Herpes zoster ophthalmicus with acute retrobulbar optic neuritis and abducens nerve palsy: a case report

Abstract

Herpes zoster Ophthalmicus (HZO) affecting the ophthalmic division (V1) of the trigeminal nerve. HZO may cause extraocular muscle palsies, with the third nerve being the most commonly affected and the fourth nerve the least. The combined involvement of the optic nerve and isolated paralysis of the eye muscle is very rare, with only limited case reports documenting this complication of ocular herpes zoster. This case report also describes a case of optic nerve involvement with 6th nerve palsy, which was treated with corticosteroid and valacyclovir.

Introduction

Herpes zoster Ophthalmicus (HZO) refers to the viral infection affecting the ophthalmic division (V1) of the trigeminal nerve, although this virus can also involve other branches of the nerve (V2-V3). Although the diagnosis of HZO does not always indicate eye involvement, ocular complications occur in approximately 50% of cases [1].

Ocular signs can be acute, chronic, or relapsing, and include conjunctivitis, keratitis (commonly epithelial), episcleritis, scleritis, uveitis, secondary glaucoma, cataract, and retinal necrosis. HZO may cause cranial nerve palsies, with the third nerve being the most commonly affected and the fourth nerve the least [2].

Involvement of the central nervous system is uncommon in VZV infections, and optic nerve involvement occurs rarely, typically in individuals with immune system deficiencies [3].

The combined involvement of the optic nerve and isolated paralysis of the eye muscle is very rare, with only limited case reports documenting this complication of ocular herpes zoster [3–7].

Here in, we present a case of right eye zoster followed by sixth nerve palsy and acute retrobulbar optic neuritis.

Case report

A male patient in his sixties with no known immunodeficiencies, with a well-controlled medical history of hypertension, hyperlipidemia, and diabetes mellitus was referred to our ophthalmology center with complaints of painful blurred vision in the right eye and diplopia. The double vision was worsened in horizontal right gaze. The patient reported a skin rash on his forehead two weeks prior. Oral Valacyclovir 1000 mg every 8 h was initiated following the appearance of the skin rash. Physical examination revealed shingles lesions in the territory of the right V1 nerve. The lesions were unilateral and in the form of brown hyperpigmented macules and papules (Fig. 1).

Fig. 1.

The figure shows scabbed rashes over the right ophthalmic branch of the trigeminal nerve (V1 distribution)

On ophthalmologic examination, the corrected distance visual acuity of the right eye was 20/70, while the left eye was 20/20. Intraocular pressure was measured by a Goldman tonometer, which was 13 mm Hg in the right eye and 11 mm Hg in the left eye. Corneal sensation (the cotton thread gently touches the cornea) was reduced in the right eye compared to the left. Extraocular movement examination revealed limited abduction of the right eye (Fig. 2).

Fig. 2.

Examination of extraocular movements across cardinal directions shows an inability to abduct the right eye

A relative afferent pupillary defect (RAPD) was positive in the right eye. Color vision, tested with Ishihara discs (24 plates edition), was impaired in the right eye (read only the base plate), but the left eye test was normal.

There was no evidence of ptosis or proptosis in either eye. Examination of the anterior chamber of both eyes showed corneal sensations were reduced, and both eyes were phakic. Examination of the posterior segment of both eyes showed evidence of mild non-proliferative diabetic retinopathy (NPDR). The optic nerve examination of both eyes revealed no swelling or hemorrhage, and the appearance of both optic discs was normal.

Brain magnetic resonance imaging (MRI) was within normal limits (Fig. 3).

Fig. 3.

MRI orbits, axial and coronal sections, show no enhancement of right optic nerve sheath

Macular optical coherence tomography and retinal nerve fiber layer optical coherence tomography and visual field were normal.

ESR and CRP were in the normal range. Other causes of optic neuritis, including inflammatory causes and vasculopathies, were evaluated. The vasculitis and inflammatory antibody panel, including anti-nuclear antibody (ANA), antineutrophilic cytoplasmic antibody (ANCA), anticardiolipin antibody, antiphospholipid antibody, lupus anticoagulant antibody, rheumatoid factor, and aquaporin-4 antibody, was negative.

Based on the patient’s history, a diagnosis of both acute retrobulbar optic neuritis and sixth nerve palsy due to VZV infection was made. The patient was treated with tablet valacyclovir 1 g every 8 h, and tablet prednisolone 50 mg daily (due to the severe increase in the patient’s blood sugar after a dose of intravenous methylprednisolone (500 mg), oral corticosteroids were started). After one month of receiving oral valacyclovir and tapered oral corticosteroids, the patient’s corrected distance visual acuity improved to 20/25. After 6 months, the movement limitation in lateral gaze were also improved and the patient’s visual acuity remained constant at 20/25 (Figs. 4 and 5).

Fig. 4.

The figure shows that zoster skin lesions have improved after 6 months

Fig. 5.

The figure shows the improvement of the patient’s eye movements after 6 months

Discussion

The presumed pathophysiology of ON is inflammation and demyelination of the optic nerve. Activated peripheral T cells migrate across the blood–brain barrier and release cytokines and other inflammatory mediators leading to neuronal cell death and axonal degeneration. In most cases, visual recovery will occur spontaneously but treatment with corticosteroid resulted in a more rapid rate of visual recovery and may be important in monocular patients, patients with significant bilateral visual loss, or those with occupations requiring faster recovery to normal visual acuity [8].

