The incidence of acute optic neuritis overdiagnosis may higher than previously thought because of clinicians who don’t conduct a thorough patient history or physical exam, and don’t generate a complete differential diagnosis, researchers said.
A retrospective study of patients referred to a university-based neuro-ophthalmology clinic for acute optic neuritis suggested that almost 60% of patients had an alternative diagnosis, according to Gregory P. Van Stavern, MD, of Washington University School of Medicine in St Louis, and colleagues.
While optic neuritis was confirmed in 49 patients (40.2%), 73 patients (59.8%) had something else, most commonly primary headache disorder with eye pain, they wrote online in JAMA Ophthalmology.
“These data, if representative of other neuro-ophthalmology practices, suggest that between 51% and 69% of patients referred for optic neuritis may have an alternative diagnosis, regardless of whether the patient was referred by an optometrist, ophthalmologist, or neurologist,” the authors stated. “Overdiagnosis in patients with alternative conditions may lead to unnecessary MRIs, lumbar punctures, treatments, loss of time, and expense.”
For the study, neuro-ophthalmologists determined definite diagnosis in 122 patients referred for optic neuritis from January 2014 to October 2016. Eighty-eight patients (72.1%) were female, and the mean age was 42.6. Data were analyzed from September 2016 to July 2017.
The most common clinician error was over-reliance on a single item of history and failure to consider alternative diagnoses. In 24 of 73 patients (33%) with an alternative diagnosis, clinicians didn’t elicit or interpret critical elements of patient history, the researchers said.
Even when alternative diagnoses was considered, too many clinicians failed to get things right. Not only were errors in alternative diagnoses made in 23 patients (32%), but physical exam findings were misinterpreted in 15 patients (21%) and diagnostic test results were misinterpreted in 11 patients (15%).
In many cases, diagnostic error reflected errors in reasoning or cognitive biases, such as premature closure, rather than lack of knowledge, Van Stavern’s group noted.
“Understanding pitfalls leading to over-diagnosis of optic neuritis may improve clinicians’ diagnostic process,” they said. “Eye pain should be considered in context with other symptoms, and headache, nonarteritic ischemic optic neuropathy (NAION), functional visual loss, and other alternative diagnoses should be considered in the differential diagnosis.”
The presence of a new relative afferent pupillary defect (APD) “was one of the more consistent examination findings that correlated with a true diagnosis of optic neuritis,” the researchers emphasized. “The lack of an APD strongly argues against a diagnosis of acute optic neuritis unless there is bilateral optic nerve involvement.”
“Eye care physicians should be able to do better,” Neil R. Miller, MD, of Johns Hopkins Medicine in Baltimore, told MedPage Today.
General ophthalmologists and optometrists tend to see patients with cataracts and glaucoma or an abnormality in the ocular fundus, explained Miller, who was not affiliated with the study. “In most cases, a simple examination is all that is needed to identify correctly most eye problems.”
When a patient presents with a disorder than isn’t related to the optic nerve, however, such as dry eye or unexplained non-organic visual loss, many general ophthalmologists get “stymied,” he said. A complete history and thorough physical exam will lead to the correct diagnosis in most cases, but many clinicians feel they are too busy to take the time, Miller added.
The study also revealed that the most common alternative diagnosis — primary headache disorder with associated eye pain and/or visual symptoms — was seen in 16 patients (22%). Functional visual loss was seen in 14 patients (19%). Other optic neuropathies, particularly NAION, was seen in nine patients (12%). Retinopathies such as neuroretinitis, central retinal artery occlusion, or branch retinal artery occlusion, were seen in 11 patients (15%).
Less frequent alternative diagnoses included ocular surface disease, congenital disc abnormalities and optic nerve sheath meningioma, seen in three patients each (4%).
Twelve patients (16%) who were referred for optic neuritis had normal findings on MR imaging, despite the fact that it is 94% sensitive to detection of optic neuritis.
“Discounting normal examination findings was a common source of diagnostic error in this study,” the researchers pointed out. “Normal [MRI] examination findings are reassuring and virtually exclude the diagnosis of acute optic neuritis.”
The study also showed that 12 patients (16%) had undergone lumbar puncture and 8 (11%) had received unnecessary treatment with intravenous steroids.
When a patient presents with eye pain, with or without eye movement, this symptom should raise concern for optic neuritis, they advised. However, when there is no associated visual loss, a primary headache disorder should also be considered.
The time course of eye pain and visual loss can also provide important diagnostic clues. “Several patients in our study described discrete, stereotyped episodes of visual loss most consistent with migraine aura, a pattern that would be extraordinarily unusual for optic neuritis,” Van Stavern’s group pointed out.
In patients with a known diagnosis of multiple sclerosis who were more likely to have optic neuritis, 4% still had an alternative diagnosis.
“It used to be that the biggest concern about misdiagnosis of optic neuritis was missing a diagnosis of a compression lesion, such as pituitary adenoma or intracranial aneurysm,” noted Miller. “This no longer appears to be the case, probably because doctors who are missing the diagnosis of optic neuritis are ordering neuroimaging and making the correct diagnosis.”
Study limitations included dependence on referral records for determining the source of diagnostic error.
The study was supported by Washington University, the Institute for Clinical and Translational Sciences, Biostat Core, Research to Prevent Blindness, and the National Institutes of Health.
Van Stavern and co-authors disclosed no relevant relationships with industry.
Robert Jasmer, MD Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, BSN, RN, Nurse Planner