Underdiagnosis of posterior communicating artery aneurysm in noninvasive brain vascular studies

Diagnostic Error in Neuro-ophthalmology: Avenues to Improve

Purpose of Review

To highlight potential avenues to reduce preventable diagnostic error of neuro-ophthalmic conditions and avoid patient harm.

Recent Findings

Recent prospective studies and studies of patient harm have advanced our understanding. Additionally, recent studies of fundus photography, telemedicine, and artificial intelligence highlight potential avenues for diagnostic improvement.

Summary

Diagnostic error of neuro-ophthalmic conditions can often be traced to failure to gather an adequate history, perform a complete physical exam, obtain adequate/appropriate neuroimaging, and generate a complete, appropriate differential diagnosis. Improving triage and identification of neuro-ophthalmic conditions by other providers and increasing access to subspecialty neuro-ophthalmology evaluation are essential avenues to reduce diagnostic error. Further research should evaluate the relationship between misdiagnosis and patient harm, and help identify the most impactful potential targets for improvement.

Multidimensional Deep Learning Reduces False-Positives in the Automated Detection of Cerebral Aneurysms on Time-Of-Flight Magnetic Resonance Angiography: A Multi-Center Study

Current deep learning-based cerebral aneurysm detection demonstrates high sensitivity, but produces numerous false-positives (FPs), which hampers clinical application of automated detection systems for time-of-flight magnetic resonance angiography. To reduce FPs while maintaining high sensitivity, we developed a multidimensional convolutional neural network (MD-CNN) designed to unite planar and stereoscopic information about aneurysms. This retrospective study enrolled time-of-flight magnetic resonance angiography images of cerebral aneurysms from three institutions from June 2006 to April 2019. In the internal test, 80% of the entire data set was used for model training and 20% for the test, while for the external tests, data from different pairs of the three institutions were used for training and the remaining one for testing. Images containing aneurysms > 15 mm and images without aneurysms were excluded. Three deep learning models [planar information-only (2D-CNN), stereoscopic information-only (3D-CNN), and multidimensional information (MD-CNN)] were trained to classify whether the voxels contained aneurysms, and they were evaluated on each test. The performance of each model was assessed using free-response operating characteristic curves. In total, 732 aneurysms (5.9 ± 2.5 mm) of 559 cases (327, 120, and 112 from institutes A, B, and C; 469 and 263 for 1.5T and 3.0T MRI) were included in this study. In the internal test, the highest sensitivities were 80.4, 87.4, and 82.5%, and the FPs were 6.1, 7.1, and 5.0 FPs/case at a fixed sensitivity of 80% for the 2D-CNN, 3D-CNN, and MD-CNN, respectively. In the external test, the highest sensitivities were 82.1, 86.5, and 89.1%, and 5.9, 7.4, and 4.2 FPs/cases for them, respectively. MD-CNN was a new approach to maintain sensitivity and reduce the FPs simultaneously.

Failure to Obtain Urgent Arterial Imaging in Acute Third Nerve Palsies

BACKGROUND

Isolated third nerve palsy may indicate an expanding posterior communicating artery aneurysm, thus necessitating urgent arterial imaging. This study aims to assess the rate and duration of delays in arterial imaging for new isolated third nerve palsies, identify potential causes of delay, and evaluate instances of delay-related patient harm.

METHODS

In this cross-sectional study, we retrospectively reviewed 110 patient charts (aged 18 years and older) seen between November 2012 and June 2020 at the neuro-ophthalmology clinic and by the inpatient ophthalmology consultation service at a tertiary institution. All patients were referred for suspicion of or had a final diagnosis of third nerve palsy. Demographics, referral encounter details, physical examination findings, final diagnoses, timing of arterial imaging, etiologies of third nerve palsy, and details of patient harm were collected.

RESULTS

Of the 110 included patients, 62 (56.4%) were women, 88 (80%) were white, and the mean age was 61.8 ± 14.6 years. Forty (36.4%) patients received arterial imaging urgently. Patients suspected of third nerve palsy were not more likely to be sent for urgent evaluation (P = 0.29) or arterial imaging (P = 0.082) than patients in whom the referring doctor did not suspect palsy. Seventy-eight of 95 (82%) patients with a final diagnosis of third nerve palsy were correctly identified by referring providers. Of the 20 patients without any arterial imaging before neuro-ophthalmology consultation, there was a median delay of 24 days from symptom onset to imaging, and a median delay of 12.5 days between first medical contact for their symptoms and imaging. One patient was harmed as a result of delayed imaging.

