Knut Wester

Peculiarities of intracranial arachnoid cysts: location, sidedness, and sex distribution in 126 consecutive patients.

OBJECTIVE To study the distribution of intracranial arachnoid cysts in a large and nonbiased patient population. METHODS One hundred twenty-six patients with 132 arachnoid cysts were studied. Patients were consecutively referred to our department during a 10-year period from a well-defined geographical area with a stable population. RESULTS The cysts had a strong predilection for the middle cranial fossa; 86 patients (65.2%) had cysts in this location. Of 106 cysts with clearly unilateral distribution, 64 were located on the left side and 42 on the right side. This significant difference resulted solely from the marked preponderance of middle fossa cysts for the left (left-to-right ratio, 2.1:1). There were significantly more males than females (92 males/34 females). This difference was exclusively due to male preponderance of unilateral middle fossa cysts (66 males/14 females; ratio, 4.7:1). For all other cyst locations, there was no difference between the two sexes (26 males/20 females) or the two sides (10 left, 16 right). The marked left-sidedness for middle fossa cysts was found only in males. Females had an even distribution between the two sides. CONCLUSION Arachnoid cysts have a strong predilection for the middle cranial fossa that may be explained by a meningeal maldevelopment theory: the arachnoid coverings of the temporal and frontal lobes fail to merge when the sylvian fissure is formed in early fetal life, thereby creating a noncommunicating fluid compartment entirely surrounded by arachnoid membranes. Why males develop more middle fossa cysts on the left side remains a mystery.

DISTRIBUTION OF TAMOXIFEN AND METABOLITES INTO BRAIN TISSUE AND BRAIN METASTASES IN BREAST CANCER PATIENTS

We determined the amount of tamoxifen, N-desmethyltamoxifen (metabolite X), N-desdimethyltamoxifen (metabolite Z), and hydroxylated metabolites (Y, B, BX) in brain metastases from breast cancer and in the surrounding brain tissues. Specimens were collected from the breast cancer patients who received tamoxifen for 7-180 days and with the last dose taken within 28 h before surgical removal of the tumour. The concentrations of tamoxifen and its metabolites were up to 46-fold higher in the brain metastatic tumour and brain tissue than in serum. Metabolite X was the most abundant species followed by tamoxifen and metabolite Z. Small but significant amounts of the hydroxylated metabolites, trans-1(4-beta-hydroxyethoxyphenyl)-1,2-diphenylbut-1-ene (metabolite Y), 4-hydroxytamoxifen (metabolite B) and 4-hydroxy-N-desmethyltamoxifen (metabolite BX) were detected in most specimens. The ratios between the concentrations of tamoxifen and various metabolites were similar in tumour, brain and serum. This is the first report on the distribution of tamoxifen and metabolites into human brain and brain tumour, and the data form a basis for further investigation into the therapeutic effects of tamoxifen on brain metastases from breast cancer.

A population based study of intracranial arachnoid cysts: clinical and neuroimaging outcomes following surgical cyst decompression in adults

Background: We have gradually adopted a liberal attitude towards surgical decompression of arachnoid cysts. This study describes the results from our institution. Methods: Long term clinical and neuroimaging results of 156 adult patients (aged ⩾16 years) operated on for arachnoid cysts in our department during the period January 1987 to September 2004 were assessed based on their medical and neuroimaging records, and on a questionnaire. Results: The clinical and/or neuroimaging results indicated that the cyst was successfully decompressed in all patients. 82% of patients were asymptomatic or had insignificant complaints at follow-up. 12% reported no symptom relief whereas 6% experienced worsening of symptoms. The cyst disappeared after surgery, or was reduced to <50% of the preoperative volume, in 66% of cases. In another 24%, the postoperative volume was also reduced, but was larger than 50% of the original cyst volume. No reduction in fluid volume was observed in 10% of cases. There was no association between volume reduction and clinical improvement. A complication occurred in 26 patients (17%), all with temporal cysts, leading to reoperation in 11 patients (7.1%). In only two patients did the complication cause a permanent slight disability. Conclusion: Decompression of arachnoid cysts yields a substantial clinical benefit with a low risk of severe complications.

