Photodynamic therapy within edematous brain tissue: Considerations on sensitizer dose and time point of laser irradiation

Photosensitizer is known to spread with vasogenic edema fluid arising from a cerebral lesion (Neurosurg 33:1075-1082, 1993), which may be essential for sensitizing malignant cells outside the main tumor mass. The present experiments seek to elucidate whether resultant necrosis of perifocal brain tissue after laser irradiation follows a corresponding time pattern and whether damage depends on the photosensitizer dose. Male Wistar rats were anaesthetized with chloralhydrate for venous cannulation, craniotomy and focal cold lesion in order to induce vasogenic edema. Simultaneously, Photofrin II (PF II) was administered at a dose of 5 mg kg-1. The animals were re-anaesthetized after either 4, 1…

Summary Background. Photodynamic therapy (PDT) has been under dis- cussion as additional treatment option for malignant gliomas. How- ever, damage not only to tumour tissue but also to normal brain has been demonstrated. The mechanisms of this unwanted side eect have not yet been clearly identified. Spreading of photosensitiser with oedema after disruption of the blood-brain-barrier and poten- tial sensitisation of normal tissue has been foundpreviously. The present study investigates the time- and dose-dependency of normal tissue damage to photodynamic therapy using Photofrin II9 after disruption of the blood-brain-barrier. Methods. Male wistar rats anaesthetisedwith chloral hydrate were s…