Brain Compliance Research Articles

Promoting Bike Helmet Safety for Urban Children Through a Culturally Tailored Educational Video Intervention

Bicycle-related falls are a significant cause of mortality and morbidity. Use of bicycle helmets substantially reduces risk of severe traumatic brain injury but compliance with this safety practice is particularly low in urban children. We recruited eleven 8- to 15-year-old youth to participate in focus groups to inform the creation of a video promoting helmet use. Key emerging themes included that youth were responsible for keeping themselves safe and that most youth had cell phones with cases to protect them. A video was created that linked the concept of use of cases to protect phones to use of helmets to protect heads. Soliciting information from urban youth was helpful for developing this educational video.

The oscillatory flow of the cerebrospinal fluid in the Sylvian aqueduct and the prepontine cistern measured with phase contrast MRI in children with hydrocephalus\u2014a preliminary report

IntroductionRecognizing patients with ventriculomegaly who are at risk of developing acute hydrocephalus presents a challenge for the clinician. The association between disturbed cerebrospinal fluid flow (CSF) and impaired brain compliance may play a role in the pathogenesis of hydrocephalus. Phase contrast MRI is a noninvasive technique which can be used to assess CSF parameters. The aim of the work is to evaluate the effectiveness of phase contrast MRI in recognizing patients at risk of acute hydrocephalus, based on measuring the pulsatile CSF flow parameters in the Sylvian aqueduct and prepontine cistern in children with ventriculomegaly.AimThe aim of the work is to characterize the parameters of cerebrospinal fluid (CSF) flow in the Sylvian aqueduct and prepontine cistern in children with ventriculomegaly with regard to patient age and symptoms. We hypothesize that the relationship between CSF flow parameters in these two regions will vary according to analyzed factors and it will allow to recognize children at risk of hydrocephalus.Materials and methodsA group of 26 children with ventriculomegaly (five girls and 21 boys) underwent phase contrast MRI examinations (Philips 3T Achieva with Q-flow integral application). Amplitudes of average and peak velocities of the CSF flow through the Sylvian aqueduct and prepontine cistern were used to calculate ratios of oscillation and peak velocities, respectively. The relationship between the oscillation coefficient, the peak velocity coefficient, and stroke volume was then assessed in accordance with age and clinical symptoms.ResultsThe peak velocity coefficient was significantly higher in patients with hyper-oscillating flow through the Sylvian aqueduct (3.04 ± 3.37 vs. 0.54 ± 0.28; p = 0.0094). Moreover, these patients tended to develop symptoms more often (p = 0.0612). No significant age-related changes were observed in CSF flow parameters.ConclusionPhase contrast MRI is a useful tool for noninvasive assessment of CSF flow parameters. The application of coefficients instead of direct values seems to better represent hemodynamic conditions in the ventricular system. However, further studies are required to evaluate their clinical significance and normal limits.

Importance of Frontal Horn Ratio and Optimal CSF Drainage in the Treatment of Very Low-Pressure Hydrocephalus.

Introduction Unlike low-pressure hydrocephalus, very low pressure hydrocephalus (VLPH) is a rarely reported clinical entity previously described to be associated with poor outcomes and to be possibly refractory to treatment with continued cerebrospinal fluid (CSF) drainage at subatmospheric pressures. 1, 2 We present four cases of VLPH following resection of suprasellar lesions and hypothesize that untreatable patients can be identified early, thereby avoiding futile prolonged external ventricular drainage in ICU. Methods We performed a retrospective chart review of four cases of VLPH encountered between 2007 and 2015 in two different institutions and practices and tried to identify factors contributing to successful treatment. We hypothesized that normalization of frontal horn ratio (FHR), optimization of volume of CSF drained, and avoidance of fluid shifts would contribute to improved Glasgow Coma Score (GCS). We examined fluid shifts by studying net fluids shifts and serum levels of sodium, urea, and creatinine. We used Pearson and Spearman correlations to identify measures that would correlate with improved GCS. Results Our study reveals that improving GCS is positively correlated with decreased FHR and increased CSF drainage within an optimal range. The most important determinant of good outcome is retention of brain viscoelasticity as evidenced by restoration and maintenance of good GCS score despite fluctuations in FHR. Conclusion Futile prolonged subatmospheric drainage can be avoided by declining to continue treatment in patients who have permanently altered brain compliance secondary to unsealed CSF leaks, irremediable ventriculitis, and who are therefore unable to sustain an improved neurologic examination.

