General
- Aka
- Craniocerebral disproportion
- Paediatric diagnosis with no consistent definition
- Albright describes "symptomatic small ventricles"
- Usually seen in patients with long-term shunts whose ventricles have become small over years
- An underdrainage disease due to a previous over drainage problem
Definition
- Cerebrospinal fluid shunt-related symptoms in the setting of small ventricles demonstrated on radiologic studies.
Pathology
- The exact aetiology behind slit ventricle syndrome is debatable but likely is related to intermittent intracranial hypertension and hypotension.
- Various hypotheses have been proposed
- Intermittent ventricular isolation, in which one overdrained ventricle collapses and occludes the shunt catheter resulting in underdrainage of the contralateral ventricle
- Noncompliant ventricles due to periventricular gliosis ("stiff ventricle"), which is unable to adapt to shunt malfunction (underdrainage), leading to intraventricular hypertension
- Overdrainage leading to venous congestion, which decreases cerebral compliance and causes susceptibility to small changes in intracranial pressure
- Capillary absorption laziness, in which the capillary-venous system in the setting of chronic overdrainage is less able to absorb variations in ventricular fluid pressures
- Overdrainage in children leading to acquired craniocerebral disproportion (container-content mismatch) due to early suture ossification, resulting in intracranial hypertension
- Young child with HCP that is shunted → over drained CSF → Volume reduce in brain → skull closed → brain cannot expand anymore → so any growth in brain causes increased ICP → headache.
- Low compliance of skull causing high pressure
- When you measure ICP: very high 30 mmHg
- Small ventricles → can lead to
- Intermittent or complete shunt malfunction.
- Apposition of the ventricular catheter to the ventricular wall increases the chance of ingrowth of ependymal cells or choroid plexus.
Clinical presentation
- Symptoms similar to shunt blockage, and often episodic
- The presence of characteristic symptoms is required to diagnose slit-ventricle syndrome and must be distinguished from slit-like ventricles, a radiologic finding.
- Patients present with chronic intermittent headache, with or without neurologic signs or symptoms such as nausea/vomiting and altered mental status. The shunt reservoir refills slowly on palpation.
- H/A possibly due to periods of insufficient CSF drainage
- Mild forms are seen in adults and more severe forms are seen in children.
- Without ventricular enlargement when there is raised pressure.
Radiographic appearance
- CT and MRI
- Small ventricles with a characteristic slit-like appearance.
Management
- Often very challenging
- ICP monitoring
- Conservatively
- Medical therapy (antimigraine medication)
- Surgery
- Low pressure states associated with symptoms may respond to valve changes or addition of antisiphon devices → prevent over drainage
- High pressure symptoms are extremely challenging; vault expansion, subtemporal decompression, ventricular catheter
Images
To be sorted
- Uncommon, late shunt complication
- Chronic intermittent intense HAs (+ vomiting), better when supine, +/- neurologic signs
- Clinical Triad
- Intermittent HAs (10-90 mins)
- Small ventricles
- Slow filling of the pumping mechanism of the valve
- Etiology
- Cyclical, intermittent collapse of ventricular walls around the catheter shunt obstruction / cyclical shunt malfunction and intermittent intracranial hyper- and hypotension
- Normally shunt will move intra-abdominally due to peristalsis
- Over shunting can cause
- Subdural haematoma
- Overlying of sutures causing early suture closure (2nd craniosynostosis)
- Corpus callosum injury when it gets pushed onto the tentorium
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