CONCLUSIONS

Third nerve palsies were typically identified correctly, but referring providers failed to recognize the urgency of arterial imaging to rule out an aneurysmal etiology. Raising awareness of the urgency of arterial imaging may improve patient safety.

Importance of the "Rule of the Pupil" in the Modern Neuroimaging Era

ABSTRACT

The "Rule of the Pupil" states that when aneurysms compress the oculomotor nerve, a dilated or sluggishly reactive pupil will result. In previous decades, when cerebral angiography was required to detect an intracranial aneurysm, the "Rule of the Pupil" was used to determine the relative risk of angiography and the likelihood of aneurysmal compression in patients with third nerve palsies (3NPs). Noninvasive imaging including computed tomography angiography (CTA) and magnetic resonance angiography has become readily accessible and can detect all aneurysms large enough to cause 3NPs. It is therefore recommended that all patients with 3NP undergo neuroimaging regardless of pupil status because the consequences of missing an aneurysm are high. The question therefore remains as to whether the "Rule of the Pupil" still has relevance in today's era of modern neuroimaging. We describe a 73-year-old man who developed a left complete, pupil-sparing 3NP and was found to have a paraclinoid meningioma in the left cavernous sinus. As compressive lesions are expected to impair the iris sphincter muscle, no intervention was recommended and his 3NP spontaneously improved within 3 months. We also describe a 54-year-old woman with diabetes and a complete 3NP with a dilated, nonreactive pupil. Initial CTA was reported as normal, but re-review of imaging revealed a posterior communicating artery aneurysm and immediate intervention to coil the aneurysm occurred. The "Rule of the Pupil" is still important in the modern neuroimaging era as demonstrated in cases of incidentally found lesions along the course of the oculomotor nerve and missed radiological findings.

Patient Harm Due to Diagnostic Error of Neuro-Ophthalmologic Conditions

PURPOSE

To prospectively examine diagnostic error of neuro-ophthalmic conditions and resultant harm at multiple sites.

DESIGN

Prospective, cross-sectional study.

PARTICIPANTS

A total of 496 consecutive adult new patients seen at 3 university-based neuro-ophthalmology clinics in the United States in 2019 to 2020.

METHODS

Collected data regarding demographics, prior care, referral diagnosis, final diagnosis, diagnostic testing, treatment, patient disposition, and impact of the neuro-ophthalmologic encounter. For misdiagnosed patients, we identified the cause of error using the Diagnosis Error Evaluation and Research (DEER) taxonomy tool and whether the patient experienced harm due to the misdiagnosis.

MAIN OUTCOME MEASURES

The primary outcome was whether patients who were misdiagnosed before neuro-ophthalmology referral experienced harm as a result of the misdiagnosis. Secondary outcomes included appropriateness of referrals, misdiagnosis rate, interventions undergone before referral, and the primary type of diagnostic error.

RESULTS

Referral diagnosis was incorrect in 49% of cases. A total of 26% of misdiagnosed patients experienced harm, which could have been prevented by earlier referral to neuro-ophthalmology in 97%. Patients experienced inappropriate laboratory testing, diagnostic imaging, or treatment before referral in 23%, with higher rates for patients misdiagnosed before referral (34% of patients vs. 13% with a correct referral diagnosis, P < 0.0001). Seventy-six percent of inappropriate referrals were misdiagnosed, compared with 45% of appropriate referrals (P < 0.0001). The most common reasons for referral were optic neuritis or optic neuropathy (21%), papilledema (18%), diplopia or cranial nerve palsies (16%), and unspecified vision loss (11%). The most common sources of diagnostic error were the physical examination (36%), generation of a complete differential diagnosis (24%), history taking (24%), and use or interpretation of diagnostic testing (13%). In 489 of 496 patients (99%), neuro-ophthalmology consultation (NOC) affected patient care. In 2% of cases, neuro-ophthalmology directly saved the patient's life or vision; in an additional 10%, harmful treatment was avoided or appropriate urgent referral was provided; and in an additional 48%, neuro-ophthalmology provided a diagnosis and direction to the patient's care.

