RESUMO
INTRODUCTION: Our objective was to evaluate the cortical metabolic changes and clinical outcome in patients affected by idiopathic normal pressure hydrocephalus (iNPH) after a placement of ventriculoperitoneal (VP) shunt. MATERIALS AND METHODS: 10 patients affected by suspected iNPH underwent a CSF hydrodynamics evaluation based on a lumbar infusion test (LIT). The main selection criterion for surgery was based on intracranial elasticity (IE)>0.30. All subjects with an IE>0.30 underwent a PET scan with 18 fluorodeoxiglucose (18F-FDG) at baseline (PET1) and 1 month after surgery (PET2). Furthermore, the same patients were submitted to clinical evaluation before and 1 month after surgery through neuropsychological tests and gait analysis. RESULTS: An overall number of 20 18F-FDG PET scans were performed in all the enrolled patients. As compared to PET1, PET2 showed an increase in glucose consumption in the left frontal and left parietal lobe in PET2 as compared to PET1 (P<.001). All the enrolled patients presented a significant increase in neuropsychological scores (i.e Frontal Assessment Battery and Montreal Cognitive Assessment) and have clinically improved at gait analysis. A significant correlation was found between the increase of cortical glucose consumption in the left parietal area and the cognitive improvement as detectable by neuropsychological assessment. CONCLUSIONS: Improvement in 18F FDG PET glucose metabolism could be considered a useful imaging marker for the assessment of iNPH response to VP shunting.
Assuntos
Córtex Cerebral/metabolismo , Hidrocefalia de Pressão Normal/cirurgia , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Derivação Ventriculoperitoneal , Idoso , Córtex Cerebral/diagnóstico por imagem , Transtornos Cognitivos/etiologia , Feminino , Radioisótopos de Flúor , Fluordesoxiglucose F18 , Transtornos Neurológicos da Marcha/etiologia , Humanos , Hidrocefalia de Pressão Normal/complicações , Hidrocefalia de Pressão Normal/diagnóstico por imagem , Hidrocefalia de Pressão Normal/metabolismo , Masculino , Período Pós-Operatório , Compostos Radiofarmacêuticos , Estudos Retrospectivos , Resultado do TratamentoRESUMO
Frailty is known to predict dementia. However, its link with neurodegenerative alterations of the central nervous system (CNS) is not well understood at present. We investigated the association between the biomechanical response of the CNS and frailty in older adults suspected of normal pressure hydrocephalus (NPH) presenting with markers of multiple co-existing pathologies. The biomechanical response of the CNS was characterized by the CNS elastance coefficient inferred from phase contrast magnetic resonance imaging and intracranial pressure monitoring during a lumbar infusion test. Frailty was assessed with an index of health deficit accumulation. We found a significant association between the CNS elastance coefficient and frailty, with an effect size comparable to that between frailty and age, the latter being the strongest known risk factor for frailty. Results were independent of CSF dynamics, showing that they are not specific to the NPH neuropathological condition. The CNS biomechanical characterization may help to understand how frailty is related to neurodegeneration and detect the shift from normal to pathological brain ageing.
