Optic Neuritis Widely Overdiagnosed, Study Suggests

Laird Harrison

December 08, 2017

Ophthalmologists, optometrists, and neurologists may be widely overdiagnosing optic neuritis, researchers say.

Neuro-ophthalmologists at Washington University in St Louis, Missouri, could confirm only 40% of suspected cases of optic neuritis referred to them.

"Overdiagnosis in patients with alternative conditions may lead to unnecessary [magnetic resonance imaging], lumbar punctures, treatments, loss of time, and expense," warn Leanne Stunkel, MD, and colleagues from the university, in an article published online December 7 in JAMA Ophthalmology.

Optic neuritis, which is an acute inflammatory demyelinating optic neuropathy, can occur in isolation or indicate an underlying disease, such as multiple sclerosis (MS) or neuromyelitis optica.

Patients typically present with acute to subacute central visual loss, pain with eye movements, and dyschromatopsia. Clinicians base their diagnosis on these symptoms, time course, and examination findings such as abnormal visual acuity, visual fields, color vision, or the presence of a new relative afferent pupillary defect (APD).

Previous studies have found that 9% to 37% of patients referred for optic neuritis were misdiagnosed, the researchers write.

To better determine this rate, they analyzed the records, including referral notes, of all patients referred for suspected optic neuritis to the university's Department of Ophthalmology and Visual Sciences Center for Advanced Medicine Eye Center between January 2014 and October 2016.

Definitive diagnosis was determined by neuro-ophthalmologists Collin M. McClelland, MD, or Gregory P. Van Stavern, MD, using history, a structured clinical examination (including acuity, color, and the presence or absence of a relative APD), visual fields, funduscopy, and MRI when available or clinically indicated.

The researchers applied the Diagnosis Error Evaluation and Research taxonomy tool to identify the type of diagnostic error.

Of 122 patients referred for optic neuritis, Dr McClelland and Dr Van Stavern confirmed the diagnosis in 49 (40.2%; 95% confidence interval, 31.4% - 49.4%). They arrived at alternative diagnoses for the others.

The mean age of those correctly diagnosed was 38.8 years compared with 45.1 years for those incorrectly diagnosed, which was a statistically significant difference (P = .01). Referring ophthalmologists, optometrists, and neurologists appeared equally likely to make wrong diagnoses.

The most common alternative diagnosis was headache with eye pain and/or visual symptoms, which accounted for 22% of the misdiagnoses. It was followed by functional visual loss (19%), optic neuropathies (16%), and retinal/macular diagnoses (15%).

The most common reason the referring clinicians misdiagnosed these patients was that they did not elicit critical elements of the patients' medical histories, or misinterpreted what they did uncover. This occurred in 33% of the misdiagnoses.

For example, some of the referring clinicians did not realize that episodes of vision loss were stereotyped, recurrent, or isolated, or that the vision loss was bilateral.

In addition, some clinicians appeared to rely too much on a known diagnosis of multiple sclerosis or a previous episode of optic neuritis. Other clinicians put too much weight on pain with eye movement, a finding documented in 29% of misdiagnoses.

Some referring clinicians appeared to rely too much on MRI findings, and some discounted normal examination findings, which, the authors say, should have virtually excluded the diagnosis of optic neuritis. They noted that red desaturation can be overrated, and that optic discs with an anomalous appearance may mimic optic disc edema.

In contrast, the authors found that most patients with a correct optic neuritis diagnosis had an APD. "The lack of an APD strongly argues against a diagnosis of acute optic neuritis unless there is bilateral optic nerve involvement," they write.

The second most common reason for misdiagnosis was the failure to consider alternatives, the researchers said. In particular, some of the referring clinicians overlooked the possibilities of headache or nonarteritic anterior ischemic optic neuropathy, which is more common in people older than 50 years.

The authors acknowledged limitations to their study. For one, they had to depend on the accuracy of details in the referral records. Also, the Diagnosis Error Evaluation and Research classification system did not allow for the possibility of multiple sources of error, and it is not clear how much of the findings from one center in the American Midwest can be extrapolated to other places. It is possible some cases were referred to the experts there because they were particularly challenging to diagnose.

Still, the authors write, "[p]hysicians may implement these findings into their clinical practice by making note of common pitfalls that may arise in the diagnosis of optic neuritis."

The study was funded by Washington University in St Louis, the Institute for Clinical and Translational Sciences, Biostat Core, Research to Prevent Blindness, and the National Institutes of Health. The authors have disclosed no relevant financial relationships.

JAMA Ophthalmology. Published online December 7, 2017. Abstract

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