Third Nerve Palsies: Review

Research hotspots and trends of oculomotor nerve palsy from 2001 to 2021 based on web of science: A bibliometric analysis

Background

Oculomotor nerve palsy (ONP) is a clinically occurring neurological disorder. Due to the complex anatomy and long travel distances of the oculomotor nerve, the causes of ONP vary and manifest in various ways. With continued interest in this area, it has become necessary to conduct a bibliometric study in ONP. This work aims to synthesize and visually identify current research themes and future trends in ONP through a literature-based analysis.

Method

Articles and reviews on ONP published from 2002 to 2021 were derived from the Web of Science Core Collection (WoSCC) database. We generated visual images and performed quantitative and qualitative analysis through an online bibliometric tool, Citespace and VOSviewer software.

Results

A total of 1,205 published articles were included in this analysis. The annual number of this area's publications is showing an overall upward trend, with the number of citations increasing every year, reaching 2,698 by 2021. The United States (367) and Japan (116) dominated the list with the most numerous articles published. The University of California Los Angeles in the USA is the institution that published the highest number of articles (47). Engle EC (23) and the JOURNAL OF NEUROSURGERY (46) are the most influential authors and journals in this field. The co-occurrence network analysis divided the keywords into five main research themes, which mainly include clinical manifestations of ONP, aneurysms, cerebral neurological symptoms, diseases with ONP as a complication, and other neurological disorders.

Conclusion

This study is the first comprehensive and systematic bibliometric analysis of the current state of global ONP research over the past 20 years. We organized current hotspots and expected trends and provided key information for exploring potential research frontiers in ONP.

Microvascular decompression for a patient with oculomotor palsy caused by posterior cerebral artery compression: A case report and literature review

BACKGROUND

Aneurysm compression, diabetes, and traumatic brain injury are well-known causative factors of oculomotor nerve palsy (ONP), while cases of ONP induced by neurovascular conflicts have rarely been reported in the medical community. Here, we report a typical case of ONP caused by right posterior cerebral artery (PCA) compression to increase neurosurgeons’ awareness of the disease and reduce misdiagnosis and recurrence.

CASE SUMMARY

A 54-year-old man without a known medical history presented with right ONP for the past 5 years. The patient presented to the hospital with right ptosis, diplopia, anisocoria (rt 5 mm, lt 2.5 mm), loss of duction in all directions, abduction, and light impaired pupillary reflexes. Magnetic resonance angiography and computed tomography venography examinations showed no phlebangioma, aneurysm, or intracranial lesion. After conducting oral glucose tolerance and prostigmin tests, diabetes and myasthenia gravis were excluded. Cranial nerve magnetic resonance imaging showed that the right PCA loop was in direct contact with the cisternal segment of the right oculomotor nerve (ON). Microvascular decompression (MVD) of the culprit vessel from the ON through a right subtemporal craniotomy was carried out, and the ONP symptoms were significantly relieved after 3 mo.

CONCLUSION

Vascular compression of the ON is a rare pathogeny of ONP that may be refractory to drug therapy and ophthalmic strabismus surgery. MVD is an effective treatment for ONP induced by neurovascular compression.

Oculomotor Nerve Palsy Due to Unusual Causes

BACKGROUND

An isolated oculomotor nerve (CN III) palsy is a diagnostic concern because of the potential for serious morbidity or life-threatening causes. We present 5 unusual causes of oculomotor nerve palsy that escaped initial diagnosis in order to raise awareness of their associated features that will facilitate correct diagnosis.

METHODS

This study consisted of a retrospective analysis of clinical features and imaging of 5 patients who were referred for neuro-ophthalmologic evaluation with presumed diagnosis of oculomotor nerve palsy of unknown reasons.

RESULTS

A complete CN III palsy and an inferior division CN III palsy were diagnosed with a schwannoma in the cavernous sinus and orbital apex portion, respectively; a middle-aged woman with aberrant regeneration was found to have a small meningioma; an adult man with ptosis was diagnosed with cyclic oculomotor paresis with spasms; and a patient after radiation was diagnosed with neuromyotonia.

CONCLUSIONS

Localizing the lesion of oculomotor nerve palsy and careful examination of the imaging is crucial. Aberrant regeneration, cyclic pupil changes, and past medical history of amblyopia, strabismus, or radiation are also very helpful for diagnosis.

Approach to patient with diplopia

This article presents an overview of the most important points a neurologist must remember when dealing with a patient complaining of diplopia. Patients with monocular diplopia and those with full ocular motility and comitant misalignment should be referred to an ophthalmologist and do not require further testing. Patients with recent onset of binocular diplopia who have associated "brainstem" symptoms should have an urgent brain MRI. All patients with 3rd cranial nerve palsy require urgent brain CTA to rule out compressive aneurysmal lesion. Management of patients over 50 years of age with microvascular risk factors with new onset of 6th nerve palsy is controversial: some image these patients at presentation while others choose a short period of observation as most of these patients would have a microvascular etiology for the 6th nerve palsy which should improve spontaneous in 2-3 months. All others with 6th nerve palsy require brain MRI with contrast. Patients with 4th palsy with hyperdeviation that worsens in downgaze should have an MRI with contrast and all others referred to an ophthalmologist. If there is more than one cranial nerve palsy, urgent neuroimaging should be performed with attention to cavernous sinus and superior orbital fissure. Ocular myasthenia should be suspected in patients with eye misalignment that does not fit a pattern for any cranial nerve palsy. Orbital pathology (most commonly thyroid eye disease) can result in restriction of ocular motility and has specific clinical signs associated with it.