gms | German Medical Science

Objective: Systemic cooling to reduce ICP has been abandoned, due to systemic undesirable side effects being more important than the beneficial cerebral effects. To overcome the dilemma we studied whether local cooling might be a reasonable alternative.

Methods: We implemented ventricular infusion studies on 25 patients suffering from the suspected NPH or BIH to assess CSF hydrodynamics. For infusion we used 24°C warm physiological sodium chloride solution with infusion rates of 3 ml/min. ICP, parenchymal P(O₂) and cerebral parenchymal temperature (CPT) were monitored.

Results: Directly after infusion start CPT dropped steadily up to 1–3°C during time periods of 17–57 min. With some time shift in all but one patients, significant P(O₂) increase occurred exceeding resting values by up to 100% (p=0.042). A correlation between the CPT-decrease of temperature and ventricular size was found: the smaller the ventricles the more pronounced was the CPT-decrease.

We hypothesize that moderate cooling decreases cerebral metabolism and by this O₂ consumption without affecting CBF. Pronounced cooling in contrast leads to vasoconstriction and reduced CBF worsening O₂ supply in critical areas. The extent of cooling depends on the ratio of intraventricular volume and infusion rate and whether free communication of all CSF space is given. In non-communicating hydrocephalus only periventricular cooling is possible. With free communication general brain cooling mediated by the large basal arteries can be gained.

Conclusions: These findings could be pioneering a new therapeutic strategy concerning cerebral protection in case of elevated ICP: using double lumen (influx and drain) catheters with tip ICP-sensors and rigorous ICP-monitoring local brain cooling might provide a new therapeutic option to treat critically increased ICP avoiding side-effects known from systemic cooling.