Cranial Compliance Research Articles

Anesthesia for preoperative non-invasive intracranial pressure measurement in a child with Apert syndrome: a case report

Introduction: The presence of craniofacial alterations such as craniosynostosis and midface hypoplasia are some features of Apert syndrome. Those characteristics may lead to intracranial hypertension. For clinical evaluation, a non-invasive intracranial pressure measurement can be performed both as a preoperative examination and to evaluate surgical treatment. Several methods have been used to measure intracranial pressure non-invasively, such as optic nerve sheath ultrasound, optical coherence tomography, and intracranial pressure waveform (ICPw) monitoring with the sensor Brain4Care®. Some methods like ICPw, require that the patient remains standstill. Because the patient wasn’t cooperative, it was decided to register the ICPw under hypnosis. A specific anesthetic planning was done to minimize the impact on the ICPw. Case presentation: We present a 6 years old child with Apert Syndrome with ICPw registered by Brain4Care® device before and after monobloc craniofacial advancement with internal distraction. The chosen anesthetic was Sevoflurane at a dose ≤ 0.9% of inspired gases and air/oxygen proportion of 50/50%, with a laryngeal mask, under spontaneous ventilation, with normal end-tidal CO2 range. The preoperative ICPw suggested low cranial compliance, with a mean P2/P1 index above 1,2. The postoperative showed a mean P2/P1 index under 1.2, demonstrating improved cranial compliance. The same anesthetic planning was done on both occasions. Conclusion: Likely, an appropriate way to obtain a reliable non-invasive ICPw measurement under hypnosis includes positioning the patient at neutral decubitus, choosing hypnotics with minimal impact on ICP, and maintaining spontaneous ventilation during the exam.

Dynamic asymmetry in cerebrospinal fluid pressure: An indicator of regional differences in compliance.

Dural compliance influences the shape and magnitude of the cerebrospinal fluid (CSF) pulsations. In humans, cranial compliance is approximately 2× greater than spinal compliance; the differential has been attributed to the associated vasculature. In alligators, the spinal cord is surrounded by a large venous sinus, which suggests that the spinal compartment may have higher compliance than is found in mammals. Pressure catheters were surgically implanted into the cranial and spinal subdural spaces of eight subadult American alligators (Alligator mississippiensis). The CSF was propelled through the subdural space by orthostatic gradients and rapid changes in linear acceleration. CSF pressure recordings taken from the cranial compartment were consistently, and significantly, larger than those taken from the spinal compartment. After the myodural bridge of Alligator was surgically released, the asymmetry in CSF pressure was decreased. Unlike the situation in humans, the spinal compartment of Alligator has greater compliance than the cranial compartment, presumably due to the presence of the large spinal venous sinus surrounding the dura. The change in CSF pressures after myodural surgical release supports the hypothesis that the myodural bridge functions, at least in part, to modulate dural compliance and the exchange of CSF between the cranial and spinal compartments.

Brain Physiological Response and Adaptation During Spaceflight.

More than half of astronauts returning from long-duration missions on the International Space Station present with neuro-ocular structural and/or functional changes, including optic disc edema, optic nerve sheath distension, globe flattening, choroidal folds, or hyperopic shifts. This spaceflight-associated neuro-ocular syndrome (SANS) represents a major risk to future exploration class human spaceflight missions, including Mars missions. Although the exact pathophysiology of SANS is unknown, evidence thus far suggests that an increase in intracranial pressure (ICP) relative to the upright position on Earth, which is due to the loss of hydrostatic pressure gradients in space, may play a leading role. This review focuses on brain physiology in the spaceflight environment, specifically on how spaceflight may affect ICP and related indicators of cranial compliance, potential factors related to the development of SANS, and findings from spaceflight as well as ground-based spaceflight analog research studies.

