Intracranial pressure monitoring

Successful treatment of post-shunt craniocerebral disproportion by coupling gradual external cranial vault distraction with continuous intracranial pressure monitoring

Authors: Sandler AL, Daniels LB 3rd, Staffenberg DA, Kolatch E, Goodrich JT, Abbott R.

A subset of hydrocephalic patients in whom shunts are placed at an early age will develop craniocerebral disproportion (CCD), an iatrogenic mismatch between the fixed intracranial volume and the growing brain. The lack of a reliable, reproducible method to diagnose this condition, however, has hampered attempts to treat it appropriately. For those practitioners who acknowledge the need to create more intracranial space in these patients, the lack of agreed-upon therapeutic end points for cranial vault expansion has limited the use of such techniques and has sometimes led to problems of underexpansion. Here, the authors present a definition of CCD based primarily on the temporal correlation of plateau waves on intracranial pressure (ICP) monitoring and headache exacerbation. The authors describe a technique of exploiting continued ICP monitoring during progressive cranial expansion in which the goal of distraction is the cessation of plateau waves. Previously encountered problems of underexpansion may be mitigated through the simultaneous use of ICP monitors and gradual cranial expansion over time.

Intracranial Pressure Monitoring as an Early Predictor of Third Ventriculostomy Outcome

Authors: Roytowski D, Semple P, Padayachy L, Carara H.

OBJECTIVES: Endoscopic third ventriculostomy (ETV) is a routinely utilized alternative to ventriculoperitoneal shunt (VPS) in obstructive hydrocephalus. We attempt to determine the usefulness of the surgeon's intraoperative impression and postoperative period intracranial pressure monitoring that may help guide clinicians in predicting the early functional outcome of ETV.
METHODS: The patients who underwent ETV between 2006 and 2011 were retrospectively reviewed. The sample included sixty-three patients, 23 female and 40 male, between the ages of 13 and 69. In each case the surgeon's intraoperative impression, cerebrospinal fluid (CSF) samplings and post-operative intracranial pressure (ICP) monitoring (via transduced external ventricular drain for upto seventy-two hours) was recorded and evaluated in light of functional outcome of ETV at discharge and early follow up. (1-2 months) RESULTS: ICP monitoring predicted initial function of the ETV in 51 cases (80.9%) and in 12 cases (19%) suggested ETV failure. Monitoring has a positive predictive value (PPV) of 76.3% and a negative predictive value (NPV) of 100%. While the surgeon's intraoperative impression of future function has a PPV of 76.5%, and NPV of 76.9%. CSF sampling has a much poorer predictive quality owing to the wide confidence interval and a PPV of 63.6% and NPV 38.2%. In our series the evidence of sepsis as a result of EVD was found to be 11.67%. Subgroup analysis, removing the patients with Posterior Fossa Tumors, results in increased PPV (85.7%) of ICP monitoring.
CONCLUSIONS: ETV is a valuable means of treating obstructive hydrocephalus. By considering the surgeon's intraoperative impression and post-operative ICP monitoring course some of the uncertainty around its functional outcome can be overcome. The surgeon's impression and the ICP monitoring offer approximately the same predictive quality for ETV outcome.

Delayed extradural haemorrhage: a case for intracranial pressure monitoring in sedated children with traumatic brain injury within tertiary centres

Authors: Hughes A, Lee C, Kirkham F, Durnford AJ.

A 15-year-old girl sustained a mild isolated traumatic brain injury  following a pedestrian road traffic accident. She was ventilated for head computed tomography (CT) scan which revealed no intracranial abnormalities. Ventilation was not withdrawn until 15 h later when poor neurological recovery prompted urgent repeat CT, which demonstrated a delayed extradural haemorrhage (EDH). She underwent surgical evacuation, and intracranial pressure (ICP) monitoring was initiated postoperatively. She developed persistently raised ICP resistant to medical therapy, prompting further CT. This showed a recurrence of the delayed EDH requiring further surgical drainage. She made a good neurological recovery. There should be a low threshold for repeat CT to exclude delayed EDH when neurological status is poor despite normal CT soon after initial primary injury. ICP monitoring should be undertaken in children and adolescents who have normal initial CT, but in whom serial neurological assessment is not possible owing to sedation.

Basic concepts about brain pathophysiology and intracranial pressure monitoring

Authors: Rodríguez-Boto G, Rivero-Garvía M, Gutiérrez-González R, Márquez-Rivas J.