Arachnoid cysts of the left temporal fossa: impaired preoperative cognition and postoperative improvement.

Thirteen adult patients were operated on for symptomatic arachnoid cysts in the left temporal fossa; seven with an internal shunt procedure during local anaesthesia, and five with a craniotomy with fenestration of the cyst to the basal cisterns. In one patient, an initial internal shunt was transformed to a cystoperitoneal shunt. After surgery, all patients experienced relief of symptoms. Reduction of cyst volume occurred in 11 patients. The patients were tested for brain asymmetries related to language and verbal memory before and after operation, with a dichotic listening technique with simultaneous presentation of different auditory stimuli to the two ears. In the preoperative memory test, the patients showed impaired total recall compared with healthy control subjects, and recall from the right ear was significantly impaired. The patients also performed poorly in a forced attention task consisting of dichotic presentations of consonant-vowel syllables. In addition to clinical improvement, the surgical procedures led to improvements in both dichotic perception and memory. Overall memory performance was enhanced, mainly because of improved recall from the right ear. This normalisation of memory function was found as early as four hours after the operation. The results indicate that arachnoid cysts in the left temporal fossa may impair cognitive function, that neuropsychological tests are necessary to disclose these impairments, and that cognitive improvement occurs after surgery.

CSF shunt infections in children: experiences from a population-based study.

Summary. The objective was to identify risk factors for shunt infections, and establish the rate of infection for shunt procedures carried out under standardized conditions in a well-defined population. All (407) paediatric shunt operations (primary and revisions) performed within a total population of 630000 inhabitants between January 1, 1986 and December 31, 1996, were analysed retrospectively. 11 shunt infections were diagnosed in 10 patients, giving an overall infection rate of 2.7% per procedure and 6.2% per patient. Infections were significantly correlated with age, type of operation, and a etiology of hydrocephalus. Thus, infections occurred more frequently during the first 6 months of life, more often following primary shunt insertions compared with revisions, and children with myelomeningocele had a higher infection risk than children with hydrocephalus due to other causes. There was a highly significant male preponderance in the patient material. Conclusion: The overall infection rate was relatively low. The risk factors for shunt infections appear to relate to epidemiological characteristics rather than to surgical factors.

Arachnoid cysts cause cognitive deficits that improve after surgery

The authors investigated cognition in patients with arachnoid cysts by assessing 55 patients and 32 control subjects on four different cognitive tests preoperatively and 3 months postoperatively. The patients improved their performance from preoperative to postoperative testing, whereas the control subjects did not show a similar improvement.

Gender distribution and sidedness of middle fossa arachnoid cysts: a review of cases diagnosed with computed imaging.

According to earlier reports, arachnoid cysts seem to occur more frequently in males, and on the left side. The latter phenomenon could, however, be explained by a greater significance attributed to symptoms from the dominant hemisphere as a justification for invasive procedures in the pre-computed tomography era. The literature from the last third of the era of computed tomography is reviewed with respect to gender distribution and sidedness for middle fossa arachnoid cysts. Also included are a few cases of our own from the same period. It is evident from this survey of the literature, based on computed tomography studies, that there is a significant tendency for these cysts to occur in males, with a male/female ratio of nearly 3:1. This preponderance toward males could not be explained by the somewhat higher frequency of associated subdural hematomas that was found in male patients. The survey also showed that middle fossa arachnoid cysts occur or are detected significantly more frequently on the left side than on the right, with a ratio of 1.8:1.

Cognitive function in patients with Parkinson's disease undergoing stereotaxic thalamotomy.

