Intracranial Pressure: More Than a Number

Czosnyka, Marek; Smielewski, Peter; Timofeev, Ivan; Lavinio, Andrea; Guazzo, E.; Hutchinson, Peter J.; Pickard, John D.

doi:10.3171/foc.2007.22.5.11

Cited by 119 publications

(81 citation statements)

References 41 publications

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“…It has been suggested that, after TBI, NICU treatment should become individualized based on each patient's CPP opt . 2,9 The CPP opt for a patient can be defined as the CPP that minimizes PRx: i.e., maximizes vascular pressure reactivity. There were no ISP or SCPP targets in our studies because we have not yet determined the optimal ISP and SCPP after TSCI.…”

Section: Discussionmentioning

confidence: 99%

Safety profile and probe placement accuracy of intraspinal pressure monitoring for traumatic spinal cord injury: Injured Spinal Cord Pressure Evaluation study

Phang

Zoumprouli

Saadoun

et al. 2016

SPI

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OBJECTIVE A novel technique for monitoring intraspinal pressure and spinal cord perfusion pressure in patients with traumatic spinal cord injury was recently described. This is analogous to monitoring intracranial pressure and cerebral perfusion pressure in patients with traumatic brain injury. Because intraspinal pressure monitoring is a new technique, its safety profile and impact on early patient care and long-term outcome after traumatic spinal cord injury are unknown. The object of this study is to review all patients who had intraspinal pressure monitoring to date at the authors' institution in order to define the accuracy of intraspinal pressure probe placement and the safety of the technique. METHODS At the end of surgery to fix spinal fractures, a pressure probe was inserted intradurally to monitor intraspinal pressure at the injury site. Postoperatively, CT scanning was performed within 48 hours and MRI at 2 weeks and 6 months. Neurointensive care management and complications were reviewed. The American Spinal Injury Association Impairment Scale (AIS) grade was determined on admission and at 2 to 4 weeks and 12 to 18 months postoperation. RESULTS To date, 42 patients with severe traumatic spinal cord injuries (AIS Grades A–C) had undergone intraspinal pressure monitoring. Monitoring started within 72 hours of injury and continued for up to a week. Based on postoperative CT and MRI, the probe position was acceptable in all patients, i.e., the probe was located at the site of maximum spinal cord swelling. Complications were probe displacement in 1 of 42 patients (2.4%), CSF leakage that required wound resuturing in 3 of 42 patients (7.1%), and asymptomatic pseudomeningocele that was diagnosed in 8 of 42 patients (19.0%). Pseudomeningocele was diagnosed on MRI and resolved within 6 months in all patients. Based on the MRI and neurological examination results, there were no serious probe-related complications such as meningitis, wound infection, hematoma, wound breakdown, or neurological deterioration. Within 2 weeks postoperatively, 75% of patients were extubated and 25% underwent tracheostomy. Norepinephrine was used to support blood pressure without complications. Overall, the mean intraspinal pressure was around 20 mm Hg, and the mean spinal cord perfusion pressure was around 70 mm Hg. In laminectomized patients, the intraspinal pressure was significantly higher in the supine than lateral position by up to 18 mm Hg after thoracic laminectomy and 8 mm Hg after cervical laminectomy. At 12 to 18 months, 11.4% of patients had improved by 1 AIS grade and 14.3% by at least 2 AIS grades. CONCLUSIONS These data suggest that after traumatic spinal cord injury intradural placement of the pressure probe is accurate and intraspinal pressure monitoring is safe for up to a week. In patients with spinal cord injury who had laminectomy, the supine position should be avoided in order to prevent rises in intraspinal pressure.

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Section: Discussionmentioning

confidence: 99%

Safety profile and probe placement accuracy of intraspinal pressure monitoring for traumatic spinal cord injury: Injured Spinal Cord Pressure Evaluation study

Phang

Zoumprouli

Saadoun

et al. 2016

SPI

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“…The use of a transfer function assumes that a linear transmission occurs from the input to the output signals. This assumption may not be valid for biological signaling, particularly in various disease states (Czosnyka et al, 2007). Another drawback of using these conventional methods is that they are time-invariant and are, therefore, not capable of tracking signal evolution over time.…”

Section: Transfer Function Between Cap and Ecpmentioning

confidence: 99%

“…It has been argued that the amplitude of the fundamental component is useful in evaluating certain indices of cerebrospinal dynamics (Czosnyka et al, 2007).…”

Section: Transfer Function Between Cap and Ecpmentioning

confidence: 99%

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Transfer function for vital infrasound pressures between the carotid artery and the tympanic membrane

Kenji

Yamashita

2013

The Journal of the Acoustical Society of America

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While occupational injury is associated with numerous individual and work-related risk factors, including long working hours and short sleep duration, the complex mechanisms causing such injuries are not yet fully understood. The relationship between the infrasound pressures of the tympanic membrane [ear canal pressure (ECP)], detected using an earplug embedded with a low-frequency microphone, and the carotid artery [carotid artery pressure (CAP)], detected using a stethoscope fitted with the same microphone, can be quantitatively characterized using systems analysis. The transfer functions of 40 normal workers (19 to 57 years old) were characterized, involving the analysis of 446 data points. The ECP waveform exhibits a pulsatile character with a slow respiratory component, which is superimposed on a biphasic recording that is synchronous with the cardiac cycle. The respiratory ECP waveform correlates with the instantaneous heart rate. The results also revealed that various fatigue-related risk factors may affect the mean magnitudes of the measured pressures and the delay transfer functions between CAP and ECP in the study population; these factors include systolic blood pressure, salivary amylase activity, age, sleep duration, postural changes, chronic fatigue, and pulse rate.

