[Biosynthesis and absorption of the cerebrospinal fluid]

[Gentamicin concentrations in cerebrospinal fluid of patients with inflamed and uninflamed meninges (author's transl)]

Determinations of gentamicin levels in serum and cerebrospinal fluid were performed in 11 tests of eight patients suffering from memingitis and in 18 tests of eight patients after neurosurgical operations. Neurosurgical operations had been performed in this group at least four days prior to testing. Only in four tests in neurosurgical patients were the gentamicin levels in CSF higher than the lowest measurable concentration of 0.4 mcg/ml, serum levels in this group ranged from below 0.4 mcg/ml up to 5.0 mcg/ml. No gentamicin level in CSF exceeded 1.5 mcg/ml. Gentamicin levels in CSF of patients with meningitis ranged from below 0.4 mcg/ml to 5.66 mcg/ml. This equals a CSF/serum ratio of 7.4-57.6%, mean 25.8%.

[Long-term follow-up study of the absorption of gas after encephalography in dilated intracranial cerebrospinal fluid spaces (author's transl)]

The absorption of gas after encephalography in different groups of patients was investigated in a long-term follow-up study. Group I (11 patients) showed no pathological findings in the encephalogram. Group II (8 patients) had encephalographic signs of diffuse cerebral atrophy. Group III (7 patients) demonstrated in the encephalogram characteristics of normal pressure hydrocephalus with variously located blocks of air in the subarachnoid space. In group I the gas located in the subarachnoid space had usually disappeared after 24 h, in some cases after 72 h. In group II the pattern of resorption was basically similar, although in one case cortical air could be seen at 96 h. In group III the absorption of air from the subarachnoid space began after 72 h in radiological relevant amounts. In none of the cases of group III could similar short times of resorption be seen in comparison to group I. It is considered that these two groups can be clearly distinguished from each other in the duration of resorption of air from the subarachnoid space. The importance of encephalography as a pathophysiological tool for investigation of both the disturbed resorption and circulation of the cerebrospinal fluid in normal pressure hydrocephalus is stressed.

Febrile convulsions and blood-cerebrospinal fluid barrier

Three single CSF proteins with different molecular size (albumin, immunoglobulin G, and alpha2-macroglobulin) were determined by the method of electroimmunoassay in 61 children with febrile convulsions (FC) in order to evaluate the permeability of the blood-CSF barrier (B-CSF-B). Forty-two children with acute extracerebral infection served as controls. In contrast to a group of 22 children who suffered from acute meningoencephalitis or encephalitis, the CSF values of 48 children with FC were within normal limits. Thus even a very mild form of inflammatory encephalopathy-undetectable with conventional CSF investigation-was excluded in the majority of the children with FC. In 11 patients, however, CSF concentrations of albumin and alpha2-macroglobulin were abnormally raised, indicating a B-CSF-B distrubance. Elevated albumin values were found most frequently. In several children with FC lasting more than 20-30 min, B-CSF-B damage was probably caused by prolonged seizure activity since there is a linear correlation between albumin concentration and duration of convulsions. Several other factors known to raise the children's risk of developing epilepsy in later life were associated with the protein pattern of B-CSF-B disturbance in some of the children. In these cases, the cause of abnormal permeability of B-CSF-B is unknown and the condition might have existed prior to the occurrence of seizures.