Activation of EEG recordings by graded sleep deprivation.

Part I. The EEG recordings of 434 patients were activated by graded sleep deprivation. In clinically manifest epilepsies with a predominantly negative EEG tracing at rest the incidence of epileptic manifestations increased after sleep deprivation from 18.03% to 59.01%, in clinically suspect epilepsies from 6.4% to 39.0%. In other paroxysmal affections such as febrile convulsions, syncopes and collapses, paroxysms of abdominal pain or headaches, affective paroxysms and nocturnal terrors, the tracing activation by sleep deprivation mostly facilitated differential diagnosis between those affections and epilepsy. In organic cerebral affections with or without epileptic seizures activation by sleep deprivation led to an increase in the occurrence of epileptic manifestations from 11.4% to 50.0% of the recordings. The authors conclude that graded sleep deprivation is a very useful activation method for the diagnosis of epilepsy. Part II. The authors studied the occurrence of generalized 2-5 Hz high-amplitude slow wave episodes in 244 patients before and after sleep deprivation. They found such episodes in the resting recordings of 37 patients and in the post-deprivation recordings of 85 patients. The described episodes were mostly observed during sleepiness and superficial sleep. They were significantly more frequent in children and adolescents than in adults. The occurrence of slow wave episodes was ascertained in epileptic as well as non-epileptic affections such as affective attacks in children, night terrors, paroxysms of abdominal pain or headaches, febrile convulsions and organic brain affections without epileptic seizures. The authors conclude that the above episodes are a non-specific manifestation of increased susceptibility to paroxysmal synchronization of EEG rhythms. Their occurrence in young children can, however, be considered normal.

Results of phenylalanine tolerance tests and EEG examination in patients under treatment for phenylketonuria.

The EEG of 10 phenylketonuric children treated by a diet and of 4 children with hyperphenylalaninaemia on a normal diet was recorded during L-phenylalanine tolerance tests. The first recording was made before administering the L-phenylalanine load (100 mg/kg b.w.) and the second 60-120 min after. In 6 of the phenylketonuric children, nonspecific abnormality became more pronounced or increased, or previously absent epileptic graphoelements appeared. A pathological EEG response to a L-phenylalanine load was found in 1 child with hyperphenylalaninaemia. The authors do not recommend relaxation of the diet in children with a pathological EEG response to a L-phenylalanine load.