Neuron tolerance during hydrocephalus.

Whether or not neuron death plays a major role in pathophysiology during hydrocephalus is not well known. The goals of this study were to determine if neural degeneration occurred during hydrocephalus, and to determine if neuron tolerance developed during this pathophysiologic procedure.Neural damage as visualized by a sensitive staining technique, silver impregnation, was observed in three experimental groups: (1) adult hydrocephalic rats induced by kaolin injection into the cisterna magna, (2) adult rats with chronic hydrocephalus for 10 weeks subjected to acute forebrain ischemia induced by four-vessel occlusion, and (3) adult rats without hydrocephalus subjected to acute forebrain ischemia. The magnitude of hydrocephalus was also evaluated during this time. In mild or moderate hydrocephalus, little cell death was found. In severe hydrocephalus, axon and neuropil degeneration was extensively distributed, but cell death was still rarely observed. Although some neuron degeneration was found after acute forebrain ischemia in hydrocephalic rats, the extensive cell death in cortical layers III and V, and in hippocampal areas CA1 and CA4 that is commonly observed in the ischemic brain without hydrocephalus, was not seen. This study suggests that neuron death was not a major pathological change in the brain during hydrocephalus, with cerebral ventricles being enlarged during the development of hydrocephalus. Less neuron death in hydrocephalic rats after acute forebrain ischemia suggests that neuronal tolerance to ischemia occurs during hydrocephalus.

Axonal damage associated with enlargement of ventricles during hydrocephalus: a silver impregnation study.

Motor and cognitive deficits are commonly associated with hydrocephalus. Although the mechanisms responsible for these impairments have not been confirmed, neuronal cell death and axon degeneration may play an important role, and have long lasting consequences on neuronal connectivity. The goal of this study was to determine if neural degeneration occurred during hydrocephalus in structures anatomically related to cognitive motor functioning, namely, the sensorimotor cortex, neostriatum, hippocampus and corpus callosum. Neural damage, as visualized by silver staining, was examined in adult rats 2-10 weeks after obstructive hydrocephalus was induced by kaolin injection into the cisterna magna. In mild or moderate hydrocephalus, mostly occurring 2-6 weeks after kaolin injections, silver-labeled axons were scattered in the white matter of the sensorimotor cortex, corpus callosum, neostriatum, and hippocampus. In severe hydrocephalus, 10 weeks after kaolin injections, axon degeneration was more extensive in these areas, as well as in layers IV through VI of the sensorimotor cortex. Axons in the subiculum and the fimbria were heavily labeled, suggesting damage to hippocampal afferent and efferent fibers. In contrast, neuron cell death was rarely observed at any stage of hydrocephalus. The major pathological change of brain regions involved in motor and learning functions during hydrocephalus is axon degeneration, and this degeneration is correlated with an enlargement of the cerebral ventricles.

Impaired motor learning in children with hydrocephalus.

Hydrocephalic (n = 19) and normal (n = 20) children in two age groups (averaged at 10 and 14 years old) were asked to learn 5 predetermined timing rhythm interval tasks (including timing duration and relative timing pattern) by pressing keys on a computer keyboard. In the acquisition phase, visual and auditory goal timing intervals, as well as visualized feedback were presented to all participants before and after their key presses, respectively. A retention test without the auditory information and visualized feedback was administered 1 day later. By using the computerized timing test, we demonstrated in this study that the hydrocephalic group had significantly (ANOVA analysis) increased relative timing errors; this function depends on the formation of an internal model or a motor program related to long-term memory disorders. These findings could lead to the formulation of training procedures with simplified movements that may help hydrocephalic children improve their motor skill learning.

Postural changes in intracranial pressure in chronically shunted patients.

