Etiology and clinical course of hydrocephalus.

This article discusses the incidence, various causes, and different clinical presentations in children and adults with hydrocephalus.

Ruptured cerebral aneurysm in a 39-day-old infant.

A case of middle cerebral artery aneurysm in a 39-day-old infant is discussed. The unique characteristics of aneurysms in the pediatric age group which distinguish them from adults are male predominance, greater frequency in middle cerebral artery and posterior circulation. In addition, they demonstrate a greater frequency of large and giant aneurysms. Theories on the etiology of cerebral aneurysms in children are discussed.

Hydrocephalus in the H-Tx rat: a monogenic disease?

The H-Tx rat is a genetic model of hydrocephalus for which thereis a poor understanding of the mode of inheritance. Previous studies suggested a polygenicmode of inheritance but the breeding data to supportthis hypothesis have not been reported. In an attempt to clarify the hereditary mode we have analyzed the data from eight generations of H-Tx rats and four generations of cross-matings between H-Tx rats and Sprague-Dawley (SD) rats. In the H-Tx rat colony 113 of 129 random brother-sister matings (87.60%) produced hydrocephalic offspring, with males and females being equally affected. The overall incidence varied greatly with an average of 30. 35%. In matings with more than three litters, all mating pairs yielded hydrocephalic pups. In cross-matings both hydrocephalic and normal H-Tx rats were mated with normal SD rats. No hydrocephalus was observed in the first generation of 124 pups (F1). Subsequent brother-sister matings of F1 animals generated hydrocephalic pups in the F2 generation with a lower incidence (4.67% in hydrocephalic HTx/SD matings and 5.11% in normal HTx/SD matings, respectively) than in the H-Tx rat colony (30.35%). Back-cross-matings between F2 rats and normal H-Tx rats yielded an incidence of hydrocephalus higher than that of the cross-matings but lower than that of the H-Tx colony. These data strongly suggest that the H-Tx rat is a homozygous carrier of an autosomal recessive hydrocephalus gene with incomplete penetrance. Furthermore, the data clearly rule out sex-linked and polygenic modes of inheritance and provide further insight with respect to genetic inheritance of hydrocephalus.

Percutaneous endoscopic recanalization of the catheter: a new technique of proximal shunt revision.

OBJECTIVE: Proximal ventricular catheter obstruction by the choroid plexus is a frequent occurrence in children with shunted hydrocephalus. In some cases, the flow is obstructed owing to membranous occlusion by a small amount of tissue. It has been shown that only a few of the multiple catheter openings need be patent to maintain adequate shunt function. Recent advances in technology have improved our ability to perform intraluminal endoscopic catheter dissection and minimize the morbidity associated with shunt maintenance. METHODS: Percutaneous endoscopic shunt recanalization was performed in 20 cases (18 children) under institutional review board study protocol. The mean age was 32 months, and all children had signs and symptoms of shunt malfunction, confirmed by computed tomography and magnetic resonance imaging and verified by shunt taps. Under aseptic conditions in the operating room, the Rickham reservoir was entered with a 16-gauge intravenous catheter, and the obstruction was visualized with a fiber endoscope (0.5-0.8 mm). Intraluminal dissection using electrocautery was performed with endoscopic guidance to visualize the catheter and flushing of the valve. RESULTS: At a mean follow-up time of 20 months (range, 15-29 mo), the children are doing well, with computed tomographic and magnetic resonance imaging confirmation of adequate ventricular decompression in the 17 successful cases (85%). There were three failures in the study, necessitating a standard open shunt revision. CONCLUSION: The percutaneous endoscopic shunt recanalization procedure can be used successfully to treat proximal shunt malfunction.

Evidence that oxidative stress is associated with the pathophysiology of inherited hydrocephalus in the H-Tx rat model.

Oxidative stress can contribute to many neurological disease processes. Because many events known to involve oxidative stress (infection, hemorrhage, brain trauma) are accompanied by hydrocephalus, the present study sought to evaluate the relationship between oxidative stress and the progression of hydrocephalus. Assays for reactive oxygen species (ROS), using dichlorofluorescein (DCF) fluorescence, and lipid peroxidation, using malondialdehyde (MDA), were performed on brain tissue from the cerebral cortex, cerebellum, basal ganglia, and hippocampus of 4-, 10-, and 25-day-old normal and hydrocephalic H-Tx rats. These rats inherit hydrocephalus at a rate of 30-50% and represent a unique model for studying the progression of hydrocephalus. When hydrocephalic and normal H-Tx rats were compared, ROS levels were significantly higher in the cerebral cortex of 4-day-old and in the cerebellum and hippocampus of 4- and 10-day-old hydrocephalic rats. ROS levels also were significantly higher in the basal ganglia of 25-day-old hydrocephalic rats. MDA levels were significantly higher in the hippocampus and basal ganglia of 25-day-old hydrocephalic rats. There were no significant differences in MDA levels at younger ages. These results indicate that, in H-Tx rats, oxidative stress is associated with the progression and molecular pathophysiology of hydrocephalus. This association suggests that oxidative brain damage may represent an important factor resulting from or contributing to the pathogenesis of hydrocephalus.

