Cerebrospinal Fluid Absorptive Capacity Research Articles

Spectral analysis of intracranial pressure: Is it helpful in the assessment of shunt functioning in-vivo?

ObjectiveShunt failure is common in hydrocephalic patients. The cerebrospinal fluid (CSF) infusion test enables the assessment of CSF absorption capacity, which is represented by the resistance to CSF outflow (ROUT) However, shunt failure may not only affect the CSF absorption capacity but also the intracranial compliance or compensatory properties. Spectral analysis of the ICP signal obtained during the infusion test may enable the comprehensive assessment of the overall deterioration caused by shunt failure. Material and methodsA total of 121 hydrocephalic shunted patients underwent the infusion test with continuous intracranial pressure (ICP) and arterial blood pressure (ABP) recording. The maximum amplitudes of three major frequency bandwidths (0.2–2.6, 2.6–4.0 and 4.0–15Hz, respectively) were calculated from the ICP. Statistical analyses were conducted to identify factors significantly associated with shunt failure, to construct an index (i.e., the shunt response parameter, SRP) for detecting shunt failure, and to define thresholds for ROUT and SRP. ResultsThe ROUT threshold for detecting shunt failure was 7.59mmHg/ml/min, and this threshold showed an accuracy of 82.64%. All spectral parameters were found to be significantly associated with shunt patency (p<0.05). The SRP exhibited significantly better accuracy than ROUT in detecting shunt failure (91.74%). ConclusionThe hydrodynamic assessment of shunted patients enhanced by spectral analysis during the infusion test detected shunt failure with high accuracy. Although further validation is needed, the SRP exhibited promising results.

The ventriculoomental bursa shunt

The aim of this study is to access the efficacy of the omental bursa (lesser sac) as a receptacle of cerebrospinal fluid (CSF) and to use it as an alternative to the ventriculoatrial or ventriculopleural shunts when the peritoneum reduces or loses its CSF absorption capacity. Three patients with hydrocephalus presented with malfunctioning of ventriculoperitoneal shunts, secondary to peritoneal blockage caused by previous episodes of shunt infections in two and peritonitis in one patient. All patients underwent previous shunt revisions due to ventriculitis and shunt obstruction ranging from three to eight times. In order to keep the peritoneal cavity as the main receptacle of CSF absorption site, the distal catheter was inserted in the omental bursa, through the foramen of Winslow, jointly by a pediatric surgeon. We denominated this new technique of CSF diversion as ventriculoomental bursa (VOB) shunting. The children have been followed at least for 1 year (range 12 to 28 months) with no recurrence of shunt. VOB shunting may be considered an acceptable technique to CSF shunting when the anterior peritoneum loses or decreases its CSF absorption capacity.

Retrospective Review of Multilevel Spinal Fusion Combined With Spinal Cord Transection for Treatment of Kyphoscoliosis in Pediatric Myelomeningocele Patients

Retrospective review of cases at a single institution from 1998 to 2005. The authors present their surgical experience, complications, and learned insight in 9 myelomeningocele children with kyphoscoliosis treated with combined spinal cord transection and spinal fusion. Complication rates in spinal fusion for treatment of kyphoscoliosis in myelomeningocele patients are high. Spinal cord transection in combination with fusion can be an appropriate strategy in selected patients, but changes in cerebrospinal fluid (CSF) dynamics that may accompany ligation of the distal CSF circulation are not well characterized. Demographic, clinical, and radiologic data were examined in 9 children with myelomeningocele level at or above T12 and no residual urologic function treated at our institution with spinal cord detethering and transection, and multilevel spinal fusion. Seven children underwent kyphectomy with posterior fusion only for severe gibbus deformities, while 2 had anterior and posterior fusions for severe kyphoscoliosis. Follow-up of patients ranged from 4 to 92 months (mean, 37.8 months). Eight children (89%) experienced postoperative complications involving wound infection or skin breakdown. One child presented with a CSF leak. Two children (22%) required revision of their ventriculoperitoneal shunts. The average angle of kyphosis before surgery was 122.3 (range, 48 degrees -180 degrees ), and the average postoperative angle was 38.2 (range, 4 degrees -113 degrees ), with average correction being 81.9 degrees (range, 29 degrees -124). Average correction of scoliosis, if present, was 59.5 degrees (range, 35 degrees -92 degrees ). Combined spinal cord transection and spinal fusion allowed an average correction of kyphosis by 81.9 degrees . The complication rate was 89%, with wound concerns being the most significant. Additionally, 22% of patients required shunt revision within 6 weeks of surgery. We attribute this to alteration of CSF dynamics resulting from loss of CSF absorption and flow-buffering capacity below the level of the spinal cord transection.

