CSF overdrainage

Last revised by Ryan Thibodeau on 15 Jul 2024

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.

Classically, patients present with headaches, although this is not always present, and a significant portion of patients with radiological overdrainage are asymptomatic 1.

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

  • pachymeningeal thickening

  • subdural collection

  • 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

The treatment of overdrainage centers 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.

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