Transcranial Doppler: a stethoscope for the brain-neurocritical care use.

Transcranial Doppler (TCD) ultrasonography is a noninvasive bedside monitoring technique that can evaluate cerebral blood flow hemodynamics in the intracranial arterial vasculature. TCD allows assessment of linear cerebral blood flow velocity, with a high temporal resolution and is inexpensive, reproducible, and portable. The aim of this review is to provide an overview of the most commonly used TCD derived signals and measurements used commonly in neurocritical care. We describe both basic (flow velocity, pulsatility index) and advanced concepts, including critical closing pressure, wall tension, autoregulation, noninvasive intracranial pressure, brain compliance, and cerebrovascular time constant; we also describe the clinical applications of TCD to highlight their utility in the diagnosis and monitoring of cerebrovascular diseases as the "stethoscope for the brain."

Shunt-dependent hydrocephalus: management style among members of the American Society of Pediatric Neurosurgeons.

OBJECTIVE The authors conducted a survey to evaluate differences in the understanding and management of shunt-dependent hydrocephalus among members of the American Society of Pediatric Neurosurgeons (ASPN). METHODS Surveys were sent to all 204 active ASPN members in September 2014. One hundred thirty responses were received, representing a 64% response rate. Respondents were asked 13 multiple-choice and free-response questions regarding 4 fundamental problems encountered in shunted-hydrocephalus management: shunt malfunction, chronic cerebrospinal fluid (CSF) overdrainage, chronic headaches, and slit ventricle syndrome (SVS). RESULTS Respondents agreed that shunt malfunction occurs most often as the result of ventricular catheter obstruction. Despite contrary evidence in the literature, most respondents (66%) also believed that choroid plexus is the tissue most often found in obstructed proximal catheters. However, free-text responses revealed that the respondents' understanding of the underlying pathophysiology of shunt obstruction was highly variable and included growth, migration, or adherence of choroid plexus, CSF debris, catheter position, inflammatory processes, and CSF overdrainage. Most respondents considered chronic CSF overdrainage to be a rare complication of shunting in their practice and reported wide variation in treatment protocols. Moreover, despite a lack of evidence in the literature, most respondents attributed chronic headaches in shunt patients to medical reasons (for example, migraines, tension). Accordingly, most respondents managed headaches with reassurance and/or referral to pain clinics. Lastly, there were variable opinions on the etiology of slit ventricle syndrome (SVS), which included early shunting, chronic overdrainage, and/or loss of brain compliance. Beyond shunt revision, respondents reported divergent SVS treatment preferences. CONCLUSIONS The survey shows that there is wide variability in the understanding and management of shunt-dependent hydrocephalus and its complications. Such discrepancies appear to be derived partly from inconsistent familiarity with existing literature but especially from a paucity of high-quality publications.

Importance of ventricle-to-brain ratio (VBR) and volume of CSF drainage in the treatment of very low pressure hydrocephalus

Introduction: Low pressure hydrocephalus is a known complication of prolonged hydrocephalus sometimes treatable with continued low-pressure drainage at subatmospheric pressures. Clarke et. al. and Filipidis et. al. have reported poor outcomes when treating very low pressure hydrocephalus (VLPH). We present 4 cases of very low pressure hydrocephalus (VLPH) following transnasal endoscopic resection of suprasellar lesions and hypothesize that poor prognostic cases can be identified thereby avoiding prolonged futile treatments. Methods: We performed a retrospective chart review of 4 cases of VLPH and tried to identify metrics contributing to successful treatment. We examined the Pearson correlations between Glasgow Coma Scale and ventricle-to-brain ratio (VBR); volume of CSF drained; net fluids; and serum sodium, urea, and creatinine. Results: Our investigation reveals that Glasgow Coma Score is positively correlated with increased CSF drainage and negatively correlated with increased ventricle-to-brain ratio. The most important determinant of good outcome is brain compliance as measured by the brain’s ability to maintain a good GCS score in the face of wide ranges in ventricle-to-brain ratio (VBR). Conclusion: We propose that futile prolonged subatmospheric drainage be avoided by declining treatment in patients who have ventriculitis and patients who have a narrow range of ventricle-to-brain ratio (VBR) concurrent with a good neurological examination.