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Encefalopatias/diagnóstico , Circulação Cerebrovascular , Fragilidade/diagnóstico , Pressão Intracraniana , Idoso , Idoso de 80 Anos ou mais , Fenômenos Biomecânicos/fisiologia , Encefalopatias/sangue , Encefalopatias/líquido cefalorraquidiano , Encefalopatias/fisiopatologia , Circulação Cerebrovascular/fisiologia , Estudos de Coortes , Feminino , Humanos , Hidrocefalia de Pressão Normal/sangue , Hidrocefalia de Pressão Normal/líquido cefalorraquidiano , Hidrocefalia de Pressão Normal/diagnóstico , Hidrocefalia de Pressão Normal/fisiopatologia , Pressão Intracraniana/fisiologia , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-IdadeRESUMO
PURPOSE: Secondary craniostenosis is a relevant problem pediatric neurosurgeons are confronted with and poses challenges regarding reliable diagnosis of raised ICP, especially in case of absent or questionable papilledema. How to identify children with elevated ICP is still controversial and diagnostics vary. We report on our experience with computerized ICP ONM in relation to imaging derived parameters. METHODS: Thirty-four children with primary or secondary craniostenosis and clinical suspicion of raised ICP were investigated. We compared clinical signs, history, and radiographic assessment with the results of computerized ICP ONM. Differences were significant at a p < 0.05. RESULTS: Baseline ICP was significantly higher in patients with combined suture synostosis, who also had a higher rate of questionable papilledema. Children with narrowed external CSF spaces in MRI had significantly higher ICP levels during REM sleep. Mean RAP was significantly elevated in patients with multi-suture synostosis, indicating poor intracranial compensatory reserve. Syndromal craniostenosis was associated with elevated ICP, RAP was significantly lower, and skull X-rays showed more impressions (copper beaten skull). RAP increased with more severe impressions only to decline in most severe abnormalities, indicating exhaustion of cerebrovascular reserve at an upper ICP breakpoint of 23.9 mmHg. Headaches correlated to lower ICP and were not associated with more severe X-ray abnormalities. CONCLUSION: Narrowed external CSF spaces in MRI seem to be associated to elevated ICP. Skull X-rays can help to identify patients at risk for chronically elevated ICP. Severe X-ray changes correlate with exhausted cerebrovascular reserve as indicated by RAP decline. Only ICP monitoring clearly identifies raised ICP and low brain compliance. Thus, in cases with ambiguous imaging, ONM constitutes an effective tool to acquire objective data for identification of surgical candidates.
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Craniossinostoses , Hipertensão Intracraniana , Papiledema , Criança , Craniossinostoses/diagnóstico por imagem , Humanos , Hipertensão Intracraniana/diagnóstico por imagem , Pressão Intracraniana , Monitorização Fisiológica , Papiledema/diagnóstico por imagem , Papiledema/etiologia , SíndromeRESUMO
OBJECTIVE: The amplitude of intracranial pressure (ICP) can be measured by ICP monitoring. Phase-contrast magnetic resonance imaging (PCMRI) can quantify blood and cerebrospinal fluid (CSF) flows. The aim of this work was to investigate intracranial compliance at rest by combining baseline ICP monitoring and PCMRI in hydrocephalus patients. MATERIALS AND METHODS: ICP monitoring was performed before infusion testing to quantify ΔICP_rest at the basal condition in 33 suspected hydrocephalus patients (74 years). The day before, patients had had a PCMRI to assess total cerebral blood flow (tCBF), intracranial blood volume change (stroke volume SVblood), and cervical CSF volume change (the stroke volume CSV). Global (blood and CSF) intracranial volume change (ΔIVC) during each cardiac cycle (CC) was calculated. Finally, Compliance: C_rest = ΔIVC/ΔICP_rest was calculated. The data set was postprocessed by two operators according to blind analysis. RESULTS: Bland-Altman plots showed that measurements presented no significant difference between the two operators. ΔICP_rest = 2.41 ± 1.21 mmHg, tCBF = 469.89 ± 127.54 mL/min, SVblood = 0.82 ± 0.32 mL/cc, CSV = 0.50 ± 0.22 mL/cc, ΔIVC = 0.44 ± 0.22 mL, and C_rest = 0.23 ± 0.15 mL/mmHg. There are significant relations between SVblood and CSV and also SVblood and tCBF. CONCLUSIONS: During "basal" condition, the compliance amplitude of the intracranial compartment is heterogeneous in suspected hydrocephalus patients, and its value is lower than expected! This new parameter could represent new information, complementary to conventional infusion tests. We hope that this information can be applied to improve the selection of patients for shunt surgery.
