ALA-induced PpIX fluorescence in epileptogenic tissue

Jonathan K. Kleen, Pablo A. Valdes, Brent T. Harris, Gregory L. Holmes, Keith D. Paulsen, David W. Roberts

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Astrogliotic tissue displays markedly increased levels of ALA-induced PpIX fluorescence, making it useful for fluorescence-guided resection in glioma surgery. In patients with temporal lobe epilepsy (TLE) and corresponding animal models, there are areas of astrogliosis that often co-localize with the epileptic focus, which can be resected to eliminate seizures in the majority of treated patients. If this epileptogenic tissue can exhibit PpIX fluorescence that is sufficiently localized, it could potentially help identify margins in epilepsy surgery. We tested the hypothesis that ALA-induced PpIX fluorescence could visually accentuate epileptogenic tissue, using an established animal model of chronic TLE. An acute dose of pilocarpine was used to induce chronic seizure activity in a rat. This rat and a normal control were given ALA, euthanized, and brains examined post-mortem for PpIX fluorescence and neuropathology. Preliminary evidence indicates increased PpIX fluorescence in areas associated with chronic epileptic changes and seizure generation in TLE, including the hippocampus and parahippocampal areas. In addition, strong PpIX fluorescence was clearly observed in layer II of the piriform cortex, a region known for epileptic reorganization and involvement in the generation of seizures in animal studies. We are further investigating whether ALA-induced PpIX fluorescence can consistently identify epileptogenic zones, which could warrant the extension of this technique to clinical studies for use as an adjuvant guidance technology in the resection of epileptic tissue.

Original languageEnglish (US)
Title of host publicationPhotonic Therapeutics and Diagnostics VII
StatePublished - 2011
Externally publishedYes
EventPhotonic Therapeutics and Diagnostics VII - San Francisco, CA, United States
Duration: Jan 22 2011Jan 24 2011

Publication series

NameProgress in Biomedical Optics and Imaging - Proceedings of SPIE
ISSN (Print)1605-7422


ConferencePhotonic Therapeutics and Diagnostics VII
Country/TerritoryUnited States
CitySan Francisco, CA


  • ALA
  • PPIX
  • epilepsy
  • fluorescence
  • neurosurgery
  • resection
  • seizures
  • tissue

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Atomic and Molecular Physics, and Optics
  • Radiology Nuclear Medicine and imaging


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