In 50 patients with normal pressure hydrocephalus (NPH) the findings on lumbar isotope cisternography (ICG) were compared to the conductance to outflow of CSF (Cout) as measured by lumbo-ventricular perfusion. The purpose was to identify those ICG-characteristics that imply a low Cout and thus may indicate CSF shunting therapy.

OBJECTIVES:To develop a shunt that drains CSF from the ventricles to the sagittal sinus under normal-physiological conditions. This shunting principle will not lead to any over-drainage, and a large proportion of the known shunt-complications will be avoided.METHODS:On the basis of the normal values for ICP, resistance to outflow and the production rate of CSF we have developed a shunt that drains CSF to the sagittal sinus and restores normal condition for the CSF dynamics. The shunt consists of two unidirectional valves, a pre-chamber, a resistance tube made of titanium, and a titanium tube leading CSF into the sagittal sinus. The shunt has been tested in 18 patients. Observation time ranged from 2 to 430 days, mean time 54 days.RESULTS:The first results from the use of the new shunt are very promising. It has an immediate effect on the clinical symptoms, it restores CSF dynamics (investigated with the shunt inserted) and the size of the ventricles is only gradually diminished. Slit ventricles have not yet been observed. In all patients the symptoms of hydrocephalus were relieved. No occlusion or thrombosis of the sagittal sinus have been observed. This is in agreement with the reports in the literature of shunting to the sagittal sinus, where 99 cases have been presented with an observation period of up to 6 years. The shunt has proven easy and safe to implant.CONCLUSIONS:Shunting to the sagittal sinus has proven easy and safe with regard to short term results. By using a dedicated shunt that drains at normal physiological parameters for the CSF dynamics any over-drainage is avoided, and it may be expected that the complication rate will be substantially smaller than with existing shunting systems.

The growth of purely intrameatal vestibular schwannoma (VS) was investigated, in the period 1973-96 in a series of 40 patients with 40 unilateral VS. In the present study, the material was analysed and updated. By the end of the observation period (mean 3.6 years), 27 tumours (67.5%) revealed growth and 13 tumours (32%) had no measurable growth. Four growth patterns were observed: (A) 15 tumours (37.5%) exhibited constant growth; (B) 13 tumours (32.5%) had no measurable growth; (C) 8 tumours (20%) revealed growth subsequent to a no-growth period; and (D) 4 tumours (10%) showed different growth patterns during the observation period. The annual diameter growth rate ranged between 00 mm/year and 6.5 mm/year and the mean diameter growth per year was 3.2 mm. The findings of the present study, especially those for group B (the non-growing tumours) and C (tumour growth subsequent to a silent period) bring into question the reliability of the results achieved by radiosurgery, as without any intervention it may be that no tumour growth occurs.

A total of 911 Danish children under 15 years of age were treated for an intracranial tumour in the 25-five year period 1960–1984. All cases were followed up to the end of 1994 or to emigration or death if one of these came sooner. The mean annual incidence was 32.5 per million children with a slight increase over the 25 years. The male/female ratio was 1.15 and close to the M/F ratio for the entire Danish population of children. Of the tumours, 46% were located in the supratentorial and 54% in the infratentorial compartment, and 94% were verified histologically. In order of frequency the most common types were astrocytomas (all grades, 35%), medulloblastomas (20%), ependymomas (14%), and craniopharyngiomas (5%). Total removal of the tumour was performed in 277 and partial removal, including biopsy, in 490 children. In 57 patients a shunt operation only was performed, and 87 children did not have an operation or died before the correct diagnosis was established. Radiotherapy was administered in 55%. The outcome depended on extent of removal, radiation, location and histology of the tumour. Most (784 or 86%) of the children survived more than 1 month after diagnosis or operation, and 353 children (39% of the whole series, 47% of those alive more than 1 month after diagnosis) were alive at follow-up. Of the survivors 29% had a tumour in the supratentorial midline, 26% one in the lateral part of the supratentorial area, 31% a cerebellar tumour and 13% a IV ventricle tumour. It was possible for 66% of the survivors with supratentorial and 90% of those with infratentorial tumours to lead a normal life. The long-term prognosis was especially good for children with cerebellar and supratentorial astrocytomas and optic chiasma tumours. Children with juvenile cerebellar astrocytoma had the best prognosis: 90% were alive at the end of the follow-up period, as against 20% of those with medulloblastoma and 6% of those with glioblastoma. A comparison of the data from the present series and from a similar Danish series of intracranial tumours in 533 children seen in the years 1935–1959 shows no significant differences in location or histology, a slight increase in annual incidence, and improved survival rates during the 50 years in question.

