden illumination in a comatose patient. A clinical and pathologic study.

A persistent blink reflex to light (BRL) was observed in a patient who became comatose after a cardiac arrest. Postmortem examination revealed severe hypoxic ganglion cell necrosis of the cerebral and cerebellar cortex, the basal ganglia, the hypothalamus, nuclei in the brain stem, and the superior colliculi. The pretectum was unaffected. These findings suggest that the afferent fibers of the BRL enter the brain stem not in the superior colliculus, but in the pretectum.

Aged↗
PubMed1984

Saccadic oscillations associated with the quick phases of caloric nystagmus in severe diffuse brain damage.

Caloric nystagmus patterns associated with ocular dysmetria, ocular flutter or flutter dysmetria were studied in ten patients being in a vegetative state, among whom were 9 patients with head injury and 1 with complications caused by a grand mal status. Brain damage was complicated by hypoxemia and especially by brain stem herniation. It was more often observed in very young children and appears to be associated with a poor clinical course. Physostigmine seems to have an activating and provocating effect on these saccadic oscillations. In view of Zee and Robinson's hypothesis on the pathophysiology of saccadic oscillations, it is suggested that these nystagmus patterns may reflect a disturbance of brain stem midline structures (pausing neurons) or an abnormal supranuclear (cerebellum) control.

Adolescent↗