Abstract
Negative spikes and sharp waves with maximum amplitude (Pz spike) are sometimes observed exclusively on the parietal midline on EEG of sleeping chidren. We studied 115 cases showing Pz spikes (67 boys and 48 girls) and compared their ages, clinical features, EEG courses and EEG of their siblings.
In eighty-nine (77%) of 115 cases, onset of Pz spike was distributed between three to seven years of age with the highest incidence (25 cases) at 4 years of age. These results suggest that the appearance of Pz spikes may be age-related.
The underlying diseases in these 115 cases showing Pz spikes were febrile convulsions in 43 cases (37%) and epilepsy in 34 cases (30%). There were also non-convulsive disorders, such as 16 cases of autonomic symptoms and 15 cases of head trauma. However, it is considered that Pz spikes may be independent of clinical seizures because 65% of the cases involving febrile convulsions or epilepsy manifested 5 or fewer seizures.
In 64 (81%) of 79 cases that were followed by EEG for 2years or more. Pz spikes disappeared by 15 years of age or earlier in 97% of the cases.
EEG was also exanined 18 siblings in 14 families with children showing Pz spikes. Pz spikes were found in the siblings belonging to 6 families. The age at onset of Pz spikes was almost the same between the patients and the siblings. We think that genetic factors may be involved the appearance of Pz spikes.
