Overdiagnosis of idiopathic intracranial hypertension

Objective: To delineate the factors contributing to overdiagnosis of idiopathic intracranial hypertension (IIH) among patients seen in one neuro-ophthalmology service at a tertiary center.

Methods: We retrospectively reviewed new patients referred with a working diagnosis of IIH over 8 months. The Diagnosis Error Evaluation and Research taxonomy tool was applied to cases referred with a diagnosis of IIH and a discrepant final diagnosis.

Results: Of 1,249 patients, 165 (13.2%) were referred either with a preexisting diagnosis of IIH or to rule out IIH. Of the 86/165 patients (52.1%) with a preexisting diagnosis of IIH, 34/86 (39.5%) did not have IIH. The most common diagnostic error was inaccurate ophthalmoscopic examination in headache patients. Of 34 patients misdiagnosed as having IIH, 27 (27/34 [79.4%]; 27/86 [31.4%]) had at least one lumbar puncture, 29 (29/34 [85.3%]; 29/86 [33.7%]) had a brain MRI, and 8 (8/34 [23.5%]; 8/86 [9.3%]) had a magnetic resonance/CT venogram. Twenty-six had received medical treatment, 1 had a lumbar drain, and 4 were referred for surgery. In 8 patients (8/34 [23.5%]; 8/86 [9.3%]), an alternative diagnosis requiring further evaluation was identified.

Conclusions: Diagnostic errors resulted in overdiagnosis of IIH in 39.5% of patients referred for presumed IIH, and prompted unnecessary tests, invasive procedures, and missed diagnoses. The most common errors were inaccurate ophthalmoscopic examination in headache patients and thinking biases, reinforcing the need for rapid access to specialists with experience in diagnosing optic nerve disorders. Indeed, the high prevalence of primary benign headaches and obesity in young women often leads to costly and invasive evaluations for presumed IIH.