Postoperative infections are major complications to cerebrospinal fluid (CSF) shunting in the treatment of hydrocephalus and other conditions with impeded CSF transportation. In a retrospective study 884 first-time shunts inserted in the years 1958-1989 are investigated. Infection rate is studied including influence of following variables: time period, age of patient, education of neurosurgeon, length and time of operation and placement of the distal drain. Overall infection rate for all implanted CSF shunts is 7.4% (5.7-9.3%) and acute rate of infection is 6.2% (4.6-7.9%). Rate of infection is virtually constant for all variables except education of the neurosurgeon. Neurosurgical trainees have significantly higher infection rates. Use of prophylactic antibiotics is still controversial No prospective, double blinded studies including sufficient number of patients to evaluate this issue exist today. Meta-analysis studies conclude that use of prophylactic antibiotics is associated with a significant reduction in subsequent CSF shunt infection. We recommend that shunt implantation primarily be performed by highly trained neurosurgeons and that there should be increased supervision during CSF shunt operations performed by neurosurgical trainees.

The results after percutaneous lumbar discectomy were evaluated in 52 patients with low back pain corresponding to the L5 or S1 root. All patients were examined with a median follow-up time of 14 weeks. The patients were divided in two groups. Group 1: patients with an obvious indication for surgery (29 patients) and group 2: patients with a relative indication for surgery (23 patients). The follow-up results for patients in group 1 were comparable with the results after conventional discectomy. The results concerning follow-up low back pain in groups 1 and 2 were good or excellent in 69% and 43% of the patients respectively. The corresponding results for sciatica were 69% and 65% respectively. It is concluded that percutaneous lumbar discectomy is a possible alternative to conventional discectomy in selected patients.

Postoperative infections are major complications of cerebrospinal fluid (CSF) shunting in the treatment of hydrocephalus and other conditions with obstructed CSF circulation. In a retrospective study 884 first-time shunted patients with hydrocephalus operated on in the years 1958-1989 were investigated with special reference to the infection rate and to the influence of the following variables: time period, age of the patient, education of the neurosurgeon, length and time of the operation and the exact placement of the distal drain.The overall infection rate for all implanted CSF shunts was 7.4% (5.7-9.3%) and the acute rate of infection was 6.2% (4.6-7.9%). The rate of infection was virtually constant for all variables with the exception of the education of the neurosurgeon. Neurosurgical trainees particularly had a significantly higher rate of infection.Shunt infection is still a major complication. The infection rate has not declined in recent decades. It is not possible to relate any main cause to the infection rate. The literature recommends removal of the infected shunt combined with antibiotics. The use of prophylactic antibiotics is still controversial. No prospective, double-blind studies, including a sufficiently large number of patients to evaluate this issue, exist today.

+-f having vestibular schwannoma (VS) was conducted in a series of 123 patients (127 tumours), over a 20 year-period from 1973 to 1993. Mean follow up period was 3.4 years, mean annual growth rate was 3.2 mm/year. Tumour growth was observed in 90 patients (94 tumours, 74%), no growth was seen in 23 patients (23 tumours, 18%) and negative tumour growth in 10 patients (10 tumours, 8%). Surgery due to tumour growth was performed in 35 patients (35 tumours, 28%). Seven patients (seven tumours, 6%) were treated with gamma radiation and/or shunt insertion. Seven patients (6%) died of brainstem herniation induced by tumour compression. Nine patients (7%) died of non tumour related causes. Twenty-eight patients were classified as candidates for hearing preservation surgery and 21 patients (75%) lost their candidature during the observation period due to tumour growth and/or deterioration of hearing. The results may limit indications for allocation of patients with VS to the "wait and see" group.

