Optic chiasm, optic nerve, and retinal involvement secondary to varicella-zoster virus

Unusual pattern of herpetic optic neuropathy: a case report and literature review of the pathophysiology of herpetic uveitis

Herpetic uveitis is a relatively common type of intraocular inflammation with a broad spectrum of manifestations ranging from mild anterior uveitis to rapidly progressing vision threatening necrotizing retinitis. Posterior herpetic uveitis presents with different clinical patterns within a spectrum depending presumably on the immune status of the patient. Systemic steroid use for viral uveitis without prior antiviral coverage is inappropriate and can lead to dramatic sequelae. Here, we report an unusual case of herpetic optic neuropathy in the contra lateral eye of a patient with acute retinal necrosis after improper use of oral steroids.

Bilateral Retrobulbar Optic Neuritis Caused by Varicella Zoster Virus in a Patient with AIDS

Aims

To report on a case of bilateral retrobulbar optic neuritis in a patient with acquired immune deficiency syndrome (AIDS) caused by varicella-zoster virus (VZV); and to review the literature focusing on: cases reported, epidemiology, pathophysiology, diagnosis and treatment.

Presentation of Case

A 38-year-old woman with AIDS presented with a 10-day history of progressive bilateral visual loss and ocular pain. She had bilateral dilated pupils with no light perception; the fundoscopic examination was normal. Facial herpes zoster lesions appeared on the second day of hospitalization Magnetic resonance imaging (MRI) findings were compatible with a bilateral optic neuritis; the cerebrospinal fluid (CSF) showed pleocytosis, increased proteins and a positive VZV-DNA PCR. She was treated with intravenous acyclovir and corticosteroids and was able, when discharged 2 weeks after admission, to carry out activities of daily living.

Discussion

VZV retrobulbar optic neuritis has previously been reported in 12 patients with AIDS, more than half of the cases had concomitant herpes zoster and an associated retinopathy. A positive VZV-DNA in the CSF is indicative of VZV infection, initial use of intravenous acyclovir is recommended, and the concomitant use of corticosteroids would be a prudent choice; the duration of antiviral therapy remains undefined.

Conclusion

VZV retrobulbar optic neuritis in AIDS patients can occur with or without herpes zoster. It is a sight-threatening infectious and inflammatory process requiring the advice of specialists in infectious diseases, ophthalmology, neurology and viral microbiology.

The optic chiasm

The optic chiasm is formed when the optic nerves come together in order to allow for the crossing of fibers from the nasal retina to the optic tract on the other side. This enables vision from one side of both the eyes to be appreciated by the occipital cortex of the opposite side. This review makes note of the embryology, anatomy and vascular supply of the optic chiasm, then discusses the clinical syndromes associated with chiasmal disease, and the diseases which commonly influence its function.

Non-compressive disorders of the chiasm

Chiasmal dysfunction produces a characteristic clinical picture, regardless of the mechanism. In most cases a compressive lesion is the cause. In occasional cases, however, no such extrinsic mass is found and other possible etiologies must be explored. In some of these cases, the pathologic process is identifiable with appropriate neuroimaging. For example, inflammation, infiltrative tumors, and radiation necrosis produce intrinsic chiasmal enhancement. Chiasmal ischemia may require specialized magnetic resonance (MR) sequences for diagnosis. Chiasmal hemorrhage, trauma and chiasmal herniation typically produce distinctive changes on noncontrasted imaging. In cases of metabolic insult, either toxic or hereditary, radiographic changes are typically absent. In each of these, the correct diagnosis can usually be made with a combination of clinical and radiographic features.

Acute retinal necrosis associated optic neuropathy

Acute retinal necrosis (ARN) syndrome is characterized by severe intraocular inflammation, occlusive vasculopathy and peripheral retinal necrosis. Vision threatening complications of this syndrome include retinal detachment, macular oedema and ischaemia and optic neuropathy. Optic nerve involvement may be the presenting sign of ARN and this condition should be included in the differential diagnosis of acute papillitis. Several mechanisms may lead to ARN associated optic neuropathy including vasculitis, optic nerve ischaemia and direct optic nerve invasion by the herpes virus. We review optic nerve involvement during ARN and present its incidence, pathogenesis, differential diagnosis and treatment.

