Magnetic resonance imaging of optic nerve

Abstract

Optic nerves are the second pair of cranial nerves and are unique as they represent an extension of the central nervous system. Apart from clinical and ophthalmoscopic evaluation, imaging, especially magnetic resonance imaging (MRI), plays an important role in the complete evaluation of optic nerve and the entire visual pathway. In this pictorial essay, the authors describe segmental anatomy of the optic nerve and review the imaging findings of various conditions affecting the optic nerves. MRI allows excellent depiction of the intricate anatomy of optic nerves due to its excellent soft tissue contrast without exposure to ionizing radiation, better delineation of the entire visual pathway, and accurate evaluation of associated intracranial pathologies.

COVID-19 presenting with ophthalmoparesis from cranial nerve palsy

“…However, the occurrence of neurological symptoms within a few days of disease onset led to consideration of direct infection. In our second case, although radiological evidence of abducens nerve involvement was lacking, the presence of optic nerve sheath enhancement of the involved eye could reflect viral leptomeningeal invasion, though these findings are non-specific 7 . Given her risk factors and the painless nature of the diplopia, the differential includes an ischemic process.…”

How Common Is Signal-Intensity Increase in Optic Nerve Segments on 3D Double Inversion Recovery Sequences in Visually Asymptomatic Patients with Multiple Sclerosis?

“…Both prechiasmatic segments join at the optic chiasm. 23,42 The term optic system comprises all optic nerve segments. The evaluation of the signal intensity of the optic nerve segments in both the comparison group and the group of patients with MS was by visual inspection.…”

“…10,[18][19][20][21][22] The enhancement is present for a mean of 30 days after the onset of visual symptoms. 21,[23][24][25][26][27][28][29][30][31] Subclinical optic nerve demyelination, however, is not easily visible on MR imaging. Routine T2-weighted images without fat suppression and contrast-enhanced T1-weighted FSE images do not show any signal abnormality in the affected optic nerve.…”

“…Fat-suppressed T2-weighted FSE images, especially STIR T2weighted images, may detect a signal-intensity abnormality in subclinical optic nerve demyelination. 23,32,33 The highly diagnostic value of fat-suppressed FLAIR images and fat-suppressed 3D DIR images in the detection of any pathologic signal intensity in the optic nerve has been evaluated in acute optic nerve demyelination. 10,34,35 In a few patients with subclinical optic nerve demyelination, signal-intensity abnormalities have been reported on 3D FLAIR.…”

Bedside measurement of the optic nerve sheath diameterwith ultrasound in cerebrovascular disorders

“…Changes in the cerebral blood flow developing as a result of CVD, the breakdown of cerebral perfusion pressure due to edema that develops at the tissue level, and ineffective CSF circulation cause an increase in ICP (17,22,23). The ON is unique because it represents an extension of the central nervous system and has a cover (dura, arachnoid, and pia) (24). The positive relationships between raised ICP and the dilatation of the ONS and papillae edema have been known for several years (25)(26)(27).…”