Magnetic resonance angiography and clinical evaluation of third nerve palsies and posterior communicating artery aneurysms

Clinical Prediction Score for Early Neuroimaging in Acquired Isolated Oculomotor Nerve Palsy

Purpose

An immediate neuroimaging investigation in patients with isolated oculomotor nerve palsy (ONP) remains controversial. We aimed to develop a clinical prediction score to determine whether or not acquired isolated ONP patients require prompt imaging.

Methods

A retrospective study was performed. Demographic data and clinical presentations were collected to determine predictive factors favored for early brain imaging using multivariate logistic regression analysis.

Results

Ninety-seven eyes of 96 patients diagnosed with isolated ONP were included. Forty-one eyes (42.3%) were caused by ischemia, while the other 56 eyes (57.7%) were caused by non-ischemic etiologies, namely aneurysm (n = 22), trauma (n = 18), inflammation (n = 5), tumor (n = 4), and others (n = 7). Eighty-two eyes (84.5%) had undergone neuroimaging study due to initially suspected non-ischemic causes. Only 36 (43.9%) revealed concordant diagnosis. The potential clinical predictors favored for neuroimaging using multivariate logistic regression analysis were age 10‒50 years (adjusted odds ratio [aOR] 9.01, 95% CI: 1.25‒64.8), age 51‒70 years (aOR 1.71, 95% CI: 0.46‒6.35), history of head trauma (aOR 7.14, 95% CI: 1.19‒42.9), absence of vascular risk factors (aOR 3.85, 95% CI: 1.23‒12.1), and poor pupillary response (aOR 6.96, 95% CI: 1.99‒24.3). The predictor scores with an area under the ROC curve of 0.852 were 4, 1, 4, 3, and 4, respectively. The optimum cut-point was 3 for a sensitivity of 96% and specificity of 44%.

Conclusion

Patients with acquired isolated ONP should be considered early neuroimaging studies when they are younger than 50 years old, have a history of head trauma, have no history of vascular risk factors, or have poor pupillary reaction.

Guidelines for radiographic imaging of cranial neuropathies

Disruption of the complex pathways of the 12 cranial nerves can occur at any site along their course, and many, varied pathologic processes may initially manifest as dysfunction and neuropathy. Radiographic imaging (computed topography or magnetic resonance imaging) is frequently used to evaluate cranial neuropathies; however, indications for imaging and imaging method of choice vary considerably between the cranial nerves. The purpose of this review is to provide an analysis of the diagnostic yield and the most clinically appropriate means to evaluate cranial neuropathies using radiographic imaging. Using the PubMed MEDLINE NCBI database, a total of 49,079 articles' results were retrieved on September 20, 2014. Scholarly articles that discuss the etiology, incidence, and use of imaging in the context of evaluation and diagnostic yield of the 12 cranial nerves were evaluated for the purposes of this review. We combined primary research, guidelines, and best practice recommendations to create a practical framework for the radiographic evaluation of cranial neuropathies.

Flow-diverter stents for endovascular management of non-fetal posterior communicating artery aneurysms-analysis on aneurysm occlusion, vessel patency, and patient outcome

Background Use of flow-diversion technology in the treatment of incidental and recanalized posterior communicating artery (PComA) aneurysms. Methods Patients treated with the Pipeline embolization device (PED) for PComA aneurysms were identified and included in our retrospective analysis. We evaluated aneurysm characteristics, modified Rankin Scale score (mRS) on admission, angiography follow-up, and patient clinical outcome at discharge, at three to nine months, and at 12-18 months. Results We included 56 patients with a mean age of 56 years. Median mRS on admission was 0. All aneurysms involved the PComA and were either new findings or found to have shown recanalization at angiography follow-up from previous coil embolization or surgical clipping. Intraprocedural device foreshortening was observed in one case requiring additional placement of a self-expanding stent. One intraprocedural aneurysm rupture occurred because of a broken distal wire. This patient had an mRS of 4 after the procedure. Three- to nine-month and 12- to 18-month follow-up angiography showed near complete or complete aneurysm occlusion in most cases. Minimal to mild intimal hyperplasia was seen in five cases at three to nine months. PComA patency over time showed 29 of 46 initially patent vessels still patent at six months. Thirteen and seven PComAs showed progressive decrease in flow at three to nine months and 12-18 months, respectively. Median mRS remained 0 for all patients at three- to nine-month and 12- to 18-month follow-up. Conclusions Our preliminary results show that flow-diversion technology is an effective and safe treatment option. Larger studies with long-term follow-up are needed to validate our promising results.

Imaging of Oculomotor (Third) Cranial Nerve Palsy

When evaluating a patient with an oculomotor cranial nerve palsy it may be unclear which neuroimaging modality is optimal; MRI, MR angiography, computed tomography, computed tomography angiography, or intraarterial digital subtraction angiography. We discuss the clinical guidelines in the evaluation of such patients and review neuroimaging techniques, outlining the advantages and disadvantages of each.

Microvascular Non-Arteritic Ocular Motor Nerve Palsies-What We Know and How Should We Treat?

Patients with isolated unilateral pupil-sparing third or isolated fourth or sixth nerve palsies over 50 years are often diagnosed with "microvascular extraocular palsies". This condition and its management provoke divergent opinions. We review the literature and describe the incidence, pathology, clinical presentation, yield of imaging, and management. A retrospective diagnosis of exclusion has little practical use. We suggest a pragmatic approach to diagnosis, investigation, and management from initial presentation.

