Presentation:

67 year-old female with new anisocoria and strabismus with history of herpes zoster ophthalmicus and autoimmune encephalitis.

Key findings:

Abnormal enhancement along the cisternal segment of right CN III and right CN V.
Punctate focus of enhancement along the right midbrain near the nerve root entry zone of CN IV and right distal CN IV.
Areas of wispy enhancement along the posterior wall of the right globe near the optic nerve attachment and intraconal fat.
Mild asymmetric enhancement along the ciliary ganglion of the right globe.

Diagnosis:

1. Abnormal enhancement of right cranial nerve III and V and nerve root entry zone of cranial nerve IV.

2. Additional enhancement along posterior wall of right globe and in region of ciliary ganglion. Findings overall are most consistent with patient's clinical history of herpes zoster of the right eye.

High-yield Sequences:

T1 + Contrast: Long segment asymmetric enhancement of the affected nerve.
MRI Orbit protocol can be used for higher, submillimeter spatial resolution to evaluate the cisternal segments of cranial nerves.

Discussion:

Varicella zoster virus (VZV) encephalitis can be related to an immune reaction to primary infection or reactivation of latent infection of a cranial nerve or dorsal root ganglia.

Common manifestations of secondary reaction:

Neuritis/Plexitis
Herpes zoster ophthalmicus
Ramsay Hunt syndrome
Myelitis
Bickestaff brainstem encephalitis

Herpes Zoster Ophthalmacus (HZO) involves reactivation of VZV (shingles) involving the eye, typically with dermatomal forehead rash and painful inflammation of the anterior and rarely posterior eye.

Autoimmune Encephalitis is an antibody-mediated brain inflammatory process, typically involving the limbic system, but other components of the brain can be involved. Presence is variable but typically involves psychiatric symptoms.

Ultimately the exact etiology for the patient's cranial nerve palsy affecting CN 3, 4, & 5 was not formally diagnosed, although opthalmoplegia associated with HZO is not uncommon. The patient was symptomatically treated.

Resource:

RadioGraphics in-depth evaluation of the cranial nerves involved with vision and visual reflex pathways.