Figure 3.

Overview showing different intracranial drug delivery techniques used to modulate epileptic brain networks. Drugs can be delivered acutely for proof-of-principle or chronically into or close to the target region of the epileptic network by controlled-release polymers (e.g., wafers, microparticles) or by an implanted catheter/cannula combined with a drug reservoir or connected to a (subcutaneously) implanted or external microinfusion pump. Depending on the technique, the spread of the drug into the brain parenchyma occurs by passive diffusion or convection-enhanced distribution. In the case of programmable microinfusion pumps, discontinuous (intermittent) drug release is achievable, thereby reducing the risk of development of pharmacological tolerance. Adding a seizure prediction/detection unit offers the possibility of responsive (closed-loop) drug delivery. For details, refer to the text.