A subset of hydrocephalic patients with indwelling shunts become symptomatic when they are upright and active. Intracranial pressure (ICP) measurements in these patients have shown a significant drop in pressure when the patient is upright with return to normal levels when the patient is supine. In 20 chronically shunted hydrocephalic patients who previously had no siphon protection devices, ICP changes in supine and upright position were studied at the time when the patient had external ventriculostomy for treatment of shunt infection. Our hypothesis was that these patients might display rapid changes in ICP from fluid shifts occurring in non-CSF compartments. To minimize the effects of hysteresis, drift and zero-point error, measurements were made using a fluid manometer rather than a strain gauge pressure transducer. The pressure-volume index was estimated using the standard technique of bolus injection. Intracranial CSF volume was estimated on CT scans. The fluid shift was calculated using a mathematical model of the CSF compartment that incorporates negative pressure and volume components that permits simulation of siphoning. Sixteen patients had small, slit ventricles; 3 patients had moderate-sized ventricles and in 1 patient the ventricular size was normal. The average intracranial CSF volume estimated on CT scan was 12 cm(3). There was a mean drop in ICP in the upright position of 159 mm H(2)O. The mean PVI of 42 ml suggested a volume displacement out of proportion to the available intracranial CSF volume. Based on these findings, we conclude that even in the absence of drainage through the shunt, chronically shunted patients still display a fall in ICP when assuming the upright position. This raises the possibility of fluid shifts other than of CSF through nonshunt pathways. Possible mechanisms involving altered CSF-venous system interaction are discussed.

Evaluation of shunt malfunction using shunt site reservoir.

OBJECTIVE: To determine the usefulness of a separate reservoir placed at the site of the shunt in evaluation of shunt malfunction. METHODS AND MATERIALS: A ventricular catheter was placed alongside the proximal catheter of the shunt and connected to a subgaleal reservoir in 17 patients, in 9 a double-lumen catheter with integrated reservoir and in 13 patients a dual catheter with a double-port reservoir was used. At presentation of suspected shunt malfunction, a standard shunt function evaluation using shunt tap, CT scan or shunt injection was performed, and subsequently, the pressure from the tap of the reservoir was obtained. RESULTS: Thirty-three patients presented with symptoms of malfunction at an interval of 2.3 +/- 3 months (range 2-429 days). The pretest probability of shunt malfunction in this population was 73%. Posttest probability of shunt malfunction was 82.5% with standard evaluation and improved to 100% by the separate reservoir tap pressure measurement. In 4 patients in whom the shunt tap was dry, shunt infection was diagnosed prior to revision using CSF obtained at the reservoir tap. In 5 patients with proximal malfunction and bradycardia, the reservoir tap allowed early ventricular decompression. CONCLUSION: This study shows that a reservoir placed at the site of the shunt remains patient even when the shunt malfunctions, suggesting that flow rather than catheter position is important in proximal malfunction. It is superior to shunt tap for detection of shunt malfunction and infection, and it allows early ventricular decompression in a sick patient awaiting surgery for shunt revision.

Kaolin-induced hydrocephalus in the hamster: temporal sequence of changes in intracranial pressure, ventriculomegaly and whole-brain specific gravity.

The development of kaolin-induced hydrocephalus in adult hamsters was monitored by measuring changes in intracranial pressure (ICP), ventriculomegaly (VG) and whole-brain specific gravity (SG). Controls were intact or sham operated animals. Relative to controls, ICP of experimental animals increased at 24 h post intracisternal kaolin injection (by approximately 7-fold), reached a maximum on day 6 (by approximately 12-fold) and remained markedly elevated through day 15 (by approximately 5-fold). Ventricles differed in time of onset of distension (third: day 1, lateral: day 2, fourth: day 4) and in time of maximum ventriculomegaly (fourth: day 6; third: day 7; and lateral: day 9). Ventricular distension resulted in alterations in the ependyma; cilia were lost and apical cell surfaces were distorted. The ependyma was ruptured and the subjacent neuropil was exposed to the cerebrospinal fluid in some regions. Whole-brain SG remained constant in controls but declined in hydrocephalic hamsters after day 3 post-kaolin injection and reached its nadir on day 9 when whole-brain water content was 18% greater than in controls. Consistent with the fact that causal relationships exist between increased ICP, ventricular distension and brain edema, the alterations in each parameter occurred sequentially rather than simultaneously, and the time-course of each manifestation of hydrocephalus differed. The data suggest that the pathophysiology of kaolin-induced hydrocephalus in the hamster is tri-phasic: an initial period of rapid change, a brief interval of maximum alteration, and a subsequent period of compensation.

Adjustable antisiphon shunt.

