Hemiakines Pupillaris

HEMIAKINESIS PUPILLARIS (from Greek he-mi- half, a- negative particle, and kinesis- movement), half-sided immobility of the pupil. With localization of the lesion in the chiasm or in the optic tract, along with heteronymous or homonymous hemianopia, there is also observed the absence of the light reflex in the blind half of the retina. When the blind part of the retina is illuminated, both the direct and consensual reactions are absent, while when the seeing part is illuminated, both reactions are obtained. All other pupillary reactions are preserved. According to the research of Behr, hemiakines is accompanied by anisocoria, with the wider pupil always being on the side corresponding to the hemianopia: with right-sided hemianopia on the right eye, with left-sided on the left eye. This phenomenon has great significance for differential diagnosis with homonymous hemianopia in case of lesions of the cerebral hemispheres, since in the latter case, if anisocoria is observed, the wider pupil is always on the side of the focus. In quadrantal hemianopia, immobility of the pupil corresponding to the blind part of the retina is also observed. The absence of hemiakines does not yet speak against localization of the damage in the optic tract, since in such a case it is possible that the visual fibers are more damaged than the pupillary ones. Hemiakines without hemianopia is observed very rarely. The lesion must in this case be localized in the centripetal pathway, before the ganglionic neuron, but in that place where the pupillary fibers have already separated from the visual ones. For the research of hemianopic immobility of the pupil, Hess proposed an apparatus - the so-called hemikinesimeter, which is based on the principle of variable illumination of two places of the retina; on the same principle is based the simpler and portable apparatus proposed by Behr.