Management of Cerebellar Tonsillar Herniation following Lumbar Puncture in Idiopathic Intracranial Hypertension.

Lumbar puncture is performed routinely for diagnostic and therapeutic purposes in idiopathic intracranial hypertension, despite lumbar puncture being classically contraindicated in the setting of raised intracranial pressure. We report the case of a 30-year-old female with known idiopathic intracranial hypertension who had cerebellar tonsillar herniation following therapeutic lumbar puncture. Management followed guidelines regarding treatment of traumatic intracranial hypertension, including rescue decompressive craniectomy. We hypothesize that the changes in brain compliance that are thought to occur in the setting of idiopathic intracranial hypertension are protective against further neuronal injury due to axonal stretch following decompressive craniectomy.

Microgravity environment and compensatory: Decompensatory phases for intracranial hypertension form new perspectives to explain mechanism underlying communicating hydrocephalus and its related disorders.

The pathogenesis underlying communicating hydrocephalus has been centered on impaired cerebrospinal fluid (CSF) outflow secondary to abnormal CSF pulsation and venous hypertension. Hydrodynamic theory of hydrocephalus fares better than traditional theory in explaining the possible mechanisms underlying communicating hydrocephalus. Nonetheless, hydrodynamic theory alone could not fully explain some conditions that have ventriculomegaly but without hydrocephalus. By revisiting brain buoyancy from a fresher perspective, called microgravity environment of the brain, introducing wider concepts of anatomical and physiological compensatory–decompensatory phases for a persistent raise in intracranial pressure, and along with combining these two concepts with the previously well-accepted concepts of Monro–Kellie doctrine, intracranial hypertension, cerebral blood flow, cerebral perfusion pressure, brain compliance and elasticity, cerebral autoregulation, blood–brain and blood–CSF barriers, venous and cardiopulmonary hypertension, Windkessel phenomenon, and cerebral pulsation, we provide plausible explanations to the pathogenesis for communicating hydrocephalus and its related disorders.

Altitude Does Not Reduce Concussion Incidence: Response.

Altitude Does Not Reduce Concussion Incidence: Response.

Quelle pression de perfusion cérébrale après traumatisme crânien chez l’enfant ?

The management of cerebral perfusion pressure (CPP) is the one of the main preoccupation for the care of paediatric traumatic brain injury (TBI). The physiology of cerebral autoregulation, CO2 vasoreactivity, cerebral metabolism changes with age as well as the brain compliance. Low CPP leads to high morbidity and mortality in pediatric TBI. The recent guidelines for the management of CPP for the paediatric TBI indicate a CPP threshold 40–50mmHg (infants for the lower and adolescent for the upper). But we must consider the importance of age-related differences in the arterial pressure and CPP. The best CPP is the one that allows to avoid cerebral ischaemia and oedema. In this way, the adaptation of optimal CPP must be individual. To assess this objective, interesting tools are available. Transcranial Doppler can be used to determine the best level of CPP. Other indicators can predict the impairment of autoregulation like pressure reactivity index (PRx) taking into consideration the respective changes in ICP and CPP. Measurement of brain tissue oxygen partial pressure is an other tool that can be used to determine the optimal CPP.

Hypertensive slit ventricle syndrome: pseudotumor cerebri with a malfunctioning shunt?

Symptomatic shunt malfunction without ventricular enlargement is known as slit ventricle syndrome (SVS). Patients presenting with this syndrome are not a homogeneous group. Of the 5 different types classified by Rekate, Type 1 is caused by CSF overdrainage and is associated with low pressures; Types 2 and 3 are associated with shunt blockage and elevated CSF pressures; Type 4 is cephalocranial disproportion that increases brain parenchymal pressure but not CSF pressure; and Type 5 is headache unrelated to shunt function. The low and normal CSF pressure types are relatively well understood, but the high-pressure forms are more problematic. In the high-pressure forms of SVS it is said that the lack of ventricular dilation is related to a reduction in brain compliance analogous to idiopathic intracranial hypertension or pseudotumor cerebri. Despite this, there is little evidence in the literature to support this conjecture. With this in mind, 3 cases of SVS associated with elevated CSF pressure are presented. The MR venogram findings and hemodynamics of these 3 cases are shown to be identical to those of pseudotumor cerebri. A literature review indicates that an underlying venous impairment may be functioning in the patients who re-present with small ventricles following shunt malfunction.

