Continuous wavelet transform in the study of the time-scale properties of intracranial pressure in hydrocephalus.

Normal pressure hydrocephalus (NPH) encompasses a heterogeneous group of disorders generally characterized by clinical symptoms, ventriculomegaly and anomalous cerebrospinal fluid (CSF) dynamics. Lumbar infusion tests (ITs) are frequently performed in the preoperatory evaluation of patients who show NPH features. The analysis of intracranial pressure (ICP) signals recorded during ITs could be useful to better understand the pathophysiology underlying NPH and to assist treatment decisions. In this study, 131 ICP signals recorded during ITs were analysed using two continuous wavelet transform (CWT)-derived parameters: Jensen divergence (JD) and spectral flux (SF). These parameters were studied in two frequency bands, associated with different components of the signal: B1(0.15-0.3 Hz), related to respiratory blood pressure oscillations; and B2 (0.67-2.5 Hz), related to ICP pulse waves. Statistically significant differences (p < 1.70 × 10-3, Bonferroni-corrected Wilcoxon signed-rank tests) in pairwise comparisons between phases of ITs were found using the mean and standard deviation of JD and SF. These differences were mainly found in B2, where a lower irregularity and variability, together with less prominent time-frequency fluctuations, were found in the hypertension phase of ITs. Our results suggest that wavelet analysis could be useful for understanding CSF dynamics in NPH.This article is part of the theme issue 'Redundancy rules: the continuous wavelet transform comes of age'.

Characterisation of the complexity of intracranial pressure signals measured from idiopathic and secondary normal pressure hydrocephalus patients.

Hydrocephalus is a condition characterised by enlarged cerebral ventricles, which in turn affects intracranial pressure (ICP); however, the mechanisms regulating ICP are not fully understood. A nonlinear signal processing approach was applied to ICP signals measured during infusion studies from patients with two forms of hydrocephalus, in a bid to compare the differences. This is the first study of its kind. The two forms of hydrocephalus were idiopathic normal pressure hydrocephalus (iNPH) and secondary normal pressure hydrocephalus (SH). Following infusion tests, the Lempel-Ziv (LZ) complexity was calculated from the iNPH and SH ICP signals. The LZ complexity values were averaged for the baseline, infusion, plateau and recovery stages of the tests. It was found that as the ICP increased from basal levels, the LZ complexities decreased, reaching their lowest during the plateau stage. However, the complexities computed from the SH ICP signals decreased to a lesser extent when compared with the iNPH ICP signals. Furthermore, statistically significant differences were found between the plateau and recovery stage complexities when comparing the iNPH and SH results (p = 0.05). This Letter suggests that advanced signal processing of ICP signals with LZ complexity can help characterise different types of hydrocephalus in more detail.

Does aqueductal stenosis influence the lumbar infusion test in normal-pressure hydrocephalus?

BACKGROUND: Late-onset idiopathic aqueductal stenosis may present with clinical features indistinct from idiopathic normal-pressure hydrocephalus (NPH). Moreover, aqueductal stenosis (AS) is not always detected by conventional magnetic resonance imaging (MRI). The aim of this study was to compare the hydrodynamic pattern among NPH patients according to the patency of the aqueduct. METHODS: Fifty-six consecutive lumbar infusion tests were performed in patients with NPH syndrome. Precipitating causes of hydrocephalus were excluded, and aqueductal patency was examined through high-resolution, T2-weighted 3D MRI. Patients were classified into two groups: non-patent aqueduct and patent aqueduct. Mean values of pressure and pulse amplitude were obtained from basal and plateau stages of infusion studies. RESULTS: Twelve of 56 patients with NPH-like symptoms presented with morphological AS (21.4 %). Patent aqueduct and non-patent aqueduct groups had similar values of mean opening lumbar pressure (8.2 vs. 8.1 mmHg), and mean opening pulse amplitude (3.1 vs. 2.9 mmHg). Mean pressure in the plateau stage (28.6 vs. 23.2 mmHg), and mean pulse amplitude in the plateau stage (12.5 vs. 10.6 mmHg) were higher in the patent aqueduct group. These differences were not statistically significant. Only Rout was significantly higher in the patent aqueduct group (13.6 vs. 10.1 mmHg/ml/min). One-third of NPH patients with AS presented Rout >12 mmHg/ml/min. CONCLUSIONS: No differences in mean pressure or pulse amplitude during basal and plateau epochs of the lumbar infusion test in NPH patients were detected, regardless of aqueductal patency. However, Rout was significantly higher in patients with patent aqueduct.

