Orbital apex syndrome secondary to herpes zoster virus infection

Abstract

A male patient with herpes zoster ophthalmicus (HZO) presented with left exophthalmos, external and internal ophthalmoplegia and decreased visual acuity. A CT scan revealed myositis without significant compression of the optic nerve. Intravenous acyclovir and oral steroids were started with improvement of the symptoms and eventual complete recovery.Orbital apex syndrome is a rare complication of HZO. Multiple pathogenic mechanisms are involved, including a direct cytopathic effect of the virus as in the present case. Early diagnosis and therapy may lead to complete recovery of visual function.

Background

Herpes zoster ophthalmicus is a condition in which the ophthalmic branch of the trigeminal nerve is affected by the varicella zoster virus. Neurological complications, such as ophthalmoplegia and optic neuritis, are rare but may lead to severe visual acuity loss.^1–3 However, early diagnosis and therapy may lead to complete recovery of visual function.

Case presentation

A 61-year-old Caucasian man was referred to our clinic with a 5-day history of inflammation and pain in his left eye (LE). He presented left facial oedema extending to the frontal region, cheek and tip of the nose associated with vesicles and crusting papules, as well as low-grade fever (37.3°C), malaise and dizziness.

Investigations

LE visual acuity (VA) was counting fingers at 1 m and the pupil was 3 mm wide with relative afferent defect. External examination revealed a complete external ophthalmoplegia and ptosis (figure 1) with Hertel exophthalmometry readings 11 and 15 mm, in his right and LE, respectively, and a left submandibular lymph node. Anterior segment and fundus examination were unremarkable. Optical coherence tomography (OCT) (Cirrus, Carl Zeiss Meditech, Dublin, California, USA) revealed an average retinal nerve fibre layer (RNFL) thickness within normal values (79 µm). An orbital CT disclosed unilateral left exophthalmos and increased thickness of the medial and superior rectus without significant compression of the optic nerve and no signs of sinusitis (figure 2).

Figure 1.

Left herpes zoster ophthalmicus with ptosis and limited supraduction and adduction of the left eye.

Figure 2.

Axial (A) and coronal (B) computerised scans revealing left extrinsic muscular engorgement, especially affecting the medial and superior rectus with left exophthalmos and soft tissue swelling. Notice the absence of orbital apex compression.

Treatment

The patient was admitted to the hospital and was started on intravenous acyclovir 10 mg/kg/8 h and oral methyl prednisolone 60 mg/day. After 7 days of treatment, LE VA was 20/400, with persistent intrinsic ophthalmoplegia, partial ptosis and restricted supraduction. The patient was discharged, and the treatment with oral antiviral and corticosteroid was completed at home. During the following 10 weeks, steroid treatment was slowly tapered as visual acuity improved to 20/25 and ocular motility was completely restored.

Outcome and follow-up

After 1 year of follow-up, visual acuity was 20/20. OCT RNFL remained unchanged showing no atrophic changes.

Discussion

It has been hypothesised that orbital apex syndrome (OAS) associated with ophthalmic zoster can be secondary to compression caused by intraorbital inflammation or myositis.^{1 4–6} Other authors have proposed a direct viral cytopathic effect caused by viral dissemination from the herpes zoster virus infecting the fifth cranial nerve to the neighbouring cranial nerves in the orbital apex. A reactive, immunologically mediated response to the virus might induce perineural inflammation, peripheral nerve demyelisation, contiguous orbital inflammation, cranial vasculitis, myositis, brainstem encephalitis and meningitis.^{1 2 4–6}

The signs and symptoms described in this case report can be ascribed to OAS. However, the orbital CT revealed myositis with no signs of orbital apex or optic nerve compression that are necessary to establish this diagnosis. We consider that the OAS was mainly secondary to a direct cytopathic effect, which might be responsible for the complete resolution of the patient's condition with restoration of visual acuity. Pion and Salu have reported on one case of herpes zoster ophthalmicus complicated with OAS without CT compressive signs; the authors hypothesised that the syndrome was the result of perineural inflammation caused by viral dissemination from the fifth cranial nerve.⁴ CT-confirmed myositis related to herpes zoster ophthalmicus has been described in two occasions in which acute compression of the orbital apex could not be demonstrated.^{1 2} In both cases, the authors considered that the OAS might involve a multiple mechanism such as myositis, a direct cytopathic effect and a reactive immunological response to the virus.

OAS is an infrequent though potentially blinding complication of HZO. Specific conservative treatment with systemic antivirals and steroids may reduce orbital inflammation preserving final visual function.

Learning points.

• Orbital apex syndrome is an infrequent though potentially blinding complication of OHZ.

• Early specific conservative treatment with systemic antivirals and steroids may reduce orbital inflammation preserving final visual function.

• Orbital computerised scan can aid in the differential diagnosis of orbital apex syndrome.

• Management of orbital apex syndrome associated with herpes zoster ophthalmicus should include systemic antiviral and steroidal therapy.