Hypothesis for intracranial hypertension in slit ventricle syndrome: New concept of capillary absorption laziness in the hydrocephalic patients with long-term shunts

Many theories have been postulated to date regarding mechanisms involved in intracranial hypertension in patients with long-term, shunt-induced slit ventricle syndrome (SVS), but it still seems difficult to define this entity more clearly. Many hypotheses have attempted to explain the causes of SVS as chronic or intermittent catheter obstruction, brain compliance change, and ventricular herniation and distortion, but this theory does not explain clearly the reason why extraventricular pressure (EVP) is increased and intraventricular pressure (IVP) is low or frequently negative. The authors attempt to postulate a hypothesis by addressing new concept of capillary absorption laziness which results in dissociation of EVP with IVP.We, the authors, propose a concept of ‘capillary absorption laziness’, which is a tendency of the brain parenchymal extracellular fluid (ECF) not to be absorbed through the brain parenchymal capillary absorption system (BPCAS) that results from the bypass of ECF to shunt in the low or even negative ECF pressure and IVP. If this continues for a prolonged period, the tendency not to be absorbed through the BPCAS, even when the IVP and extracellular fluid pressures increases more than the intracranial pressure (ICP), may be established. This leads to situations of the brain such as parenchymal accumulation of the ECF which results in brain edema or swelling, and eventually distortion or herniation which can act as a functional obstruction and consequent dissociation between the IVP and EVP.Hypothesis of capillary absorption laziness may explain several common phenomena of the SVS such as low or even negative IVP in coexistence with high EVP and high ICP, and in these cases, we expect serious complications of SVS such as brain distortion and herniation. From this hypothesis we attempt to find new shunt management protocols to prevent long-term shunt induced complications.

Stroke volume‐directed administration of hydroxyethyl starch or Ringer's acetate in sitting position during craniotomy

To determine the volumes required for stable haemodynamics and possible effects on the coagulation, we studied stroke volume (SV)-directed administration of hydroxyethyl starch (HES 130 kDa/0.4) and Ringer's acetate (RAC) in neurosurgical patients operated on in a sitting position. Thirty craniotomy patients were randomised to receive either HES or RAC. Before positioning, SV, measured by arterial pressure waveform analysis, was maximised by boluses of fluid until SV did not increase more than 10%. SV was maintained by repeated administration of fluid. RAC 3 ml/kg/h was infused in both groups during surgery. Comparable haemodynamics were achieved with the mean [standard deviation (SD)] cumulative doses of HES or RAC 271 (47) or 264 (50) ml (P = 0.699) before the sitting position. Mean (SD) doses of HES or RAC at 30 min after the positioning were 343 (94) or 450 (156) ml (P = 0.036), and at the end of surgery 464 (284) or 707 (425) ml, respectively (P = 0.087). The intraoperative fluid balance was more positive in the RAC than in the HES group [P = 0.044, 95% confidence interval (CI) -978 to -14]. Cardiac and stroke volume indexes [CI and stroke volume index (SVI)] increased in the HES group (P < 0.05) but not in the RAC group [non significant (N.S.)]. Neither coagulation profile nor blood loss differed between the groups. Fluid filling with HES boluses resulted in a positive response in CI and SVI during the sitting position. The 34% smaller volume of HES than crystalloid and less positive fluid balance in the HES group might be important in craniotomy patients with decreased brain compliance.