Effect of infusion tests on the dynamical properties of intracranial pressure in hydrocephalus.

BACKGROUND AND OBJECTIVE: Hydrocephalus comprises a number of conditions characterised by clinical symptoms, dilated ventricles and anomalous cerebrospinal fluid (CSF) dynamics. Infusion tests (ITs) are usually performed to study CSF circulation and in the preoperatory evaluation of patients with hydrocephalus. The study of intracranial pressure (ICP) signals recorded during ITs could be useful to gain insight into the underlying pathophysiology of this condition and to further support treatment decisions. In this study, two wavelet parameters, wavelet turbulence (WT) and wavelet entropy (WE), were analysed in order to characterise the variability, irregularity and similarity in spectral content of ICP signals in hydrocephalus. METHODS: One hundred and twelve ICP signals were analysed using WT and WE. These parameters were calculated in two frequency bands: B1 (0.15-0.3 Hz) and B2 (0.67-2.5 Hz). Each signal was divided into four artefact-free epochs corresponding to the basal, early infusion, plateau and recovery phases of the IT. We calculated the mean and standard deviation of WT and WE and analysed whether these parameters revealed differences between epochs of the IT. RESULTS: Statistically significant differences (p < 1.70⋅10(-3), Bonferroni-corrected Wilcoxon signed-rank tests) in pairwise comparisons between phases of ITs were found using the mean and standard deviation of WT and WE. These differences were mainly found in B2. CONCLUSIONS: Wavelet parameters like WT and WE revealed changes in the signal time-scale representation during ITs. Statistically significant differences were mainly found in B2, associated with ICP pulse waves, and included a higher degree of similarity in the spectral content, together with a lower irregularity and variability in the plateau phase with respect to the basal phase.

The Prediction of Shunt Response in Idiopathic Normal-Pressure Hydrocephalus Based on Intracranial Pressure Monitoring and Lumbar Infusion.

BACKGROUND: Intracranial pressure (ICP) monitoring and infusion studies have long been used in the preoperative workup of patients with suspected idiopathic normal-pressure hydrocephalus (iNPH). We have analysed the predictive values of different measures derived from both investigations, emphasising the differences between responders and nonresponders. MATERIALS AND METHODS: ICP monitoring and lumbar infusion studies were routinely performed during a 6-year period. Shunting was proposed when the resistance to cerebrospinal fluid outflow (ROUT) >12 mmHg/ml/min and/or a minimum 15 % of slow waves were detected. The outcome was evaluated 6 months after surgery. Recorded data from ICP monitoring were mean pressure and pulse amplitude, the total percentage of slow waves and the presence of different types of slow waves following the classification proposed by Raftopoulos et al. Recorded data from lumbar infusion studies were mean values of pressure and pulse amplitude during three epochs (basal, early infusion and plateau), ROUT and the pulsatility response to the increase in mean pressure during the infusion. This response was quantified by two pulse amplitude indexes: the pulse amplitude index during the early infusion stage (A1) and the pulse amplitude index during the plateau stage (A2). RESULTS: Thirty shunted patients were evaluated at the end of the follow-up and 23 (76.7 %) of them improved. Differences in the percentage of slow waves, ROUT and both pulsatility indexes were not statistically significant. The proportion of patients with great symmetrical waves and pulse amplitude during the early infusion stage were higher in responders (p < 0.05). The predictive analysis yielded the highest accuracy, with ROUT and A1 as a logical "OR" combination. CONCLUSION: The combined use of ICP monitoring and lumbar infusion to forecast the response to shunting in patients with suspected iNPH did not improve the accuracy provided by any of them alone.

Intracranial pressure for the characterization of different types of hydrocephalus: A Permutation Entropy study.

