Cerebrospinal compensation in hydrocephalic children.

One hundred and fifteen cases of hydrocephalus in children were analysed. Cerebrospinal compensatory reserve was assessed by a computerized, constant rate, lumbar infusion test. Head circumference and ventricular size were measured and a psychometric examination carried out. A classification of hydrocephalus based on resting cerebrospinal fluid pressure (CSFP) and resistance to cerebrospinal fluid outflow (RCSF) was introduced. Parameters of compensatory reserve were compared in atrophy (low CSFP, low RCSF), normal-pressure hydrocephalus (low CSFP, increased RCSF), non-communicating hydrocephalus (high CSFP, low RCSF) and acute hydrocephalus (high CSFP and increased RCSF). Significant differences were found between the factors describing compensatory ability in these groups. Sixty-two patients could be classified on the basis of resting CSFP and RCSF. Differentiation between the types of hydrocephalus was shown to be more accurate when all variables measured during the pressure-volume test were considered. The patterns of the time courses of CSFP during rate infusion tests in the different types of hydrocephalus are presented.

Histological grading and bromodeoxyuridine labeling index of astrocytomas. Comparative study in a series of 60 cases.

The histological grade and the bromodeoxyuridine (BUdR) labeling index of 60 astrocytomas of "ordinary" cell types (fibrillary, protoplasmic, gemistocytic, and anaplastic astrocytomas and glioblastomas) were compared to determine whether the grading system reflects the proliferative potential of the tumors. The tumor grade was based on the presence or absence of four criteria (nuclear abnormalities, mitosis, necrosis, and vascular endothelial proliferation): Grade 1, no criterion, Grade 2, one criterion, Grade 3, two criteria; and Grade 4, three or four criteria. The BUdR labeling index, or percentage of S-phase cells, was calculated in paraffin-embedded tumor sections after in situ labeling by intraoperative intravenous infusion of BUdR, 200 mg/sq m. Exponential regression analyses showed a positive correlation between the histological grade and labeling index (r = 0.88, p less than 0.001) that was stronger than the correlations between log labeling index and age (r = 0.55, p less than 0.001) and between grade and age (r = 0.55, p less than 0.001). These results indicate that the histological grading system reflects the proliferative potential of "ordinary" astrocytomas.

[Characteristics of intracranial volume-pressure relationship in hydrocephalic children with reference to age]. / Charakterystyka wewnatrzczaszkowych stosunków objetosciowo-cisnieniowych u dzieci z wodoglowiem, z uwzglednieniem czynnika wieku.

The purpose of the study was establishing of the effect of child's age, and thus the biomechanical properties of cranial coverings, on the parameters characterizing the intracranial space in the infusion test. The results of the infusion tests performed as a supplementary diagnostic examination in 59 cases of infantile hydrocephalus were subjected to statistical analysis. The studied material and the methods used for its processing no significant differences were found in the mean values of the biomechanical parameters of intracranial space were found between the group of younger children (aged up to 2 years) and older children (over 2 years). This finding may be important in the interpretation of the results of the infusion test, since it was not found that the biomechanical properties of the cranial coverings had any significant effect on the results of this test.

Comparison between classic-differential and automatic shunt functioning on the basis of infusion tests.

Infusion tests were performed in order to examine cerebrospinal compensatory ability in two groups of patients with impaired compensation, subjected to shunt implantation. The functioning of the classic differential shunts was compared to the automatically (Orbis-Sigma) functioning shunts. The reference group, with intact compensatory parameters is also presented. The influence of different types of shunts on the intracranial compensation ability was compared. Automatic shunts produce less decrease in the resorption resistance of CSF in the post-shunted examination than the classic differential shunts. Classic differential shunts disturb the mono-exponential character of the pressure-volume relationship in a higher degree than automatic shunts. Shunt functioning models were proposed as well as the method of detection of eventual recovery to the normal resorption reserve. This method can be applied only to patients with automatic shunts.

A computer system for the identification of the cerebrospinal compensatory model.

A computer system, based on IBM PC, was designed for the cerebrospinal compensatory model identification. The intracranial pressure (ICP) signal, registered during the lumbo-lumbar infusion test is analyzed by means of the spectral analysis algorithm in order to measure precisely the pulse wave amplitude. The amplitude and the mean ICP level, calculated repetetively within the period of about 8 seconds, are stored on the disk and form the basis for further model identification. Three different methods of identification were applied. They enable one to estimate the fundamental model parameters, such as: resistance to the cerebrospinal fluid resorption, pressure-volume index, baseline pressure, rate of formation of the cerebrospinal fluid. Statistical evaluation of the results of the infusion test analysis obtained by means of the system described in two groups of hydrocephalic patients (children and adults) is presented.

Analysis of intracranial pressure waveform during infusion test.

An analysis of intracranial pressure (ICP), based on an examination of the temporary correlation between the changes in amplitude of the pulse wave and the mean ICP level, is presented. The paper contains a discussion of the preliminary results of the method when applied to the analysis of ICP as monitored during infusion tests in a group of 24 children. Infusion of a certain volume of CSF is a good example of an uncompensated volume process, introduced externally into the intracranial space. Results allow an interpretation of the short term correlation coefficient RAP (correlation coefficient between ICP and variations of the amplitude of fundamental component of the pulse wave AMP), as a steady state index. According to this interpretation, the presented analysis enables the observation of a loss of equilibrium during the test. Other phenomena can also be observed, for instance a recovery to equilibrium after the test, nonlinearities of amplitude-pressure relationship, vasomotor reflexes etc.

Analysis of CSF dynamics by computerized pressure-elastance resorption test in hydrocephalic children. Indications for surgery.

Since 1982, 23 hydrocephalic children have been studied for compensatory mechanisms of the cerebrospinal fluid system. The authors describe the method and results of a computerized pressure-elastance resorption test (CPERT), a spinal steady-state infusion test, in hydrocephalic children. Computerized analysis of the P/V and AMP/P curve provides valuable data that precisely describe the degree of disturbances of CSF dynamics. The following parameters were quantitatively determined: out-flow resistance, opening pressure, elastance, elasticity, reference pressure and optimum (break-point) pressure. It is concluded that the described test allows the differential diagnosis of chronic hydrocephalus in children. The value of optimum pressure (analysis of AMP-P relation) gives precise indications for surgery and the selection of a valve system with adequate opening pressure. In some cases, the CPERT test can be used instead of continuous ICP monitoring.