Congenital idiopathic hydrocephalus of infancy: the results of treatment by endoscopic third ventriculostomy with or without choroid plexus cauterization and suggestions for how it works

The traditional bulk flow model of communicating hydrocephalus does not support treatment by endoscopic third ventriculostomy (ETV), but successful treatment is reported in adults. This study is the first to report long-term success of ETV +/- choroid plexus cauterization (CPC) for infants with congenital idiopathic hydrocephalus (CIH). The results are interpreted in the context of current models for hydrocephalus. The CURE Children's Hospital of Uganda prospective database was reviewed for the years 2001-2006 to identify children <24months of age meeting the criteria for CIH who underwent ETV with or without bilateral CPC. Kaplan-Meier method was used to assess treatment success survival. Gehan-Breslow-Wilcoxin and logrank tests were used to determine significance of survival differences. Fisher's exact test was used to determine the significance of differences between groups. Sixty-four infants (mean/median age, 6.1/5.0months) met the inclusion criteria. Sixteen consecutive patients were treated by ETV alone, and the subsequent 48 by ETV/CPC (mean/median follow-up 34.4/36.0months). ETV was successful in 20% and ETV/CPC in 72.4% at 4years (p < 0.0002, logrank test; p = 0.0006, Gehan-Breslow-Wilcoxin; hazard ratio 6.9, 95% CI 2.5-19.3). ETV/CPC was significantly more successful than ETV alone in treating CIH. The primary effect of ETV, as a pulsation absorber, and of CPC, as a pulsation reducer, may be to abate the net force of intraventricular pulsations that produce ventricular expansion. ETV alone may be less successful for infants because of greater brain compliance. ETV/CPC should be considered an effective primary treatment option.

Impaired pulsation absorber mechanism in idiopathic normal pressure hydrocephalus

The pathophysiology of normal pressure hydrocephalus (NPH), and the related problem of patient selection for treatment of this condition, have been of great interest since the description of this seemingly paradoxical condition nearly 50 years ago. Recently, Eide has reported that measurements of the amplitude of the intracranial pressure (ICP) can both positively and negatively predict response to CSF shunting. Specifically, the fraction of time spent in a "high amplitude" (> 4 mm Hg) state predicted response to shunting, which may represent a marker for hydrocephalic pathophysiology. Increased ICP amplitude might suggest decreased brain compliance, meaning a static measure of a pressure-volume ratio. Recent studies of canine data have shown that the brain compliance can be described as a frequency-dependent function. The normal canine brain seems to show enhanced ability to absorb the pulsations around the heart rate, quantified as a cardiac pulsation absorbance (CPA), with properties like a notch filter in engineering. This frequency dependence of the function is diminished with development of hydrocephalus in dogs. In this pilot study, the authors sought to determine whether frequency dependence could be observed in humans, and whether the frequency dependence would be any different in epochs with high ICP amplitude compared with epochs of low ICP amplitude. Systems analysis was applied to arterial blood pressure (ABP) and ICP waveforms recorded from 10 patients undergoing evaluations of idiopathic NPH to calculate a time-varying transfer function that reveals frequency dependence and CPA, the measure of frequency-dependent compliance previously used in animal experiments. The ICP amplitude was also calculated in the same samples, so that epochs with high (> 4 mm Hg) versus low (≤ 4 mm Hg) amplitude could be compared in CPA and transfer functions. Transfer function analysis for the more "normal" epochs with low amplitude exhibits a dip or notch in the physiological frequency range of the heart rate, confirming in humans the pulsation absorber phenomenon previously observed in canine studies. Under high amplitude, however, the dip in the transfer function is absent. An inverse relationship between CPA index and ICP amplitude is evident and statistically significant. Thus, elevated ICP amplitude indicates decreased performance of the human pulsation absorber. The results suggest that the human intracranial system shows frequency dependence as seen in animal experiments. There is an inverse relationship between CPA index and ICP amplitude, indicating that higher amplitudes may occur with a reduced performance of the pulsation absorber. Our findings show that frequency dependence can be observed in humans and imply that reduced frequency-dependent compliance may be responsible for elevated ICP amplitude observed in patients who respond to CSF shunting.

Slit Ventricle Syndrome

Slit ventricle syndrome is a rare condition whereby brain compliance is reduced and can be associated with intermittent intracranial hypertension. A 19-year-old male with a ventriculoperitoneal shunt for congenital hydrocephalus presented with a 1-day history of headache and drowsiness-symptoms from which he suffered in many recurrent episodes over the past 5 years. The improvement of headaches without surgical intervention led to the diagnosis of migraine. During this hospitalization, episodes of intermittent intracranial hypertension were documented along with the remission and relapse of the symptoms. While the patient's intracranial pressure was within normal range in over 90% of his monitoring period, which postponed shunting, replacement of his ventriculoperitoneal shut eventually resolved his symptoms. Slit ventricle syndrome with reduced ventricular compliances should be considered in patients with clinical evidence of intermittent intracranial hypertension and small ventricular size. The authors advocate shunt replacement as an appropriate treatment for this condition.

