CSF overdrainage, also known as overshunting, is the most common complication of ventriculoperitoneal shunts and other CSF diversion procedures and may result in slit ventricle syndrome, although the two are not synonymous.
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Clinical presentation
Classically, patients present with headaches, although this is not always present, and a significant portion of patients with radiological overdrainage are asymptomatic 1.
Radiographic features
Typical features of chronic overdrainage include 1:
small "slit-like" ventricles
sometimes, this may be isolated to a single ventricle or even only part of the ventricle
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subdural collection
subdural effusions
thickened layered skull (layer cake skull)
hyperpneumatization of the frontal sinuses
premature suture closure or sutural sclerosis
narrowed of skull base foramina
brain sagging and other feature of intracranial hypotension
Treatment and prognosis
The treatment of overdrainage centres on symptoms control as well as, if needed, the identification and correction of the underlying cause.
In cases where symptoms are mild or intermittent, medical management may suffice, including medications (e.g. antimigraine drugs, analgesics, steroids) and postural changes (e.g. lying down or decubitus position) 1.
In more severe or refractory cases, revision of the shunt may be required (e.g. changing valve setting, changing valve, shunt removal, ventriculostomy etc.) 1.