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

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.

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.

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.