Assuntos
Encéfalo/fisiopatologia , Líquido Cefalorraquidiano , Circulação Cerebrovascular/fisiologia , Hidrocefalia/fisiopatologia , Pressão Intracraniana/fisiologia , Monitorização Fisiológica , Idoso , Idoso de 80 Anos ou mais , Encéfalo/irrigação sanguínea , Encéfalo/diagnóstico por imagem , Volume Sanguíneo Cerebral , Complacência (Medida de Distensibilidade)/fisiologia , Feminino , Hemodinâmica , Humanos , Hidrocefalia/diagnóstico por imagem , Hidrodinâmica , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-IdadeRESUMO
OBJECTIVES: Suspected cerebrospinal fluid shunt (CSF) dysfunction in hydrocephalic patients poses a diagnostic uncertainty. The clinical picture can be non-specific and CT imaging alone is not always pathognomonic. Infusion tests are an increasingly used investigation for real-time hydrodynamic assessment of shunt patency. We report the correlation between infusion test results with the quality of ventricular drain placement on CT scans in a large retrospective group of hydrocephalic patients. MATERIALS & METHODS: Three hundred and six infusion test results performed in 200 patients were correlated with 306 corresponding CT head scans. Nominal logistic regression was used to correlate shunt catheter position on CT imaging to patency of ventricular drain as determined by infusion tests. RESULTS: Infusion test results of shunt patency are statistically congruent with the analysis of shunt catheter position on CT head scans. Catheter tips completely surrounded by either parenchyma or CSF on CT imaging are strongly associated with evidence of occlusion or patency from infusion tests, respectively (χ² = 51.68, P < 0.0001, n = 306 and χ² = 31.04, P < 0.0001, n = 306). CONCLUSIONS: The most important anatomical factor for shunt patency is the catheter tip being completely surrounded by CSF. Infusion tests provide functional and reliable assessment of shunt patency in vivo and are strongly correlated with the position of the ventricular catheter on CT imaging.
Assuntos
Derivações do Líquido Cefalorraquidiano/normas , Hidrocefalia , Punção Espinal/normas , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Derivações do Líquido Cefalorraquidiano/efeitos adversos , Criança , Pré-Escolar , Feminino , Humanos , Hidrocefalia/líquido cefalorraquidiano , Hidrocefalia/diagnóstico por imagem , Hidrocefalia/cirurgia , Lactente , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Tomografia Computadorizada por Raios X , Adulto JovemRESUMO
Clinical measurement of intracranial pressure (ICP) is often performed to aid diagnosis of hydrocephalus. This review discusses analysis of ICP and its components' for the investigation of cerebrospinal fluid (CSF) dynamics. The role of pulse, slow and respiratory waveforms of ICP in diagnosis, prognostication and management of hydrocephalus is presented. Two methods related to ICP measurement are listed: an overnight monitoring of ICP and a constant-rate infusion study. Due to the dynamic nature of ICP, a 'snapshot' manometric measurement of ICP is of limited use as it might lead to unreliable results. Therefore, monitoring of ICP over longer time combined with analysis of its waveforms provides more detailed information on the state of pressure-volume compensation. The infusion study implements ICP signal processing and CSF circulation model analysis in order to assess the cerebrospinal dynamics variables, such as CSF outflow resistance, compliance of CSF space, pressure amplitude, reference pressure, and CSF formation. These parameters act as an aid tool in diagnosis and prognostication of hydrocephalus and can be helpful in the assessment of a shunt malfunction.
Assuntos
Hidrocefalia/líquido cefalorraquidiano , Pressão Intracraniana/fisiologia , HumanosRESUMO
BACKGROUND: This study aimed to compare four non-invasive intracranial pressure (nICP) methods in a prospective cohort of hydrocephalus patients whose cerebrospinal fluid dynamics was investigated using infusion tests involving controllable test-rise of ICP. METHOD: Cerebral blood flow velocity (FV), ICP and non-invasive arterial blood pressure (ABP) were recorded in 53 patients diagnosed for hydrocephalus. Non-invasive ICP methods were based on: (1) interaction between FV and ABP using black-box model (nICP_BB); (2) diastolic FV (nICP_FVd); (3) critical closing pressure (nICP_CrCP); (4) transcranial Doppler-derived pulsatility index (nICP_PI). Correlation between rise in ICP (∆ICP) and ∆nICP and averaged correlations for changes in time between ICP and nICP during infusion test were investigated. RESULTS: From baseline to plateau, all nICP estimators increased significantly. Correlations between ∆ICP and ∆nICP were better represented by nICP_PI and nICP_BB: 0.45 and 0.30 (p < 0.05). nICP_FVd and nICP_CrCP presented non-significant correlations: -0.17 (p = 0.21), 0.21 (p = 0.13). For changes in ICP during individual infusion test nICP_PI, nICP_BB and nICP_FVd presented similar correlations with ICP: 0.39 ± 0.40, 0.39 ± 0.43 and 0.35 ± 0.41 respectively. However, nICP_CrCP presented a weaker correlation (R = 0.29 ± 0.24). CONCLUSIONS: Out of the four methods, nICP_PI was the one with best performance for predicting changes in ∆ICP during infusion test, followed by nICP_BB. Unreliable correlations were shown by nICP_FVd and nICP_CrCP. Changes of ICP observed during the test were expressed by nICP values with only moderate correlations.