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“…4,6,10,14 Analysis of ICP and CSF dynamics studies were conducted with ICM+ software (Cambridge University Enterprise, Ltd.). 17 The median correlation coefficient between pulse amplitude and ICP (RAP), amplitude of ICP pulse (1 harmonic sine wave), slow wave amplitude (using the morphological clustering and analysis of ICP pulse [MOCAIP] algorithm), and mean ICP values were recorded and calculated during OVM according to the protocols of Czosnyka et al and Kasprowicz et al 2,3,9 LIFT yielded baseline and plateau values of ICP and pulse amplitudes as well as resistance of CSF outflow (ROut). Furthermore, the ICP amplitude quotient (AMP Q) was defined as the quotient between baseline and plateau ICP pulse wave amplitudes.…”

mentioning

confidence: 99%

Idiopathic normal pressure hydrocephalus: diagnostic and predictive value of clinical testing, lumbar drainage, and CSF dynamics

Mahr¹,

Dengl²,

Nestler³

et al. 2016

JNS

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591CliNiCal artiCle J Neurosurg 125:591-597, 2016 I dIopathIc normal pressure hydrocephalus (iNPH) has been a challenging entity for the past 50 years, since its first description by Hakim.21 Despite extensive research, its pathophysiological basis and pathogenesis remain matters of ongoing debate. Due to the uncertainty in diagnostic measures, several algorithms, diagnostic tools, and scoring systems have been proposed. A recent multicenter trial based the decision for surgical therapy on clinical signs and symptoms only, dividing cases into questionable and typical iNPH.23 Given the multitude of noninvasive and invasive measures to select symptomatic patients for hydrocephalus therapy, a prospective analysis of diagnostic and predictive parameters and their individual contributions within the diagnostic algorithm was warranted. Patients and MethodsPatients with suspicious clinical and MRI signs for iNPH were examined in a prospective study. Local ethics committee approval was obtained.abbreviatioNs AMP Q = ICP amplitude quotient; ELD = external lumbar drainage; ETV = endoscopic third ventriculostomy; ICP = intracranial pressure; iNPH = idiopathic normal pressure hydrocephalus; LIFT = lumbar infusion test; MMSE = Mini-Mental State Examination; mRS = modified Rankin Scale; OVM = overnight ICP monitoring; RAP = correlation coefficient between pulse amplitude and ICP; ROC = receiver operating characteristic; ROut = resistance to outflow of CSF; SLHS = Stein and Langfitt Hydrocephalus Score; VP = ventriculoperitoneal; ∆Kiefer = change in Kiefer score. obJeCtive The aim of the study was to analyze the diagnostic and predictive values of clinical tests, CSF dynamics, and intracranial pulsatility tests, compared with external lumbar drainage (ELD), for shunt response in patients with idiopathic normal pressure hydrocephalus (iNPH). Methods Sixty-eight consecutive patients with suspected iNPH were prospectively evaluated. Preoperative assessment included clinical tests, overnight intracranial pressure (ICP) monitoring, lumbar infusion test (LIFT), and ELD for 24-72 hours. Simple and multiple linear regression analyses were conducted to identify predictive parameters concerning the outcome after shunt therapy. results Positive response to ELD correctly predicted improvement after CSF diversion in 87.9% of the patients. A Mini-Mental State Examination (MMSE) value below 21 was associated with nonresponse after shunt insertion (specificity 93%, sensitivity 67%). Resistance to outflow of CSF (ROut) > 12 mm Hg/ml/min was false negative in 21% of patients. Intracranial pulsatility parameters yielded different results in various parameters (correlation coefficient between pulse amplitude and ICP, slow wave amplitude, and mean ICP) but did not correlate to outcome. In multiple linear regression analysis, a calculation of presurgical MMSE versus the value after ELD, ROut, and ICP amplitude quotient during LIFT was significantly associated with outcome (p = 0.04). CoNClusioNs Despite a multitude of invasive tests, presurgical cl...

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Intracranial Pressure: More Than a Number

Cited by 119 publications

References 41 publications

Safety profile and probe placement accuracy of intraspinal pressure monitoring for traumatic spinal cord injury: Injured Spinal Cord Pressure Evaluation study

Safety profile and probe placement accuracy of intraspinal pressure monitoring for traumatic spinal cord injury: Injured Spinal Cord Pressure Evaluation study

Transfer function for vital infrasound pressures between the carotid artery and the tympanic membrane

Idiopathic normal pressure hydrocephalus: diagnostic and predictive value of clinical testing, lumbar drainage, and CSF dynamics

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