2446 Unilateral altitudinal hemianopia as a falsely localizing signal of a falx meningiomal

w The major difficulty in albino diagnosis is that although foveal hypoplasii seems a consistent feature, it is not uncommon for an albino to have normal fundus pigmentation, normal iris pigmentation and/or no nystagmus. Only a retina-ge.nicula-coni misprojection seems pathognomonic to albinism since all species of albino mammals share this feature. With appropriate stimulus and recording conditions, VEP topography can reveal the " misroutcd " optic pathway projections (Apkarian et al., 1983). However, from VEP asymmetry it can never be concluded whether all or only part of the temporal retinal fibers decussate erroneously at the optic chiasm, due to the spread of the VEP field by volume conduction. Such an answer can be found by integrating VEP with SPET. M&Q& The albino pathway anomaly was evinced by umbalateral hemispheric VEP dominance upon full field monocular stimulation of pattern onset, motion onset and luminance flash. The same elcctrcde montage was used in control subjects and their VEPs recorded to the same stimuli but presented in either tbe left nor right half visual field. During stimulation p9p Tc-HMPAO was injected as tracer for regional cerebral blood flow and they emission recorded with a neuro-SPET camera consisting of 12 detectors in 6 opposite pairs. Each pair scanned a 1.2 cm thick slice through the brain and by translocation of the detectors up to 9 slices were recorded. R&u+.& Irrespective of the strength of the VEP asymmetry upon monocular stimulation, all albinos showed the largest increase in blood flow (as 96 of the mt state) in the contralateral thalamic and striate cortex. This hemispheric increase was similar to that observed in normal subjects upon half field stimulation. Qu.&.&m We therefore conclude that in albinos all temporal retinal fibers decussatc erroneously at the optic chiasm, disrupting rctinotopic organization throughout the visual pathway. The authm &scribe a clInical case of' a 47-yea-old noman who attended the Eye Clinic of Honpital de Santa Maria-w cba right eye vinual field lors. The neumqhthalm&gical examinabion ah&d a right eye pppilary &kt and a right eye inferior attitudinal hemiapia CT and MR imaging studies revealed a mettingioma of the arderiof third IA the fak, compssing the frontal lc&mdbcatedfarawayfromthevimlalpath~. Totat surgical excision wan pfmmed and the clinical condition remaned stdde during a two war follow-uo. 3in of present 3tllZy ~2.3 to find out if G.'.TX.'. another opioid receptor egotist ilcto li!re SctaenTorphi ne and if T,: affccto it. Methods: The experiAaento …