Assuntos
Hidrocefalia/diagnóstico por imagem , Pressão Intracraniana , Ultrassonografia Doppler Transcraniana , Adulto , Velocidade do Fluxo Sanguíneo , Circulação Cerebrovascular , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos ProspectivosRESUMO
OBJECTIVE: Infusion tests are important tools to assess cerebrospinal fluid (CSF)dynamics used in the preoperative selection of patients for shunt surgery, or to predict the scope of improvement from shunt revision. The aim of this study was to assess the repeatability of the key quantitative parameters describing CSF dynamics that are determined with infusion testing. MATERIALS AND METHODS: Eighteen patients in whom a constant infusion test was repeated within 102 days, without any intermediate surgical intervention, were studied. From each test baseline ICP, baseline pulse amplitude, outflow resistance, elastance coefficient and slope of the amplitude-pressure line were calculated and investigated with a regression and Bland-Altman analysis. RESULTS: Significant correlations (P < 0.01) were found for the outflow resistance (R = 0.96), the elastance coefficient (R = 0.778) and the slope of the amplitude-pressure line (R = 0.876). The estimated 95% confidence level for outflow resistance was 3 mmHg/ml min. Likewise, the elastance coefficient lay within a range of 0.16/ml and the slope of the amplitude-pressure line within 0.25. The most inconsistent parameter found were baseline ICP (R = 0.272) and baseline pulse amplitude (R = 0.171). CONCLUSION: The results of this study imply that the parameters resulting from an infusion study have to be considered within a range rather than as an absolute value.
Assuntos
Pressão do Líquido Cefalorraquidiano/fisiologia , Derivações do Líquido Cefalorraquidiano/métodos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Líquido Cefalorraquidiano/fisiologia , Criança , Pré-Escolar , Estudos de Coortes , Humanos , Lactente , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Estudos Retrospectivos , Adulto JovemRESUMO
INTRODUCTION: Inside the craniospinal system, blood, and cerebrospinal fluid (CSF) interactions occurring through volume exchanges are still not well understood. We built a physical model of this global hydrodynamic system. The main objective was to study, in controlled conditions, CSF-blood interactions to better understand the phenomenon underlying pathogenesis of hydrocephalus. MATERIALS AND METHODS: A structure representing the cranium is connected to the spinal channel. The cranium is divided into compartments mimicking anatomical regions such as ventricles or aqueduct cerebri. Resistive and compliant characteristics of blood and CSF compartments can be assessed or measured using pressure and flow sensors incorporated in the model. An arterial blood flow input is generated by a programmable pump. Flows and pressures inside the system are simultaneously recorded. RESULTS: Preliminary results show that the model can mimic venous and CSF flows in response to arterial pressure input. Pulse waveforms and volume flows were measured and confirmed that they partially replicated the data previously obtained with phase-contrast magnetic resonance imaging. The phantom shows that CSF oscillations directly result from arteriovenous flow, and intracranial pressure measurements show that the model obeys an exponential relationship between pressure and intracranial volume expansion. CONCLUSION: The phantom will be useful to investigate the hydrodynamic hypotheses underlying development of hydrocephalus.
