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Biomedical subjects

G J Lammers

Publications and source records attributed to G J Lammers.

At least 37 records · Page 2Linked to original sources
PubMed2000

Effects of startle and laughter in cataplectic subjects: a neurophysiological study between attacks.

OBJECTIVES: Cataplexy, when unequivocally present together with excessive daytime sleepiness, is diagnostic for narcolepsy. Unfortunately, it is difficult to induce cataplexy during consultation. In this study we tried to assess presumed subclinical expressions of cataplexy using neurophysiological tests. METHODS: In this controlled explorative study, we studied 14 patients with a clear history of cataplexy and 12 matched controls using standard H-reflex, H/M ratios, audiospinal reflex, H-reflexes modulated by emotions and startle reflexes. RESULTS: H-reflexes were attenuated during laughter in patients as well as controls. Startle reflexes were increased in patients. Audiospinal reflexes were not influenced. CONCLUSIONS: The patterns found add relevant knowledge concerning pathophysiological mechanisms and involved brain areas in cataplexy, and may reflect subclinical expressions of cataplexy. The presumed specificity of the abolishment of H-reflexes during cataplectic attacks is questioned by our findings. The exaggerated startle reflex is in line with recent findings concerning involved brain areas in narcolepsy.

Acoustic Stimulation↗
PubMed2000

A mutation in a case of early onset narcolepsy and a generalized absence of hypocretin peptides in human narcoleptic brains.

We explored the role of hypocretins in human narcolepsy through histopathology of six narcolepsy brains and mutation screening of Hcrt, Hcrtr1 and Hcrtr2 in 74 patients of various human leukocyte antigen and family history status. One Hcrt mutation, impairing peptide trafficking and processing, was found in a single case with early onset narcolepsy. In situ hybridization of the perifornical area and peptide radioimmunoassays indicated global loss of hypocretins, without gliosis or signs of inflammation in all human cases examined. Although hypocretin loci do not contribute significantly to genetic predisposition, most cases of human narcolepsy are associated with a deficient hypocretin system.

Adult↗
PubMed1999

Weak with laughter.

We found a marked reduction of H-reflex amplitude during laughter, suggesting that motor inhibition may underlie the feeling of being "weak with laughter". This effect may have a role in cataplexy, which is preferentially elicited by laughter.

Cataplexy↗
PubMed1999

An uncommon cause of stroke in young adults.

We describe a previously healthy 48-year-old man who presented with clinical characteristics suggestive of internal carotid artery dissection, confirmed by magnetic resonance imaging. He developed a massive infarction of the left cerebral hemisphere and died after 3 days of transtentorial herniation. Post-mortem examination identified a dissection of the thoracic aorta caused by Erdheim-Gsell cystic medionecrosis, with the characteristic degeneration of the elastic fibers of the lamina media. The dissection showed an unusually large extension not only distally into both iliac arteries, but also proximally into both carotid arteries. To our knowledge, such an extensive dissection has not been described previously. Underlying vessel wall disorders of the aorta, such as Erdheim Gsell cystic medionecrosis, should be considered in young patients with spontaneous arterial dissection.

Aortic Dissection↗
PubMed1999

Numerous and widespread alpha-synuclein-negative Lewy bodies in an asymptomatic patient.

Lewy bodies (LB) and pale bodies (PB), their putative precursors, can be found in a spectrum of diseases characterized by parkinsonism and/or dementia. Furthermore, LB are occasionally observed in some other neurodegenerative diseases and in normal aging. Classical LB are typically found in the brain stem, especially in the substantia nigra, where these inclusions are associated with neuronal loss and clinical signs of idiopathic Parkinson's disease (PD). The so-called cortical LB occur in the cerebral cortex, amygdala and claustrum with little or no neuronal loss and are clinically associated with dementia in dementia with LB (DLB). We describe a patient without apparent clinical signs of parkinsonism and/or dementia, whose brain contained numerous classical-like LB, pale inclusions with features of PB and transitions between these two. These inclusions had similar immunohistological (ubiquitin positive; neurofilament positive; tau negative) and ultrastructural features as the LB in PD and DLB except for the lack of immunoreactivity for alpha-synuclein. The pons and cerebral cortex showed the highest number of LB, up to 165/1.76 mm2. These numbers were contrasted by the lack of obvious neuronal loss or gliosis. The absence of alpha-synuclein reactivity in the LB in this symptomless patient corroborates the hypothesis that alpha-synuclein accumulation in LB is an important step in neurodegeneration in PD and DLB, but tones down the role of alpha-synuclein in LB formation in general. This patient seems to represent a new variant in the spectrum of diseases associated with LB.

Brain↗
PubMed1998

Prolonged coma and severely attenuated EEG after a single seizure.