Shunt complications and revisions are common in hydrocephalic patients treated with a ventriculo-atrial or a ventriculo-peritoneal shunt. The reported revision rate differs very much but the rate of revision is close to 50% in many papers. Data from 884 hydrocephalic patients treated with various shunt types in the period 1958-1989 were recorded retrospectively in order to evaluate the frequency of revision for various shunt types and secondly to analyse the specific reasons for the shunt revisions. The rate of shunt revision was 45%. The Pudenz shunt was revised more often (62%) than the remaining shunt types. The Hakim and the Orbis-Sigma shunts had fewer revisions (35% and 27%, respectively) than the other observed shunt types. A defect of or an obstruction in the ventricular catheters was a frequent cause of revision followed by a defect or an obstruction of the distal catheter, a displacement of the distal catheter and an acute infection. Because of the higher rate of revision for the Pudenz shunt the rate of the above mentioned specific complications is also higher in most of the subgroups for that specific shunt type. Driven by these experiences it is reasonable to seek to develop and introduce new shunt types in an attempt to reduce the complication rate.

The purpose of this study is to describe and analyze Apert and Crouzon skulls from three-dimensional (3-D) reconstructions of CT-scans. 12 Apert patients and 19 with Crouzon syndrome were included in the study. The age range was 0 to 23 years. All CT-scannings were carried out according to the same protocol with a slice thickness of 2 or 4 mm and 3-D reconstructions of the craniofacial region included midsagittal and horizontal cuts. A number of qualitative characteristics of the calvaria and cranial base were recorded and the cranial base angle was measured on the 3-D models. Our results showed that Apert and Crouzon syndromes are very different in cranial development and their dysmorphology is highly age dependent. We suggest that cartilage abnormalities, especially in the anterior cranial base, play a primary role in cranial development in the Apert syndrome from very early intrauterine life. Several cranial anomalies observed postnatally, however, are caused by the resultant dysmorphic and compensatory growth and are probably compounded by early cranial deformation. The primary abnormality in Crouzon syndrome appears to be premature fusion of sutures and synchondroses. Based on the findings at birth and early infancy it would seem that such fusions occur relatively late in fetal life. The adult cranial form in Crouzon's patients is explainable by resultant dysmorphic and compensatory growth changes. Very early release of the coronal suture areas with advancement of the frontal bone is advocated in both syndromes but for somewhat different reasons. In Apert syndrome, the primary indication for such treatment is to reduce further dysmorphic growth changes in the calvaria and cranial base, whereas the risk for increased intracranial pressure is low considering the large midline calvarial defect found in early infancy. In contrast, newborns with Crouzon syndrome develop multiple suture synostoses and fused synchondroses, and early surgery is most often indicated to prevent or treat increased intracranial pressure.

While it is generally agreed that measurement of resistance to outflow of CSF (Rout) is valuable in the diagnosis of diseases associated with disturbances in the CSF-dynamics, the invasive character and practical difficulties connected with steady state infusion or perfusion tests have limited their general use. A plain lumbar infusion at constant rate (the so-called Katzman test [7]) is easy to perform, but the interpretation of the results is difficult and the obtained values unreliable. With the introduction of computer analysis of the ICP-signal an exact filtration of artifacts in the pressure measurements is possible. Czosnyka et al. [4] have constructed a software program which makes it possible within a very short time to measure Rout together with other CSF dynamic parameters with an uncomplicated set-up. The purpose of the present study was to compare the values of Rout measured with this programme to a conventionally measured Rout. An acceptable correlation would render a lumbo-ventricular perfusion obsolete.

In the period from 1979 to 1990, a series of 59 patients with 59 acoustic neuromas were operated upon in five departments of neurosurgery by at least five different neurosurgical teams, employing the suboccipital approach. The perioperative mortality rate was 8.5%. Complications including hematoma, ventricular hemorrhage, meningitis, hemiparalysis, abducens nerve paralysis, recurrent nerve paralysis, postoperative wound infection and CSF leak were observed in 21 patients (35.6%). Radical removal of the tumor was not possible in 17 patients (28.8%). Converting the postoperative facial nerve function to the House-Brackmann (HB) classification, 34 patients (57.6%) were regarded as HB VI. Reconstruction of the facial nerve was attempted in 19 patients (32.2%). Attempts at preservation of hearing were unsuccessful in all patients. Failure to attain better results and the importance of the centralized Danish model of acoustic neuroma surgery are emphasized.