Assuntos
Aqueduto do Mesencéfalo/fisiologia , Líquido Cefalorraquidiano/fisiologia , Hemodinâmica , Imagens de Fantasmas , Velocidade do Fluxo Sanguíneo/fisiologia , Aqueduto do Mesencéfalo/anatomia & histologia , Pressão do Líquido Cefalorraquidiano , Circulação Cerebrovascular/fisiologia , Humanos , Modelos Biológicos , Exame FísicoRESUMO
OBJECTIVES: The term hydrocephalus encompasses a range of disorders characterised by clinical symptoms, abnormal brain imaging and derangement of cerebrospinal fluid (CSF) dynamics. The ability to elucidate which patients would benefit from CSF diversion (a shunt or third ventriculostomy) is often unclear. Similar difficulties are often encountered in shunted patients to predict the scope for improvement by shunt re-adjustment or revision. In this study we aimed to update our knowledge of how key quantitative parameters describing CSF dynamics may be used in diagnosis of shunt-responsive hydrocephalus and in the assessment of shunt function. METHODS: A number of quantitative parameters [including resistance to CSF outflow (Rcsf), pulse amplitude of intracranial pressure waveform (AMP), RAP index and slow vasogenic waves] were studies in 1423 patients with 2665 CSF infusion tests and 305 overnight intracranial pressure (ICP)-monitoring sessions over a 17 year period. OBSERVATIONS: We demonstrate our observations for typical values of Pb, Rcsf, AMP, slow vasogenic waves derived from infusion studies or overnight ICP monitoring in differentiating atrophy from shunt-responsive normal pressure hydrocephalus or acute hydrocephalus. From the same variables tested on shunted patients we demonstrate a standardised approach to help differentiate a properly-functioning shunt from underdrainage or overdrainage. CONCLUSIONS: Quantitative variables derived from CSF dynamics allow differentiation between clinically overlapping entities such as shunt-responsive normal pressure hydrocephalus and brain atrophy (not shunt responsive) as well as allowing the detection of shunt malfunction (partial or complete blockage) or overdrainage. This observational study is intended to serve as an update for our understanding of quantitative testing of CSF dynamics.
Assuntos
Derivações do Líquido Cefalorraquidiano/métodos , Hidrocefalia/líquido cefalorraquidiano , Hidrocefalia/fisiopatologia , Pressão Intracraniana/fisiologia , Dinâmica não Linear , Adulto , Idoso , Idoso de 80 Anos ou mais , Atrofia/líquido cefalorraquidiano , Encéfalo/patologia , Encéfalo/fisiopatologia , Encéfalo/cirurgia , Diagnóstico por Computador , Feminino , Humanos , Hidrocefalia/cirurgia , Estudos Longitudinais , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Modelos Biológicos , Observação , Estudos Retrospectivos , Adulto JovemRESUMO
OBJECTIVE: 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)? METHODS: 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. RESULTS: 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). CONCLUSION: 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.
Assuntos
Ventrículos Cerebrais/fisiopatologia , Pressão do Líquido Cefalorraquidiano/fisiologia , Líquido Cefalorraquidiano/fisiologia , Hidrocefalia de Pressão Normal/epidemiologia , Hidrocefalia de Pressão Normal/fisiopatologia , Idoso , Idoso de 80 Anos ou mais , Ventrículos Cerebrais/patologia , Feminino , Humanos , Hidrocefalia de Pressão Normal/cirurgia , Masculino , Pessoa de Meia-Idade , Fatores de Tempo , Resultado do TratamentoRESUMO
A pressure reactivity index (PRx) can be assessed in patients with continuous monitoring of arterial blood pressure (ABP) and intracranial pressure (ICP) as a moving correlation coefficient between slow fluctuations of these two signals within a low frequency bandwidth. The study aimed to investigate whether the invasive ABP monitoring can be replaced with non-invasive measurement of ABP using a Finapres plethysmograph (fABP) to calculate the fPRx. There is a well-defined group of patients, suffering from hydrocephalus and undergoing CSF pressure monitoring, which may benefit from such a measurement. 41 simultaneous day-by-day monitoring of ICP, ABP and fABP were performed for about 30 min in 10 head injury patients. A Bland-Altman assessment for agreement was used to compare PRx and fPRx calculations. Performance metrics and the McNemary test were used to determine whether fPRx is sensitive enough to distinguish between functioning and disturbed cerebrovascular pressure reactivity. The fPRx correlated with PRx (R(Spearman) = 0.92, p < 0.001; bias = -0.04; lower and upper limits of agreement: -0.26 and 0.17, respectively). The fPRx distinguished between active and passive reactivity in more than 89% cases. The fPRx can be used with care for assessment of cerebrovascular reactivity in patients for whom invasive ABP measurement is not feasible. The fPRx is sensitive enough to distinguish between functional and deranged reactivity.
