Inaccuracy of idiopathic intracranial hypertension diagnosis in case reports

We reviewed the medical case report literature to determine the proportion of cases of idiopathic intracranial hypertension (IIH) that were either inappropriately labelled as IIH or prematurely given this diagnosis.

We searched OVID MEDLINE from 2012 to 2022 to identify case reports that diagnosed patients with IIH. Case reports were assessed for diagnostic accuracy using Friedman et al.'s revised diagnostic criteria for primary pseudotumor cerebri syndrome. Our primary outcome was the crude prevalence of inappropriate or premature IIH diagnoses. Our secondary outcome was determining if inaccurate IIH diagnoses were associated with variables such as journal subscription model and impact factor, author affiliation, country of origin, and year of publication.

A total of 33/185 case reports (17.8%) either incorrectly labelled a patient as having IIH or did not perform all of the investigations necessary to make a diagnosis of IIH. Some of these studies (4.8%) were believed to still represent 'probable' IIH given the clinical presentation, whereas 13.0% of studies were determined to have mislabelled their patients as having IIH. The most common reason that case reports did not meet diagnostic criteria included: a lack of MRV in atypical patient cases (42.4%, n = 14), no papilledema in addition to a lack of characteristic neuroimaging features (33.3%, n = 11), intracranial hypertension being secondary to another documented cause (12.1%, n = 4), normal LP opening pressure in addition to other factors (12.1%,n = 4), no description of neuroimaging (6.1%, n = 2), and abnormal CSF composition (6.1%, n = 2). Case reports that used the term 'IIH' incorrectly had a significantly lower journal impact factor (2.0 vs. 2.6, p = 0.01).

There is a high prevalence of premature or inappropriate diagnoses of IIH in the peer-reviewed case report literature. Adherence to published diagnostic criteria is needed when publishing IIH case reports, and authors are expected to report all relevant data in their report to ensure that an accurate diagnosis is made.