Predictors for delayed ventriculoperitoneal shunt placement after external ventricular drain removal in patients with subarachnoid hemorrhage
By Ariane Lewis, MD
Assistant Professor, Department of Neurology (Division of Neurocritical Care)
NYU Langone Medical Center
Subarachnoid hemorrhage (SAH) is a type of bleed that can occur in the spaces surrounding the brain spontaneously or after an aneurysm ruptures. Patients with SAH often develop hydrocephalus and require placement of an external ventricular drain (EVD) to temporarily drain cerebrospinal fluid (CSF) and decrease intracranial pressure (ICP). The drain generally remains in place throughout the period of time after a SAH when the blood vessels in the brain are at risk for narrowing which leads to reduced blood flow to the brain (the vasospasm period). Once this period has ended, the EVD is clamped to stop external drainage of CSF. Once CSF drainage has stopped, doctors determine if the hydrocephalus has improved and if the patient can tolerate removal of the drain. This is called a clamp trial. If the hydrocephalus is not improved or gets worse after the EVD has been clamped, the patient will require placement of a permanent ventriculoperitoneal (VP) shunt.
In some cases, a patient passes the clamp trial, the EVD is removed, and no VP shunt is placed, but later, the patient suffers from delayed cognitive and motor recovery, such as continued memory problems and trouble walking. If the doctors believe that hydrocephalus is causing the delay in recovery, they may decide that a VP shunt is required. This is termed delayed VP shunt placement. Little is known about the risk factors for delayed VP shunt placement in patients who pass a clamp trial and have their EVD removed. In order to explore the risk factors associated with delayed VP shunt placement, we studied a retrospective cohort of SAH patients who required EVD placement during their hospitalization and then had their EVDs removed.
Of 91 patients who passed a clamp trial and had their EVD removed, 12 (13%) required delayed VP shunt placement at a median of 54 days (interquartile range 15-75 days) after EVD removal. Eight of these patients (67%) had documented clinical changes, such as headaches and trouble walking, and nine of these patients (75%) had enlarged ventricles on brain imaging that prompted delayed VP shunt placement. We examined many possible risk factors for delayed VP shunt placement including:
- severity of the SAH (Hunt Hess and Fisher scores)
- neurologic exam on admission (Glasgow Coma Scale)
- presence of an aneurysm as well as its location/size/treatment method
- length of stay in the intensive care unit
- initial and final CSF red blood cell count
- initial and final CSF protein levels
- ventricular size prior to EVD removal
- presence of blood in the ventricles (intraventricular hemorrhage)
- idevelopment of infection of the ventricles (ventriculitis)
We found that two factors increased the risk for delayed VP shunt placement. These factors were: increased CSF protein within the first seven days of EVD placement and increased third ventricular size prior to EVD removal. Nine of the twelve patients (75%) who had delayed VP shunt placement were noted to have subjective clinical improvement at a follow-up appointment.
Delayed hydrocephalus after SAH is associated with delayed cognitive and motor recovery and delayed transition to independent activities of daily living. If we can diagnose delayed hydrocephalus early, we may be able to prevent additional neurological deterioration, but this diagnosis is difficult.