[Pathologic findings in auditory brain stem evoked potentials in 10 children with brain stem tumors]. / Patologické nálezy sluchových kmenových evokovaných potenciálu u 10 detí s tumory mozkového kmene.

The authors examined brain stem acoustic evoked potentials (BAEP) in 10 children aged 2-14 years with tumours in the posterior cranial fossa infiltrating the cerebellum and brain stem. The tumours were diagnosed by computed tomography and in eight patients confirmed on operation. For stimulation a monaural click was used. The authors assessed the latency of waves, intervals between and investigated the presence of waves and evaluated their amplitudes. They compared the results with normal values. In abnormal findings the latency of components was delayed, the components were generated in a rostral manner from the site of the lesion in all children. In four patients with severe affections of the brain stem the investigated components were lacking. In nine patients the BAEP evoked by monaural stimulation helped to asses the lateralization of the lesion. In eight patients a bilateral abnormality of the V wave was recorded. The most sensitive indicator for assessment of the site of the lesion was assessment of the interval between two consecutive waves.

[Ambulatory long-term EEG monitors]. / Mobiles Kassetten-Langzeit-EEG.

Ambulatory EEG monitoring is indicated in patients with attacks of uncertain origin. The method is useful to distinguish non-epileptic and epileptic attacks and to differentiate the kind of epileptic seizures which is important for the choice of antiepileptic drugs and for prognosis. It is necessary to describe in detail behaviour and seizures of patient during monitoring. EEG long term monitoring is only useful if attacks were seen frequently, at least once or twice a week.

[Developmental study of somatosensory evoked potentials in the median nerve in children]. / Vývojová studie SEP n. medianus u detí.

By evaluation of the findings in 134 healthy children aged one month to 14 years the authors obtained normal values of SEP of the median nerve and investigated developmental changes which involved among others an increased rate of conduction along the fibres of the peripheral neuron and changes of the distance between electrodes. From the findings ensued that the conduction velocity in mixed fibres of the median nerve in the portion wrist- Erb's point increased most in children aged 2-4 years where it increased to as much as 10 ms-1, while at the age of 1 month to 2 years the increase was 6 ms-1. This difference can be explained by a different maturity of fibres transmitting the impulses. The great scatter in the youngest children confirmed this view. The latency of the cortical response (N 18) in the youngest children was longest and declined gradually. At the age of 2-4 years it was even lower than in older children which may be explained by a more rapid transmission of the impulse in this age group than was the increment of distances between electrodes. Later, on the other hand, the growth of the extremities was more manifested. The above changes were less apparent in latencies of the spinal wave (N 13) and in values of the central conduction time where some part may have been played also by the relative maturity of structures of the brain stem.

[Central infantile hypotonia syndrome]. / Centrální infantilní hypotonický syndrom.

Czechoslovak child neurologists devoted much attention to central infantile hypotonic syndrome (CIHS) in a series of investigations conducted in 1959-1986. They found that it is a developmental syndrome caused by affection of the immature brain, and later, at the age of 3-5 years, it disappears or transforms into other syndromes: most frequently cerebellar syndromes and developmental disintegrations (disintegration of the development of the CNS and medium-grade mental retardation). These groups overlap only little. From the hypotonic syndrome also the spastic syndrome or minor cerebral syndromes may develop. CIHS has, similarly as some other manifestations of CNS affections, multiple causes. One of them is most probably a defect of or lack of development of facilitating pathways of gamma fibres from the cerebellum or possibly from the reticular formation of the brain stem to the spinal cord; another probable cause is longer immaturity of the afferent system (which leads finally to developmental disintegration). It may be assumed that the facilitating systems of pathways develop later and are thus more immature and therefore more vulnerable. According to the latest information it seems that in CIHS also the muscular component participates as prenatal cerebral affections can cause myopathy with hypotonia.

Prenatal diagnosis of GM2 gangliosidosis with high residual hexosaminidase A activity (variant B1; pseudo AB variant).

A case of infantile GM2 gangliosidosis with high residual beta-hexosaminidase A activity toward the synthetic substrate 4-methylumbelliferyl-2-acetamido-2-deoxy-beta-D-glucopyranoside was diagnosed prenatally. Extracts from cultured amniotic fluid cells of the fetus had a hexosaminidase A activity of 27% of total hexosaminidase but were almost completely unable to degrade [3H]ganglioside GM2 (less than 0.5% of control values) when assayed in the presence of the natural activator protein. These results were confirmed by analyses of fetal muscle fibroblasts, liver, and brain. All tissues examined showed a profound deficiency of ganglioside GM2 galactosaminidase despite hexosaminidase A levels in the heterozygote range. In brain tissue, ganglioside GM2 content was elevated more than 4-fold. Hydrolysis of p-nitrophenyl glucosaminide-6-sulfate, a substrate specific for hexosaminidases A and S, by tissue extracts was also markedly reduced but the residual activities found (5% in liver, 12% in fibroblasts, and 16% in brain) were much higher than those with the physiological lipid substrate, ganglioside GM2.