Intracranial pressure

Elevated Intracranial Pressure in Patients with Spontaneous Cerebrospinal Fluid Otorrhea

Authors: Allen KP, Perez CL, Kutz JW, Gerecci D, Roland PS, Isaacson B.

OBJECTIVES/HYPOTHESIS: To determine the prevalence of elevated intracranial hypertension in patients with spontaneous cerebrospinal fluid otorrhea (SCSFO).
STUDY DESIGN: Case series with chart review at a tertiary care academic medical center following institutional review board approval.
METHODS: A retrospective review was performed of patients undergoing operative repair of SCSFO between January 2007 and May 2012.
RESULTS: Thirty-eight patients underwent operative repair of SCSFO. Of these, 22 underwent postoperative lumbar puncture with measurement of opening pressure. The opening pressure was elevated (> 20 cm/H2 0) in eight patients (36.4%). Preoperative magnetic resonance imaging was available for review by a neuroradiologist in 27 patients. Radiographic evidence of elevated intracranial pressure (ICP) was present in 48.1% of patients.
CONCLUSION: Elevated ICP is common in patients with SCSFO. However, as only a minority of patients have elevated ICP, it is not the sole factor in the development of SCSFO.
LEVEL OF EVIDENCE: 4. Laryngoscope, 2013.

Intracranial pressure and glaucoma

Authors: Jonas JB, Wang N.

Eyes with normal-tension and high-tension glaucoma can have a similar optic nerve head appearance, which differs markedly from the optic disc appearance in vascular optic neuropathies. Factors in addition to intraocular pressure (IOP) may play a role in the pathogenesis of glaucomatous optic neuropathy. Clinical and experimental studies have shown (1) physiologic associations between cerebrospinal fluid pressure (CSFP), systemic arterial blood pressure, IOP, and body mass index; (2) that a low CSFP was associated with the development of glaucomatous optic nerve damage in cats; and (3) that patients with normal-tension glaucoma had significantly lower CSFP and a higher trans-lamina cribrosa pressure difference when compared to normal subjects. Due to anatomic reasons, the orbital CSFP and the optic nerve tissue pressure (and not the atmospheric pressure) form the retro-laminar counter-pressure against the IOP and are thus part of the trans-lamina cribrosa pressure difference and gradient. Assuming that an elevated trans-lamina cribrosa pressure difference and a steeper trans-lamina cribrosa pressure gradient are important for glaucomatous optic nerve damage, a low orbital CSFP would therefore play a role in the pathogenesis of normal-tension glaucoma. Due to the association between CSFP and blood pressure, a low blood pressure would also be indirectly involved.

Noninvasive estimation of raised intracranial pressure using ocular ultrasonography in liver transplant recipients with acute liver failure -A report of two cases-

Authors: Kim YK, Seo H, Yu J, Hwang GS.

Intracranial pressure (ICP) monitoring is an important issue for liver transplant recipients, since increased ICP is associated with advanced hepatic encephalopathy or graft reperfusion during liver transplantation. Invasive monitoring of ICP is known as a gold standard method, but it can provoke bleeding and infection; thus, its use is a controversial issue. Studies have shown that optic nerve sheath diameter > 5 mm by ocular ultrasonography is useful for evaluating ICP > 20 mmHg noninvasively in many clinical settings. In this case report, we present experiences of using ocular ultrasound as a diagnostic tool that could detect changes in ICP noninvasively during liver transplantation.

Intracranial Pressure Monitoring in Severe Traumatic Brain Injury: Results from the American College of Surgeons Trauma Quality Improvement Program

Authors: Alali AS, Fowler RA, Mainprize TG, Scales DC, Kiss A, de Mestral C, Ray JG, Nathens AB.

While existing guidelines support the utilization of intracranial pressure (ICP) monitoring in patients with traumatic brain injury (TBI), the evidence suggesting benefit is limited. To evaluate the impact on outcome, we determined the relationship between ICP monitoring and mortality in centers participating in the American College of Surgeons Trauma Quality Improvement Program (TQIP). Data on 10,628 adults with severe TBI were derived from 155 TQIP centers over 2009-2011. Random-intercept multilevel modeling was used to evaluate the association between ICP monitoring and mortality after adjusting for important confounders. We evaluated this relationship at the patient-level and at the institutional-level. Overall mortality (n=3,769) was 35%. Only 1,874 (17.6%) patients underwent ICP monitoring, with a mortality of 32%. The adjusted odds ratio (OR) for mortality was 0.44 (95% CI: 0.31-0.63) comparing patients with ICP monitoring to those without. It is plausible that patients receiving ICP monitoring were selected because of an anticipated favorable outcome. To overcome this limitation, we stratified hospitals into quartiles based on ICP monitoring utilization. Hospitals with higher rates of ICP monitoring use were associated with lower mortality: the adjusted OR of death was 0.52 (95% CI: 0.35-0.78) in the quartile of hospitals with highest use compared to the lowest. ICP monitoring utilization rates explained only 9.9% of variation in mortality across centers. Results were comparable irrespective of the method of case-mix adjustment. In this observational study, ICP monitoring utilization was associated with lower mortality. However, variability in ICP monitoring rates contributed only modestly to variability in institutional mortality rates. Identifying other institutional practices that impact on mortality is an important area for future research.

Intracranial pressure dynamics are not linked to aqueductal cerebrospinal fluid stoke volume

Authors: Tain RW, Alperin N.

TO THE EDITOR: A recent study by Hamilton et al. (4) proposes that aqueductal cerebrospinal fluid (CSF) stroke volume (ASV) is significantly associated with the width of the second peak of the intracranial pressure (ICP) waveform in normal pressure hydrocephalus. Existing evidence and current understanding of ICP physiology do not support a mechanistic link between aqueductal CSF flow and ICP dynamics.

Measuring Elevated Intracranial Pressure through Noninvasive Methods: A Review of the Literature

Authors: Kristiansson H, Nissborg E, Bartek J Jr, Andresen M, Reinstrup P, Romner B.

Elevated intracranial pressure (ICP) is an important cause of secondary brain injury, and a measurement of ICP is often of crucial value in neurosurgical and neurological patients. The gold standard for ICP monitoring is through an intraventricular catheter, but this invasive technique is associated with certain risks. Intraparenchymal ICP monitoring methods are considered to be a safer alternative but can, in certain conditions, be imprecise due to zero drift and still require an invasive procedure. An accurate noninvasive method to measure elevated ICP would therefore be desirable. This article is a review of the current literature on noninvasive methods for measuring and evaluating elevated ICP. The main focus is on studies that compare noninvasively measured ICP with invasively measured ICP. The aim is to provide an overview of the current state of the most common noninvasive techniques available. Several methods for noninvasive measuring of elevated ICP have been proposed: radiologic methods including computed tomography and magnetic resonance imaging, transcranial Doppler, electroencephalography power spectrum analysis, and the audiological and ophthalmological techniques. The noninvasive methods have many advantages, but remain less accurate compared with the invasive techniques. None of the noninvasive techniques available today are suitable for continuous monitoring, and they cannot be used as a substitute for invasive monitoring. They can, however, provide a reliable measurement of the ICP and be useful as screening methods in select patients, especially when invasive monitoring is contraindicated or unavailable.

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