ヘルペス単純ウイルス2型による急性網膜壊死に関連した小児患者におけるステロイド反応性視神経炎

Optic neuritis (ON) associated with acute retinal necrosis (ARN) has traditionally been considered a complication resulting from direct viral infiltration of the optic nerve. Although it is currently treated with intravenous acyclovir, the appropriate dosage and duration of treatment in the pediatric population remain unclear, and no standardized effective treatment has been established in clinical guidelines.

A 14-year-old boy was referred for panuveitis in the right eye (RE), with a visual acuity (VA) of hand motions. Fundus examination revealed intense vitritis, and PCR testing was positive for HSV-2. Empirical treatment with intravenous (IV) acyclovir and intravitreal foscarnet was initiated; however, the patient developed peripheral ARN with multiple retinal detachments that required surgery, leaving silicone oil tamponade in place, and was maintained on oral valacyclovir prophylaxis. Fourteen months later, he presented with discomfort in the left eye (LE), where an active focus of ARN was identified, leading to a diagnosis of bilateral ARN. Despite urgent treatment with IV acyclovir and an intravitreal foscarnet injection, the disease progressed in the LE, and four days later, the patient developed optic neuritis associated with ARN, with VA of light perception. Since the LE was the only functional eye, high-dose intravenous methylprednisolone boluses were started.

One month later, the optic disc edema had significantly improved, and VA had improved to counting fingers. Currently, the patient has shown a remarkable recovery, with VA improving to 20/32.

These positive outcomes may suggest new therapeutic possibilities and highlight the possibility that HSV-2 may trigger an intense inflammatory or autoimmune response that could be the primary cause of ON, rather than direct infection of the optic nerve, as previously believed. Importantly, in our case, high-dose corticosteroid therapy was initiated at the onset of optic neuritis, after several days of antiviral therapy, which supports the safety of corticosteroid administration at this stage. To our knowledge, this case and two other cases of ON associated with herpetic encephalitis in the literature represent the first instances treated with corticosteroid boluses, all of which showed significant improvement.