INTRODUCTION: Many brain processes that cause death are mediated by intracranial hypertension (ICH). The natural course of this condition inevitably leads to brain death. The objective of this study is to carry out a systematic review of cerebral pathophysiology and intracranial pressure (ICP) monitoring.
DEVELOPMENT: Studying, monitoring, and recording ICP waves provide data about the presence of different processes that develop with ICH.
CONCLUSIONS: Correct monitoring of ICP is fundamental for diagnosing ICH, and even more importantly, providing appropriate treatment in a timely manner.
Copyright © 2012 Sociedad Española de Neurología. Published by Elsevier Espana. All rights reserved.

Overheated and melted intracranial pressure transducer as cause of thermal brain injury during magnetic resonance imaging

Authors: Tanaka R, Yumoto T, Shiba N, Okawa M, Yasuhara T, Ichikawa T, Tokunaga K, Date I, Ujike Y.

Magnetic resonance imaging is used with increasing frequency to provide accurate clinical information in cases of acute brain injury, and it is important to ensure that intracranial pressure (ICP) monitoring devices are both safe and accurate inside the MRI suite. A rare case of thermal brain injury during MRI associated with an overheated ICP transducer is reported. This 20-year-old man had sustained a severe contusion of the right temporal and parietal lobes during a motor vehicle accident. An MR-compatible ICP transducer was placed in the left frontal lobe. The patient was treated with therapeutic hypothermia, barbiturate therapy, partial right temporal lobectomy, and decompressive craniectomy. Immediately after MRI examination on hospital Day 6, the ICP monitor was found to have stopped working, and the transducer was subsequently removed. The patient developed meningitis after this event, and repeat MRI revealed additional brain injury deep in the white matter on the left side, at the location of the ICP transducer. It is suspected that this new injury was caused by heating due to the radiofrequency radiation used in MRI because it was ascertained that the tip of the transducer had been melted and scorched. Scanning conditions-including configuration of the transducer, MRI parameters such as the type of radiofrequency coil, and the specific absorption rate limit-deviated from the manufacturer's recommendations. In cooperation with the manufacturer, the authors developed a precautionary tag describing guidelines for safe MR scanning to attach to the display unit of the product. Strict adherence to the manufacturer's guidelines is very important for preventing serious complications in patients with ICP monitors undergoing MRI examinations.

Non-invasive estimation of intracranial pressure : MR-based evaluation in children with hydrocephalus

Authors: Muehlmann M, Steffinger D, Peraud A, Lehner M, Heinen F, Alperin N, Ertl-Wagner B, Koerte IK.

ISSUE: The intracranial pressure (ICP) is a crucially important parameter for diagnostic and therapeutic decision-making in patients with hydrocephalus. STANDARD RADIOLOGICAL
METHODS: So far there is no standard method to non-invasively assess the ICP. Various approaches to obtain the ICP semi-invasively or non-invasively are discussed and the clinical application of a magnetic resonance imaging (MRI)-based method to estimate ICP (MR-ICP) is demonstrated in a group of pediatric patients with hydrocephalus. METHODICAL INNOVATIONS: Arterial inflow, venous drainage and craniospinal cerebrospinal fluid (CSF) flow were quantified using phase-contrast imaging to derive the MR-ICP. PERFORMANCE: A total of 15 patients with hydrocephalus (n=9 treated with shunt placement or ventriculostomy) underwent MRI on a 3 T scanner applying retrospectively-gated cine phase contrast sequences. Of the patients six had clinical symptoms indicating increased ICP (age 2.5-14.61 years, mean 7.4 years) and nine patients had no clinical signs of elevated ICP (age 2.1-15.9 years; mean 9.8 years; all treated with shunt or ventriculostomy). Median MR-ICP in symptomatic patients was 24.5 mmHg (25th percentile 20.4 mmHg; 75th percentile 44.6 mmHg). Median MR-ICP in patients without acute signs of increased ICP was 9.8 mmHg (25th percentile 8.6 mmHg; 75th percentile 11.4 mmHg). Group differences were significant (p < 0.001; Mann-Whitney U-test). ACHIEVEMENTS: The MR-ICP technique is a promising non-invasive tool for estimating ICP. 
RECOMMENDATIONS: Further studies in larger patient cohorts are warranted to investigate its application in children with hydrocephalus.

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