Underdiagnosis of posterior communicating artery aneurysm in noninvasive brain vascular studies

BACKGROUND

Expert interpretation of modern noninvasive neuroimaging such as computed tomographic angiography (CTA) or MRA should detect nearly all aneurysms responsible for an isolated third nerve palsy. Whether a catheter angiogram should still be obtained in cases with negative CTA or MRA remains debated and mostly relies on whether the noninvasive study was correctly performed and interpreted. The aim of our study was to review the diagnostic strategies used to evaluate patients with isolated aneurysmal third nerve palsy at a large academic center.

METHODS

Retrospective review of all cases with posterior communicating artery (PCom A) aneurysmal third nerve palsies seen at our institution since 2001.

RESULTS

We identified 417 cases with third nerve palsy, aneurysm, or subarachnoid hemorrhage, among which 17 presented with an acute isolated painful third nerve palsy related to an ipsilateral PCom A aneurysm (mean age: 52 years; range: 33-83 years). Patients were classified into 3 groups based on the results of the noninvasive imaging obtained at initial presentation. Group I included 4 cases with subarachnoid hemorrhage on initial noncontrast head CT initially obtained in an emergency department for evaluation of their isolated third nerve palsy. Group II included 5 cases with isolated third nerve palsy and normal noncontrast head CT at presentation, immediately correctly diagnosed with a PCom A aneurysm at the referring institution. Group III included the 8 remaining cases who all had aneurysms that were missed on noninvasive studies at outside institutions. Review of these outside studies at our institution showed a PCom A aneurysm, confirming misinterpretation of these tests by the outside radiologists, rather than inadequate technique. Absence of specific training in neuroradiology and inaccurate clinical information provided to the interpreting radiologist were associated with test misinterpretation at the outside institutions. The average size of PCom A aneurysms causing an isolated third nerve palsy across all 3 groups was 7.3 mm and was similar in each group.

CONCLUSION

Our study suggests that aside from an accurate history, the training and experience of the interpreting radiologist is probably the most important factor in determining the reliability of a noninvasive scan in patients with isolated third nerve palsies.

Headache attributable to disorders of the eye

Sensory innervation to the eye and periocular area arises from the ophthalmic branch of the trigeminal nerve. Thus, ocular, orbital, and systemic disorders may produce head pain with ocular signs and symptoms. Whereas some of these entities have characteristic diagnostic features, others mimic primary headache disorders such as migraine and cluster headache. This article reviews common ocular and neuro-ophthalmic conditions that are accompanied by pain in or near the eye.

Early endovascular management of oculomotor nerve palsy associated with posterior communicating artery aneurysms

Palsy of the third cranial nerve (oculomotor nerve, CNIII) is a well-known clinical presentation of posterior communicating artery (P-com) aneurysm. We report a series of 11 patients with partial or complete third nerve palsy secondary to P-com aneurysm. All were treated with endovascular embolization within seven days of symptom onset. Third nerve palsy symptoms resolved in 7/11 (64%), improved in 2/11 (18%) and did not change in 2/11 (18%) patients.

Imaging of intracranial aneurysms causing isolated third cranial nerve palsy

Isolated third cranial nerve palsies may be caused by compressive intracranial aneurysms located at the junction of the internal carotid and posterior communicating arteries or, less commonly, at the apex of the basilar artery or its junction with the superior cerebellar or posterior cerebral arteries. Such aneurysms typically measure at least 4 mm in diameter. Technical improvements in noninvasive techniques, including CT and MRA, have yielded a detection rate of such aneurysms that approaches that of catheter cerebral angiography (CCA), which itself carries a small but serious risk. Multidetector technology, which allows a rapid scan time, has promoted CT to the first choice for investigating aneurysms in this setting except when dye or radiation exposure is unacceptable, as with pregnant women, children, and those with renal or severe cardiac disease. Major impediments to accurate detection are a lack of availability of trained technicians, who must perform manipulation of the raw imaging data ("post-processing"), and a paucity of certified neuroradiologists with the time, skill, and experience to devote to interpreting difficult cases. To avoid diagnostic mishaps, noninvasive studies should be reviewed by at least one neuroradiologist before aneurysm is rejected as the cause or before the patient undergoes CCA.

The dilated pupil: an update

The dilated pupil can present a significant challenge to the clinician. Although in most cases a complete history and physical examination is sufficient to make an accurate diagnosis, selected patients will require further investigation, including pharmacologic testing and neuroimaging. This review outlines the physiology, clinical features, and diagnostic approach to the most important causes of the dilated pupil. Particular attention is given to recent publications on this topic.

Diagnosis and management of third nerve palsy

PURPOSE OF REVIEW

To provide clinically relevant information regarding the diagnosis, etiology, work-up and treatment of third cranial nerve palsies, while incorporating information from current publications and providing our opinions on these studies.

RECENT FINDINGS

In the past year, an important study focused on the confirmation of current neuro-imaging guidelines for third cranial nerve palsies. Recent case reports have highlighted etiologies such as giant cell arteritis, trauma, neuro-syphilis and demyelination secondary to infliximab and multiple sclerosis. Surgically, newer studies have focused on globe-tethering procedures for correcting strabismus and the use of frontalis suspension for correcting ptosis. Improved imaging technology with high-resolution magnetic resonance imaging (hr-MRI) allows for direct visualization of the entire nerve path and the affected muscles.

SUMMARY

Management of a third nerve palsy depends upon localization of the causative lesion and determination of the underlying etiology. Once these issues are addressed, strabismus surgery can be both challenging and rewarding in these complex patients.