Bifrontal Biparietal Cruciate Decompressive Craniectomy in Pediatric Traumatic Brain Injury

Background: We investigated a novel surgical approach to decompressive craniectomy (DC), the bifrontal biparietal, or “cruciate,” craniectomy, in severe pediatric traumatic brain injury (TBI). Cruciate DC was designed with a fundamentally different approach to intracranial pressure (ICP) control compared to traditional DC. Cruciate DC involves craniectomies in all 4 skull quadrants. The sagittal and coronal bone struts are disarticulated at the skull to allow the decompression of the sagittal sinus and bridging veins in addition to permitting cerebral expansion, thereby maintaining cranial compliance. Objective: To characterize ICP control with cruciate DC in pediatric TBI. Methods: We performed a retrospective review of TBI patients who underwent cruciate DC. We investigated mortality and preoperative and postoperative ICP. Group 1 underwent medical therapy prior to DC and Group 2 required immediate DC. Results: Fifteen of 18 patients survived. In Group 1, mean preoperative ICP was 18.5 mm Hg and mean postoperative ICP was 11.5 mm Hg. In Group 2, mean preoperative ICP was 27.3 mm Hg and mean postoperative ICP was 15.0 mm Hg. Conclusion: Cruciate DC was associated with lowering ICP. We observed acute drops in ICP and long-term ICP control. The floating bone struts of the cruciate DC permits the decompression of the sagittal sinus and bridging veins, with maximal relief of cerebral edema.

Patient-specific cranio-spinal compliance distribution using lumped-parameter model: its relation with ICP over a wide age range

BackgroundThe distribution of cranio-spinal compliance (CSC) in the brain and spinal cord is a fundamental question, as it would determine the overall role of the compartments in modulating ICP in healthy and diseased states. Invasive methods for measurement of CSC using infusion-based techniques provide overall CSC estimate, but not the individual sub-compartmental contribution. Additionally, the outcome of the infusion-based method depends on the infusion site and dynamics. This article presents a method to determine compliance distribution between the cranium and spinal canal non-invasively using data obtained from patients. We hypothesize that this CSC distribution is indicative of the ICP.MethodsWe propose a lumped-parameter model representing the hydro and hemodynamics of the cranio-spinal system. The input and output to the model are phase-contrast MRI derived volumetric transcranial blood flow measured in vivo, and CSF flow at the spinal cervical level, respectively. The novelty of the method lies in the model mathematics that predicts CSC distribution (that obeys the physical laws) from the system dc gain of the discrete-domain transfer function. 104 healthy individuals (48 males, 56 females, age 25.4 ± 14.9 years, range 3–60 years) without any history of neurological diseases, were used in the study. Non-invasive MR assisted estimate of ICP was calculated and compared with the cranial compliance to prove our hypothesis.ResultsA significant negative correlation was found between model-predicted cranial contribution to CSC and MR-ICP. The spinal canal provided majority of the compliance in all the age groups up to 40 years. However, no single sub-compartment provided majority of the compliance in 41–60 years age group. The cranial contribution to CSC and MR-ICP were significantly correlated with age, with gender not affecting the compliance distribution. Spinal contribution to CSC significantly positively correlated with CSF stroke volume.ConclusionsThis paper describes MRI-based non-invasive way to determine the cranio-spinal compliance distribution in the brain and spinal canal sub-compartments. The proposed mathematics makes the model always stable and within the physiological range. The model-derived cranial compliance was strongly negatively correlated to non-invasive MR-ICP data from 104 patients, indicating that compliance distribution plays a major role in modulating ICP.

Automated Quantitation of Spinal CSF Volume and Measurement of Craniospinal CSF Redistribution following Lumbar Withdrawal in Idiopathic Intracranial Hypertension.