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Pressão Sanguínea , Encéfalo/irrigação sanguínea , Encéfalo/fisiologia , Pressão Intracraniana , Pletismografia/métodos , Artérias , HumanosRESUMO
OBJECTIVES: Over a 3-year period, we have performed 312 tests in 197 shunted patients. The data have been analyzed retrospectively to: (1) investigate the parameters describing CSF dynamics that correlate with shunt under-drainage and (2) estimate accuracy of this method. METHODS: Constant rate infusion tests into shunt prechamber were performed. RESULTS: In 161 of the 312 infusion tests, results indicated under-draining shunts. Patients in the under-draining group had higher baseline and plateau CSF pressures, higher resistance to CSF outflow and higher levels of baseline pulse amplitude waveform. During the test, a significantly greater vasogenic waves and lower compensatory reserve was noticed in patients with blocked shunts. In 21 patients with suggestion of shunt blockage and who subsequently underwent operative revision of the shunt, reports of intraoperative shunt patency were available. Shunt blockage was confirmed intra-operatively during surgery in 19 cases. CONCLUSIONS: In vivo shunt testing is easy, safe and clinically useful, aiding decision in difficult clinical situations, where shunt malfunction is suspected but not certain. It also has satisfactory positive predictive power.
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Derivações do Líquido Cefalorraquidiano , Hidrocefalia/cirurgia , Teste de Materiais , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Pressão do Líquido Cefalorraquidiano , Criança , Pré-Escolar , Falha de Equipamento , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Fatores Sexuais , Processamento de Sinais Assistido por Computador , Resultado do TratamentoRESUMO
OBJECTIVE: Hydrocephalus is much more complex than a simple disorder of cerebrospinal fluid (CSF) circulation. Shunting primarily corrects disturbed fluid flow which may have an impact on cerebral blood flow and metabolism. We studied hydrocephalic patients before and after shunting to characterize changes in their CSF compensatory parameters. MATERIAL AND METHODS: We selected 25 patients and studied them retrospectively. All patients had ventriculomegaly and clinical symptoms of normal pressure hydrocephalus. After shunting, they were still presenting with some adverse symptoms, mainly headaches, slow improvement or no improvement of ventriculomegaly. Therefore, they underwent further infusion studies to assess shunt function. In all cases, the shunts were confirmed to be draining CSF adequately. Parameters of CSF dynamics: baseline intracranial pressure (ICP), resistance to CSF outflow, cerebrospinal elasticity, content of vasogenic pressure waves (pulse, respiratory and B waves) and compensatory reserve assessed as moving correlation coefficient between mean CSF pressure and pulse amplitude (RAP), were compared before and after shunting. RESULTS: Mean ICP and resistance to CSF outflow decreased (P < 0.003) after shunting. All vasogenic pressure waves decreased (P < 0.005). Compensatory reserve (RAP) significantly improved (P < 0.005). CONCLUSION: A functioning shunt has an important impact on CSF circulation and pressure-volume compensation. Infusion studies can demonstrate the return of disturbed CSF dynamics to normal values even if clinical or radiological changes are not dramatic.
Assuntos
Derivações do Líquido Cefalorraquidiano/efeitos adversos , Líquido Cefalorraquidiano/fisiologia , Humanos , Hidrocefalia de Pressão Normal/cirurgia , Pressão Intracraniana/fisiologia , Estudos RetrospectivosRESUMO
The pathophysiology of hydrocephalus can be modelled and described in terms of altered biomechanical parameters. Shunting is aimed to correct the patient's cerebrospinal fluid dynamics, compensating for inadequate cerebrospinal fluid re-absorption or insufficient volume buffering reserve. Computerized infusion studies implement intracranial pressure and arterial pressure signal processing and model analysis to allow the estimation of cerebrospinal dynamics variables such as cerebrospinal fluid outflow resistance, brain compliance and pressure-volume index, estimated sagittal sinus pressure, cerebrospinal fluid formation rate, compensatory reserve and cerebral vasoreactivity. Infusion studies can assist in the prognostication of normal pressure hydrocephalus and in the diagnosis of idiopathic intracranial hypertension. The technique is also helpful in the assessment of shunt malfunction, including posture-related over-drainage and shunt obstruction.
