High-pressure Hydrocephalus Research Articles

Severe hydrocephalus in L1-deficient mice

The neural adhesion molecule L1, a member of the immunoglobulin superfamily of cell recognition molecules, performs important functions in the developing and adult nervous system. This view is confirmed by the fact that mutations in the human L1 gene cause a severe neurological disease, termed CRASH (acronym for: c orpus callosum hypoplasia, r etardation, a dducted thumbs, s pastic paraplegia, and h ydrocephalus). X-linked hydrocephalus is certainly the most prominent symptom of CRASH syndrome. Mouse mutants deficient in L1 also develop enlarged ventricles. Here, we report that ventricular dilation in L1-deficient mice is not correlated with stenosis of the aqueduct of Sylvius nor with ultrastructural abnormalities of ependymal cells lining the lateral ventricles or the aqueduct. However, a few L1 mutant mice displayed severe hydrocephalus, characterized by a significant enlargement of the skull and an almost complete atrophy of the cerebral cortex. The aqueduct of these severely affected animals was completely closed. Since mutant animals from two independently generated L1-deficient mouse lines displayed a similar phenotype, we consider severe hydrocephalus as a specific consequence of L1-deficiency. However, results of the present study also indicate that severe hydrocephalus represents a secondary rather than a primary defect of the L1 mutation; our combined data suggest that deformations of the brain as a result of massively enlarged ventricles secondarily cause stenosis of the aqueduct and subsequently high pressure hydrocephalus.

Posttraumatic ventriculomegaly: hydrocephalus or atrophy? A new approach for diagnosis using CSF dynamics.

Cerebrospinal fluid (CSF) dynamics were correlated to the changes in ventricular size during the first 3 months posttrauma in patients with severe head injury (Glasgow Coma Scale score < or = 8, 75 patients) to distinguish between atrophy and hydrocephalus as the two possible causes of posttraumatic ventriculomegaly. Using the bolus injection technique, the baseline intracranial pressure (ICP), pressure volume index, and resistance for CSF absorption (R0) provided a three-dimensional profile of CSF dynamics that was correlated with ventricular size and Glasgow Outcome Scale (GOS) score at 3, 6, and 12 months posttrauma. Patients were separated into five different groups based on changes in ventricular size, presence of atrophy, and CSF dynamics. Group 1 (normal group, 41.3%) demonstrated normal ventricular size and normal ICP. Group 2 (benign intracranial hypertension group, 14.7%) showed normal ventricular size and elevated ICP. Group 3 (atrophy group, 24%) displayed ventriculomegaly, normal ICP, and normal R0. Group 4 (normal-pressure hydrocephalus group, 9.3%) had ventriculomegaly, normal ICP, and high R0. Group 5 (high-pressure hydrocephalus group, 10.7%) showed ventriculomegaly and elevated ICP with or without high R0. The GOS score in the nonhydrocephalic groups (Groups 1, 2, and 3) was better than in the hydrocephalic groups (Groups 4 and 5). It is concluded from these results that 44% of head injury survivors may develop posttraumatic ventriculomegaly. Posttraumatic hydrocephalus, as identified by abnormal CSF dynamics, was diagnosed in 20% of survivors and their outcome was significantly worse. This study demonstrates the importance of using CSF dynamics as an aid in diagnosis of posttraumatic hydrocephalus and identifying those patients who may benefit from shunt placement.

Testing of cerebrospinal compensatory reserve in shunted and non-shunted patients: a guide to interpretation based on an observational study.

