Abstracto

Congenital homonymous hemianopia and afferent pupillary defect due to concomitant dysplasia of the optic radiation and dorsal midbrain.

Kaori Ueda*, Akiyasu Kanamori, Yuko Yamada-Nakanishi, Makoto Nakamura

Information regarding visual field and light reflex is transmitted through the same afferent pathway until the optic tract; thereafter, the former travels to the occipital lobe via the Lateral Geniculate Nucleus (LGN) and the latter to the efferent pathway through the pretectal area. Therefore, the combination of visual field defect and light reflex abnormalities depends on the locations of the lesion on the visual pathway. We present a rare case of congenital dysplasia of the left-sided optic radiation, dorsal midbrain, and cerebellar hemisphere, with other neurological symptoms. An 18-year-old female showed right-side homonymous hemianopia and Relative Afferent Pupillary Defect (RAPD). Optical Coherence Tomography (OCT) revealed a homonymous hemianopic thinning of the Ganglion Cell Layer (GCC) and the Circumpapillary Retinal Nerve Fiber Layer (cpRNFL) in both eyes. MRI indicated dysplasia of the left dorsal midbrain, optic radiation, and cerebellum. In this case, RAPD was detected in the right eye, but the amount of visual field defect was smaller than that in the left eye, indicating that these symptoms were independently caused by the lesions of the optic radiation and the dorsal midbrain, respectively. OCT findings appeared similar to those of congenital occipital hemianopia, suggesting trans-synaptic axonal degeneration of retinal ganglion cells.