Atypical Neurological Manifestations of Shunt Overdrainage: Illustrative Case and Systematic Literature Review

Ventricular shunting is the standard treatment for hydrocephalus. However, excessive drainage of cerebrospinal fluid (overdrainage) is a recognized complication. There is no consensus definition of overdrainage, and its reported incidence varies widely depending on the criteria used. Although overdrainage is classically associated with orthostatic headache, it can also present with focal neurological deficits, altered mental status, subdural collections, slit ventricle syndrome, intracranial hypotension, or spinal cord compression from epidural venous engorgement (Miyazaki syndrome). These less typical presentations may delay diagnosis and treatment. Most of the available evidence comes from isolated case reports and small case series, and previous reviews have focused on single complications rather than on the full spectrum of overdrainage-related presentations. This systematic review pools individual patient data from published case reports and case series of complications attributed to shunt overdrainage in patients with hydrocephalus. PubMed, Embase and Scopus were searched, and 44 articles reporting 50 patients were included. The objectives are to (1) describe the clinical presentation, imaging findings and types of overdrainage-related complications; (2) describe the management strategies used, including valve reprogramming, valve replacement or upgrade, and addition of antisiphon or gravitational devices; and (3) describe clinical outcomes and explore factors associated with outcome, such as type of complication, age group, sex and valve type. Results are summarized descriptively, and subgroup comparisons are exploratory. We expect this review to show that overdrainage often presents without the classic orthostatic headache, and to identify clinical and imaging features that may support earlier recognition. Because the data come from published case reports, the findings are subject to reporting and publication bias and are intended to be descriptive and hypothesis-generating. The review accompanies an illustrative case of a patient with bilateral ventriculoperitoneal shunts who developed reversible neurological deficits attributed to overdrainage. This protocol was registered retrospectively, after completion of the review.