Brain compliance: the old story with a new ‘et cetera’

Brain compliance: the old story with a new ‘et cetera’

Impact of duration of symptoms on CSF dynamics in idiopathic normal pressure hydrocephalus

Cerebrospinal fluid (CSF) pressure-volume compensation may change over time as part of normal ageing, where the resistance to CSF outflow increases and the formation of CSF decreases with age. Is CSF compensation dependent on duration of symptoms in idiopathic normal pressure hydrocephalus (iNPH)? We investigated 92 patients presenting with iNPH. Mean age was 73 (range 47-86). There were 60 men and 32 women. They all presented with gait disturbance and ventricular dilatation. Memory deficit occurred in 72% and urinary incontinence in 52% of patients. All patients underwent computerized CSF infusion tests. Sixty-four shunted patients were available for follow-up, and their improvement was expressed using the NPH score. Mean intracranial pressure (ICP) was 10.1±5.1 mmHg, and mean resistance to CSF outflow was 17.3±5.2 mmHg/(ml/min). Mean duration of symptoms was 24±19 months (range from 2 weeks to 86 months). Baseline ICP, magnitude of ICP pulse waveform, brain compliance and improvement after shunting (72% of patients improved) did not exhibit any dependency on the duration of symptoms. The resistance to CSF outflow showed a strong tendency to decrease in time with the duration of symptoms beyond 2 years (R= -0.702; P<0.005). This is a preliminary observation, and it suggests that for patients with duration of symptoms longer than 2-3 years, the threshold for normal resistance to CSF outflow should be duration-adjusted.

Prediction of Postoperative Drainage Volume and Brain Expansion of Chronic Subdural Hematoma: Supplementary Study-Clinical Study

Objective: The authors studied the factors associated with postoperative drainage volume after burr-hole craniostomy for chronic subdural hematoma (CSDH) to predict real postoperative drainage volume, and the relation between brain expansion and drained hematoma volume. Methods: During the last 7 years, 75 patients with CSDH had been undertaken burrhole drainage. For these, demographical and radiological data regarding CSDH were gathered and reviewed, including hematoma density, volume, and parameters of brain compliance on computed tomography (CT) scan. We estimated the brain expansion using the degree of frontal horn compression and midline shifting by the B/A ratios, and made statistical analyses for relation with the postoperative drainage volume. Results: In a whole, the estimated volume was 139 mL, mean real drainage volume was 261 mL, and mean B/A ratio was 0.53. There was no statistical significance between estimated and real drainage volumes. Among 4 groups, low density subgroup showed the largest difference between estimated volume (128 mL) and mean real drainage volume (214 mL), and lowest mean B/A ratio of 0.5. B/A ratio had inverse relationship with real drainage volume (p<0.05). Conclusion: The postoperative drainage volume after operation of CSDH was affected by brain expansion. Postoperative drainage volume was decreased as the B/A ratio was increased, and vice versa. Postoperative drainage volume of CSDH, in some extent, can be predicted with the density types of CSDH and the degree of frontal horn compression. (J Kor Neurotraumatol Soc 2010;6:33-37)

The Problem of Non-Invasive Monitoring in Neurological Emergencies

Raised intracranial pressure is the final common pathway for many intracranial problems. ICP monitoring is the most widely used intracranial monitor because prevention and control of increased ICP and maintenance of cerebral perfusion pressure are fundamental therapeutic goals after TBI. According to the disadvantages of invasive ICP monitoring methods it would be very helpful to measure ICP, and to have a continuous monitoring of brain compliance and cerebrovascular autoregulation without invasive catheters. Only prof. dr. A. Ragauskas patented methods can measure absolute value of ICP with no necessary calibration. The essential point of all other methods is correlation or functional dependence between any parameter of the head and ICP. To express the results of such measurements in pressure units the calibration procedure is needed, i.e. the non-invasive ICP meter with benchmark accuracy is needed. But the main problem is that there is no such meter. Ill. 2, bibl. 9 (in English; abstracts in English, Russian and Lithuanian).