News from NORD
BOSTON—Misdiagnosing optic neuritis may expose patients to risks associated with undergoing MRI with a contrast agent, lumbar puncture, and high-dose steroid treatment. It also costs patients and hospitals time and money. Leanne Stunkel, MD, a neurology resident at Washington University in St. Louis, and her colleagues observed a 60% misdiagnosis rate of optic neuritis among patients who were referred to their neuro-ophthalmology clinic, according to a study presented at the 69th Annual Meeting of the American Academy of Neurology.
Leanne Stunkel, MD
“The most common [diagnostic] errors were overreliance on a single item of history and failure to consider alternative diagnoses,” said Dr. Stunkel.
Optic neuritis is an acute inflammatory demyelinating condition of the optic nerve. Presenting symptoms include acute or subacute vision loss, pain with eye movement, and changes in color vision, especially affecting the color red, said Dr. Stunkel. Many patients who were referred to their tertiary care clinic for optic neuritis turned out to have other conditions, which prompted the researchers to find out more about optic neuritis misdiagnosis.
Previous studies found a misdiagnosis rate of between 10% and 40%, but none of these studies examined which errors led to these misdiagnoses. To determine how often optic neuritis is misdiagnosed and which diagnostic errors play a role, and to identify diagnoses commonly mistaken for optic neuritis, Dr. Stunkel and colleagues performed a retrospective chart review.
The researchers reviewed new patient encounters between January 2014 and October 2016 to identify patients referred with a diagnosis of optic neuritis. Experienced neuro-ophthalmologists determined the final diagnosis. The researchers then applied the Diagnosis Error Evaluation and Research (DEER) taxonomy tool to identify diagnostic errors in cases in which the patient did not have optic neuritis.
A total of 122 patients were referred for optic neuritis during the study period. Only 40% of these patients were diagnosed with optic neuritis, and 60% of patients had alternative diagnoses. The most common alternative diagnoses were headache with eye pain and visual symptoms (22%), functional visual loss (19%), and other optic neuropathies (16%).
In addition, 15% of patients had retinal or macular problems rather than pathology of the optic nerve. Other diagnoses included neoplasms, congenital disk abnormalities, and inflammatory conditions that affected other parts of the eye.
The most common diagnostic errors were from problems eliciting or interpreting the history (33%). “We saw an overreliance on history of risk factors such as multiple sclerosis or other inflammatory disorders and some failure to elicit the fact that these were brief stereotyped episodes of vision loss, like in a migraine aura,” said Dr. Stunkel.
Twenty-one percent of diagnostic errors were due to errors interpreting physical exam findings, and 14% of errors were due to misinterpretation of diagnostic tests. Finally, 32% of diagnostic errors resulted from failure to consider alternative diagnoses. Of patients who did not have optic neuritis, 17% had already received a lumbar puncture, 17% had received a contrast MRI that turned out to be negative, and 11 patients had inappropriately received IV steroids, said Dr. Stunkel.
Some of the study limitations include that the DEER category assignments were subjective, and that not every referral for optic neuritis was included in the study due to limitations of the clinic’s electronic medical records system, said Dr. Stunkel.
—Erica Tricarico