Clinical Significance of MRI Contrast Enhancement of the Oculomotor Nerve in Ischemic Isolated Oculomotor Nerve Palsy

Abstract

Background and Purpose Contrast enhancement of the oculomotor nerve in MRI was recently noticed in patients with clinical ischemic isolated oculomotor nerve palsy (iIONP). The opinions about whether this is a sign of inflammation and whether or not to administer steroids vary between doctors. The study aimed to determine the associations between this enhancement and vascular-disease risk factors (VRFs) and inflammatory factors in iIONP patients. Methods The study recruited patients who had experienced iIONP during the previous 2 years. They were divided into groups A and B based on whether or not they exhibited an enhanced oculomotor nerve in MRI of the cavernous sinus using thin-section, fat-suppressed, and contrast-enhanced sequences. VRFs, inflammatory factors, and improvement scores were compared between the two groups. Results Most (71.1%) of the 45 included iIONP patients had enhanced oculomotor nerves in MRI. VRFs, periorbital pain, elevated C-reactive protein and erythrocyte sedimentation rate, the neutrophil-to-lymphocyte ratio, and the platelet-to-lymphocyte ratio were not significantly associated with the enhancement. Four of the five patients in group A exhibited an elevated cerebrospinal fluid (CSF) IgG synthesis rate. The improvement score of eight patients who received 80 mg of methylprednisolone in addition to the routine therapy was not significantly different from the scores of the other patients (p=0.485). Conclusions More than half of the iIONP patients had an enhanced oculomotor nerve in MRI. A few of them also had elevated CSF IgG synthesis rate, but no further evidence for inflammation was found. The administration of steroids seemed to have no benefit other than increasing the blood glucose level.

Diabetic Oculomotor Nerve Palsy Displaying Enhancement of the Oculomotor Nerve in the Orbit and Cavernous Sinus on MRI

“…We and our colleagues found no statistical differences in improvement scores between patients with and those without 80 mg of methylprednisolone in addition to ­routine therapy [8]. Similar to the previous studies, >3 months were required for our patients to achieve complete restoration even with corticosteroid use.…”

“…There were also no significant differences in the levels of HbAlc and fasting blood glucose between the enhancement group and nonenhancement group, which suggested that blood glucose levels were not a major risk factor for the development of cranial nerve enhancement. Among patients with ischemic ONP, our colleagues did not detect differences in the levels of some common plasmatic inflammatory factors such as erythrocyte sedimentation rate and C-reactive protein between patients with and those without the enhancement of the oculomotor nerve [8]. Two patients presented abnormal oligoclonal bands and intrathecal IgG synthesis, and it suggested that some other inflammatory components may accompany nerve enhancement in a hyperglycemia-independent manner [18, 19].…”

“…Mark AS et al did not observe enhancement of the oculomotor nerve in 3 patients with diabetic ONP [6, 7], but no further studies had been performed. In clinical practice, we and our colleagues noticed that some patients with a clinical diagnosis of diabetic ONP presented with enhancement of the oculomotor nerve, and they were usually treated with corticosteroids just because of the nerve enhancement, which was habitually interpreted as inflammation [8]. Hence, through analyzation of these imaging presentations, our study aimed to determine whether such abnormalities could offer some clues to differentiate this etiology from others.…”

Cerebral small vessel disease as imaging biomarker predicting ocular cranial nerve palsy of presumed ischemic origin at admission

“…Currently, only a few studies have reported findings suggestive of OCNPi. One study group showed enhancement of the third cranial nerve on thin-section MRI but did not confirm the same findings of the fourth or sixth cranial nerves, and further validation is needed 18 , 19 . WMH was associated with OCNPi regardless of the cranial nerve involved in this study.…”

Case Report: Isolated, unilateral oculomotor palsy with anti-GQ1b antibody following COVID-19 vaccination

“…If this condition is associated with GQ1b, there may be changes in CSF protein. Contrast-enhanced findings of the oculomotor nerve on MRI have been reported in diabetic oculomotor palsy and idiopathic oculomotor palsy (Zhao et al 2021 1 ; Yang et al 2020 2 ). This finding is not specific to MFS.…”