Hydrocephalus is a condition characterized by altered cerebrospinal fluid (CSF) dynamics and chronic rises in intracranial pressure (ICP). However, the reason why hydrocephalic physiologies fail to inhibit dangerously high ICP levels is not known. Infusion studies are used to raise ICP and evaluate CSF circulation disorders. In this pilot study, ICP signals recorded during infusion tests from 33 patients with normal pressure hydrocephalus and 36 patients having developed a secondary form of normal pressure hydrocephalus were characterized using Permutation Entropy (PE), a symbolic non-linear method to quantify complexity. Each ICP signal was divided into four epochs--baseline (before infusion begins), infusion, plateau, and recovery (after infusion has stopped)--and the mean PE was calculated for each epoch. Statistically significant differences were found between PE for most epochs (p<;0.00833, Bonferroni-corrected Wilcoxon tests), with a significant decrease in the plateau phase. However, differences between PE for normal pressure and secondary hydrocephalus were not significant. Results suggest that the increase in ICP during infusion studies is associated with a significant decrease in PE. PE analysis of ICP signals could be useful for increasing our understanding of CSF dynamics in normal pressure hydrocephalus.

Leiomioma intraorbitario. Caso clínico y revisión de la literatura / Orbital leiomyoma. Case report and review of the literature

Los leiomiomas son lesiones de lento crecimiento originarias del músculo liso. La localización orbitaria solo ha sido descrita en 25 casos. Sus características histológicas y la ausencia de recurrencia tras la resección total apoyan su comportamiento benigno. Presentamos un caso de hemangioleiomioma intraconal en una mujer de 55 años tratado quirúrgicamente mediante craneotomía fronto-orbitaria con resección total y sin recurrencia de la lesión tras 15 meses de seguimiento. Se discuten los hallazgos histológicos y radiológicos, enfatizando en el papel pronóstico de la cirugía

Leiomyoma are slowly growing lesions arising from smooth muscle. Orbital location hasbeen reported in 25 cases. Histological findings and no recurrence after total resectionsupport their benign behaviour. We report an intraconal orbital haemangioleiomyoma ina 55-year-old female treated by total resection through fronto-orbital craniotomy, with norecurrence after 15 months of follow-up. Radiological and pathological features are discussed, emphasising the prognostic role of the surgery

[Orbital leiomyoma. Case report and review of the literature]. / Leiomioma intraorbitario. Caso clínico y revisión de la literatura.

Leiomyoma are slowly growing lesions arising from smooth muscle. Orbital location has been reported in 25 cases. Histological findings and no recurrence after total resection support their benign behaviour. We report an intraconal orbital haemangioleiomyoma in a 55-year-old female treated by total resection through fronto-orbital craniotomy, with no recurrence after 15 months of follow-up. Radiological and pathological features are discussed, emphasising the prognostic role of the surgery.

Analysis of intracranial pressure signals recorded during infusion studies using the spectral entropy.

Hydrocephalus includes a range of disorders characterized by clinical symptoms, abnormal brain imaging and altered cerebrospinal fluid (CSF) dynamics. Infusion tests can be used to study CSF circulation in patients with hydrocephalus. In them, intracranial pressure (ICP) is deliberately raised and CSF circulation disorders evaluated through measurements of the resulting ICP. In this study, we analyzed 77 ICP signals recorded during infusion tests using the spectral entropy (SE). Each signal was divided into four artifact-free epochs. The mean SE, , and the standard deviation of SE, SD[SE], were calculated for each epoch. Statistically significant differences were found between phases of the infusion test using and SD[SE] (p<1.7 · 10(-3), Bonferroni-corrected Wilcoxon tests). Furthermore, we found significantly lower and SD[SE] values in the plateau phase than in the basal phase. These findings suggest that the increase in ICP during infusion studies is associated with a significant decrease in irregularity and variability of the spectral content of ICP signals, measured in terms of SE. We conclude that the spectral analysis of ICP signals could be useful for understanding CSF dynamics in hydrocephalus.

Spectral analysis of intracranial pressure signals recorded during infusion studies in patients with hydrocephalus.

Hydrocephalus includes a number of disorders characterised by clinical symptoms, enlarged ventricles (observable using neuroimaging techniques) and altered cerebrospinal fluid (CSF) dynamics. Infusion tests are one of the available procedures to study CSF circulation in patients with clinical and radiological features of hydrocephalus. In them, intracranial pressure (ICP) is deliberately raised and CSF circulation disorders evaluated through measurements of the resulting ICP. In this study, we analysed seventy-seven ICP signals recorded during infusion tests using four spectral-based parameters: median frequency (MF) and relative power (RP) in three frequency bands. These measures provide a novel perspective for the analysis of ICP signals in the frequency domain. Each signal was divided into four artefact-free epochs (corresponding to the basal, early infusion, plateau and recovery phases of the infusion study). The four spectral parameters were calculated for each epoch. We analysed differences between epochs of the infusion test and correlations between these epochs and patient data. Statistically significant differences (p < 1.7 × 10(-3), Bonferroni-corrected Wilcoxon signed-rank tests) were found between epochs of the infusion test using MF and RP. Furthermore, some spectral parameters (MF in the basal phase, RP for the first frequency band and in the early infusion phase, RP for the second frequency band and in all phases of the infusion study and RP in the third frequency band and in the basal phase) revealed significant correlations (p < 0.01) between epochs of the infusion test and signal amplitude in the basal and plateau phases. Our results suggest that spectral analysis of ICP signals could be useful for understanding CSF dynamics in hydrocephalus.

