Isolated presumed optic nerve gumma, a rare presentation of neurosyphilis

Abstract

Purpose: The incidence of syphilitic infections continues to rise and represents a major public health concern, particularly in patients co-infected with human immunodeficiency virus (HIV). The infection has a multitude of clinical presentations and is often referred to as the 'great imitator.' We present a rare case of an isolated presumed syphilitic optic nerve gumma and characterize it using newer imaging modalities.

Observations: A 36-year-old HIV-positive man, compliant with treatment, presented with a five day history of decreased vision in the left eye. On examination his visual acuity was 20/30 with mild dyschromatopsia and an inferior altitudinal field defect in the left eye. Funduscopy demonstrated small cup to disc ratios bilaterally and a swollen and hyperemic left optic disc. Following five months of stable vision, the patient's vision in the left eye declined to 20/60, associated with diffuse visual field loss and continued swelling of the left optic disc. Subsequent magnetic resonance imaging with contrast demonstrated enhancement of the left optic nerve, and his serologies were positive for syphilis. Fluorescein angiography and optical coherence tomography were used to better characterize the lesion being most consistent with a syphilitic optic nerve gumma.

Conclusions and importance: Gummas of the central nervous system are a rare presentation of neurosyphilis and the last reported gumma of the optic nerve was in 1990. Such lesions have not been characterized using newer imaging modalities including optical coherence tomography and fluorescein angiography, both of which may assist in the diagnosis of this rare entity. With the increased prevalence of syphilis and remarkable response to therapy, syphilitic gummas should be considered in at-risk patients presenting with an optic neuropathy.

Keywords: Syphilis optic neuropathy.

Fig. 1

Development of presumed left optic nerve head gumma over time. At initial presentation the patient had an inferior altitudinal defect on the pattern deviation of the automated Humphrey visual field (a) a hyperemic and swollen left optic disc (c) a normal right optic disc (b) and no signs of optic nerve enhancement on the coronal T1 post-contrast magnetic resonance imaging (MRI) (d). Five months later, the patient's visual field progressed (e), the left optic nerve head was elevated and hyperemic with superotemporal pallor (g) with the right optic nerve head remaining unchanged (f) and the MRI showed left optic nerve enhancement on the coronal T1 post-contrast BRAVO MRI (H).

Fig. 2

Fluorescein angiography and optical coherence tomography imaging of presumed left optic nerve head gumma. Early (a) and late (b) fluorescein angiography of the left optic nerve head gumma before treatment, demonstrating nasal telangiectatic vessels and late leakage. Early (c) and late (d) images after treatment, showing resolution. Optical coherence tomography of the affected area of the nerve clearly demonstrates the elevated gumma (e).