Automated methods for quantitation of tissue and CSF volumes by MR imaging are available for the cranial but not the spinal compartment. We developed an iterative method for delineation of the spinal CSF spaces for automated measurements of CSF and cord volumes and applied it to study craniospinal CSF redistribution following lumbar withdrawal in patients with idiopathic intracranial hypertension. MR imaging data were obtained from 2 healthy subjects and 8 patients with idiopathic intracranial hypertension who were scanned before, immediately after, and 2 weeks after diagnostic lumbar puncture. Imaging included T1-weighted and T2-weighted sequences of the brain and T2-weighted scans of the spine. Repeat scans in 4 subjects were used to assess measurement reproducibility. Whole CNS CSF volumes measured prior to and following lumbar puncture were compared with the withdrawn amounts of CSF. CSF and cord volume measurements were highly reproducible with mean variabilities of -0.7% ± 1.4% and -0.7% ± 1.0%, respectively. Mean spinal CSF volume was 77.5 ± 8.4 mL. The imaging-based pre- to post-CSF volume differences were consistently smaller and strongly correlated with the amounts removed (R = 0.86, P = .006), primarily from the lumbosacral region. These differences are explained by net CSF formation of 0.41 ± 0.18 mL/min between withdrawal and imaging. Automated measurements of the craniospinal CSF redistribution following lumbar withdrawal in idiopathic intracranial hypertension reveal that the drop in intracranial pressure following lumbar puncture is primarily related to the increase in spinal compliance and not cranial compliance due to the reduced spinal CSF volume and the nearly unchanged cranial CSF volume.

Sonographic and Doppler Sonographic Diagnosis of Posthemorrhagic Hydrocephalus.

Severe intracranial hemorrhages occur especially in very immature premature infants born with a gestational age under 28 weeks of gestation and a birth weight below 1000 g. Severe hemorrhages are often complicated by a post-hemorrhagic hydrocephalus (PHH). PHH can be caused by a blockage of the cerebro-spinal fluid pathways or by obliterative arachnoiditis of the posterior cranial fossa. Cerebral sonography can differentiate between both entities. In cases of obstruction of the cerebro-spinal fluid circulation the parts of the ventricular system infront of the obstruction are dilated. Color coded Doppler sonography can display the patency or obstruction of the physiologic constrictions of the ventricular system. Increased intracranial pressure can noninvasively be detected by spectral Doppler: The increase of the peak systolic flow velocity in the intracranial section of the internal carotid artery in comparison with the extra-cranial part is an early indication of a raised intracranial pressure. The decrease of the end-diastolic flow velocity during fontanel compression is indicative of abolished cranial compliance and increased intracranial pressure. In the case of raised intracranial pressure diastolic amplitudes and end-diastolic flow velocities are decreased and the resistive-indices are increased.

Brain tissue viscoelasticity in chronically shunted patients with headaches using Magnetic Resonance Elastography

Chronic headaches are a well-documented complaint of shunted hydrocephalic patients. However, it is also one of the signs of shunt malfunction. Cranial compliance deficiency may be a cause of chronic headaches in some chronically shunted patients with functioning shunts (often with slit or smaller than normal ventricles). This study aims to use a novel, non-invasive imaging technique, Magnetic Resonance Elastography (MRE) to investigate the role of brain viscoelasticity in pediatric hydrocephalic patients.

Fundamental Basis, Informational Meaning and Data Analysis of Multifrequency Reoencephalography

A long historical experience of monofrequency rheoencephalography (REG) showed its limited capabilities. The new approach is presented – multifrequency REG that is REG recording simultaneously at three frequencies - 16, 100 and 200 kHz. The different brain impedances received were analyzed on the base of equivalent electrical circuits of brain tissue. First, this enables to calculate intra-extracellular electrical component for evaluation of brain tissue hydration state by means of an original computational method. Second, dynamic cooperative analysis of multi-REG and transcranial Doppler pulsations provides the indices of intracranial CSF mobility (CSFm) and cranial compliance (CCe). Third, spectral analysis of processes recorded provides the new valuable information about regulatory processes and brain metabolism involved, and this enables to evaluate indirectly brain cognitive capabilities. Fourth, comparison of spectrum diagrams of slow intracranial volume fluctuations in ranges 0 – 0.3 Hz demonstrates their similarity both in healthy human and in awake rabbits, notwithstanding their rates differences of heart pulsations and respiratory chest movements. The application of this new approach to investigation of intracranial circulation in healthy humans of different ages and in neurosurgical patients showed its promising efficacy.