The optic chiasm

In the first part of this chapter the anatomy and vascular supply of the chiasm are recounted, and the visual symptoms that may arise in chiasmal disease are noted. The neuro-ophthalmic signs, including the pattern of visual field defects, appearance of the optic disc, and various uncommon clinical accompaniments, are described. The second part deals with a comprehensive list of disease processes that may directly or indirectly affect the chiasm. These are divided into inflammatory disorders, including sarcoidosis, multiple sclerosis, and idiopathic chiasmitis; infective disorders, including tuberculosis; and a large section on tumors, including pituitary adenomas, cysts, and choristomas, malignant disorders, including germ cell tumors and glioma, and meningioma; and finally vascular disorders and compression due to hydrocephalus. In each case the clinical features and management of the disorder are noted, as well as the prognosis for visual improvement following treatment.

Multiple sclerosis on steroids

A 57-year-old man developed acute bilateral vision loss clinically consistent with bilateral optic neuritis. Within 1 month of diagnosis, he developed progressive and severe neurologic dysfunction, and repeat MRI demonstrated enhancement of the optic chiasm and optic tracts, as well as a large enhancing lesion within the right parieto-occipital lobe. Stereotactic-guided brain biopsy demonstrated demyelination consistent with multiple sclerosis. A diagnosis of fulminant multiple sclerosis was made. The patient died within 2 months of diagnosis. Multiple sclerosis and a fulminant subtype known as Marburg disease are discussed.

A 16-year-old girl with bilateral visual loss and left hemiparesis following an immunization against human papilloma virus

We report the course of a 16-year-old girl who presented with near complete visual loss associated with chiasmal neuritis and a biopsy proven tumefactive demyelinating lesion on magnetic resonance imaging (MRI) in association with a recent immunization against human papilloma virus.

Cytomegalovirus infection with MRI signal abnormalities affecting the optic nerves, optic chiasm, and optic tracts

A 49-year-old woman who had been immunosuppressed after a renal transplant developed bilateral severe visual loss. Visual acuities were finger counting and hand movements in the two eyes. Both optic nerves were pale. There were no other ophthalmic abnormalities. Brain MRI disclosed marked signal abnormalities involving the optic nerves, optic chiasm, and optic tracts. Cerebrospinal fluid polymerase chain reaction (PCR) was positive for cytomegalovirus. Treatment did not restore vision. Such extensive clinical and imaging involvement of the anterior visual pathway, which has been previously reported with other herpes viruses, illustrates the propensity for this family of viruses to track along axons.

Infectious optic neuropathy

A wide variety of infectious agents are known to cause optic neuropathy. This article will consider the bacteria, spirochetes, fungi, and viruses that most commonly affect the optic nerve. Clinical presentation is variable, but some pathogens often produce a characteristic funduscopic pattern. Diagnosis is usually made on the basis of clinical suspicion and serologic testing. Polymerase chain reaction is also increasingly utilized. Most infectious agents can be effectively treated but visual recovery is highly variable.

Central and Paracentral Visual Field Defects and Driving Abilities

The effect of central and paracentral visual field defects on driving abilities has until now received little attention. To date studies and surveys have concentrated on visual acuity and peripheral field loss. Here we summarise for the first time those diseases causing central visual field defects likely to be associated with binocular visual acuity adequate for driving.

Optic chiasm involvement secondary to herpetic encephalitis. A case report

Herpes simplex (HSV) encephalitis is one of the most common central nervous system (CNS) viral infections in adults. Early diagnosis is essential for treatment. We describe the case of a 70-year-old man who reported sudden bilateral reduction of visus. Four days after admission the patient showed high fever, followed the next day by a generalised convulsive crisis and coma. A first magnetic resonance imaging (MRI) showed no alterations, whereas the second showed the usual patterns of HSV encephalitis. With a clinical suspicion of herpetic encephalitis an intravenous therapy with acyclovir was established. The diagnosis of herpetic encephalitis was confirmed by cerebrospinal fluid (CSF) detection of herpes simplex DNA sequences. A further ten days later we performed a third MRI, demonstrating the typical pattern of HSV encephalitis and an increase in size and signal of the optic chiasm.

Unilateral retrobulbar optic neuritis due to varicella zoster virus in a patient with AIDS: A case report and review of the literature

Unilateral retrobulbar optic neuritis developed in a 43-year-old man with acquired immune deficiency syndrome (AIDS). This was secondary to varicella zoster virus (VZV) as confirmed by cerebrospinal fluid (CSF) polymerase chain reaction (PCR) detection of VZV in the cerebrospinal fluid. There was no typical cutaneous infection and no evidence of retinitis. The onset of unexplained visual loss due to optic neuritis in HIV positive individuals may be due to VZV infection. Prompt recognition, and early intervention with antiVZV therapy may preserve vision. Retrobulbar optic neuritis secondary to VZV infection should be considered in immunocompromised patients even in the absence of cutaneous or retinal lesions. Previous cases are reviewed and the varied nature of viral transport in the nervous system is noted.