Giant-cell granuloma of the axis.

Giant-cell granuloma is a benign and nonneoplastic lesion with an expansive and locally destructive behavior. It typically involves the mandible and the maxilla. Only 1 case arising from the odontoid process of the axis has been reported previously. The authors report on a 64-year-old man with a giant-cell granuloma of the axis. They review this uncommon entity, emphasizing the complexity of differentiating between this lesion and other giant-cell tumors.

Complexity analysis of the cerebrospinal fluid pulse waveform during infusion studies.

PURPOSE: Nonlinear dynamics has enhanced the diagnostic abilities of some physiological signals. Recent studies have shown that the complexity of the intracranial pressure waveform decreases during periods of intracranial hypertension in paediatric patients with acute brain injury. We wanted to assess changes in the complexity of the cerebrospinal fluid (CSF) pressure signal over the large range covered during the study of CSF circulation with infusion studies. METHODS: We performed 37 infusion studies in patients with hydrocephalus of various types and origin (median age 71 years; interquartile range 60-77 years). After 5 min of baseline measurement, infusion was started at a rate of 1.5 ml/min until a plateau was reached. Once the infusion finished, CSF pressure was recorded until it returned to baseline. We analysed CSF pressure signals using the Lempel-Ziv (LZ) complexity measure. To characterise more accurately the behaviour of LZ complexity, the study was segmented into four periods: basal, early infusion, plateau and recovery. RESULTS: The LZ complexity of the CSF pressure decreased in the plateau of the infusion study compared to the basal complexity (p=0.0018). This indicates loss of complexity of the CSF pulse waveform with intracranial hypertension. We also noted that the level of complexity begins to increase when the infusion is interrupted and CSF pressure drops towards the initial values. CONCLUSIONS: The LZ complexity decreases when CSF pressure reaches the range of intracranial hypertension during infusion studies. This finding provides further evidence of a phenomenon of decomplexification in the pulsatile component of the pressure signal during intracranial hypertension.

New classification scheme for the prognostic stratification of meningioma on the basis of chromosome 14 abnormalities, patient age, and tumor histopathology.

PURPOSE: Meningiomas are usually considered benign tumors. However, relapses occur in 10% to 20% of all patients, including both histopathologically aggressive and benign tumors. This study explored the value of numerical abnormalities for 10 different chromosomes in meningiomas for predicting relapse-free survival (RFS). PATIENTS AND METHODS: This study prospectively analyzed the frequency of numerical abnormalities of chromosomes 1, 9, 10, 11, 14, 15, 17, 22, X, and Y in 70 meningioma patients by fluorescence in situ hybridization and their relationship with disease characteristics at diagnosis and patients' outcome. RESULTS: Results showed the presence of numerical abnormalities for one or more chromosomes in most patients (77%). Chromosome 22 in the whole series and chromosome Y in males were those more frequently altered, followed by chromosomes 1, 14, and X in females. Patients with abnormalities of chromosomes 1, 9, 10, 11, 14, 15, 17, the sex chromosomes, and gains of chromosome 22 were associated with adverse prognostic features, more frequent relapses, and shorter RFS. Multivariate analysis showed that tumor grade together with chromosome 14 status and age were the best combination of independent variables for predicting RFS. According to these variables, all patients with a score of two or more than two adverse prognostic factors had experienced relapse at 5 years, whereas none of those with a score of zero had experienced relapse 10 years after surgery. CONCLUSION: In addition to age and histologic grade, abnormalities of chromosome 14 contribute to a better prognostic stratification of meningioma patients at diagnosis. Additional prospective studies in larger series of patients, also including larger numbers of patients who experienced relapse, are necessary to confirm the utility of the proposed predictive model.