In vivo optical properties of cortical tubers in children with tuberous sclerosis complex (TSC): a preliminary investigation

Abstract

Purpose: Medically refractory epilepsy caused by cortical tubers resulting from tuberous sclerosis complex (TSC) often requires surgical intervention. The locations of cortical tubers generally are determined by preoperative magnetic resonance imaging (MRI). In this pilot study, we explored the feasibility of using the optical characteristics of cortical tubers as a potential means to guide their resection intraoperatively.

Methods: Optical characteristics of normal cortex and cortical tubers were measured intraoperatively using diffuse reflectance spectroscopy in three children undergoing epilepsy surgery for drug-resistant seizures. Unique diffuse reflectance spectroscopic features of cortical tubers were identified and their physiologic associations determined.

Key findings: Diffuse reflectance spectra revealed several features that distinguish cortical tubers from normal cortex. In tubers, diffuse reflectance intensities at oxy- and deoxyhemoglobin isobestic points, like 500, 530, and 570 nm, were consistently higher than those in normal cortex. According to the profile of diffuse reflectance spectra from 520-580 nm, hemoglobin oxygenation in tubers often was lower than in normal cortex.

Significance: Albeit preliminary, our findings suggest that the optical characteristics of cortical tubers differ from intervening normal cortex, likely reflecting the lower cerebral blood volumes and reduced hemoglobin oxygenation of cortical tubers. The results of this study can be used to design biomedical instruments that aid tuberectomies.