High-resolution magnetic resonance imaging of the intraorbital optic nerve and subarachnoid space in patients with papilledema and optic atrophy
Y. Mashima, K. Oshitari, Y. Imamura, S. Momoshima, H. Shiga and Y. Oguchi
Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan.
OBJECTIVE: To evaluate the orbital portion of the optic nerve and the
subarachnoid space using fast spin-echo magnetic resonance imaging in
normal subjects and in patients with papilledema or optic atrophy. DESIGN:
Measurements of the optic nerve complex on coronal images were made using
high-resolution magnetic resonance imaging with fast spin-echo sequences.
PATIENTS: Twenty-one patients, including 5 patients with papilledema due to
congenital hydrocephalus, intracranial tumors, or meningitis, as well as 16
patients with optic atrophy, were studied. Sixteen healthy volunteers
served as controls. MAIN OUTCOME MEASURES: The longitudinal diameter of the
optic nerve, the longitudinal outer diameter of the subarachnoid space, the
diameter ratio, and the area of the subarachnoid space were determined.
RESULTS: In normal subjects, the ring-shaped area of high signal intensity
that represented the subarachnoid space was widest behind the globe, then
narrowed toward the orbital apex. In patients with papilledema, the area of
the subarachnoid space was markedly dilated, the optic nerve was
compressed, and the nerve sheath was widened, resulting in a small diameter
ratio compared with that of controls. Patients with pallor of the temporal
aspect of the optic disc appeared to exhibit dilation of the subarachnoid
space; the size of the optic nerve was decreased more than that of the
nerve sheath, resulting in a small diameter ratio compared with controls.
Patients with complete pallor of the disc, however, exhibited hyperintense
optic nerve complexes without a ring-shaped appearance toward the orbital
apex. CONCLUSION: Fast spin-echo magnetic resonance imaging appears useful
for objectively evaluating the optic nerve and surrounding subarachnoid
space in patients with papilledema and optic atrophy.
