Imaging of Oculomotor (Third) Cranial Nerve Palsy

Radiologic Imaging in Third Nerve Palsy: A Case Series Investigating Etiology, Patterns, and Clinical Implications

Third nerve palsy (TNP) is a neurologic condition characterized by dysfunction of the oculomotor nerve, leading to various ocular manifestations. Optic nerve evaluation is of utmost important among all cranial nerve palsies affecting the eye. Dysfunction of the third nerve can indicate an underlying neurologic emergency, such as cavernous arteriovenous fistula or giant cell arteritis. Early recognition and prompt treatment are vital in reversing the clinical and visual impairments associated with oculomotor nerve palsy. The typical presentation of isolated TNP involves deviation of the eye in a downward and outward direction, accompanied by ptosis (drooping of the eyelid) and, potentially, pupil involvement. The decision to use vascular imaging is influenced by factors such as age and clinical risk for an aneurysm. If TNP is isolated or partially present with pupil involvement, it suggests compression of the third nerve and necessitates immediate imaging. Given the serious implications of an intracranial aneurysm, physicians often prioritize vascular imaging during the initial evaluation, if available. However, if clinical findings indicate underlying microvascular ischemia, a delay in imaging may be considered. This case series aims to explore the role of radiologic imaging in understanding the etiology, patterns, and clinical implications of TNP.

Afterglow Implant for Arterial Embolization and Intraoperative Imaging

Transcatheter arterial embolization (TAE) is wildly used in clinical treatments. However, the online monitoring of the thrombosis formation is limited due to the challenges of the direct visualization of embolic agents and the real-time monitoring of dynamic blood flow. Thus, we developed a photochemical afterglow implant with strong afterglow intensity and a long lifetime for embolization and imaging. The liquid pre-implant injected into the abdominal aorta of mice was rapidly transformed into a hydrogel in situ to embolize the blood vessel. The vascular embolism position can be observed by the enhanced afterglow of the fixed implant, and the long lifetime of afterglow can also be used to monitor the effect of embolization. This provides an excellent candidate in bio-imaging to avoid the autofluorescence interference from continuous light excitation. The study suggests the potential usefulness of the implant as an embolic agent in TAE and artery imaging during a surgical procedure.

High-resolution magnetic resonance imaging in isolated, traumatic oculomotor nerve palsy: A case report

Traumatic, isolated oculomotor nerve palsy is a rare clinical finding and only few reports demonstrate associated magnetic resonance imaging (MRI) findings. Here, we present the case of a 70-year-old woman with left-sided oculomotor nerve palsy following a mild head trauma due to an e-bike accident. Post-traumatic cerebral computed tomography revealed punctiform hemorrhage in the left interpeduncular cistern and the following MRI confirmed an intraneural hemorrhage of the left oculomotor nerve. Nine weeks later, the follow-up MRI showed progressive atrophy and contrast-enhancement of the left oculomotor nerve. To support functional recovery, a treatment with intravenous corticosteroids was started. Six months later, the patient presented with improved oculomotor nerve function and partial recovery of ptosis and diplopia. In accordance, MRI demonstrated recurrent contrast-enhancement of the atrophic nerve. In conclusion, high-resolution MRI allows the reliable delineation of the oculomotor nerve and can support diagnosis in trauma patients with isolated oculomotor nerve palsy.

Cranial Nerve Imaging and Pathology

This review provides a symptom-driven approach to neuroimaging of disease processes affecting the cranial nerves. In addition to describing characteristic imaging appearances of a disease, the authors emphasize exceptions to the rules and neuroimaging pearls. The focus is on adult neurology although some important pediatric conditions are included. On reviewing this material, the reader should be able to (1) differentiate intra- and extra-axial causes of cranial nerve dysfunction and (2) appropriately use neuroimaging to investigate abnormalities of cranial nerve function.

Approach to a Patient with Diplopia in the Emergency Department

BACKGROUND

Diplopia can be the result of benign or life-threatening etiologies. It is imperative for the emergency physician to be proficient at assessing diplopia and recognize when urgent referral or neuroimaging is required.

OBJECTIVE

The first part of this review highlights a simple framework to arrive at the appropriate disposition of diplopic patients presenting to the emergency department (ED). The second part of this review provides more detail and further management strategies.

DISCUSSION

ED strategies for assessment of diplopia are discussed. Management strategies, such as when to image, what modality of imaging to use, and urgency of referral, are discussed in detail.

CONCLUSIONS

Unenhanced plain computed tomography (CT) of the head or orbits is largely not useful in the work-up of diplopia. Magnetic resonance imaging is preferred for ocular motor nerve palsies. Due to limited resources in the ED, patients with isolated fourth and sixth nerve palsies with the absence of other neurological signs on examination should be referred to Neurology or Ophthalmology for further work-up. All patients presenting with an acute isolated third nerve palsy should be imaged with CT and CT angiography of the brain to rule out a compressive aneurysm. Contrast-enhanced CT imaging of the brain and orbits would be indicated in suspected orbital apex syndrome or a retro-orbital mass, thyroid eye disease, or ocular trauma. CT and CT venogram should be considered in cases of suspected cavernous sinus thrombosis. In any patient over the age of 60 years presenting with recent (1 month) history of diplopia, inflammatory markers should be obtained to rule out giant cell arteritis.