Considering that the patient presented with symptoms of painful vision loss accompanied by color vision disorder, and after consultation with the neurology service and brain MRI evaluation of the patient, no pathological lesion and compressive mass were observed, the most probable diagnosis for the patient was acute retrobulbar optic neuritis. This case presented an unusual manifestation of involvement following HZO, characterized by acute retrobulbar optic neuritis and sixth nerve palsy.

One of the proposed differential diagnoses for cranial nerve involvement, especially 6th nerve, in patients with vascular risk factors such as diabetes and hypertension, is vascular causes. But in this case, due to the presence of skin lesions from 2 weeks ago and also the occurrence of painful blurred vision, which was not sudden, and the patient gradually developed pain and blurred vision over the course of several days, and also because two cranial nerves (2 and 6) have been involved and also because in multiple cranial nerve palsy, involvement in the field of vascular causes is less likely, non-vascular causes were suggested for this patient.

In very rare instances, limited number of case reports have documented the simultaneous involvement of the abducens nerve and optic neuritis in patients with HZO (Table 1).

Table 1.

Review of 4 patients with abducens nerve palsy and optic neuritis in patients with HZO, including the present patient

Case no	Authors (year)	Age at onset	Gender	Abducens nerve palsy laterality	Vision symptom and laterality	Diagnosis	Brain imaging	Treatment	Outcome
1	Ryu et al (2016) [3]	65	male	Left side	Acute painless visual field defect in the left eye	VZV perioptic neuritis preceding the onset of sixth cranial nerve palsy and progressive outer retinal necrosis	enhancement around the left optic nerve, consistent with perioptic neuritis	1 g of intravenous methylprednisone daily and acyclovir 10 mg/kg per 8 h	The retinal lesion in the left eye stabilized with no visual improvement
2	Abid et al (2019) [9]	55	Female	Right side	Afferent pupillary defect on right side	Optic perineuritis	Contrast enhancement of optic nerve sheath on MRI	Intravenous acyclovir Oral valacyclovir	Complete vision recovery Normal abduction in 4 months
3	Seddon and Skolnick (2021) [5]	47	Female	Left side	Photophobia on both sides	Optic neuritis	No finding on MRI	Oral valacyclovir Oral prednisolone 30 mg daily and tapered	No photophobia Normal abduction in 7 weeks
4	This case (2024)	62	male	Right side	acute blurred vision in the right eye and diplopia	Herpes zoster ophthalmicus with acute retrobulbar optic neuritis and abducens nerve palsy	No finding on MRI	valacyclovir 1 g every 8 h, and prednisolone 50 mg daily	the patient’s corrected distance visual acuity improved to 20/25. The movement limitation in lateral gaze were also improved

In the case reported by Ryu et al., the patient presented with ON and sixth nerve palsy simultaneously, but the patient’s vision was no light perception (NLP) and there was progressive outer retinal necrosis (PORN). In contrast, our patient experienced much milder vision loss with no evidence of retinal detachment [3].

Additionally, the patient in Ryu et al.’s report had a history of pulmonary tuberculosis, suggesting a compromised immune system, whereas our patient appears to have a favorable immune status. In Ryu et al.’s case, optic nerve involvement was bilateral, with the opposite eye showing an abnormal visual field. However, in our patient, there was no evidence of involvement of the opposite optic nerve.

In the case reported by Matsuo et al., there was no retinal involvement, and the degree of vision loss was similar to that of our patient. However, the patient in Matsuo et al.’s study exhibited optic disc swelling, which was not present in our patient [4].

The amount of vision loss of the patient was also similar to our patient. The difference between the patient in this study and our patient is optic disc swelling, which is not present in our patient. Additionally, Muhammad Abbas Abid et al. reported cases of optic neuritis and sixth nerve involvement following ocular herpes zoster. In their patient, there was no vision loss, and vision remained normal. The only indication of optic nerve involvement was the presence of a positive relative afferent pupillary defect (RAPD) [9].

The pathogenesis of ophthalmoplegia is controversial, and several mechanisms have been postulated. The first is a direct cytopathic effect of the virus on the surrounding neural tissue. The second is an immune response of the central nervous system to the virus. The third attributes it to an occlusive vasculitis induced by the virus. A fourth theory suggests that VZV activates another latent neuropathic virus within the brain [10].

Conclusion

In conclusion, the involvement of different cranial nerves, either in isolated or combined forms, should be considered in cases of HZO. Physicians should be aware of this complication and consider the early initiation of antiviral and corticosteroid therapy.

Authors’ contributions

Farshad Afshar and Mohammad Sadegh Khalilian and Mohsen Pourazizi and Mohammad Amin Najafi wrote the main manuscript text and Mohammad Sadegh Khalilian prepared figures and tabel.

Funding

No funding.

Data availability

No datasets were generated or analysed during the current study.

Declarations

Ethics approval and consent to participate

The research adhered to the ethical standards outlined in the Helsinki Declaration and obtained approval from the Institutional Review Board of Isfahan University of Medical Sciences.

Consent for publication

Written informed consent for publication of their clinical details and clinical images was obtained from the patient.

Competing interests

The authors declare no competing interests.