Clinical evaluation of an adjustable cerebrospinal fluid shunt valve

University dissertation from Göran Zemack and Bertil Romner, Department of Clinical Neuroscience, Division of Neurosurgery, Lund University Hospital, 221 85, Lund, Sweden

Abstract: Introduction: Shunting systems are implanted for draining cerebrospinal fluid to treat hydrocephalus, intracranial cysts, and idiopathic intracranial hypertension. Most shunt systems include a valve which regulates drainage. A differential pressure valve opens when intracranial pressure exceeds the valve’s opening pressure. The difficulty with these valves is selecting and predicting the most suitable valve opening pressure for the individual patient after insertion. Using a valve with a non-adjustable opening pressure requires surgery to change the opening pressure. Potentially, an adjustable valve, such as the Codman Hakim programmable valve, allows non-invasive valve pressure-adjustment for managing over- and underdrainage by being able to fine-tune the valve's opening pressure to the patient’s changing intracranial hydrodynamics. Objective: To evaluate the use of an adjustable valve in a consecutive, non-selected group of patients. To evaluate its reliance, spectrum of complications, use and effects of opening pressure adjustments and economical impact. Results and conclusions: An adjustable valve has the advantage of enabling trans-cutaneous alterations of the valve's opening pressure as the patients’ clinical course changes during the postoperative period. Pressure-adjustment optimized treatment, and clinical outcome improved following the majority of adjustments. Subdural fluid collections could be managed with pressure-adjustment. The rate of shunt complications was similar to other studies. Valve malfunction was uncommon. Accidental pressure-resetting, other than that caused by magnetic resonance imaging, was rare. Avoided shunt revisions reduce cost. Because we cannot predict which patient will need pressure-adjustment, our preference is to use an adjustable valve for all conditions.

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