TGF-beta1 expression is reduced in hydrocephalic H-Tx rat brain.

Transforming growth factor-beta1 (TGF-beta1) is a cytokine with diverse biological effects. Overexpression of TGF-beta1 in mice has been shown to induce progressive hydrocephalus. We have used a quantitative RT-PCR method to analyze the TGF-beta1 expression in the brains of H-Tx rat, a model of congenital hydrocephalus. Our studies have shown that rather than increased expression, the 3- and 10-day hydrocephalic H-Tx rats have significantly lower TGF-beta1 levels than their normal siblings (p < 0.01). This difference became insignificant in the 21-day group. Besides, both hydrocephalic and normal H-Tx rats have significantly lower TGF-beta1 levels in all three age groups of 3-, 10- and 21-days than SD control rats (p < 0.01 in all three groups) although the difference tends to become less significant with development. We also tested the expression of another cytokine, the epidermal growth factor, and observed a similar reduction. This suggests that the TGF-beta1 expression change is not unique to the development of hydrocephalus in this rat model. Our hypothesis is that the TGF-beta1 expression decrease in the H-Tx rat is not the cause of the disease. Rather it might be the result of feedback inhibition by increase in the expression of the gene it regulates, including an extracellular matrix component. Effort is currently being made to test this hypothesis.

Spinal cord thromboplastin-induced coagulopathy in a rabbit model.

Coagulopathy results from many diverse events, including several neurogenic causes. Using a rabbit model, we produced coagulopathy by injecting autologous spinal cord and extracted thromboplastin intravenously. Serial coagulation panels were performed to evaluate the activation of the thrombotic and fibrinolytic pathways. Group 1 animals (n = 4) received intravenous injections of homogenized spinal cord tissue. Coagulopathy was not produced with 36 mg of homogenized spinal cord tissue, but 50 mg or more resulted in death. Group 2 animals (n = 12) received intravenous injections of extracted rabbit cord thromboplastin, which contained approximately 60% activity of a commercially purified rabbit brain thromboplastin. Five animals receiving 2.5 to 5.5 mg of thromboplastin per kilogram of body weight survived with evidence of coagulopathy. Seven animals receiving 2.5 to 100 mg of thromboplastin per kilogram of body weight died. Group 3 (4 control animals) received normal saline injections without changes in clinical or laboratory status. The thrombotic pathway was activated in all animals as evidenced by decreased platelet counts and fibrinogen levels. Activation of the fibrinolytic system was demonstrated by increased concentrations of protamine sulfate and abnormal euglobulin clot lysis times. The most sensitive parameters were the platelet count, protamine sulfate concentration, and white cell count (margination), which became abnormal within 15 minutes after the injections and returned to normal within 1 hour.

Desmoplastic cerebral astrocytoma of infancy. Light microscopy, immunocytochemistry, and ultrastructure.

The first detailed ultrastructural study of a superficial desmoplastic cerebral astrocytoma of infancy is reported. This is a neoplasm which mimics a mesenchymal tumor, originally described in 1984 under the name of "superficial cerebral astrocytoma attached to dura." This tumor, which is believed to have a good prognosis, was resected from the frontoparietal region of a 6.5-month-old girl, in whom it had presented as a large densely enhancing vascular and cystic mass. The ultrastructure of the tumor appeared to be distinctive, characterized by the absence of neuronal elements, and the presence of large amounts of redundant and sometimes extensively duplicated basal laminal material and collagen between nonpleomorphic and nonlipidized astrocytes, corresponding to the reticulin fibers seen by light microscopic analysis between the S-100 protein and glial fibrillary acidic protein (GFAP)-positive cells. The features of the tumor, its differential diagnosis, and its relationship to other pediatric supratentorial tumors are discussed.

Disseminated intravascular coagulation associated with spinal cord laceration: a case report.

A 31-year-old man was thrown from his motorcycle, sustaining a thoracolumbar fracture and cervical spine fracture with no evidence of neurologic function below L1. At the time of spinal fusion, there was diffuse bleeding from the soft tissues. Visualization of the thoracolumbar fraction revealed separation of the laminae with a dural tear and extruding spinal cord tissue. Laboratory evaluation identified abnormal clotting studies intraoperatively and postoperatively. We postulate that release of potent spinal cord thromboplastins into the systemic circulation may elicit a coagulopathy, as has been recognized following craniocerebral trauma.

Stereotactic surgery in children.

