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Proceedings Paper

Photodynamic therapy for epilepsy
Author(s): Edie Zusman; Manpreet Sidhu; Valerie Coon; Nicholas Scott; Stuart Bisland; Tara Tsukamoto
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Paper Abstract

Epilepsy is surgically curable if the seizure focus can be localized and does not include areas of eloquent cortex. Because epileptic cells are indistinct from surrounding brain, resection typically includes normal tissue. Using the rat kindling model of epilepsy, we evaluated Photodynamic Therapy (PDT) as a super-selective lesioning technique. We present a series of pilot studies to evaluate: 1) Protoporphyrin IX (PpIX) fluorescence, 2) the efficacy of PDT to raise seizure thresholds, 3) the safety of PDT using behavioral studies, and 4) histologic results. Bipolar electrodes were chronically implanted into the cortex and animals received successive low-level stimulation generating seizures of increasing severity. Following 5-aminolevulinic acid (ALA) administration, fully kindled rats received electrical stimulation to induce a generalized seizure. Animals were irradiated with laser light focused onto a temporal craniectomy. Our results show: 1) an increase in PpIX fluorescence in the seizure group, 2) PDT treated animals failed to demonstrate seizure activity following repeat stimulation, 3) no statistically significant difference between treated and control animals were observed on behavioral tests, 4) histology showed pyknotic hippocampal pyramidal cells in the CA3 region without areas of obvious necrosis. In conclusion, this is the first report of heightened PpIX-mediated fluorescence in epileptic brain. The selective accumulation of PpIX with laser PDT may provide a less invasive and more precise technique for obliteration of epileptic foci. PDT warrants additional research to determine if this technique may augment or replace existing procedures for the surgical management of epilepsy.

Paper Details

Date Published: 6 March 2006
PDF: 9 pages
Proc. SPIE 6139, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XV, 61390W (6 March 2006); doi: 10.1117/12.648288
Show Author Affiliations
Edie Zusman, Sutter Neuroscience Institute (United States)
Univ. of California, Davis (United States)
Ctr. for Biophotonics, Science, and Technology (United States)
Manpreet Sidhu, Univ. of California, Davis (United States)
Ctr. for Biophotonics, Science, and Technology (United States)
Valerie Coon, Univ. of California, Davis (United States)
Univ. of Utah (United States)
Nicholas Scott, Univ. of California, Davis (United States)
Stuart Bisland, Univ. of Toronto (Canada)
Ctr. for Biophotonics, Science, and Technology (United States)
Tara Tsukamoto, Univ. of California, Davis (United States)
Ctr. for Biophotonics, Science, and Technology (United States)


Published in SPIE Proceedings Vol. 6139:
Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XV
David Kessel, Editor(s)

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