Resistance to cerebro-spinal fluid outflow is together with intracranial pressure the most important parameter in the investigation of patients with disturbances of CSF dynamics. The methods for determination of resistance are either unreliable or too time-consuming for routine clinical use, which has limited the popularity of this kind of measurement. In this paper a method for computerized acquisition and processing of an infusion test is described. A good correlation to a standard technique is documented.

From 1979 to 1990, a series of 59 patients with 59 acoustic neuromas were operated on in five departments of neurosurgery by at least five different neurosurgical teams, employing the suboccipital approach. Perioperative mortality rate was 8.5%. Complications including hematoma, ventricular hemorrhage, meningitis, hemiparalysis, abducens nerve paralysis, recurrent nerve paralysis, postoperative wound infection and CSF leak were observed in 21 patients (35.6%). Total tumor removal was not possible in 17 patients (28.8%). Converting the postoperative facial nerve function to House-Brackmann (HB) classification, 34 patients (57.6%) were regarded as HB6. Reconstruction of the facial nerve was attempted in 19 patients (32.2%). Attempts at hearing preservation were unsuccessful in all patients. Failure to attain better results and the importance of centralized treatment of acoustic neuroma are emphasized.

New investigate methods have extended the scientific and clinical knowledge of the circulation of the cerebrospinal fluid (CSF). Methods of measurement of resistance to CSF outflow have improved during the last 15 years (Børgesen et al. 1978; Ekstedt 1978; Shapiro et al. 1984; Kosteljanetz 1987; Gjerris et al. 1989 a). A thorough knowledge of the dynamic equilibrium between CSF production and absorption is essential for the understanding of the changes in the intracranial space during pathological conditions. CSF dynamics comprehend all factors concerning formation, flow rate, direction, and absorption of CSF.

Receiver operating characteristic (ROC)-curves are a statistical method which may be employed inter alii for assessing a diagnostic test. These have been employed particularly in radiology but have also been employed for assessing laboratory tests and obstetric estiamation scales. The method is based on an analysis of nosological probabilities for varying limits of decision thresholds. ROC-curves may be employed for data on ratio/interval scales and data on rank scales. Parametric and non-parametric methods are available for obtaining a single quantitative measurement for the entire ROC-curve and to carry out significance tests between several ROC-curves.

We reviewed all medical records concerning patients suffering from spinal cord or cauda equina compression (SCC) secondary to cancer, in the eastern part of Denmark, from 1979 through 1985.

A retrospective study of 398 patients suffering from metastatic compression of the spinal cord or cauda equina is presented. The study comprised almost all relevant medical records of patients admitted to hospital in the eastern part of Denmark in the period 1979 through 1985. Carcinoma of the lung, prostate, breast and kidney were the most frequent primary malignancies causing spinal compression. Most patients were treated with laminectomy, or radiotherapy or with laminectomy and radiotherapy combined. The effect of the treatment was estimated by evaluation of motor function and sphincter control. Treatment with laminectomy followed by radiotherapy was significantly superior to treatment with laminectomy or radiotherapy alone. But if the patients' motor function and primary tumour were taken into account, no significant difference between the treatments was observed. The efficacy of treatment depended upon the symptoms when the diagnosis was established, and accordingly early diagnosis is of the utmost importance. The incidence of metastatic compression increased during the period covered by the study, and since this condition must not go untreated, awareness of the symptoms, primarily pain, is essential.

It is generally agreed that the main site of CSF absorption is the arachnoid villi. The CSF resorptive capacity can be evaluated by several methods which, during the last decade, have been evaluated especially in patients with hydrocephalus (for review: see Børgesen 1984, Kosteljanetz 1987). Measurement of conductance to CSF outflow, or the reciprocal value resistance to CSF outflow (Rout), is a parameter which especially has shown its use as a predictive value of clinical results after shunting in patients suffering from normal pressure hydrocephalus (Børgesen and Gjerris 1982), and also in the treatment of patients with pseudotumor cerebri (Sørensen et al. 1989). However, as stressed by Børgeson (1984) the measurements must be reliable and reproducible. In a previous study we found an acceptable concordance of repeated investigations of Rout in 28 patients (Gjerris et al. 1986).