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

Four-hour-delayed 3D-FLAIR MRIs in patients with acute unilateral peripheral vestibulopathy

OBJECTIVE

Conventionally, MRI aids in differentiating acute unilateral peripheral vestibulopathy/vestibular neuritis (AUPV/VN) from mimickers. Meanwhile, the diagnostic utility of MRIs dedicated to the inner ear remains to be elucidated for diagnosing AUPV/VN.

METHODS

We prospectively recruited 53 patients with AUPV/VN (mean age ± SD = 60 ± 15 years, 29 men). Initial MRIs were performed with a standard protocol, and an additional axial 3D-fluid-attenuated inversion recovery (3D-FLAIR) sequence was obtained 4 h after intravenous injection of gadoterate meglumine. Abnormal enhancement was defined as a signal intensity that exceeded the mean + 2SD value on the healthy side. The findings of neurotologic evaluation and MRIs were compared.

RESULTS

Overall, the inter-rater agreement for gadolinium enhancement was 0.886 (Cohen's kappa coefficient). Enhancement was observed in 26 patients (49%), most frequently in the vestibule (n = 20), followed by the anterior (n = 12), horizontal (HC, n = 8), posterior canal (n = 5), and superior (n = 3) and inferior (n = 1) vestibular nerves. In multivariable logistic regression analysis, the enhancement was associated with decreased HC gain in video head-impulse tests (p = 0.036), increased interaural difference in ocular vestibular-evoked myogenic potentials (p = 0.001), and a longer onset-to-MRI time span (p = 0.024). The sensitivity and specificity were 92.3% and 81.5%, respectively, with an area under the curve of 0.90 for predicting gadolinium enhancement.

INTERPRETATION

Robust gadolinium enhancement was observed on 4-hour-delayed 3D-FLAIR images in nearly half of the patients with AUPV/VN, with a good correlation with the results of neurotologic evaluation. The positivity may be determined by the extent of vestibular deficit, timing of imaging acquisition, and possibly by the underlying etiology causing AUPV/VN. MRIs may aid in delineating the involved structures in AUPV/VN.

Cavernous Sinus MRI Findings in Inflammatory and Ischemic Oculomotor Cranial Nerve Palsies

BACKGROUND

The significance of asymmetric enhancement on cavernous sinus MRIs in the differential diagnosis of ischemic and inflammatory oculomotor cranial nerve (OCN) palsies remains controversial. This study explored the cavernous sinus MRI findings for cavernous sinus idiopathic inflammation (inflammation group), microvascular ischemic OCN palsy (ischemic group), and ocular myasthenia gravis (OMG group) patients.

METHODS

A total of 66, 117, and 60 patients were included in the inflammation, ischemic, and OMG groups, respectively. Cavernous sinus MRIs were retrospectively analyzed.

RESULTS

The abnormality rates of cavernous sinus MRIs for OMG and ischemic groups were 41.7% (25/60) and 61.5% (72/117), respectively. Inconsistency rates between clinical topical diagnosis and imaging findings for inflammation and ischemic groups were 3.0% (2/66) and 13.7% (16/117), respectively ( P = 0.020). In the inflammation group, cavernous sinus thickness, thickening enhancement, and enhancing adjacent lesions were noted in 90.9% (60/66), 71.2% (47/66), and 25.8% (17/66) of the patients, whereas in the ischemic group, they were noted in 51.3% (60/117), 38.5% (45/117), and 0.9% (3/117) of the patients, respectively ( P < 0.001). Among ischemic CN III palsy patients, 55.5% (15/27) and 16.7% (2/12) of the cases had CN III enlargement and enhancement in the diabetic and nondiabetic groups, respectively ( P = 0.037).

CONCLUSIONS

Cavernous sinus MRI abnormalities can be explained by specific pathologic mechanisms of the primary disease based on the complex neuroanatomy. However, suspicious inflammatory changes cannot exclude the possibility of ischemia and over reliance on these findings should be avoided.

[Neuroradiology for the Ophthalmologist - Part 2 Efference]

Eye movements are a complex task requiring a large number of structures coordinated by three cranial nerves and their centres in the brainstem. Various pathologies may affect any part of the pathway controlling the eye movements and their diagnosis is often based on history and clinical examination. Modern advances in computed tomography and magnetic resonance imaging have recently added a valuable tool in the diagnosis of oculo-motor-related diseases.

A Case Report of Shingles Vaccine as a Cause of Third Nerve Palsy: A Novel Etiology

Vaccines are biological preparations widely used to provide acquired immunity against various life-threatening organisms and prevent severe complications of different infections. Vaccines typically demonstrate a high level of safety with minimal adverse effects. Nevertheless, it is crucial to enhance awareness when a potential new side effect emerges, as exemplified in the case discussed ahead. Despite the rarity of independent third nerve palsy occurrences, its association with the zoster vaccine remains unprecedented.

