Neuroendoscopic surgery in empty ventricular system under continuous gas infusion experimental study of pressure...

The most important limitations to endoscopic procedures in the ventricular system of the brain are due to the constraint of working inside a fluid. The evacuation of cerebrospinal fluid (CSF) from the ventricles is performed often in microsurgical interventions using a surgical microscope. This study aimed at studying the evacuation of CSF during neuroendoscopic surgery in animals while infusing gas to avoid ventricular collapse.

Hydrocephalus was provoked in five adult New Zealand rabbits by intracisternal injection of kaolin. Endoscopic intervention was performed later; fluid was given as a continuous infusion at constant speed into the CSF for 3 min. In the next stage, CSF was evacuated from the ventricles, which were infused with gas at a stable rate for the same amount of time. The intracranial pressure (ICP) of the rabbits was recorded during both operations. The animals were sacrificed and the brain subjected to pathology examination at the end of the experiment.

Mean ICP value in the rabbit ventricle was 19.1 while working in CSF and 17.6 when working in air. The difference by a paired test was statistically significant for each individual rabbit except one. The ICP measurement, however, was never lower than the ambient pressure, even while working in continuous gas infusion. No epidural or subdural hematomas were found at autopsy.

Endoscopic surgery is feasible in a ventricular system that has been insufflated with gas after CSF has been evacuated. During the experiment, however, steadily diminishing ICP values were measured. As a result, new devices, such as small-flow insufflators able to perform sensitive pressure adjustments are needed.