Influence of acute cerebellar lesions on somatosensory evoked potentials (SEPs) in cats.

We studied the effect of acute unilateral cerebellar lesions on the cerebello-thalamo-cortical projection in cats. The lesions were classified into two groups according to their extent. In group I the lesion only covered the cerebellar cortex, while in group II both the cerebellar cortex and deep cerebellar nuclei were removed. Early (short-latency) and late (long-latency) waves, evoked by an electrical stimulation of a forelimb, were collected contralateral to the stimulated leg hemisphere. Pre- and postsurgery recordings from primary and non-primary (motor and parietal) cortices were compared. Cerebellar impairment had a strong influence on discharges of all the considered cortical areas. Early non-primary and primary responses increased in group I and remained unchanged in group II. Late somatosensory evoked potentials components were suppressed in both groups. An inhibitory influence of the cerebellar cortex on the thalamo-cortical projection was confirmed. Changes within the primary sensory cortex may suggest an engagement of that area in the compensation process of cerebellar dysfunction shortly after cerebellar lesion. An alteration in the unaffected hemisphere activation indicate that the spino-cerebellar and cerebello-cortical inputs, responsible for somatosensory evoked potentials generation, are regulated through contralateral and ipsilateral pathways. These pathways are unmasked by cerebellar lesion.

[Prognostic value of evoked potentials of the spinal cord in surgical treatment of lumbar intervertebral disk prolapse]. / Prognostyczne znaczenie wywolanych potencjalów rdzeniowych w chirurgicznym leczeniu ledzwiowych przepuklin krazkowych.

Spinal potentials were evoked stimulating the peripheral nerves of lower extremities in healthy people and in patients with manifestations of lumbar disc prolapse. The patients were studied before and early after the operation. In healthy subjects the velocity of impulse conduction was nearly identical when both extremities were compared. In the patients the test before the operation revealed a significant prolongation of the latency of the potentials on the side of the damaged nerve root. After the operation a significant difference between the healthy and the affected side was still present early after the operation but it was significantly smaller than before the operation since the conduction velocity was improved on the side of the operation. The study of spinal evoked potentials makes possible recognition of disturbed function of nerve roots, and after the operation the rate of changes of potential latency is an important prognostic sign.

[Computerized infusion test. II. Clinical use]. / Skomputeryzowany test infuzyjny. II. Zastosowanie kliniczne.

In 39 patients with intracranial lesions the resorption resistance was measured using an own computerized infusion test. A high usefulness of this test was demonstrated in the diagnosis of hydrocephalus and for establishing indications to ventriculocardiac valve implantation. In patients after craniocerebral injuries a rise was observed of the resorption resistance immediately after trauma in cases with subarachnoid haemorrhage. Later on, this resistance decreased gradually reaching a stable value after 1-2 years. Data obtained in the infusion test make possible establishing of optimal intracranial pressure and choice of an appropriate valve. The determination can be performed intraoperatively.

CSF absorptive capacity in patients without intracranial pathology.

The role of changes in CSF inflow in patients without intracranial pathology has been studied. The CSF outflow resistance has been calculated, by dividing the CSF pressure rise by the speed of intrathecal saline infusion. The average CSF pressure rise produced during infusion test (infusion 2 ml/min) amounted to 11.15 mmHg. The calculated CSF outflow resistance equaled to 5.58 +/- 1.1 mm Hg/ml/min. On-line computer assisted analysis during infusion test helps to shorten the procedure and makes it more precise.

A method of estimating intracranial decompensation in man.

A new method of estimating intracranial decompensation in man is described. An on-line computer system is connected to an intracranial pressure (ICP) monitoring system to compute regression plots of mean ICP vs standard deviation; standard deviation is used as a measure of ICP instability. Two zones with distinctly different slopes are a characteristic feature of these plots. It is thought that the changes of slope signify intracranial decompensation.

[System of rapid automatic digital recording of cerebrospinal fluid pressure]. / System szybkiej, automatycznej, cyfrowej rejestracji cisnienia plynu mózgowo-rdzeniowego

The authors describe a system for rapid digital automatic recording of cerebrospinal fluid pressure. The results are recorded in numerical form by a recorder. Owing to this quantitative expression of results the subjective evaluation of analog curves is avoided. The system may be used also to measure other slowly changing physiological processes.

Computer-assisted analysis of intraventricular pressure after mannitol administration.

The effect of prolonged mannitol infusion upon intraventricular pressure was investigated with the aid of a specially-designed automatic digital recording system; the data recorded were processed off-line by a minicomputer. The character of the pressure curves is thought to result from interaction between the mannitol effect and the observed system's shifting equilibrium position, which is caused by other factors. The character of the pressure curves prior to mannitol infusion must be taken into consideration in estimating the actual effect of the drug; the authors suggest that in certain cases it might be possible to decrease further the rate of mannitol administration. The advantages of statistical approach to the evaluation of intracranial pressure variations are discussed.