Dados do Trabalho

Título

Reversible bitemporal hemihypokinetic pupil without hemianopsia: a new chiasmal sign

RESUMO

Case Report: A 38-year-old woman presented with a complain of a two-day right retro-orbital pain and right progressive visual loss. Upon examination, she had a right relative afferent pupillary defect (RAPD) and dyschromatopsia, with normal visual field testing (confrontation) and funduscopic findings. The visual acuity was 0.8 in the right eye and 1.0 in the left eye. The automated perimetry test (APT) demonstrated a mild superior temporal reduction in sensitivity in the field of the left eye and a superior temporal scotoma with diffuse loss of sensitivity (pseudoconstriction) in the right eye. A more thorough pupil examination was performed and it was noted that the pupil finding was not simply a RAPD. When hemifield light stimulation of each eye was performed individually (while occluding the non-tested eye) with a beam flashlight, a peculiar pupil response was noted: right nasal hemiretina light stimulation demonstrated feeble pupil contraction, whereas stimulation of the temporal hemiretina resulted in better pupil contraction. In the left eye, the difference was not as significant as contralaterally, but it was also notable . These findings have neen reversed after surgical treatment of the lesion. Discussion: In this study, we describe a novel chiasmal sign, reporting a patient in which a pupillary bitemporal hemihypokinesia was not accompanied by hemianopsia and the phenomenon was reversible after the surgical treatment. We hypothesizes that there would be a separation between the afferent visual fibres and the pupillomotor fibres in the chiasm, being the last ones responsible for the referred chiasmal sign (like an ‘alarm signal’) and superficially distributed in this anatomical structure, similarly to the parasympathetic fibers along the third cranial nerve; they would be, therefore, susceptible to extrinsic compressive lesions (and reversible after decompression). Final Considerations: We hope that other researchers will be able to address the main question of our study and assess the accuracy of the indicated chiasmal sign in the diagnosis and screening of patients with chiasmal diseases of different aetiologies (e.g., neoplastic, demyelinating, vascular, and inflammatory diseases) by comparing the results of automated methods (e.g., pupillometry, pupillary cycle, retinal ganglion cell analysis) and non-automated methods (flashlight, slit lamp).

Palavras Chave

hemihypokinetic pupil chiasmal lesion wernicke hemianoptic phenomenon relative afferent pupillary defect