Single enzyme defects of peroxisomal beta-oxidation
Mar. 15, 2023
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Occipital paroxysms in their most classical form with fixation-off sensitivity occurred only once in the first EEG of this boy. Three hours of video-EEG recording showed bilateral, high amplitude, sharp-slow wave occipital paroxysms when the eyes were closed or open provided that central vision was eliminated binocularly (patient looking through +10 spherical lenses, underwater goggles fixed with semi-transparent tape, darkness). An EEG performed 7 days later with no medication was normal, as were all subsequent awake and sleep EEGs. (First sequence) Effect of eyes closed and eyes open on occipital paroxysms in routine EEG recording. High amplitude, continuous occipital sharp and slow-wave complexes (occipital paroxysms) occurred immediately after closing of the eyes, lasting as long as the eyes were closed. The EEG normalized immediately after opening of the eyes and as long as the eyes were open, though some breakthrough occipital spikes could occur. (Second sequence) Effect of the elimination of central vision and fixation on occipital paroxysms. The occipital paroxysms are activated by the elimination of fixation and central vision (fixation-off sensitivity) even in the presence of ample light. Elimination of fixation and central vision can be achieved by many means. In this case, this was achieved either by +10 spherical lenses or underwater glasses covered with semi-transparent tape. When fixation and illumination are totally eliminated (by any means), the occipital paroxysms become continuous irrespective of whether the eyes are open or closed. Thus, when the eyes are open, but fixation is eliminated, occipital paroxysms are inhibited by fixation and activated by the absence of fixation. (Used with permission from: Panayiotopoulos CP. A practical guide to childhood epilepsies. Oxford: Medicinae, 2006.)