Patients with ONSM often misdiagnosed with optic neuritis

In this study, researchers identified factors contributing to the misdiagnosis of optic nerve sheath meningiomas (ONSM).

Study design

The authors retrospectively reviewed records from 35 patients who were seen at a tertiary neuro-ophthalmology practice at Emory University School of Medicine between 2002 and 2017. Each patient had unilateral ONSM that were initially misdiagnosed, either at Emory or elsewhere. The authors identified causes for diagnostic errors which included clinical assessment failure and errors in diagnostic testing.

Outcomes

Of 35 patients in this analysis, 25 (71%) had a diagnosis delayed for a mean of 63 months. The most common diagnostic error was clinician assessment failure (mistakes in hypothesis generation and weighing) followed by errors in diagnostic testing. Optic neuritis and failure to recognize the presence of optic neuropathy were the most common misdiagnoses. Errors in diagnostic testing included performing unnecessary lumbar punctures and laboratory testing, and prescribing unnecessary steroid treatment. Sixteen patients had MRI scans elsewhere before being correctly diagnosed at Emory; the scans were incorrectly interpreted as normal, were misread or performed incorrectly.

More than half of the cohort had poor visual outcome. Education regarding neuroimaging of the optic nerve and inclusion of ONSM in the differential diagnosis for optic neuropathy should help to prevent diagnostic errors in the future.

Limitations

The study was limited by its small sample size and retrospective nature.

Clinical significance

Ophthalmologists should be cognizant of the inclusion of optic nerve sheath meningiomas in the differential for optic neuropathy and understand what type of imaging study to order to evaluate for this diagnosis.