Potential Difference Records from Human Cerebrospinal Fluid

Summary

The electrical potential difference (PD) between ventricular cerebrospinal fluid (CSF) and blood was recorded simultaneously with intraventricular pressure in children with shunted hydrocephalus. The mean basal value was +4.1 mV. The ECG and small amplitude PD changes which matched the respiratory trace were seen in all patients. More prolonged wave-like PD changes, lasting about ten minutes, preceded A, or plateau, wave changes on the pressure trace, and were followed by a small positive change which lasted throughout the plateau wave. Similar briefer PD waves preceded individual B waves in the pressure trace. During episodes of recurrent B wave activity the overall PD showed more prolonged wave-like changes lasting up to an hour. In one patient a negative PD change was also associated with an episode of increased pulse pressure without an overall rise in pressure. The PD changes suggest that A and B pressure waves in the ventricular CSF are triggered by active secretion.