Stereotactic biopsy has been popularized over the last decade since the advent of newer, more sophisticated instrumentation and technology. However, less than 300 cases of pediatric stereotaxy are recorded in the literature and few reports emphasize the necessary modifications required in children. Sixty-six stereotaxic procedures were performed on 62 children using the Brown-Roberts-Well (BRW) apparatus at our institutions. The mean age was 9.0 years (range 5 months to 18 years). The indication for the technique was diagnostic in 36 cases and therapeutic in 9 cases; location was a factor in 21 children with the lesion involving a 'deficit-prone' area of the brain. The BRW technique was applicable in 61 procedures (93%). Inability to enter cysts or biopsy of necrotic tissue and tumor capsule occurred in 5 cases. One patient had a transient increase in cerebral edema, for an overall complication rate of 2%. It appears that the BRW stereotactic technique is equally effective in children and adults and will no doubt play an ever increasing role in the future of pediatric neurosurgery.

Medulloblastoma in association with the Coffin-Siris syndrome.

An 8-year old patient with Coffin-Siris syndrome is presented, who was found to have a medulloblastoma during the evaluation of apnea and ventilator dependency. Although several cases of Dandy Walker cysts and one case of brain-stem heterotopia have been described in this rare syndrome, this is the first report of medulloblastoma in a patient with Coffin-Siris syndrome. Possible pathogenetic mechanisms are briefly discussed.

Supratentorial pressures. Part I: Differential intracranial pressures.

Dynamic supratentorial pressure changes may differentially alter tissue pressure and intraventricular fluid pressure. To evaluate these pressures, we used a floppy cuff intracerebral catheter and an intraventricular catheter in the cat and rhesus monkey. Baseline intraventricular pressures exceeded intracerebral pressure in both species. Intraventricular pressure was 3-4 mmHg in cats and 6-14 mmHg in monkeys, while the intracerebral pressure was in the range 0-4 mmHg in both. Saline injection into the spinal or cranial subarachnoid space resulted in a greater increase in ventricular fluid pressure, and the time for return to baseline was one and a half times longer in the intraventricular compartment. Jugular venous and abdominal compression resulted in a greater rise in the ventricular pressure than intracerebral pressure. Inflation of subdural balloons and intracerebral injection of silicone caused a differential pressure across the brain with the pressure being greatest in the ipsilateral hemisphere and lowest in the contralateral hemisphere. Rapidly evolving epidural masses produced varied results. We did not evaluate compensatory pressure changes in these animals. Those pressures that involve cerebrospinal fluid (CSF) dynamics alter intraventricular pressure more than tissue pressure. Alternatively, rapidly forming masses tend to increase tissue pressure near the mass more than intraventricular pressure.

Supratentorial pressures. Part II: Intracerebral pulse waves.

Intracerebral pulse waves were recorded in cat and monkey while intracranial pressure (ICP) manipulations were performed. The intracerebral pulse waves appeared comparable to cerebrospinal fluid (CSF) pulsations. The wave forms were divided into multiple smaller waves, designated P1 to P4. The P1 component was primarily of arterial origin and was accentuated by increasing ICP unrelated to increased venous pressure, most commonly from a mass lesion. Bilateral carotid occlusion resulted in decreased amplitude of P1. Venous hypertension from jugular venous or sagittal sinus occlusion, on the other hand, accentuated waves P2 and P3 more than P1. This is consistent with a Starling resistor model of the cerebral venous system in which mass lesions may compress low-pressure veins and accentuate the arterial pressure-dependent P1 wave, whereas venous hypertension causes increased prominence of the later P2 and P3 waves.

Intervertebral disc calcification in children.

Calcification of cervical intervertebral discs in children is due to an uncommon, but distinct, disease of unknown etiology. Signs and symptoms of nerve root or spinal cord compression are unusual and acute symptoms are followed by a benign course and spontaneous recovery. We describe a 5-year-old patient with symptomatic cervical disc calcification and discuss the relevant clinical and radiographic features.

Subdural empyemas in children.

Subdural empyema is a neurosurgical emergency which is rapidly fatal if not recognized and managed promptly. Most series report a 30-40% mortality, and recommend a craniotomy along with aggressive medical therapy. Between 1978 and 1986, 8 children (2 months to 13 years) with subdural empyemas were diagnosed and treated at our institution, and form the basis for this study. Burr hole and catheter drainage was the treatment of choice in 5 children, while craniotomy was required in 1 case of sinusitis with osteomyelitis. Three infants received multiple subdural taps via the anterior fontanel. All patients responded to surgical intervention and antibiotic therapy. The average follow-up period was 29 months, and 5 children had no developmental delay, decrease in school performance, or impairment of intellectual function. There were no deaths in our series. Although the surgical management of subdural empyemas remains controversial, it appears that burr hole and catheter drainage is sufficient in most cases. With earlier diagnosis, aggressive antibiotic therapy, and timely surgical intervention, the morbidity and mortality of subdural empyemas have significantly diminished in recent years.