Overdrainage from siphoning, a result of negative distal pressure, has been a major problem with the existing differential pressure shunt devices. The antisiphon/siphon control devices used to reduce siphoning often malfunction owing to fibrous scar formation around the valve. Similarly, the functioning of gravity-actuated systems is adversely affected by body movements. Constant flow shunt systems may not be superior to existing differential pressure valves, as has been shown in a recent multicenter study. In view of these difficulties, we investigated the possibility of developing a shunt valve based on the Starling resistor concept of flow regulation that allows proximal pressure-dependent and distal pressure-independent flow. The valve designed is capable of proximal pressure-dependent and distal pressure-independent flow. The valve allows for adjustable negative pressure in the vertical position.

Appropriate imaging in children with skull fractures and suspicion of abuse.

PURPOSE: To define the role of computed tomography (CT) in children aged 2 years and younger with head trauma, suspected abuse, and normal neurologic findings. MATERIALS AND METHODS: From 1992 through 1995, 87 consecutive children with skull fractures visible at plain radiography were referred to child protective services for evaluation of suspected abuse. Their cases were retrospectively reviewed. RESULTS: Of 67 children with normal neurologic findings, 35 (52%) were not referred for CT. No patient in this group developed delayed findings requiring further evaluation. Of the 32 (48%) who underwent head CT, only six (19%) had evidence of acute intracranial injury, despite the presence of minimal depression and stellate, multiple, and diastatic fractures. Of 20 children with acute neurologic findings, 16 (80%) had positive CT scans, which led to neurosurgical intervention in nine (45%). CONCLUSION: No child with normal neurologic findings had a clinically important abnormality depicted at CT. CT scans did not alter clinical management, clinical outcome, or legal outcome. Thus, routine CT of all patients with skull fractures in this population may be unnecessary.

Anterolateral lumbar lipomyelomeningocele: case report and review of the literature.

OBJECTIVE AND IMPORTANCE: Meningoceles associated with defects of the abdominal wall are exceedingly rare. One such complex case is presented along with a review of the relevant literature. The current pathophysiological theories and surgical management are discussed. CLINICAL PRESENTATION: A case of a patient with an anterolateral lumbar lipomyelomeningocele associated with multiple congenital anomalies, including defects in the abdominal wall and urogenital system, is presented. The lipomyelomeningocele presented as an expanding abdominal mass. INTERVENTION: Ventriculoatrial shunting and two operations to repair the myelomeningocele were performed to control the expanding abdominal mass. CONCLUSION: This report illustrates that the surgical management of complex lipomyelomeningoceles is similar to the more common types. It also demonstrates that in the infant in whom the intra-abdominal cerebrospinal fluid collection is the primary cause of the symptoms, cerebrospinal fluid shunting may be used to delay the definitive repair until the dura strengthens, thus avoiding the complications of complex repairs of dura with low tensile strength.

Tumor necrosis factor-alpha, interleukin-1 beta, and interleukin-6 concentrations in cerebrospinal fluid predict ventriculoperitoneal shunt infection.

OBJECTIVE: To determine the diagnostic value of cerebrospinal fluid tumor necrosis factor (TNF)-alpha, interleukin (IL)-1 beta, and IL-6 released into the cerebrospinal fluid of patients with ventriculoperitoneal shunt infection. DESIGN: Prospective, observational study. SETTING: University teaching hospital. PATIENTS: Sixty-four patients requiring cerebrospinal fluid aspiration for suspected ventriculoperitoneal shunt malfunction. INTERVENTIONS: Cerebrospinal fluid samples were obtained by shunt aspiration at the time of patient presentation. MEASUREMENTS AND MAIN RESULTS: TNF-alpha and IL-1 beta concentrations were measured by enzyme-linked immunosorbent assay, and IL-6 activity by bioassay. The sensitivity, specificity, predictive values, and overall efficiency for each cytokine were determined based on the cerebrospinal fluid culture results. Ten patients had positive cerebrospinal fluid cultures, eight of which yielded Staphylococcus species, and one each Acinetobacter and Pseudomonas. Cerebrospinal fluid TNF-alpha, IL-1 beta, IL-6, protein, and leukocyte concentrations were significantly increased in patients with shunt infection. Cerebrospinal fluid IL-6 activity had the highest diagnostic accuracy of the cytokines evaluated, with sensitivity of 80% and specificity of 98%. CONCLUSIONS: The presence of cerebrospinal fluid inflammatory cytokines strongly suggests ventriculoperitoneal shunt infection. Detection of these cytokines in the cerebrospinal fluid could be used for earlier diagnosis of bacterial infection.