OBJECTIVE--To determine whether thalamotomy leads to cognitive disturbances in patients with Parkinsons disease. METHODS--A total of 53 patients with Parkinsons disease undergoing stereotaxic ventrolateral thalamotomy for tremor and rigidity were tested for cognitive functions before and after surgery. The cognitive functions investigated involved visuospatial perception and memory. verbal memory, attention shift, and executive functions including set maintenance and shift. A neuropsychological test battery was used that contained the Wisconsin card sorting test, Street completion test, Stroop test, a dichotic memory listening test, and a facial recognition test. RESULTS--Clinically, a good or moderately good effect on parkinsonian symptoms was obtained in 50 patients. The neuropsychological investigations showed that the patients were impaired compared with healthy age matched control subjects on most tests, showing slight improvement postoperatively on verbal memory and visuospatial perception. No major differences were found between tests before and after operation, and there were no significant differences between patients undergoing surgery in the right or in the left thalamus. CONCLUSION--The study indicates that ventrolateral thalamotomy does not reduce the cognitive capacity in this group of patients.

Intracystic pressure in patients with temporal arachnoid cysts: a prospective study of preoperative complaints and postoperative outcome.

Background: Arachnoid cysts (AC) can cause a wide spectrum of clinical symptoms. Only a limited number of studies have investigated intracranial pressure in patients with AC. We wished to investigate the relationship between intracystic pressure, preoperative complaints and postoperative symptom relief in adult patients operated on for a unilateral temporal AC. Material and methods: This was a prospective, population based study involving 38 adult (>18 years) patients (mean age 43 years; range 18–69) with a previously untreated unilateral temporal AC. Results: For all cyst types, mean pressure was 131 mm H2O. The main preoperative complaints were headache and dizziness/nausea. By median split, patients were divided into a low pressure (<130 mm H2O) and a high pressure (>130 mm H2O) group. Patients with high intracystic pressure had a significantly higher preoperative visual analogue scale (VAS) score (54.7) than that found in patients with low intracystic pressure (39.4). Both pressure groups had a significant fall in VAS score after surgical decompression of the cyst. Intracystic pressure correlated significantly with arterial pCO2 and mean arterial pressure. Conclusion: There was a significant correlation between intracystic pressure and the preoperative level of complaints. Mean intracystic pressure in adult patients with unilateral temporal AC seems to lie within the limits of normal intracranial pressure. We therefore hypothesise that factors other than absolute pressure, such as altered compliance and impedance of the brain, may be involved in the pathophysiology of intracranial AC.

Location, sidedness, and sex distribution of intracranial arachnoid cysts in a population-based sample

OBJECT The aim of this study was to examine the distribution of intracranial arachnoid cysts in a large and unselected patient population with special emphasis on sidedness and sex distribution. METHODS In total, 299 patients with 305 arachnoid cysts were studied. These patients were consecutively referred to our department during a 20-year period from a well-defined geographical area with a stable population. RESULTS There was a strong predilection (198 patients [66.2%]) for intracranial arachnoid cysts in the temporal fossa. Forty-two patients had cysts overlying the frontal convexity, 36 had cysts in the posterior fossa, and 23 patients had cysts in other, different locations. Of 269 cysts with clearly unilateral distribution, 163 were located on the left side and 106 on the right side. This difference resulted from the marked preponderance of temporal fossa cysts on the left side (left-to-right ratio 2.5:1; p < 0.0001 [adjusted < 0.0005]). For cysts in the cerebellopontine angle (CPA), there was preponderance on the right side (p = 0.001 [adjusted = 0.005]). Significantly more males than females had cysts in the temporal fossa (p = 0.002 [adjusted = 0.004]), whereas in the CPA a significant female preponderance was found (p = 0.016 [adjusted = 0.032]). For all other cyst locations, there was no difference between the 2 sexes. CONCLUSIONS Arachnoid cysts have a strong predilection for the temporal fossa. There is a sex dependency for some intracranial locations of arachnoid cysts, with temporal cysts occurring more frequently in men, and CPA cysts found more frequently in women. Furthermore, there is a strong location-related sidedness for arachnoid cysts, independent of patient sex. These findings and reports from the literature suggest a possible genetic component in the development of some arachnoid cysts.