CONCLUSIONS

Misdiagnosis of neuro-ophthalmic conditions, mismanagement before referral, and preventable harm are common. Early appropriate referral to neuro-ophthalmology may prevent patient harm.

Diagnostic Error of Neuro-ophthalmologic Conditions: State of the Science

BACKGROUND

Diagnostic error is prevalent and costly, occurring in up to 15% of US medical encounters and affecting up to 5% of the US population. One-third of malpractice payments are related to diagnostic error. A complex and specialized diagnostic process makes neuro-ophthalmologic conditions particularly vulnerable to diagnostic error.

EVIDENCE ACQUISITION

English-language literature on diagnostic errors in neuro-ophthalmology and neurology was identified through electronic search of PubMed and Google Scholar and hand search.

RESULTS

Studies investigating diagnostic error of neuro-ophthalmologic conditions have revealed misdiagnosis rates as high as 60%-70% before evaluation by a neuro-ophthalmology specialist, resulting in unnecessary tests and treatments. Correct performance and interpretation of the physical examination, appropriate ordering and interpretation of neuroimaging tests, and generation of a differential diagnosis were identified as pitfalls in the diagnostic process. Most studies did not directly assess patient harms or financial costs of diagnostic error.

CONCLUSIONS

As an emerging field, diagnostic error in neuro-ophthalmology offers rich opportunities for further research and improvement of quality of care.

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.

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.

Diagnostic Errors in Initial Misdiagnosis of Optic Nerve Sheath Meningiomas

Importance

Diagnostic errors can lead to the initial misdiagnosis of optic nerve sheath meningiomas (ONSM), which can lead to vision loss.

Objective

To identify factors contributing to the initial misdiagnosis of ONSM.

Design, Setting, and Participants

We retrospectively reviewed 35 of 39 patients with unilateral ONSM (89.7%) who were seen in the tertiary neuro-ophthalmology practice at Emory University School of Medicine between January 2002 and March 2017. The Diagnosis Error Evaluation and Research taxonomy tool was applied to cases with missed/delayed diagnoses.

Exposures

Evaluation in a neuro-ophthalmology clinic.

Main Outcomes and Measures

Identifying the cause of diagnostic errors for patients who initially received a misdiagnosis who were found to have ONSM.

Results

Of 35 patients with unilateral ONSM (30 women [85.7%]; mean [SD] age, 45.26 [15.73] years), 25 (71%) had a diagnosis delayed for a mean (SD) of 62.60 (89.26) months. The most common diagnostic error (19 of 25 [76%]) was clinician assessment failure (errors in hypothesis generation and weighing), followed by errors in diagnostic testing (15 of 25 [60%]). The most common initial misdiagnosis was optic neuritis (12 of 25 [48%]), followed by the failure to recognize optic neuropathy in patients with ocular disorders. Five patients who received a misdiagnosis (20%) underwent unnecessary lumbar puncture, 12 patients (48%) unnecessary laboratory tests, and 6 patients (24%) unnecessary steroid treatment. Among the 16 patients who initially received a misdiagnosis that was later correctly diagnosed at our institution, 11 (68.8%) had prior magnetic resonance imaging (MRI) results that were read as healthy; 5 (45.5%) showed ONSM but were misread by a non-neuroradiologist and 6 (54.5%) were performed incorrectly (no orbital sequence or contrast). Sixteen of the 25 patients (64%) had a poor visual outcome.

Conclusions and Relevance

Biased preestablished diagnoses, inaccurate funduscopic examinations, a failure to order the correct test (MRI brain/orbits with contrast), and a failure to correctly interpret MRI results were the most common sources of diagnostic errors and delayed diagnosis with worse visual outcomes and increased cost (more visits and tests). Easier access to neuro-ophthalmologists, improved diagnostic strategies, and education regarding neuroimaging should help prevent diagnostic errors.

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.

Referral Patterns in Neuro-Ophthalmology

BACKGROUND

Neuro-ophthalmologists specialize in complex, urgent, vision- and life-threatening problems, diagnostic dilemmas, and management of complex work-ups. Access is currently limited by the relatively small number of neuro-ophthalmologists, and consequently, patients may be affected by incorrect or delayed diagnosis. The objective of this study is to analyze referral patterns to neuro-ophthalmologists, characterize rates of misdiagnoses and delayed diagnoses in patients ultimately referred, and delineate outcomes after neuro-ophthalmologic evaluation.

