P3-3-10. Electroencephalographic findings of central nervous system symptoms after human papillomavirus vaccine

Little is known about the mechanism of central nervous system (CNS) symptoms after human papillomavirus (HPV) vaccine, and there is no report on electroencephalographic (EEG) findings about these symptoms. This study shows postictal and interictal EEG findings of two girls with CNS symptoms after HPV vaccine. Case1: a 16-year-old girl. Her attack was left dominant dystonia followed by loss of consciousness. Her interictal EEG showed unilateral (the right side) loss of a photic driving response, B(I) RDs (Brief Potentially Ictal Rhythmic Discharges) on T6 electrode. Her postictal EEG showed asymmetric alpha rhythm amplitude (suppression of the left side; the left was less than 50% of the right). This asymmetry disappeared within 5 min EEG recordings. Case2: a 19-year-old girl. Her attack was right dominant dystonia followed by loss of consciousness. Her interictal EEG showed the left dominant incomplete alpha blocking, asymmetric alpha rhythm frequency (the left side was slower). Trihexyphenidyl was effective in reducing attacks of these patients. These EEG findings look like hemiplegic migraine, epilepsy, so the mechanism of CNS symptoms after HPV vaccine may be similar to these disorders. This study demonstrates objective findings about CNS symptoms (dystonia, loss of consciousness) after HPV vaccine, and that these symptoms are not functional/psychogenic disorders.