Elsevier

World Neurosurgery

Volume 104, August 2017, Pages 167-170
World Neurosurgery

Original Article
Use of Intracranial Pressure Monitoring Frequently Refutes Diagnosis of Idiopathic Intracranial Hypertension

https://doi.org/10.1016/j.wneu.2017.04.080Get rights and content

Background

The diagnosis and management of patients with idiopathic intracranial hypertension (IIH) frequently relies on lumbar puncture to ascertain intracranial pressure (ICP). However, ICP values derived this way may be spurious owing to patient body habitus and behavior. We recently incorporated direct continuous ICP monitoring into the work-up for IIH.

Methods

Through billing records, we identified all patients during a 3-year period who had a diagnosis of IIH and who underwent ICP monitoring before shunt placement or revision. Patient demographics and clinical data were reviewed.

Results

Of 30 patients who underwent ICP monitoring with an intraparenchymal wire, 17 had undergone lumbar puncture within the previous 6 months. Results from lumbar punctures showed an elevated opening pressure in all 17 patients, whereas only 2 patients (12%) were found to have consistently elevated ICP with direct ICP monitoring. Of 15 patients being evaluated for shunting, 4 (27%) were found to have elevated ICP. Of the 15 patients with existing shunts, 2 patients (13%) were found to have malfunctioning shunts after pressure monitoring, and 3 patients (20%) had shunts that were found to be unnecessary and were removed. No patient experienced any complication from invasive monitoring.

Conclusions

Direct ICP monitoring is the gold standard for determining ICP and can be safely and effectively applied to the work-up and treatment of patients with IIH to reduce the occurrence of misdiagnosis and unnecessary surgery.

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

References (10)

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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.

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