Gonococcal infection in cerebrospinal fluid and the presence of a ventriculoperitoneal shunt.

BACKGROUND: Neisseria gonorrhoeae is one of the most common organisms associated with pelvic disease in a woman of reproductive age. CASE: We present an unusual case of cerebrospinal fluid infection with N. gonorrhoeae in a woman with a ventriculoperitoneal shunt who complained of abdominal pain. Her shunt was removed and after adequate antibiotic therapy, it was re-inserted. CONCLUSION: Sexually active women, especially those with ventriculoperitoneal shunts, should be encouraged to use a barrier method of contraception, and should have a pelvic examination as part of their evaluation when they present with complaints of abdominal pain.

Maternal neurosurgical shunts and pregnancy outcome.

OBJECTIVE: To assess pregnancy outcome in women with ventriculoperitoneal or lumboperitoneal shunts. METHODS: Charts were reviewed retrospectively for mothers with ventriculoperitoneal or lumboperitoneal shunts delivered at Hutzel Hospital from 1976-1992. Patients were identified by cross-referencing medical records from Children's Hospital Neurosurgical Division and medical records at Hutzel Hospital during this period. RESULTS: Eight patients with 25 pregnancies were identified from 1976-1992. Indications for shunt placement were pseudotumor cerebri (four with lumboperitoneal shunts) and congenital hydrocephalus (four with ventriculoperitoneal shunts). Pregnancy outcomes were two elective abortions, five spontaneous abortions, two preterm vaginal deliveries, one mid-forceps rotation, two primary low transverse cesareans, two repeat low transverse cesareans, and 11 spontaneous vaginal deliveries. No patient received prophylactic antibiotics during labor and vaginal delivery because of the shunt. There were no shunt-related complications. CONCLUSIONS: This series doubles the number of previously reported pregnancy outcomes in women with neurosurgical shunts. Contrary to the literature suggesting cesarean delivery and prophylactic antibiotics for all patients, our experience suggests that vaginal delivery can be considered and that prophylactic antibiotics are not an absolute necessity in uncomplicated vaginal deliveries.

Intracerebral hemorrhage after evacuation of a subdural hematoma in an infant.

Intracerebral hematomas following evacuation of a subdural hematoma have been described in adults resulting from sudden decompression during the drainage of the hematoma. In infants an open fontanelle and patent sutures are expected to offer protection against sudden decompression. We report the occurrence of intracerebral hematoma in an infant following evacuation of a subdural hematoma. The multiplicity and centripetal spread of the postoperative hematomas suggested that they had resulted from sudden decompression.

Ultrasound abnormalities in term infants on ECMO.

The charts and cranial ultrasounds of 29 infants treated with extracorporeal membrane oxygenation (ECMO) for respiratory insufficiency secondary to meconium aspiration syndrome, primary pulmonary hypertension, congenital diaphragmatic hernia and/or sepsis were examined to identify ultrasound abnormalities. Seventeen (58.6%) developed extra-axial fluid collections, only two of which were progressive. Ten (34.5%) developed evidence of intracranial hemorrhage (ICH): seven caudate, one each in the thalamus, parietal and occipital lobes. Eight (27.65%) of the neonates had seizures while on ECMO, 5 of whom had concurrent ICH.

Useful components of the shunt tap test for evaluation of shunt malfunction.

Results of shunt tap were studied in 224 clinically or radiologically suspected instances of shunt malfunction. In 130 retrospectively studied patients the results of the tap had reported the opening pressure and ease of aspiration. In 94 prospectively studied instances the shunt tap parameters described were (i) the opening pressure, (ii) the drip interval, i.e., the interval between the drops of cerebrospinal fluid when the open end of the butterfly used for tapping was placed 5 cm below the level of the valve, and (iii) the closing pressure. The efficacy of the aspiration procedure for proximal malfunction was 40.3%, compared with the efficacy of drip interval which was 95.1%. For distal malfunction, the efficacy of measurement of opening pressure was 54.3% whereas that of closing pressure was 60.6%. An in vitro model of a functioning shunt showed that the opening and the closing pressures were related to the flow rate and the level of the distal catheter tip with respect to the valve, whereas the drip interval was linearly related to the flow through the proximal catheter and was independent of the distal catheter position. The opening pressure, closing pressure, and the drip interval recorded at surgery were not significantly different from the values obtained by shunt tap. The results suggested that shunt tap accurately provides information otherwise obtained at surgery and the drip interval is most useful for evaluating a proximal malfunction. The subjective impression of the distal flow may be more helpful in diagnosing distal malfunction rather than the absolute level of opening or closing pressures.

