Original ArticleUse of Intracranial Pressure Monitoring Frequently Refutes Diagnosis of Idiopathic Intracranial Hypertension
Introduction
Idiopathic intracranial hypertension (IIH), previously called pseudotumor cerebri, is typically treated by neurosurgeons with cerebrospinal fluid shunting. Diagnostic criteria for IIH include the documentation of papilledema, a normal neurologic examination except for cranial nerve function, the absence of structural causes of elevated intracranial pressure (ICP), and an elevated lumbar puncture opening pressure.1 However, in our experience, some patients do not undergo a full diagnostic work-up before surgical referral because the referring physician has concerns related to rapidly progressing visual symptoms. In other cases, the diagnosis is made by default when no clear cause for chronic cephalgia can be determined. Lumbar puncture may often inaccurately show an elevated ICP, especially in overweight or obese patients. The end result is that patients may be misdiagnosed and treated ineffectively with cerebrospinal fluid shunting, misdirecting future medical care and work-up.
At our institution, a quality improvement effort was recently initiated to incorporate ICP monitoring into the diagnostic work-up for IIH and for patients possessing a shunt for IIH without clear evidence of malfunction. Our rationale was that despite an unclear pathophysiology, the driving mechanism behind IIH is elevated ICP, which may be inaccurately determined via lumbar puncture. In this study, we present our interim experience with the use of intraparenchymal pressure wire testing as a diagnostic tool in these patients.
Section snippets
Patient Identification
We reviewed the billing records at our institution for the period from June 2012 to August 2015 to identify patients with an International Classification of Diseases, Ninth Revision, code of 348.2 (idiopathic intracranial hypertension) and a Current Procedure Terminology code of 61107 (twist drill hole for subdural or ventricular puncture; for implanting ventricular catheter or pressure recording device) during their hospital stay. Eligible patients were adults ≥18 years old. Inpatient and
Demographics
We identified 30 patients for this study. Similar to the classic description of patients with IIH, 29 of 30 patients were female, the mean age of patients was 33.4 years (range, 19.0–41.0 years), and the mean body mass index was 38.0 (range, 25.1–54.5) (Table 1). An existing shunt was present in 15 patients; 10 patients had a ventriculoperitoneal shunt, 4 had a lumboperitoneal shunt, and 1 had both. All patients presented with complaints of visual symptoms and progressive headaches.
Discussion
The diagnosis of IIH requires demonstration of high ICP, with the current standard being an elevated lumbar puncture opening pressure of at least 25 cm H2O. However, our study reveals that ICP values recorded after lumbar puncture are often inaccurate and misleading. All 17 patients who underwent a lumbar puncture had opening pressures >20 cm H2O, but only 2 of those patients had elevated ICP on invasive testing. When undergoing a lumbar puncture, patients ideally should be placed in the
Conclusions
Per current guidelines, the diagnosis of IIH requires the demonstration of elevated ICP by lumbar puncture, which in this patient population may be difficult. Direct ICP monitoring is currently a gold standard for determining ICP, and our early experience with a select group of patients with a presumed diagnosis of IIH demonstrates that direct ICP monitoring can assist with determining a definitive diagnosis. It may also assist with monitoring the function of an existing shunt or verifying the
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Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.