Bilateral optic neuropathy following bite from brown recluse spider (Loxosceles reclusa)

Abstract

A 63-year-old female with history of a resected frontal lobe meningioma presented with bilaterally decreased vision after a bite from a brown recluse spider. The exam was significant for a left relative afferent pupillary defect, bilateral optic nerve pallor, decreased foveal sensitivity in the left eye and new bilateral visual field defects, despite stability of her meningioma. The findings remained stable at 1-year follow-up. To our knowledge, this is the first reported case of optic neuropathy secondary to a brown recluse spider bite. Visual field tests performed prior to the bite allowed us to compare and localize changes related to the bite.

Keywords: Brown recluse spider; Loxosceles reclusa; envenomation; optic neuropathy; spider bite; toxic.

Figure 1

A–F Humphrey Visual Fields (HVF) of both eyes. 24-2 HVF after craniotomy for bifrontal meningioma resection and before brown recluse spider bite showing mild superior hemifield defect and inferonasal mild constriction OD (A) as well as mild non-specific visual field defects OS (B). 30-2 HVF, four months after the spider bite, showing mild general depression on top of superior hemifield defect respecting the midline OD (C) and new general depression on top of an inferior hemifield defect respecting the horizontal midline OS (D). Foveal sensitivity OS (24dB) on the same day was decreased from baseline (37dB). 30-2 HVF during the one year follow up, and after cataract surgery OU showing superior arcuate defect and peripheral nasal constriction (E) and general depression OS (F). The foveal sensitivity remained low OS (27dB).

Figure 2

Fundus photos, during the 1-year follow up exam, showing moderate temporal pallor OU. The optic discs were not suspicious for glaucoma, based on the small cup to disc ratio (A and B). OCT-RNFL with decreased RNFL thickness, after the spider bite, but overall stable in the 6-month and the 1-year follow up OD (66 μm, 69 μm and 71μm RNFL thickness respectively (C)) and OS (73 μm, 74 μm and 71μm RNFL thickness respectively - (D)). Pre-operative axial T2 MRI (six years prior to spider bite), showing plenum sphenoidale meningioma, extending up to the right and left orbital apices (E). The last brain MRI, performed 7 years after meningioma resection and 1 year after the spider bite (F) was negative for any evidence of meningioma enlargement.