METHODS

Retrospective chart review of 300 new patients seen over 45 randomly chosen days between June 2011 and June 2015 in one tertiary care neuro-ophthalmology clinic. Demographics, distance traveled, time between onset and neuro-ophthalmology consultation (NOC), time between appointment request and NOC, number and types of providers seen before referral, unnecessary tests before referral, referral diagnoses, final diagnoses, and impact of the NOC on outcome were collected.

RESULTS

Patients traveled a median of 36.5 miles (interquartile range [IQR]: 20-85). Median time from symptom onset was 210 days (IQR: 70-1,100). Median time from referral to NOC was 34 days (IQR: 7-86), with peaks at one week (urgent requests) and 13 weeks (routine requests). Median number of previous providers seen was 2 (IQR: 2-4; range:0-10), and 102 patients (34%) had seen multiple providers within the same specialty before referral. Patients were most commonly referred for NOC by ophthalmologists (41% of referrals). Eighty-one percent (242/300) of referrals to neuro-ophthalmology were appropriate referrals. Of the 300 patients referred, 247 (82%) were complex or very complex; 119 (40%) were misdiagnosed; 147 (49%) were at least partially misdiagnosed; and 22 (7%) had unknown diagnoses. Women were more likely to be at least partially misdiagnosed-108 of 188 (57%) vs 39 of 112 (35%) of men (P < 0.001). Mismanagement or delay in care occurred in 85 (28%), unnecessary tests in 56 (19%), unnecessary consultations in 64 (22%), and imaging misinterpretation in 16 (5%). Neuro-ophthalmologists played a major role in directing treatment, such as preserving vision, preventing life-threatening complications, or avoiding harmful treatment in 62 (21%) patients.

CONCLUSIONS

Most referrals to neuro-ophthalmologists are appropriate, but many are delayed. Misdiagnosis before referral is common. Neuro-ophthalmologists often prevent vision- and life-threatening complications.

Convolutional Neural Networks for the Detection and Measurement of Cerebral Aneurysms on Magnetic Resonance Angiography

Aneurysm size correlates with rupture risk and is important for treatment planning. User annotation of aneurysm size is slow and tedious, particularly for large data sets. Geometric shortcuts to compute size have been shown to be inaccurate, particularly for nonstandard aneurysm geometries. To develop and train a convolutional neural network (CNN) to detect and measure cerebral aneurysms from magnetic resonance angiography (MRA) automatically and without geometric shortcuts. In step 1, a CNN based on the U-net architecture was trained on 250 MRA maximum intensity projection (MIP) images, then applied to a testing set. In step 2, the trained CNN was applied to a separate set of 14 basilar tip aneurysms for size prediction. Step 1-the CNN successfully identified aneurysms in 85/86 (98.8% of) testing set cases, with a receiver operating characteristic (ROC) area-under-the-curve of 0.87. Step 2-automated basilar tip aneurysm linear size differed from radiologist-traced aneurysm size on average by 2.01 mm, or 30%. The CNN aneurysm area differed from radiologist-derived area on average by 8.1 mm2 or 27%. CNN correctly predicted the area trend for the set of aneurysms. This approach is to our knowledge the first using CNNs to derive aneurysm size. In particular, we demonstrate the clinically pertinent application of computing maximal aneurysm one-dimensional size and two-dimensional area. We propose that future work can apply this to facilitate pre-treatment planning and possibly identify previously missed aneurysms in retrospective assessment.

Diagnostic error and neuro-ophthalmology

PURPOSE OF REVIEW

This review summarizes the recent literature on diagnostic error relevant to the practice of neuro-ophthalmology, and evaluates the potential for increased access to neuro-ophthalmology to decrease rates of diagnostic error, thereby reducing medical harm and spending on unnecessary tests and treatments.

RECENT FINDINGS

Despite medical advances, current research continues to show alarmingly high rates of diagnostic error. Research into diagnostic error shows that many of these errors can be traced to cognitive errors. Recent studies on diagnostic problems relevant to neuro-ophthalmology, including studies of misdiagnosis of posterior communicating artery aneurysms, idiopathic intracranial hypertension, optic neuritis, and optic nerve sheath meningiomas, have identified major causes of diagnostic error in these conditions.

