Unilateral alpha reactivity: An electroencephalographic finding in albinism

Persons with various forms of albinism frequently have misrouting of their optic nerve fibers. Visual evoked potential (VEP) studies can confirm this because monocular stimulation tends to result in asymmetrical rather than s ymmetrical occipital response; This type of decussation abnormality is asso ciated only with albinism. In the electroencephalogram (EEG) of normal subj ects, unilateral eye opening or closing does not affect the frequency, reac tivity, regulation, and symmetry of alpha rhythm. Tn contrast, in our study , 6 of 19 persons with oculocutaneous and ocular albinism responded to unil ateral eye opening with contralateral disappearance or significant attenuat ion of their alpha rhythm. The most likely explanation of this phenomenon i s that the visual pathway misrouting is complete or nearly complete in some children with albinism so that one rather than both occipital lobes receiv e visual information from each eye. This type of alpha behavior, like VEP s tudies, supports the diagnosis of albinism, and such testing can be easily performed during a routine EEG recording.