Recurrence and long-term outcomes of Tolosa-Hunt syndrome

BACKGROUND AND PURPOSE

Tolosa-Hunt Syndrome (THS) is a rare disorder, and detailed clinical information and treatment outcomes have yet to be fully elucidated. This study aims to investigate the clinical features and factors associated with the treatment outcomes of THS, as defined by the established diagnostic criteria.

METHODS

This study retrospectively recruited 91 patients with a diagnosis of THS from 2003 to 2020. We analyzed the clinical features and outcomes, the initial treatment response, recurrences, and the final treatment response.

RESULTS

Isolated ocular motor nerve palsy was the most common (82.4%) finding of ophthalmoplegia, involving the oculomotor nerve in more than half of the cases (52.0%). The MRI lesions were mostly observed in the cavernous sinus (94.5%) with an extracavernous extension in about one-third of them. Five patients showed only extracavernous lesions. A total of 25 (27.5%) patients experienced recurrence. Recurrence occurred during steroid tapering as part of the initial treatment in seven, while in 18 patients, it happened after the successful termination of the initial treatment. However, all patients achieved complete remission at the final. Age was associated with a decrease in initial symptom duration (HR = 1.023, CI = 1.004-1.044) as well as an increase in recurrence-free duration (HR = 0.944, CI = 0.911-0.978). High-dose corticosteroid treatment was associated with a decrease in initial symptom duration (HR = 1.642, CI = 1.001-2.695) and total treatment duration (HR = 2.203 CI = 1.302-3.730).

CONCLUSIONS

THS can recur frequently especially in younger but have a favorable prognosis. High-dose corticosteroids can be an effective initial treatment and reduce the total treatment duration.

Ocular motor nerve palsy in patients with diabetes: High-resolution MR imaging of nerve enhancement

OBJECTIVE

To evaluate the extent of signal abnormality in impaired ocular motor nerves using high signal and spatial resolution MRI sequences and to discuss the involvement of inflammatory or microvascular impairment in patients with diabetic ophthalmoplegia.

METHODS

We conducted a retrospective study of 10 patients referred for acute ocular motor nerve palsy in the context of diabetes mellitus from September 15th, 2021 to April 24th, 2022. 3T MRI evaluation included diffusion, 3D TOF, FLAIR, coronal STIR and post-injection 3D T1 SPACE DANTE sequences.

RESULTS

Ten patients were included: 9 males and 1 female aged from 46 to 79 years. Five patients presented with cranial nerve (CN) III palsy, and 5 presented with CN VI palsy. Third nerve palsy was pupil-sparing in 4 patients and pupil-involved in 1 patient. Pain was associated in all patients with CN III deficiencies and in 2 patients CN VI deficiencies. In all patients, MRI sequences ruled out mass effect and vascular pathology, such as acute stroke or aneurysm. Eight patients presented with STIR hypersignals, some with enlargement of the involved nerve. The diagnosis was confirmed through a post-injection 3D T1 SPACE DANTE sequence, which showed extended enhancement along the abnormal portion of the nerve.

CONCLUSION

High-resolution MRI evaluation of diplopia in diabetic patients is used to rule out a diagnosis of acute stroke and contributes to the positive diagnosis of ocular motor nerve impairment, possibly combining the influences of inflammatory and microvascular phenomena. Dedicated MR imaging should be included in the initial diagnosis and longitudinal follow-up of patients with diabetic ophthalmoplegia.

Enhancement of the Third Cranial Nerve due to Microvascular Ischemia: Case Report

Third nerve palsy (3NP) commonly results from a microvascular ischemic insult. Typically, computed tomography or magnetic resonance angiography is performed to rule out a posterior communicating artery aneurysm. If this is normal and the pupil is spared, patients are often observed with the expectation of spontaneous improvement within 3 months. Oculomotor nerve enhancement on MRI with contrast in the context of microvascular 3NP is not well recognized. Here, we report third nerve enhancement in a case of a 67-year-old woman with diabetes and other vascular risk factors who presented with left eye ptosis and a limitation of extraocular eye movements consistent with 3NP. She underwent an extensive inflammatory workup that was negative and the diagnosis of a microvascular 3NP was made. A spontaneous recovery was achieved within 3 months, and she did not receive any treatment. She remained clinically well, although increased T2 signal in the oculomotor nerve persisted after 10 months. While the exact mechanism remains unknown, it is likely that microvascular ischemic insults lead to intrinsic changes of the third nerve that may result in enhancement and persistent T2 signal. Additional workup for inflammatory causes of 3NP may not be required when enhancement of the oculomotor nerve is seen in the right clinical context. Further study is required to understand why enhancement is a rarely reported finding in patients with microvascular ischemic 3NP.