SUMMARY

Studies on diagnostic error in neuro-ophthalmologic conditions show that prior to evaluation by a neuro-ophthalmologist, patients may undergo unnecessary tests and treatments that are costly and potentially harmful. Further research on diagnostic error will inform better utilization of neuro-ophthalmologists as a resource to decrease diagnostic error.

Intracranial Aneurysms of Neuro-Ophthalmologic Relevance

BACKGROUND

Intracranial saccular aneurysms are acquired lesions that often present with neuro-ophthalmologic symptoms and signs. Recent advances in neurosurgical techniques, endovascular treatments, and neurocritical care have improved the optimal management of symptomatic unruptured aneurysms, but whether the chosen treatment has an impact on neuro-ophthalmologic outcomes remains debated.

EVIDENCE ACQUISITION

A review of the literature focused on neuro-ophthalmic manifestations and treatment of intracranial aneurysms with specific relevance to neuro-ophthalmologic outcomes was conducted using Ovid MEDLINE and EMBASE databases. Cavernous sinus aneurysms were not included in this review.

RESULTS

Surgical clipping vs endovascular coiling for aneurysms causing third nerve palsies was compared in 13 retrospective studies representing 447 patients. Complete recovery was achieved in 78% of surgical patients compared with 44% of patients treated with endovascular coiling. However, the complication rate, hospital costs, and days spent in intensive care were reported as higher in surgically treated patients. Retrospective reviews of surgical clipping and endovascular coiling for all ocular motor nerve palsies (third, fourth, or sixth cranial nerves) revealed similar results of complete resolution in 76% and 49%, respectively. Improvement in visual deficits related to aneurysmal compression of the anterior visual pathways was also better among patients treated with clipping than with coiling. The time to treatment from onset of visual symptoms was a predictive factor of visual recovery in several studies. Few reports have specifically assessed the improvement of visual deficits after treatment with flow diverters.

CONCLUSIONS

Decisions regarding the choice of therapy for intracranial aneurysms causing neuro-ophthalmologic signs ideally should be made at high-volume centers with access to both surgical and endovascular treatments. The status of the patient, location of the aneurysm, and experience of the treating physicians are important factors to consider. Although a higher rate of visual recovery was reported with neurosurgical clipping, this must be weighed against the potentially longer intensive care stays and increased early morbidity.

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.

Efficacy of Orbital Color Doppler Imaging and Neuroimaging in the Diagnosis of Carotid Cavernous Fistulas

PURPOSE

To evaluate the diagnostic sensitivity and specificity of orbital color Doppler imaging (CDI) and conventional neuroimaging (CT/MRI) compared with cerebral angiography in patients with carotid-cavernous fistulas (CCFs).

METHODS

The study design was a retrospective patient chart and imaging review. The authors reviewed 655 charts of all patients who underwent CDI and neuroimaging (CT/MRI) between 2006 and 2015 at one institution. Sixty patients had a presumptive diagnosis of CCF without thrombosis. Thirty-seven patients with 43 events met the inclusion criteria of the study. The diagnostic sensitivity of the 3 noninvasive imaging modalities (CDI, CT, MRI) for CCF was compared with the gold standard 6-vessel cerebral angiography. Significance testing was performed using the 2-tailed Fisher test.

RESULTS

Color Doppler imaging had high sensitivity (96.8%) but low specificity (41.7%) for the diagnosis of CCFs with anterior orbital findings. A negative CDI had more diagnostic value than a positive CDI. While an arterial wave form in the superior ophthalmic vein was the most common finding of CCF on CDI, enlargement of the superior ophthalmic vein was the only statistically significant finding. Posterior cortical venous drainage was noted in about 10% of the patients with indirect (low-flow) fistulas, who presented with unilateral orbital signs and symptoms, a finding not previously reported in the literature.

CONCLUSION

Color Doppler imaging is a useful noninvasive, radiation-free modality for diagnosis of CCF with anterior drainage, with higher sensitivity than CT or MRI, but equivalent specificity. A significant limitation of CDI is the lack of usefulness in diagnosing fistulas with posterior cortical venous drainage, which carry a risk of intracerebral hemorrhage and stroke. In this series, 10% of unilateral CCFs with anterior orbital signs and symptoms showed angiographic evidence of posterior cortical venous drainage.