To design a computerised infusion test to compensate for the disadvantages of Katzman's lumbar infusion method: inadequate accuracy of estimation of the resistance to cerebrospinal fluid outflow and poor predictive value in normal pressure hydrocephalus. Accuracy was improved by intracranial pressure signal processing and model analysis for measurement of cerebrospinal compensatory variable. These include the CSF outflow resistance, brain compliance, pressure-volume index, estimated sagittal sinus pressure, CSF formation rate, and other variables. Infusion may be made into the lumbar space, ventricles, or, when assessing shunt function in vivo, the shunt chamber. The computerised test has been used for five years in a multicentre study in 350 hydrocephalic patients of various ages, aetiologies, and states of cerebrospinal compensation. The principles of using the test to characterise different types of CSF circulatory disorders in patients presenting with ventricular dilatation, including brain atrophy and normal and high pressure hydrocephalus, are presented and illustrated. Previous studies showed a positive correlation between cerebrospinal compensatory variables and the results of shunting, but such a prediction remains difficult in idiopathic normal pressure hydrocephalus, particularly in elderly patients. The technique is helpful in the assessment of shunt malfunction, including posture-related overdrainage, over-drainage related to the nocturnal B wave activity, and proximal or distal shunt obstruction. The appendix presents an introduction of the mathematical modelling of CSF pressure volume-compensation included in computerised infusion test software.

Measurement of blood flow in the superior sagittal sinus in healthy volunteers, and in patients with normal pressure hydrocephalus and idiopathic intracranial hypertension with phase-contrast cine MR imaging.

To measure blood flow and velocity in the superior sagittal ++sinus. MR velocity mapping was used to examine 14 healthy volunteers, 15 patients with normal pressure hydrocephalus (NPH), 3 patients with high pressure hydrocephalus (HPH), and 11 patients with idiopathic intracranial hypertension (IIH). Mean blood flow was 443 ml/min in healthy volunteers with a tendency towards reduced blood flow with increasing age. In NPH patients significantly lower superior sagittal sinus blood flow values were found, but this difference was no longer significant when patients and controls were matched for age. In HPH and IIH patients blood flow and velocity were within the normal range. In one patient with thrombosis of the superior sagittal sinus the blood flow was reduced to 40 ml/min. MR velocity mapping methods may be of value in the assessment of blood flow in the dural sinuses in various pathologies resulting in dural sinus occlusion, such as dural sinus thrombosis, and for following the progress of these patients while undergoing treatment.

Increased Self-Diffusion of Brain Water in Hydrocephalus Measured MR Imaging

We used MR imaging to measure the apparent brain water self-diffusion in 5 patients with normal pressure hydrocephalus (NPH), in 2 patients with high pressure hydrocephalus (HPH), and in 8 age-matched controls. In all patients with NPH significant elevations of the apparent diffusion coefficients (ADC) of brain water were found within periventricular white matter, in the corpus callosum, in the internal capsule, within cortical gray matter, and in cerebrospinal fluid, whereas normal ADCs were found within the basal ganglia. In 2 patients with HPH elevated ADCs were found most prominently within white matter, and in one patient reexamined one year after surgery, ADCs were unchanged in nearly all brain regions. The increased ADC values in hydrocephalus patients may be caused by factors such as changes in myelin-associated bound water, increased Virchow-Robin spaces, and increased extracellular brain water fraction. For further studies of brain water diffusion in hydrocephalus patients, echo-planar imaging techniques with imaging times of a few seconds may be valuable.

Increased Self-Diffusion of Brain Water in Hydrocephalus Measured by MR Imaging

We used MR imaging to measure the apparent brain water self-diffusion in 5 patients with normal pressure hydrocephalus (NPH), in 2 patients with high pressure hydrocephalus (HPH), and in 8 age-matched controls. In all patients with NPH significant elevations of the apparent diffusion coefficients (ADC) of brain water were found within periventricular white matter, in the corpus callosum, in the internal capsule, within cortical gray matter, and in cerebrospinal fluid, whereas normal ADCs were found within the basal ganglia. In 2 patients with HPH elevated ADCs were found most prominently within white matter, and in one patient reexamined one year after surgery, ADCs were unchanged in nearly all brain regions. The increased ADC values in hydrocephalus patients may be caused by factors such as changes in myelin-associated bound water, increased Virchow-Robin spaces, and increased extracellular brain water fraction. For further studies of brain water diffusion in hydrocephalus patients, echo-planar imaging techniques with imaging times of a few seconds may be valuable.

