Herpes zoster ophthalmicus (HZO) is a common ocular emergency caused by reactivation of the varicella zoster virus (VZV), leading to vesicular rash eruption in the ophthalmic division of the trigeminal nerve (V1). Clinical diagnosis is obtained with V1-distributed dermatomal rashes after a prodromal period of ocular pain, chemosis, visual impairment, diplopia, and ptosis.

Early recognition of this condition is important for timely medical management to prevent complications such as postherpetic neuralgia (PHN) and blindness. A less-documented, rare presentation of HZO is orbital myositis, which may be an early indicator of future vesicular rash eruption. We present a case of acute orbital myositis preceding vesicular rash eruption in HZO.

An 89-year-old female presented with a 4-day history of left periorbital edema, pain, and binocular diplopia. Her left eye (OS) demonstrated incomplete ophthalmoplegia, tonic pupil (fixed 5 mm), mild ptosis, proptosis, and conjunctival injection. The patient’s medical and surgical history was unremarkable except for 3+ nuclear sclerotic cataracts bilaterally. Retinal examination was unremarkable.

Two days after the initial presentation, the patient developed a vesicular rash in the left V1 distribution, with a positive Hutchinson sign. Slit-lamp examination demonstrated anterior chamber cells OS, and there was diffuse chemosis and complete ophthalmoplegia. Visual acuity OS declined from 20/200 to counting fingers, and her intraocular pressure increased from 19–22 mm Hg over these 2 days.

Axial computed tomography of the orbit (Fig. 1) and magnetic resonance imaging (MRI) brain (Fig. 2) demonstrated enlarged lateral, inferior, and medial recti muscles and proptosis OS. Immunologic and serologic analysis excluded autoimmune disorders and thyroid disease. The patient was started on intravenous acyclovir 450 mg TID and oral prednisone 60 mg. Repeat MRI done 2 weeks after initiation of treatment revealed improvement in the extraocular muscle (EOM) inflammation (Fig. 3). The patient reported localized ocular pain at initial presentation; however, this pain progressed to left facial discomfort in the V1 distribution over the following 2 months. PHN was diagnosed, and gabapentin 100 mg PO TID was started. By 4 months, her eye movements normalized in the left eye, coinciding with further improvement of the EOM thickening on MRI (Fig. 4). Visual acuity improved back to 20/200 and intraocular pressure normalized to 10 mm Hg. Symptoms of PHN resolved by the 11-month mark; MRI brain demonstrated resolution of proptosis and normal EOMs at this time (Fig. 5).

Ocular myositis is a rare inflammatory disorder of the EOMs. There are 2 major forms of ocular myositis, limited oligosymptomatic ocular myositis with conjunctival injection and severe exophthalmic ocular myositis with accompanying ptosis, diplopia, chemosis, and proptosis.

Our patient’s initial symptoms and imaging findings correlated well with severe exophthalmic ocular myositis. When the patient’s vesicular lesions erupted 2 days later, a diagnosis of HZO after reactivation of VZV was concluded. The reduction of visual acuity from 20/200 to counting fingers OS was most likely owing to uveitis secondary to HZO as demonstrated by the anterior chamber cells and the positive Hutchinson sign.

To our knowledge, only 7 previous cases of orbital myositis preceding vesicular rash eruption in patients with VZV reactivation have been published in literature. The first case published on this presentation by Volpe et al in 1991 described a 45-year-old male with unilateral periorbital edema, sharp pain, ptosis, chemosis, and diplopia owing to limited upgaze and adduction in his left eye.

Six other case reports with similar presentations of orbital myositis preceding vesicular rash eruption have since been noted in literature.

In all 6 previous cases, mean time to vesicular eruption after initial symptoms of orbital myositis was 4.8 days (range, 2–7 days); our patient presented with a V1 rash 6 days after initial symptoms. In concordance with our patient, all previous 6 cases demonstrated resolution of orbital symptoms after intravenous or oral antiviral and corticosteroid therapy. Our case further adds to the relative paucity of literature regarding the clinical course of orbital myositis preceding HZO rash presentation.

Of note, the case reported by Kim et al in 2012 was the only patient to develop PHN after initial presentation; this is a similar disease course as our patient, who experienced neurogenic left-sided facial pain.

PHN is a chronic, painful sequela of acute VZV reactivation that is the most common neurological complication of HZO and is associated with reduced quality of life.

Early and aggressive treatment of HZO with antiviral therapy could possibly reduce the risk for developing this neurological complication.

With over 90% of the world population currently hosting latent VZV, and with an estimated 25% recurrence of VZV infections, HZO is not an uncommon ocular emergency.

Common ocular involvement such as iritis, scleritis, and keratoconjunctivitis are seen in about 50% of patients with HZO,

and some of these patients may develop PHN, which can persist.

Acute orbital myositis as the initial presentation of HZO is very rare. Early recognition and prompt treatment of ocular myositis caused by HZO can possibly reduce the risk for blindness and PHN.

https://www.canadianjournalofophthalmology.ca/article/S0008-4182(19)30863-4/fulltext