Peripheral third cranial nerve enhancement in multiple sclerosis

Abstract

Cranial nerve III dysfunction in multiple sclerosis (MS) is uncommon. Seven cases of isolated cranial nerve III paresis associated with MS have been reported in the English-language literature. MR imaging was obtained in five cases demonstrating lesions within the midbrain. We present the detailed clinical and MR imaging findings of a young woman with MS and an isolated, painful pupil involving complete left cranial nerve III palsy. Initial MR imaging showed isolated enhancement of the cisternal portion of the cranial nerve III, suggesting that peripheral nervous system involvement may develop as part of the disease process in some patients with MS.

Fig 1.

Coronal gadolinium-enhanced T1-weighted images (TR/TE, 600/14) through the cerebral peduncle and cisternal course of cranial nerve III (A) demonstrate marked enhancement and subtle enlargement of cranial nerve III on the left side (white arrows in A). Notice the normal appearance of cranial nerve III on the right (arrowheads in A). There is also subtle enhancement at the cranial nerve III exit zone on the left side (black arrows in A and B), which is better appreciated on the axial gadolinium-enhanced T1-weighted image (B) performed with the same imaging parameters.

Fig 2.

Axial fluid-attenuated inversion recovery (FLAIR) image (TR/TE, 9500/110) through the midbrain (A) demonstrates a subtle area of increased signal intensity (arrows) along the medial margin of the cerebral peduncle on the left side. No enhancement is seen on the axial gadolinium-enhanced T1-weighted image (600/17) (B) in this region. The coronal gadolinium-enhanced T1-weighted images (600/14) through the cisternal course of cranial nerve III (C) demonstrate subtle enhancement of the cranial nerve III on the left side (arrows in C). Notice the normal appearance of cranial nerve III on the right (arrowheads in C).

Fig 3.

Coronal FLAIR-weighted image (TR/TE, 10,002/168) obtained at the level of the anterior horns of the lateral ventricles shows a focal area of increased signal intensity (arrows) in the subcortical white matter of the inferior frontal lobe on the left side.

Fig 4.

Coronal gadolinium-enhanced T1-weighted image (TRTE, 882/14) obtained at the level of the anterior horns of the lateral ventricles shows multiple enhancing white matter lesions (arrows). There is also a nonenhancing lesion in the corpus callosum in midline (arrowhead).