Case of the week Details

B.LEGENDS

• Bulky and enhancing extra-ocular muscles on left side
• Mild diffuse edema with thickening and post contrast enhancement in left preseptal space with mild fat stranding in the intraconal fat
• Mild left perioptic fat stranding and subtle post contrast enhancement of nerve sheath
• Mild congestive changes seen as increased enhancement of the left orbital apex

DIAGNOSIS

Left herpes zoster ophthalmicus with orbital myositis and optic perineuritis.

DISCUSSION

• Herpes zoster ophthalmicus (HZO) represents a vision-threatening reactivation of latent varicella-zoster virus within the ophthalmic branch of the trigeminal nerve.
• This condition accounts for a significant proportion of herpes zoster cases and carries a disproportionately high risk of ocular and neurologic morbidity.
• Clinical manifestations range from painful cutaneous eruptions across the ophthalmic dermatome to serious intraocular and orbital complications, including keratitis, uveitis, scleritis, retinitis, and optic neuropathy.

Pathophysiology of Ocular Involvement

• Once reactivated, VZV replicates and travels along sensory axons to the ophthalmic dermatome, producing the classic painful vesicular rash on the forehead, eyelid, and nose. Viral particles and immune-mediated inflammation extend into ocular tissues, where they can cause:
• Conjunctivitis and episcleritis (early involvement)
• Keratitis (epithelial, stromal, or neurotrophic) due to direct viral cytopathy and immune response
• Anterior uveitis from viral antigen-induced inflammation
• Retinitis, optic neuritis, and vasculitis in severe or disseminated cases

Key Radiological Findings

• MRI (Orbit/Brain): Typically shows enhancement of the optic nerve (optic neuritis), thickened or inflamed extraocular muscles (orbital myositis), and enhancement of cranial nerves III, IV, V, or VI
• Orbital Apex Syndrome: MRI may reveal inflammation, enhancement, or soft tissue density at the orbital apex, causing multiple cranial nerve dysfunctions
• Intracranial Involvement: MRI/MRA can detect VZV-induced vasculitis, stroke, or, rarely, encephalitis.
• Orbital Cellulitis: Imaging helps differentiate preseptal from postseptal orbital cellulitis, showing fat stranding and extraocular muscle enlargement.

Complications

• Orbital Myositis: Often appears as swelling and enhancement of one or more extraocular muscles.
• Ophthalmoplegia: Caused by cranial nerve palsy or direct muscle inflammation, visualized on neuroimaging.
• Optic Neuritis: Indicated by high signal intensity on T2-weighted MRI and contrast enhancement of the optic nerve.
• Stroke: Risk is 4.3 times higher within one year post-infection, often secondary to vasculitis.

Management

• Supportive care
• Antiviral agents
• Antibiotics
• Corticosteroids
• Topical aqueous suppressants
• Debridement

REFERENCES

https://www.ncbi.nlm.nih.gov/books/NBK557779/

By Kathryn Lewis, BS, Bea Palileo, MS, Charles Pophal, BS, Joseph Yasmeh, BS, and Ray Glendrange, MD Edited By: Ingrid U. Scott, MD, MPH, and Bennie H. Jeng, MD

Zhou Wenting, Sandy, and Srinivasan Sanjay. 2014. “Role of Magnetic Resonance Imaging in Herpes Zoster Ophthalmicus Ophthalmoplegia”. Ophthalmology Research: An International Journal 2 (4):189-95. https://doi.org/10.9734/OR/2014/8098.

Dr. Neha Sathyanarayana
Radiology Resident
Manipal Hospital, Yeshwanthpur, Bengaluru.

Dr. Anita Nagadi
Senior Consultant Radiologist
Manipal Hospital, Yeshwanthpur, Bengaluru.