Multifrequency REG: Fundamental Background, Informational Meaning and Ways of Data Analysis and Automation

A long historical experience of monofrequency rheoencephalography (REG) showed its limited capabilities. The new approach ispresented - multifrequency REG that is REG record ing simultaneously at three frequencies - 16, 100 and 200 kHz. The d ifferent brain impedances received were analysed on the base of equivalent electrical circuits of brain tissue. First, this enables to calculate intra-extracellu lar electrical co mponent for evaluation of brain tissue hydration state by means of an original co mputational method. Second, dynamic cooperative analysis of mu lti -REG and transcranial Doppler pulsations provides the indices of intracranial CSF mobility (CSFm) and cranial co mpliance (CCe). Th ird, spectral analysis of processes recorded provides valuable information of regulatory processes involved. The application of this new approach to investigation of intracranial circu lation in healthy persons of different aging groupos and in neurosurgical patients showed its promising effectiv ity.

Endoscopic therapy for obstructive hydrocephalus caused by cysts in the pathway of CSF circulation

To explore the process and technique of neuroendoscopic operation to treat obstructive hydrocephalus caused by cysts located in the pathway of CSF circulation. The cine MRI examinations and endoscopic operations were taken to treat 30 cases with obstructive hydrocephalus. Among all the cases, there are 11 intraventricular cysts (8 lateral ventricular cysts, 4 fourth ventricular cysts), 4 suprasellar arachnoid cysts, 1 quadrigeminal cistern arachnoid cyst, 6 Dandy-Walker malformations and 8 posterior fossa arachnoid cysts. CSF dynamic of all patients improved to different extents post-operation. It was observed that CSF passed through the stoma after ETV in all patients. The volume of 9 intraventricular cysts, 4 suprasellar arachnoid cysts, 1 quadrigeminal cistern arachnoid cyst and 4 posterior fossa arachnoid cysts diminished for different degrees. There were no surgery-related serious complications or deaths. There were not cyst enlarged and stoma obstructed cases. Obstructive hydrocephalus caused by cysts in the pathway of CSF circulation is the optimal indication for neuro-endoscopic surgery. After resecting cyst partially, we should take the endoscopic third ventriculostomy to rebuild the passway of CSF and elevate the cranial compliance. Cine MRI and radionuclide cisternography are helpful to understand the CSF dynamic and absorption.

Biomechanical properties of human cranium: Age-relayed aspects

Biomechanical properties of the human skull affect its dynamic tensility (pliability or compliance) at changes of intracranial volume and pressure (ΔV/ΔP). The work substantiates a possibility of noninvasive and dynamic evaluation of cranial compliance by synchronous recording of transcranial dopplerogram of middle cerebral artery and cranial bioimpedance that provides information about pulsative changes of intracranial pressure and volume, respectively, with subsequent computer pattern and phasic analysis of these processes. The characteristic peculiarities of the cranial compliance at rest and during action of functional hemo- and liquorodynamic tests were traced in people of the middle (40–50 years) and elderly (70–85 years) age groups as compared with the young group (20–30 years). A relative decrease of this parameter has been revealed in the middle age group due to an increase of rigidity of skull bones and ligaments, which indicates a decrease of tolerance of the intracranial circulatory system. However, in the group of 70–85 years the compliance parameters rose due to an increase of intracranial liquor volume and activation of liquor circulation inside the craniospinal space, which is a compensatory mechanism for maintenance of the adequate brain circulatory-metabolic activity.

Relation of age cognitive disorders with cranial compliance, cerebrospinal fluid mobility and cerebral circulation

Relation of age cognitive disorders with cranial compliance, cerebrospinal fluid mobility and cerebral circulation

The effect of craniotomy on the intracranial hemodynamics and cerebrospinal fluid dynamics in humans