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

Ocular cranial nerve palsy of presumed ischemic origin (OCNPi) is the most common type of ocular cranial nerve palsy (OCNP) in patients aged ≥ 50 years; however, no definite diagnostic test exists. As diagnostic criteria include clinical improvement, diagnoses are often delayed. Diagnostic biomarkers for OCNPi are required; we hypothesized that cerebral small vessel disease is associated with OCNPi. We analyzed 646 consecutive patients aged ≥ 50 years with isolated unilateral OCNP who underwent work-ups at two referral hospitals. White matter hyperintensities (WMHs), silent infarctions, and cerebral microbleeds (CMBs) were assessed. In multivariate analyses, mild (grades 1-3) and moderate to severe (grades 4-6) WMHs were significantly associated with OCNPi compared to OCNP of other origins (odds ratio [OR] 3.51, 95% confidence interval [CI] 1.91-6.43, P < 0.001; OR 3.47, 95% CI 1.42-8.48, P = 0.006, respectively). Silent infarction and CMBs did not remain associated (OR 0.96, 95% CI 0.54-1.70, P = 0.870; OR 0.55, 95% CI 0.28-1.08, P = 0.080, respectively). Associations between WMH and OCNPi remained after excluding patients with vascular risk factors. In conclusion, the presence of WMH could independently predict ischemic origin in patients with isolated unilateral OCNP at early stage of admission.

Clinical and Cerebrospinal Fluid Characteristics in 55 Cases of Tolosa-Hunt Syndrome: A Retrospective Analytical Study

BACKGROUND

Several case series of patients with Tolosa-Hunt syndrome have been described in the literature; however, few studies have focused on the cerebrospinal fluid (CSF) characteristics. This study aimed to analyse the CSF characteristics of patients with Tolosa-Hunt syndrome.

METHODS

Fifty-five patients who fulfilled the 3rd Edition of the International Classification of Headache Disorders diagnostic criteria for Tolosa-Hunt syndrome were included in this study. We retrospectively analysed data on CSF parameters, imaging findings, and clinical characteristics of these patients.

RESULTS

Oligoclonal bands (OBs) were detected in the CSF of 13 (13/44, 29.5%) patients. The sex ratio was balanced. The mean age at onset of Tolosa-Hunt syndrome was 46.9 ± 10.23 (range 22-72) years. Eight (8/13, 61.5%) patients had multiple cranial nerve palsies. Lesions limited to the cavernous sinus were found on magnetic resonance imaging in 7 (7/13, 53.8%) patients. OBs were significantly detected more frequently in patients whose samples were evaluated less than 30 days after the onset of this diseases (p = 0.026); however, there were no significant differences in the protein level (p = 0.360) and IgG synthesis rate (p = 0.614).

CONCLUSIONS

The detection of OBs in the CSF of patients with Tolosa-Hunt syndrome was not rare. It would be interesting to follow-up patients with OBs to determine whether they eventually developed an otherwise more specific inflammatory diagnosis.

Magnetic Resonance Imaging in Diplopia: Neural Pathway, Imaging, and Clinical Correlation

The role of magnetic resonance imaging (MRI) in diplopia is to diagnose various diseases that occur along the neural pathway governing eye movement. However, the lesions are frequently small and subtle and are therefore difficult to detect on MRI. This article presents representative cases of diseases that cause diplopia. The purpose of this article was to 1) describe the anatomy of the neural pathway governing eye movement, 2) recommend optimal MRI targets and protocols for the diagnosis of diseases causing diplopia, 3) correlate MRI findings with misalignment of the eyes (i.e., strabismus), and 4) help familiarize the reader with the imaging diagnosis of diplopia.

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

INTRODUCTION

Imaging data were scarce on diabetic oculomotor nerve palsy (ONP). Our study explored the MRI features and their clinical implications for diabetic ONP.

METHODS

Fifty-nine patients with a clinical diagnosis of diabetic ONP were recruited from our department between January 2015 and December 2019. Orbital MRI was retrospectively analyzed, and follow-up scans were obtained for 5 patients. Based on the ocular motor nerve palsy scale, the difference in the scores on the first and last hospital days was defined as the improvement score and was used to assess the treatment effects in all.

RESULTS

Thirty-eight (64.41%) patients presented thickening and enhancement of the cavernous segment and inferior division of the intraorbital segment of the ipsilateral oculomotor nerve, with the cisternal segment spared in all. After complete resolution of symptoms, follow-up MRI in 5 patients revealed that the enhancement was less obvious compared with the previous images. 6 patients in the enhancement group and 4 patients in the nonenhancement group were treated with 80 mg of methylprednisolone. Significant differences were not detected in the median improvement scores between patients with and those without corticosteroid use (p = 0.240).

CONCLUSION

Thickening and enhancement of the unilateral oculomotor nerve were common imaging findings in diabetic ONP, and they persisted after complete resolution of symptoms in some patients. The cavernous segment and the inferior division of the intraorbital segment were simultaneously involved, and the cisternal segment was often spared. Refraining from corticosteroids was recommended even with nerve enhancement.