Introduction: Focal cortical cooling stops seizures and inhibits epileptogenesis in rodents. To investigate its potential clinical utility, we examined the thermal characteristics of canine and human brain undergoing active and passive surface cooling.
Methods: Four patients with intractable epilepsy were treated in standard fashion. Before the resection of a neocortical epileptogenic focus, multiple intraoperative studies of active (perfused grid) and passive (stainless steel probe) cooling were performed. We also actively cooled the neocortices of two dogs with temporarily implanted perfused grids.
Results: Focal surface cooling of human brain causes predictable, depth-dependent cooling of the underlying brain tissue. Cooling of 0.6 to 2°C was achieved both actively and passively to a depth of 10 to 15 mm from the cortical surface. The perfused grid produced comparable cooling of dog neocortex when the craniotomy was closed.
Conclusions: The human cortex can easily be cooled during invasive monitoring with the use of simple devices such as a cooling grid or a small passive probe. These techniques provide pilot data for the design of a permanently implantable device to control intractable epilepsy.
Patient Care: Our group has been evaluating focal brain cooling for the prevention and treatment of epilepsy (D'Ambrosio et al., 2013) and are designing implantable devices that use active or passive cooling technology to treat refractory seizures without resecting eloquent cortex. As a step toward human implementation, it will be necessary to determine the thermal response of human brain tissue to surface cooling to better inform device design and development. The data presented in this study suggest that direct surface cooling, using either active or passive cooling methods, can achieve potentially therapeutic temperature reductions up to 15 mm below the brain surface.
Learning Objectives: By the conclusion of this session, participants should be able to : 1) Understand the roles of active vs. passive cooling of brain, 2) Describe the thermal effects of cooling on the cortex, 3) Describe the temperatures achieved at the surface, as well as at 5, 10, and 15 mm depths, and 4) Discuss the potential utility of focal brain cooling for treating patients with refractory epilepsy or preventing the development of epilepsy in at-risk patients.
References: Mild passive focal cooling prevents epileptic seizures after head injury in rats. D'Ambrosio R, Eastman CL, Darvas F, Fender JS, Verley DR, Farin FM, Wilkerson HW, Temkin NR, Miller JW, Ojemann J, Rothman SM, Smyth MD. Ann Neurol. 2013 Feb;73(2):199-209.