A 63-year-old woman presented with a comatose state after a fall. Results of cranial computed tomography (CT) and magnetic resonance imaging (MRI) scans were normal. An EEG recorded 5 h after admission was very severely attenuated and slowed. Consciousness and EEG were improved the next day. No cause was detected initially. After sleep deprivation, the patient had a generalized seizure followed by a similar coma and EEG. Even a single seizure may cause a prolonged coma with a very severely attenuated and slowed EEG.

Accidental Falls↗
PubMed1997

Sleep scoring at a lower resolution.

Sleep scoring of whole-night polysomnograms is labor intensive. Scoring fewer epochs saves labor at the cost of accuracy; this study investigates the trade-off between the two. Whole-night sleep measures of 12 patients with sleep apnea syndrome, 10 patients with narcolepsy, and 35 controls were first computed using conventional successive 30-second epochs. Using the resulting list of sleep stages, a variable number of epochs was skipped among remaining epochs; the measures were recomputed for the reduced lists. The Bland-Altman analysis was used to define the agreements among the sleep measures at the conventional resolution and those at the lower resolutions. Scoring one-half to one-third of the number of epochs changes the duration of sleep stages only up to 2.5% and 5%, respectively, for all groups and sleep stages. In apnea patients, rapid eye movement (REM) latency deviates < 15 minutes when half of the epochs are scored. In controls and narcoleptics, much lower resolutions can be used before reaching the same level. Potential restrictions for the application of the method are discussed.

Adolescent↗
PubMed1996

Repetitive CMAPs: mechanisms of neural and synaptic genesis.

Repetitive compound muscle action potentials (R-CMAPs) occur when a single nerve shock excites muscle fibers repeatedly. "Double discharges" are due to intramuscular nerve reexcitation. "Synaptic" R-CMAPs, due to excess acetylcholine in the neuromuscular synapse, can occur in congenital myasthenia, the slow-channel syndrome, and acetylcholinesterase inhibition. Secondary nerve excitation can reexcite muscle fibers. Synaptic R-CMAPs in a patient consisted of two discharges. The second diminished during repetitive stimulation and began 3.5-4.0 ms after the first, which is slightly longer than the synapse-muscle refractory period. Neural R-CMAPs, due to ectopic nerve activity, occur in neuromyotonia (NMT). R-CMAPs in a patient consisted of about 20 discharges at 200-300 Hz. Studies in healthy subjects showed that such trains represent added single CMAPs. Impulse frequency in the patient lied close to the threshold of refractoriness. Refractoriness of the synapse-muscle cell assembly determines the characteristics of R-CMAPs regardless of the primary cause.

Action Potentials↗
PubMed1995

Circadian distribution of motor activity and immobility in narcolepsy: assessment with continuous motor activity monitoring.

The circadian distribution of motor activity and immobility of 14 unmedicated narcoleptics and matched controls was evaluated by monitoring continuous wrist motor activity 5 successive days and nights at home. Sleep was also assessed by sleep logs. The amplitude of the circadian rhythm of motor activity and immobility was significantly lower in narcoleptics than in controls. The variables that best distinguish narcoleptics from controls were the diurnal and nocturnal mean duration of uninterrupted immobility, which can be explained by excessive daytime sleepiness and frequent nocturnal awakenings, respectively. Thus, measures of diurnal and nocturnal motor activity and immobility appear useful for the objective assessment of some of the sleep-wakefulness manifestations of narcolepsy.

Adolescent↗
PubMed1993

Gammahydroxybutyrate and narcolepsy: a double-blind placebo-controlled study.

We treated 24 patients with narcolepsy for 4 weeks with gammahydroxybutyrate (GHB), 60 mg/kg/night, in a randomized double-blind placebo-controlled cross-over trial. Both clinical and polysomnographic criteria were used to assess the results. Compared to placebo, GHB reduced the daily number of hypnagogic hallucinations (from 0.87 to 0.28; p = 0.008), daytime sleep attacks (from 2.27 to 1.40; p = 0.001) and the severity of subjective daytime sleepiness (from 1.57 to 1.24 on a 0-4 scale; p = 0.028). The number of daily cataplexy attacks was reduced from 1.26 at baseline to 0.56 after 4 weeks of GHB intake. This reduction, however, was not statistically significantly different from the difference between baseline and placebo. GHB stabilized nocturnal rapid eye movement (REM) sleep, i.e. it reduced the percentage of wakefulness during REM sleep (p = 0.007) and the number of awakenings out of REM sleep (p = 0.016), and tended to increase slow wave sleep (p = 0.053). Adverse events were few and mild. We conclude that GHB is an effective and well-tolerated treatment for narcolepsy.

Adolescent↗
PubMed1992

The Multiple Sleep Latency Test: a paradoxical test?

The Multiple Sleep Latency Test (MSLT) has gradually gained acceptance as an objective equivalent of the complaint of sleepiness. The history of this test and questions considering the validity of the MSLT in different situations are discussed.

Arousal↗