Changes in near-infrared spectroscopy and the bispectral index during tilt-table examination.

The head-upright tilt-table test is an important tool for the diagnosis of vasodepressor or neurocardiogenic syncope. The use of noninvasive near-infrared spectroscopy (NIRS) monitoring and bispectral index (BIS) monitoring during these cases can add another tool to the real-time monitoring and aid in their diagnosis. The authors report their experience using NIRS and BIS monitoring during tilt-table testing to investigate syncope in a 14-year-old adolescent. In this case, changes in the NIRS occurred earlier than changes in either blood pressure or the development of clinical symptoms. The change in the NIRS and BIS values correlated with the patient's level of consciousness. One major advantage of monitors such as the BIS, and more importantly, the NIRS is that they provide an instantaneous and continuous noninvasive measure of cerebral perfusion.