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.

Diplopia due to ocular motor cranial neuropathies

PURPOSE OF REVIEW

Determining which cranial nerve(s) is (are) involved is a critical step in appropriately evaluating a patient with diplopia.

RECENT FINDINGS

New studies have looked at the various etiologies of cranial nerve palsies in the modern imaging era. The importance of the C-reactive protein test in evaluating the possibility of giant cell arteritis has recently been emphasized.

SUMMARY

Dysfunction of the oculomotor (third), trochlear (fourth), or abducens (sixth) cranial nerve will produce ocular misalignment and resultant binocular diplopia or binocular blur. A misalignment in the vertical plane of as small as 200 μm is enough to produce diplopia. Diagnosing diplopia from a cranial nerve abnormality requires an understanding of structure (the anatomy of the cranial nerves from nucleus to muscle), function (the movements controlled by the cranial nerves), possible etiologies, and exceptions to the rules.

Neuro-ophthalmological emergencies: which ocular signs or symptoms for which diseases?

There are five possible ocular signs or complaints of a life or sight threatening neuro-ophthalmological condition: diplopia, isolated anisocoria, transient visual loss, severe pain in head or neck (with or without photophobia) and oscillopsia/nystagmus. In this review, the ocular signs and symptoms of neuro-ophthalmological emergencies are described together with their practical work-up and the risks associated with missing the diagnosis. Concerning diplopia, the associated signs pointing to a possible threatening condition are emphasized. Six focus points resuming core messages are displayed throughout this review.

Neuro-imaging: a review for the general ophthalmologist

The diagnosis of many neuro-ophthalmic conditions is facilitated with neuro-imaging. The two main modalities are Computed Tomography (CT) and Magnetic Resonance Imaging (MRI). Clinicians who refer patients for either of these techniques must not only know which of them to choose, but also where the imaging should be performed (e.g. brain, orbit), whether or not contrast is indicated, and if angiography should be supplemented. These complexities often result in imaging studies that are either unneeded or unhelpful. The goal of this manuscript is to provide a practical set of guidelines for the general ophthalmologist of how to choose the correct parameters for neuro-imaging studies.

Neuroimaging in patients referred to a neuro-ophthalmology service: the rates of appropriateness and concordance in interpretation

OBJECTIVE

Neuroimaging studies frequently are ordered to investigate neuro-ophthalmic symptoms. When misused, these studies are expensive and time consuming. This study describes the type and frequency of neuroimaging errors in patients referred to an academic neuro-ophthalmology service and measures how frequently these neuroimaging studies were reinterpreted.

DESIGN

Prospective cohort study.

PARTICIPANTS

Eighty-four consecutive patients referred to an academic neuro-ophthalmology practice.

METHODS

From November 2009 through July 2010, 84 consecutive new patients who had undergone a neuroimaging study in the last 12 months specifically to evaluate their presenting neuro-ophthalmic symptoms were enrolled prospectively. Participants then underwent a complete neuro-ophthalmic evaluation, followed by a review of prior neuroimaging. Questions regarding appropriateness of the most recent imaging, concordance of radiologic interpretation, and re-evaluation of referring diagnoses were answered by the attending physician.

MAIN OUTCOME MEASURES

The frequency and types of errors committed in the use of neuroimaging and the frequency of reinterpretation of prereferral neuroimaging studies after neuro-ophthalmic history and examination.

RESULTS

Most study participants (84.5%; 71/84) underwent magnetic resonance imaging before referral; 15.5% (13/84) underwent only computed tomography. The rate of suboptimal neuroimaging studies was 38.1% (32/84). The 3 most common reasons for suboptimal studies were incomplete area of imaging (34.4%; 11/32), wrong study type (28.1%; 9/32), and poor image quality (21.9%; 7/32). Twenty-four of 84 subjects (28.6%) required additional neuroimaging. The authors agreed with the radiology interpretation of the prior neuroimaging studies in most patients (77.4%; 65/84). The most common anatomic locations for discordance in interpretation were the intraorbital optic nerve (35%; 7/20) and the brainstem (20%; 4/20).

CONCLUSIONS

There was a high rate of suboptimal neuroimaging studies performed in patients referred for neuro-ophthalmology examination. These findings have significant implications given the increasing attention to resource use currently and in the near future.