Cerebral Oxygenation and the Recoverable Brain
By: Richard A. Neubauer and Phillip James
Stroke is the third leading cause of death in the United States and a major source of disability. It is not only devastating to the patient and the family, but also creates a large financial drain on resources. In stroke it is often stated that most recovery takes place in the first three months. However, sequential SPECT scanning has indicated that some recovery may take place spontaneously up to six months. Although stroke tissue in the center of the lesion becomes necrotic, in the surrounding zone of tissue, less affected by hypoxia, cells survive to form the ischemic penumbra’. The timing of these events is uncertain but sufficient oxygen is available to these cells to maintain membrane ion pump mechanisms, but not enough for them to generate action potentials and therefore function as neurons. The existence of such areas has been suspected for some time based upon the nature of clinical recovery, but has now been demonstrated by SPECT imaging using a high plasma oxygen concentration under hyperbaric conditions. The use of hyperbaric oxygen therapy has been described in a large series of stroke patients . Another approach to this problem has been the transposition of omental tissue which can revascularise the area to elevate oxygen delivery.