Severe acute encephalopathy following inadvertent intrathecal doxorubicin administration

In a female with acute lymphoblastic leukemia, inadvertent doxorubicin administration intrathecally caused severe, life-threatening, acute encephalopathy with high-pressure hydrocephalus. Ventriculo-peritoneal shunting led to complete reversal of hydrocephalus with progressive disappearance of the acute encephalopathy.

Hydromechanical testing in non-communicating hydrocephalus to select patients for microsurgical third ventriculostomy.

To select adult patients with benign non-communicating hydrocephalus for microsurgical third ventriculostomy, cerebrospinal fluid (CSF) pressure, intercompartmental flow of CSF, and CSF draining capacity were measured in 14 patients with clinical high pressure hydrocephalus and 5 patients with clinical normal pressure hydrocephalus. The testing was of value in selecting patients with high pressure hydrocephalus for third ventriculostomy. Based on the clinical picture and the hydromechanical balance between the two separate CSF compartments one could distinguish two different patterns: (1) unbalanced high pressure hydrocephalus which improved after third ventriculostomy, and (2) balanced high pressure hydrocephalus which had to have a ventriculo-atrial shunt. All patients with normal pressure hydrocephalus had an almost balanced hydrocephalus, and the testing was shown to be of no value in this small group.

Relationships between intracranial pressure, ventricular size, and resistance to CSF outflow.

In 230 patients with normal-pressure hydrocephalus, high-pressure hydrocephalus, or benign intracranial hypertension, measurements of the intracranial pressure (ICP), ventricular size, and cerebrospinal fluid (CSF) outflow resistance (Ro) have revealed a linear relationship between ICP and Ro. It is shown that on average the CSF formation rate tends to decrease with increasing ICP. It is also shown that the size of the ventricles increases as the ICP levels off toward normal values. The clinical implication of this is that a small or normal ventricular size in acute or subacute phases does not preclude defective CSF resorption.

Resistance to cerebrospinal fluid outflow and intracranial pressure in patients with hydrocephalus after subarachnoid haemorrhage.

Resistance to CSF-outflow (Rout) and intracranial pressure (ICP) were measured in 33 patients with hydrocephalus after subarachnoid haemorrhage (SAH). Eleven patients examined between 10 to 30 days after SAH had high pressure hydrocephalus (HPH). Twenty-two patients had normal pressure hydrocephalus (NPH). All HPH-patients had ICP above 15 mmHg, plateau waves and B-waves, a median Rout of 59 mmHg x ml-1 x min-1 (range 29-100). All NPH-patients had a normal ICP level, no plateau waves, but long periods of B-waves and a median Rout of 22 mmHg x ml-1 x min-1 (range 6-47). Of the 11 patients with HPH six were shunted and five had temporary ventricular drainage. Five patients improved and six died. Of the five survivors only one went back to work. Of the 22 NPH-patients 18 were treated with a shunt, one refused shunt operation and three had normal Rout. Seventeen improved after shunting. At follow-up 12 had a normal social life, 5 lived in a nursing home and 1 was dead. Thus, early development of hydrocephalus after subarachnoid haemorrhage is associated with a high Rout and a high ICP, whereas late (more than one month) hydrocephalus may be associated with normal ICP and high Rout. Patients with NPH and a high Rout have frequent B-waves and should be shunted. Patients with a long interval from subarachnoid haemorrhage to the diagnosis of hydrocephalus often have a normal ICP, low frequency of B-waves, normal CSF-dynamics and need no shunting.

Cerebrospinal fluid vasopressin in neurological and psychiatric disorders.