Balanced reciprocal translocation mosaicism associated with an abnormal phenotype.

Balanced reciprocal translocation mosaicism is rarely reported in humans. Only two previous cases have been associated with an abnormal phenotype. We report on a third case of apparently balanced reciprocal translocation mosaicism associated with an abnormal phenotype, largely different from those reported previously. Since low levels of mosaicism may not be detected in routine cytogenetic analyses, balanced reciprocal translocation mosaicism may be associated with an abnormal phenotype more often than has been recognized to date.

Emotional adjustment of children with hydrocephalus and of their parents.

Emotional and behavioral adjustment after infantile hydrocephalus were investigated. Children's and parents' adjustments were assessed by means of questionnaires (PIC-R, SCL-90-R) in a sample of 48 children with shunted hydrocephalus. The PIC-R patterns of the children were mostly reflective of their anomalous physical and cognitive development, but there was no evidence for a specific "hydrocephalic personality" pattern. Discriminant analyses revealed that there were no strong relationships between distress of the parents (as assessed by the SCL-90-R) and a variety of physical and psychosocial variables, despite the fact that many parents were significantly distressed. It was concluded that the majority of children with hydrocephalus do not present with a specific psychiatric profile, that clinically significant levels of distress are quite common in their parents, and that such distress is typically not related to the hydrocephalus per se.

Limitations of the Glasgow Coma Scale in predicting outcome in children with traumatic brain injury.

OBJECTIVE: To study the hypothesis that, in the absence of an ischemic-hypoxic state, children with severe traumatic brain injury and with unfavorable Glasgow Coma Scale scores may have good recovery. DESIGN: Retrospective, observational, cross-sectional study with factorial design. SETTING: Inpatient population in a university hospital. PATIENTS: Seventy-nine children with traumatic brain injury admitted to the intensive care unit. INTERVENTIONS: All patients received close monitoring and strict control of intracranial pressure (less than 20 mm Hg) and cerebral perfusion pressure (greater than 60 mm Hg). MEASUREMENTS AND RESULTS: Admission Glasgow Coma Scale score, survival, need for cardiopulmonary resuscitation, presence of shock, peak intracranial pressure, duration of coma, Glasgow Outcome Scale score, and the results of neuropsychologic tests were analyzed. Of 79 children, 70 (89%) survived. Although the mortality rate was higher among patients with Glasgow Coma Scale scores of 3 to 5, 14 (64%) of 22 of these children survived. Nonsurvivors had a significantly higher incidence of shock and need for cardiopulmonary resuscitation. Except for two patients who had prolonged hypoxemia, all children, including those with Glasgow Coma Scale scores of 3 to 5, had a satisfactory outcome (Glasgow Outcome Scale scores of 4 or 5). Neuropsychologic outcome was not significantly different in the survivors with Glasgow Coma Scale scores of 3 to 5 and those with Glasgow Coma Scale scores of 6 or more. CONCLUSIONS: A low Glasgow Coma Scale score does not always accurately predict the outcome of severe traumatic brain injury; in the absence of hypoxic-ischemic injury, children with traumatic brain injury and Glasgow Coma Scale scores of 3 to 5 can recover independent function.

Neuropsychological functioning of hydrocephalic children.

A group of 30 five- to eight-year-old hydrocephalic children was administered a comprehensive battery of neuropsychological tests. As a group, they displayed a pattern of lower PIQ than VIQ. Their performance was within the average range of many neuropsychological tests, but they performed poorly on some measures of complex visuospatial functioning. It is concluded that hydrocephalic children at this early age exhibit relatively reduced efficiency in processing complex or novel nonverbal stimuli. The possibility of dysfunction in the posterior regions of the right cerebral hemisphere is discussed.