Stimulus-sensitivity in treated status epilepticus.
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Anticonvulsants↗
Biomedical subjects
Stewart G Boyd
Publications and source records attributed to Stewart G Boyd.
A neurophysiological perspective on sleep and its maturation.
Neurophysiological studies of sleep have increasingly focused on underlying dynamic processes. This would appear particularly relevant to the developmental aspects of sleep. Involvement of sleep-dependent mechanisms in emotional processing, as well as perceptual-sensory, perceptual-motor, and cognitive learning, mostly studied in adults, may play major roles in development. Rapid eye movement (REM) sleep, which is generated by complex neuronal interactions within the pontine reticular formation, and non-REM sleep, which arises from activities in the thalamocortical network, are specifically implicated in different aspects of long-term memory systems. They evolve from previous physiological and behavioural states which can be traced back to the fetal period. Further studies are needed to clearly identify functions reflected by hallmarks of sleep stages, such as spindles and K complexes. A better understanding of the maturational aspects of sleep should provide important insights into physiological development. Assessment approaches taking dynamic characteristics of sleep into account may contribute to the design of better targeted management of sleep-related problems in neurodevelopmental conditions.
Cerebral Cortex↗
Stimulus-sensitive burst-spiking in burst-suppression in children: implications for management of refractory status epilepticus.
Status epilepticus refractory to sequential trials of multiple medication is a rare but significant problem in children. We describe stimulus sensitivity arising during the treatment of convulsive status epilepticus in children (stimulus-sensitive burst-spiking in burst-suppression). We reviewed retrospectively clinical and EEG features in six children (three months to ten years), with status epilepticus requiring intensive care, in whom tactile, auditory and visual stimulation induced myoclonic jerks and bursts of EEG spikes. Sensitivity was not present at onset, but appeared after 24 hours as myoclonic jerks of the eyes, face and limbs, irrespective of the modality and site of stimulation. These were associated with burst-suppression in the EEG, the induced spiking forming the burst component. Various antiepileptic drugs, including GABAergic and NMDA blockers had no effect, but halogenated agents (used in two patients) abolished the sensitivity. Two children died, but the remainder returned to their previous clinical state. We conclude that stimulus sensitivity may appear in the context of refractory status epilepticus treated with high-dose barbiturates. Outcome may be more favorable than previously reported in adults, mostly in the context of post-anoxic or toxic coma. Evaluation of ventilated children in status epilepticus should include electroclinical assessment using sensory stimulation. If present, the drug regime should be reviewed and halogenated agents considered.
Anesthetics, Inhalation↗
From electrophysiology to chromatin: a bottom-up approach to Angelman syndrome.
Angelman syndrome is one of the most studied human diseases related to a gene that is expressed on the maternal chromosome only in at least some brain cells. It is caused by inactivation of the UBE3A gene in the brain due to various abnormalities of the 15q11-q13 chromosome inherited from the mother. It is characterized by severe developmental delay, seizures, virtual absence of speech, motor impairment, and a particular behavioral phenotype. Studies of cortical, electromyographic and cerebellar electrophysiology in patients with Angelman syndrome and a mouse model revealed unique rhythmic neurophysiological activities in the cerebral cortex, cerebellar cortex, and muscles. The oscillatory patterns may be linked to molecular pathophysiology of the syndrome involving dysregulation of synaptic neurotransmission through UBE3A-related modulation of functional GABAA receptor complexes.
Angelman Syndrome↗