Vasopressin was determined in CSF and plasma of 243 patients with different neurological and psychiatric disorders, including control patients. CSF vasopressin was significantly higher in patients with high pressure hydrocephalus, intracranial tumour, benign intracranial hypertension, intracranial haemorrhage, ischaemic stroke, and craniocerebral trauma. In patients with primary degenerative dementia, CSF vasopressin was lower than in control patients. Among patients with psychiatric disorders, CSF vasopressin was increased in manic patients, while in patients with depression CSF concentration of this hormone did not differ from that found in controls. However, an increase in CSF vasopressin level was found in patients recovering from a depression. The clinical significance of changes in CSF vasopressin concentrations in groups of patients with neurological and psychiatric disorders is still unknown.

Sympathetic nervous control of cerebrospinal fluid production in experimental obstructive hydrocephalus

Hydrocephalus was induced in rabbits by cisternal injection of kaolin (0.5 ml of a 30 g 100 ml solution of hydrated aluminium silicate). The rate of bulk production of cerebrospinal fluid (CSF) was measured with a modified Pappenheimer [ 14C]inulin dilution technique in a ventriculoventricular perfusion system 3 days and 3 weeks after treatment. In the acute state of high-pressure hydrocephalus, CSF formation was reduced to almost one-half normal. Bilateral electrical stimulation of the cervical sympathetic nerves lowered the production rate by another 18%, with only an insignificant tendency to normalization after cessation of stimulation. In the chronic state of low-pressure hydrocephalus at 3 weeks after the kaolin injection, the rate of CSF formation was of the same magnitude as in animals studied after 3 days. However, sympathetic nerve stimulation now reduced the production rate by a further 39%, and prestimulation values were almost restored within 1 h after termination of stimulation. Thus, cranial sympathetic stimulation was very effective in reducing CSF formation in the chronic stage of low-pressure hydrocephalus. During acute high-pressure hydrocephalus, the sympathetic defence mechanisms were probably already recruited to such an extent that electrical activation of the sympathetic nerves was not able to further affect significantly the rate of CSF formation.

Value of continuous spinal drainage in normal pressure hydrocephalus and secondary communicating hydrocephalus

Out of 30 cases of suspected normal pressure hydrocephalus (NPH) and/or secondary communicating hydrocephalus which showed mental disturbance and ventricular dilatation on CT scan and/or by pneumoencephalography, 18 showed a lumbar CSF pressure within normal limits, seven over 200 mmH2O, and five under 100 mm H2O. On 16 cases, continuous spinal drainage (CSD) was performed. The CSD procedure consisted of placing an epidural anesthesia catheter into the lumbar subarachnoid space for about 7 days. The amount of drained CSF was limited to 150-200 ml/day and was adjusted according to the clinical symptoms. If a certain improvement in the clinical symptoms was noted, the patient was diagnosed as a treatable communicating hydrocephalus and was then submitted to a shunting operation. The authors achieved 100% success in the shunting operations of the 13 cases, which fulfilled the above diagnostic criteria. The other three cases, without the effective CSD, did not show any satisfactory results from the shunting operation. CSF drainage test has reportedly been performed to diagnose the reversible brain changes and indications for the shunting operation. This test appears to have the same meaning as the CSD in the early stage of NPH or in the high pressure hydrocephalus, and is also less cumbersome to patients than the CSD. But, in the late stage of NPH and in the low pressure hydrocephalus, this test is apparently unable to predict the effectiveness. The CSD should be performed in cases with an ineffective CSF drainage test. In secondary hydrocephalus, especially in NPH, the most important factor in the success of the shunting operation, should be that there are still reversible changes in the brain tissue on the circumference of the ventricles. Therefore, NPH should mean the condition of the brain and not the name of a disease. The authors would like to name the treatable secondary hydrocephalus as the “Adams-Hakim's syndrome”, and to classify it into the low pressure type, normal pressure type, and high pressure type.

Ventricle to sagittal sinus shunt for hydrocephalus.