Assuntos
Líquido Cefalorraquidiano , Hidrocefalia/terapia , Encéfalo/patologia , Pressão do Líquido Cefalorraquidiano , Derivações do Líquido Cefalorraquidiano , Desenho de Equipamento , Feminino , Humanos , Hidrocefalia/diagnóstico , Hidrocefalia de Pressão Normal/diagnóstico , Hidrocefalia de Pressão Normal/terapia , Hipertensão Intracraniana/terapia , Pressão Intracraniana , Masculino , Tomografia Computadorizada por Raios XRESUMO
Since shunting is almost a purely mechanical treatment that radically affects pressure-volume compensation, patients' cerebrospinal fluid hydrodynamics compensation should be examined before a shunt is implanted. Apart from an opening pressure and a resistance to cerebrospinal fluid outflow, pulse amplitude of intracranial pressure and the content of vasogenic waves are useful to gauge cerebrospinal fluid dynamics. Infusion studies, although invasive, may help with the decision about surgery. They also provide basic information for further management of shunted patients, when complications, such as shunt blockage, under- and over-drainage, arise.
Assuntos
Derivações do Líquido Cefalorraquidiano/instrumentação , Pressão Intracraniana , Idoso , Algoritmos , Pressão do Líquido Cefalorraquidiano , Circulação Cerebrovascular , Feminino , Humanos , Hidrocefalia de Pressão Normal/líquido cefalorraquidiano , Hidrocefalia de Pressão Normal/diagnóstico , Doenças do Sistema Nervoso/líquido cefalorraquidiano , Doenças do Sistema Nervoso/diagnóstico , Pressão , Processamento de Sinais Assistido por Computador , Software , Fatores de TempoRESUMO
BACKGROUND: There is increasing interest in evaluation of the pulse amplitude of intracranial pressure (AMP) in explaining dynamic aspects of hydrocephalus. We reviewed a large number of ICP recordings in a group of hydrocephalic patients to assess utility of AMP. MATERIALS AND METHODS: From a database including approximately 2,100 cases of infusion studies (either lumbar or intraventricular) and overnight ICP monitoring in patients suffering from hydrocephalus of various types (both communicating and non-communicating), etiology and stage of management (non-shunted or shunted) pressure recordings were evaluated. For subgroup analysis we selected 60 patients with idiopathic NPH with full follow-up after shunting. In 29 patients we compared pulse amplitude during an infusion study performed before and after shunting with a properly functioning shunt. Amplitude was calculated from ICP waveforms using spectral analysis methodology. FINDINGS: A large amplitude was associated with good outcome after shunting (positive predictive value of clinical improvement for AMP above 2.5 mmHg was 95%). However, low amplitude did not predict poor outcome (for AMP below 2.5 mmHg 52% of patients improved). Correlations of AMP with ICP and Rcsf were positive and statistically significant (N = 131 with idiopathic NPH; R = 0.21 for correlation with mean ICP and 0.22 with Rcsf; p< 0.01). Correlation with the brain elastance coefficient (or PVI) was not significant. There was also no significant correlation between pulse amplitude and width of the ventricles. The pulse amplitude decreased (p < 0.005) after shunting. CONCLUSIONS: Interpretation of the ICP pulse waveform may be clinically useful in patients suffering from hydrocephalus. Elevated amplitude seems to be a positive predictor for clinical improvement after shunting. A properly functioning shunt reduces the pulse amplitude.