Changes in cerebrospinal fluid hydrodynamics following endoscopic third ventriculostomy for shunt-dependent noncommunicating hydrocephalus.

The aim of this study was to analyze physiological changes in cerebrospinal fluid (CSF) dynamics following endoscopic third ventriculostomy (ETV) for shunt-dependent noncommunicating hydrocephalus. . Clinical data obtained in 15 patients treated with ETV for shunt malfunction were analyzed. Magnetic resonance imaging studies demonstrated the obstruction of the ventricular system preoperatively. After ETV, the existing shunt system was removed and a continuous extraventricular drain, set at 30 cm H2O in height, was installed to measure daily amounts of CSF outflow. Cerebrospinal fluid dynamics after ETV were also evaluated using 111In-diethylenetriamine pentaacetic acid radioisotope cisternography in six of 15 patients within 1 month of the procedure. Three patients underwent cisternography at 6 months after ETV. Cisternograms were obtained at 1, 5, 24, and 48 hours after injection of the radioisotope. To study CSF absorptive capacity, ratios of radioisotope counts at 48 and 5 hours after injection were calculated (C48:C5). Seven of 15 patients had daily outflows of CSF of less than 20 ml; this volume decreased quickly within a few days. The other eight patients demonstrated an outflow of more than 150 ml of CSF for several days, three of whom had signs of transiently increased intracranial pressure. Their CSF outflow volume decreased gradually and symptoms improved within 1 week. Ratios of C48:C5 were within normal limits in five of six patients who had undergone cisternography 1 month after ETV. These ratios were decreased in all three patientswho had undergone cisternography at 6 months after ETV compared with that measured at 1 month after the procedure. Our data suggest that CSF dynamics convert from a shunt-dependent state to a shunt-independent state within I week following ETV in patients with shunt-dependent noncommunicating hydrocephalus. Nonetheless, intraventricular pressure does not decrease quickly in certain cases. Cerebrospinal fluid absorptive capacity or CSF circulation through the subarachnoid space may show further improvement several months after ETV.

Physiological features of the pressure-volume function of brain elasticity in man.

The intracranial pressure-volume relationship of brain elasticity was examined in 20 patients with suspected disorders of the cerebrospinal fluid (CSF) system. Elasticity measurements were made as the patients were studied with a servo-controlled lumbar infusion technique to measure CSF absorptive capacity. The data were evaluated to determine the relationship between intracranial pressure (ICP) and volume, and between ICP variability and the level of ICP. The results confirm the exponential nature of the pressure-volume elasticity function in patients who are not critically ill. Eight of the 20 patients were shown to have normal CSF absorptive capacities, and there was no difference between their elasticity measurements and those of patients with absorptive defects. In addition, ICP variability was shown to be linearly related to the actual level of ICP. The physiological features of the pressure-volume elasticity function are reviewed. Based on these considerations, the clinical value and significance of elasticity measurements is questioned.

Experimental hydrocephalus. Changes in cerebrospinal fluid dynamics as a function of time.

Cerebrospinal fluid (CSF) turnover was studied in cats by ventricular perfusion at various time intervals after the intracisternal injection of 175 to 200 mg of kaolin. At seven days, CSF absorptive capacity was minimal and intraventricular pressure was high. During this time interval, the occurrence of quadriplegia in some animals was attributed to microscopic changes observed in kaolin meningitis and also to the elevated intraventricular pressure. After three weeks, when transventricular absorption occurred, CSF absorptive capacity increased, and intraventricular pressure returned to normal. The development of transventricular absorption was accompanied by an increase in water content of periventricular white matter. Results from perfusion studies at a constant perfusion pressure demonstrated that CSF production rates were similar in both acute and chronic hydrocephalic cats. However, CSF production was affected by changes in perfusion pressure.