A technique of shunting the lateral ventricle to the superior sagittal sinus is described. It has been used in 36 adult patients; infection occured in 2 patients (5.6%), and 2 patients required shunt revision (5.6%). The outcome of 18 patients with high pressure hydrocephalus could be validly evaluated, and successful control was achieved in 15 (83%). One of the 3 failures could have been avoided because shunting was undertaken before the ventricular fluid had cleared of blood. Four patients with normal or low pressure hydrocephalus were treated; only 1 had a successful result. This technique is suitable for patients with high pressure hydrocephalus and is of particular value in very ill or debilitated patients because of the rapidity with which it can be performed under local analgesia. Its use in normal or low pressure hydrocephalus must still be evaluated. In any event, the sagittal sinus is certainly a feasible alternate receptor site for ventricular shunting.

Subdural hematoma as a complication of shunting procedures for normal pressure hydrocephalus.

✓ The authors report five patients with normal-pressure hydrocephalus (NPH) who developed subdural hematomas following shunt procedures. None of the hematomas was directly related to surgery, and all appeared after the patients had shown initial clinical improvement; one was conceivably related to trauma. These patients appear to be especially susceptible to this complication, as the high incidence of 5 of 24 cases is not seen in the treatment of high-pressure hydrocephalus. The symptoms and signs of this complication, diagnosis, and treatment are described and emphasized. It is concluded that shunting procedures for NPH should not be undertaken lightly, and rigid criteria should be applied in the selection of patients to exclude other causes of dementia.

X-ray manifestations of the Holter valve in hydrocephalus.

The exact mechanism of production and absorption of cerebrospinal fluid remains in question. Also lacking is a clear understanding of the alternate pathways that can develop when the normal flow of cerebrospinal fluid is obstructed. When there is obstruction to the ventricles, overproduction or poor absorption of cerebrospinal fluid, the resulting high-pressure hydrocephalus destroys brain tissue. A number of operative shunting procedures have been developed to allow egress of the fluid from the ventricular system and thus limit the extent of brain damage. Radiologic control during the procedure and postoperative follow-up studies are important in the proper management of the patient. It is the radiologist's responsibility to detect malplace-ment, mechanical breakdown, and other causes of shunt failures. Davidoff in 1929 (3) reviewed the approaches to the therapy of hydrocephalus. He traced the treatment back to Hippocrates who is given credit for forming trephine holes in the skull and then puncturing the ventricles. Payr in 1908 used a vascular graft, connecting the longitudinal sinus to the lateral ventricles by an autogenous or homologous vein. Postoperative follow-up is not well documented. Melnic in 1909 used a F-shape vessel and transplanted it to the jugular vein in the neck. His single patient died after the operation (8). Since these early attempts, numerous shunting procedures have been tried. The present-day method for treatment had its origin with Ingraham and his associates in 1948 (5). They studied dogs having obstructed hydrocephalus with shunts to the venous system both in the anesthetized state and while awake. The cerebrospinal fluid flow was away from the ventricles when the animals were anesthetized. Upon awakening, however, the dogs became active and the reversal of flow from increased venous pressure caused the shunts to clot. It was concluded that a unidirection valve system was needed to prevent clotting in the tubing. The three basic shunting systems utilized today are the ventricular-atrial shunts, ventricular-pleural shunts, and ventricular-peritoneal shunts. The peritoneal and pleural shunts are used as temporary measures when intracranial hemorrhage or infection is present. They are later replaced by the more efficient ventricular-atrial shunt (9). The shunting device has a valve that opens at a determined pressure and thus permits drainage of cerebrospinal fluid from the ventricles of the brain to another body compartment. The two popular valve mechanisms used are the Holter valve and the Hakim valve (4). Although they are basically similar in construction, our experience has been chiefly with the Holter valve and its use in ventricular auriculostomies. The Holter valve is composed of a double fish-mouth valve that opens at variable intracranial pressures. At one end of the valve is a catheter that extends into the ventricular system.