The goal of the research was to study the effect of the trephination of the human cranial cavity on the intracranial hemodynamics and cerebrospinal fluid (CSF) dynamics. The sample comprised 15 patients of a neurosurgical clinic in whom a trephine opening in the cranial bones was made for medical indications. In these patients, at rest and during an appropriate functional load, we recorded pulse changes in blood circulation (by transcranial Doppler sonography) and in the ratio between the pulse fluctuations in the blood and CSF volumes (by rheoencephalography) before and after surgery. Simultaneous recording of these parameters followed by computer pattern and phase analyses allowed evaluation of the complex biomedical compliance of the cranium during successive phases of the cardiac rhythm: the inflow of arterial blood, the redistribution of blood/CSF volumes, and the outflow of venous blood. Analysis of the results showed a beneficial influence of craniotomy on the intracranial hemodynamics and CSF dynamics. This was reflected in an increase in the cranial compliance, which increased the pulse increment in the volume of the arterial blood in the skull almost twofold. After craniotomy, the cross-flow of CSF between the cranial and spinal cavities decreased significantly, giving way to volumetric compensatory translocations of blood and CSF within the cranial cavity per se during the cardiac cycle, which increased the intracranial utilization of the energy of the cardiac output and contributed to the outflow of venous blood from the cranium. The results suggest a beneficial effect of craniotomy on the physiological mechanisms of the circulatory and metabolic maintenance of the brain activity.

SONOGRAPHIC ASSESSMENT OF POSTHEMORRHAGIC VENTRICULAR DILATATION

Sonography plays a key role in the initial evaluation and monitoring of ventricular dilatation in the newborn. The use of supplemental imaging approaches by the mastoid fontanelle and foramen magnum can help identify the cause and location of obstruction. Duplex Doppler of intracranial vessels during anterior fontanelle compression is a useful indicator of altered cranial compliance in these infants. Additional views of the thoracolumbar spine can help identify which infants will likely benefit from lumbar puncture for therapy of progressive ventricular dilatation.

Effects of fiberoptic bronchoscopy on intracranial pressure in patients with brain injury: a prospective clinical study.

Fiberoptic bronchoscopy (FB) plays an important role in making the diagnosis of nosocomial pneumonia and resolving lobar atelectasis in critically injured trauma patients. It has been shown to be a safe procedure with only occasional complications. However, in patients with head injuries, FB can lead to intracranial hypertension. Sustained increases in intracranial pressure (ICP) leads to poor outcome in these patients. Because of this, a prospective study was done not only to assess the effect of FB on ICP and cerebral perfusion pressure (CPP) in patients with brain injuries, but also to identify a regimen of sedation and anesthesia that could prevent significant increases in ICP during FB. Twenty-six FB were performed in 23 patients with ICP monitors or ICP monitors and ventriculostomy drains in place for Glasgow Coma Scale score < 8 or management of postcraniotomy trauma. FB was performed to aid in the diagnosis of nosocomial pneumonia or to aid in resolving lobar atelectasis. Before FB, all patients received a standard anesthetic regimen consisting of vecuronium (10 mg), morphine sulfate (4 mg), and midazolam (2.5 mg). Patients with diminished cranial compliance, defined as ICP > 10 mm Hg, also received a nebulizer treatment of 3 mL of 4% lidocaine before FB. All patients were preoxygenated with FIO2 = 1.0 for 10 minutes. Intracranial pressure, mean arterial pressure, and CPP were monitored continuously throughout the procedure. These same variables were also recorded at baseline and at 2-minute intervals during the procedure. The time to return to baseline ICP was also recorded. The mean ICP at baseline (immediately before FB) was 12.6 mm Hg. After introduction of the bronchoscope, the ICP rapidly increased in 21 procedures (81%) and the mean highest ICP was 38.0 mm Hg. There was also a concomitant increase in mean arterial pressure such that there was no substantial change in CPP. The mean lowest CPP was 73.1 mm Hg. The average time for return of ICP to baseline was 13.9 minutes. In the subgroup of patients with ICP > 10, attempting to blunt the tracheal stimulation by anesthetizing the trachea with 4% nebulized lidocaine did not seem to be successful. The mean highest ICP in this subgroup was 41.8 mm Hg. The CPP changed in a similar manner, as the mean lowest CPP was 74.0 mm Hg. The mean time to return to baseline was 12.5 minutes. No patient had acute neurologic deterioration secondary to FB. Although FB is an important procedure in the pulmonary care of head injured patients, it produces substantial, but transient, increases in ICP and should be used with caution in patients with diminished cranial compliance. Sedation, analgesia, paralysis, and topical tracheal anesthesia did not completely prevent the rise in ICP. Although no acute deterioration in condition occurred, secondary brain injury caused by localized cerebral ischemia is certainly possible. Because of the substantial increases in ICP, herniation may be precipitated in an occasional patient. Further study is needed to identify a regimen that will confer protection.