Assuntos
Hidrocefalia/fisiopatologia , Pressão Intracraniana/fisiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Biofísica , Pressão Sanguínea , Derivações do Líquido Cefalorraquidiano/métodos , Bases de Dados Bibliográficas/estatística & dados numéricos , Feminino , Humanos , Hidrocefalia/classificação , Hidrocefalia/cirurgia , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Monitorização Fisiológica , Pulso Arterial , Transdutores de Pressão , Adulto JovemRESUMO
BACKGROUND: Narrowing of the cranial dural venous sinuses has been implicated as contributing to elevated intracranial pressure in idiopathic intracranial hypertension [IIH]. Such narrowing may be either a fixed stenosis or secondary to raised ICP. We have investigated whether narrowing of the venous sinuses may reflect direct coupling between cerebrospinal fluid pressure and sagittal sinus pressure. METHODS: Nine patients with the clinical features of IIH [8F, 1M; mean age 41 (range 22-55)] were studied as part of their standard clinical investigations by simultaneous lumbar CSF infusion study and direct retrograde cerebral venography whereby a catheter is placed within the sagittal sinus under fluoroscopic guidance. FINDINGS: In all cases, both CSF pressure (Pcsf) and sagittal sinus pressure (Pss) were elevated with Pcsf slightly exceeding Pss (27.0 +/- 2.3 mm Hg. 25.2 +/- 7.5 mm Hg; difference P = 0.026; correlation R = 0.97, P = 0.0032). There was a gradient of pressure along the sagittal and transverse sinuses. CSF infusion provoked rises in both Pcsf and Pss (R = 0.97, P < 0.0007). During drainage of CSF after the test (8 cases), Pcsf decreased to values lower than Pss (-3.26 +/- 3.9 mm Hg; P = 0.0097). There was excellent correlation between slow waves of Pcsf and Pss (mean R = 0.9) and between baseline pulse amplitudes of both pressures (R = 0.91; P = 0.03). CONCLUSIONS: In the 9 patients studied with IIH, Pcsf and Pss were coupled both statically (mean values) and dynamically (vasogenic components). During drainage, both pressures decreased until probably central venous pressure was reached and then Pcsf decreased further while Pss remained constant. This suggests that, in many cases of IIH, there is functional obstruction of venous outflow through the dural sinuses. Raised Pcsf partly obstructs venous sinus outflow, thereby increasing Pss which, in turn, leads to a further rise in Pcsf, et sequor. This vicious cycle can be interrupted by draining CSF.
Assuntos
Pressão Sanguínea/fisiologia , Pressão do Líquido Cefalorraquidiano/fisiologia , Cavidades Cranianas/fisiopatologia , Pseudotumor Cerebral/patologia , Pseudotumor Cerebral/fisiopatologia , Adulto , Feminino , Humanos , Angiografia por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , Adulto JovemRESUMO
The majority of contemporary hydrocephalus valves are designed to introduce a low resistance to flow into the cerebrospinal fluid (CSF) drainage pathway, and an therefore intended to stabilise intracranial pressure (ICP) at a level close to the shunt's operating pressure. However, this goal cannot always be attained. Accelerated CSF drainage with vertical body posture in ventriculo-peritoneal shunts is one reason for the ICP decreasing below the shunt's operating pressure. Another possible factor has been studied: the impact of the pulsating pattern in the ICP on the operating pressure. Six popular constructions of medium-pressure valves were studied (Radionics Low-profile, Delta, Hakim Precision, Holter, Integra In-line and Hakim NMT). Valves were mounted in the testing rig in the UK. Shunt Evaluation Laboratory and perfused with de-ionised water at a rate of 0.3 ml min(-1), and proximal pulsating pressures of different amplitudes (from 2 to 30mmHg peak-to-peak) and frequencies (70-10 cycles min(-1)) were superimposed. Laboratory findings were compared with clinical material containing recordings of ICP made in patients to diagnose reasons for ventriculomegaly. The mean operating pressure decreased in all valves when the simulated amplitude of heart pulsations increased. The rate of this decrease was dependent on the type of valve (variable from 2.5 to 5 mm Hg per increase in peak-to-peak amplitude by 10 mm Hg). The decrease was not related to the frequency of the wave. The relationship between pulse amplitude and ICP in 35 patients with blocked shunts was strong (R = 0.48; p < 0.03; slope 0.14) and in 25 patients with properly functioning shunts was non-significant (R = 0.057; p = 0.765). Two examples of decrease in mean ICP in the presence of increased vasogenic ICP waves in shunted patients are presented. The shunt operating pressure, which 'sets' the ICP in shunted patients may be influenced by the dynamics of a patient's ICP waveform.