Intracranial compliance in infants: evaluation with Doppler US.

To test graded fontanelle compression during Doppler ultrasound (US) scanning to identify and monitor infants with altered cranial compliance. An ophthalmodynamometer exerted pressure on the anterior fontanelle during Doppler US scanning of the middle cerebral artery. Sixty examinations were performed in 43 infants--13 full-term and 11 premature healthy control subjects, 10 with increased intracranial volume, and nine with suspected abnormal cranial compliance but without increased intracranial volume. Resistive index (RI) and angle-corrected time-averaged mean velocities (TAV) of blood flow were compared at three different pressures. Baseline RI values in healthy full-term infants were significantly lower than in healthy premature infants and infants with abnormal compliance (P < .05). Values for healthy premature infants and infants with abnormal compliance were indistinguishable (P > .5). Neither RI nor TAV changed significantly in healthy infants, but both changed significantly with compression in infants with abnormal cranial compliance. This procedure may be more useful than measurement of RI of the anterior cerebral artery alone to evaluate infants with altered cranial compliance.

Role of cranial bone mobility in cranial compliance.

Increases in intracranial pressure are normally buffered by the displacement of blood and cerebrospinal fluid from the cranium when there is an increase in intracranial volume (ICV). How much pressure increases with an increase in ICV is expressed in the calculation of cranial compliance (delta ICV/delta P, where delta P is change in pressure) and elastance (delta P/delta ICV). Data reported here indicate that the movement of the cranial bones at their sutures is an additional factor defining total cranial compliance. Using controlled bolus injections of artificial cerebrospinal fluid into a lateral cerebral ventricle in anesthetized cats and a newly developed instrument to quantify cranial bone movement at the midline sagittal suture where the bilateral parietal bones meet, we show that these cranial bones move in association with increases in ICV along with corresponding peak intracranial pressures and changes in intracranial pressure. External restraints to the head restrict these movements and reduce the compliance characteristics of the cranium. We propose that total cranial compliance depends on the mobility of intracranial fluid volumes of blood and cerebrospinal fluid when there is an increase in ICV, but it also varies as a function of cranial compliance attributable to the movement of the cranial bones at their sutures. Our data indicate that although the cranial bones move apart even with small (nominally 0.2 ml) increases in ICV, total cranial compliance depends more on fluid migration from the cranium when ICV increases are less than approximately 3% of total cranial volume. Cranial bone mobility plays a progressively larger role in total cranial compliance with larger ICV increases.

Role of Cranial Bone Mobility in Cranial Compliance

Role of Cranial Bone Mobility in Cranial Compliance

Effect of scanning pressure on intracranial hemodynamics during transfontanellar duplex US.

The purpose of this study was to determine the effect of transducer scanning pressure during duplex ultrasonographic evaluation of intracranial hemodynamics in newborns. Doppler spectra were obtained from the anterior cerebral artery with use of light and firm scanning pressure over the anterior fontanelle in 23 healthy infants and 20 infants with reduced cranial compliance due to ventricular dilatation, intracranial hemorrhage, diffuse cerebral edema, and extraaxial fluid. In healthy infants, the mean resistive index (RI) increased from 69.9 +/- 3 to 74.8 +/- 3 (P < .005), and mean time average velocity (TAV) decreased from 11.1 cm/sec +/- 1.3 to 8.6 cm/sec +/- 1.3 (P < .0001) with firm scanning pressure. In infants with decreased cranial compliance, mean RI increased from 67.8 +/- 4 to 85 +/- 5, and mean TAV decreased from 16.3 cm/sec +/- 2 to 10.7 cm/sec +/- 2 (P < .0001 for both comparisons). A significant alteration in RI with firm technique (> or = 20% increase in RI, or reversal of diastolic flow) was observed in 12 of 28 examinations in infants with decreased cranial compliance and in only one of 23 healthy infants (P < .005). These data show that scanning pressures during duplex ultrasonography can significantly affect intracranial hemodynamics, especially in infants with altered cranial compliance.