- Julia Finkel, MD
- Zenaide Quezado, MD
- Patrick Cheng, MS, MBA
- Jonathan Tan, MD, MPH
The Algometer is a device and method that is designed to measure pain intensity and type and can guide analgesic drug delivery in verbal and non-verbal patients. The device integrates a neurospecific neurostimulator and near-infrared spectroscopy signal responses (NIRS) over the somatosensory, frontal and occipital cortices to determine a composite cortical pain response index (CCPRI). The first prototype was delivered in 2012 and used commercially available optodes, which precluded use through hair. The second and improved prototype was designed in collaboration with a small business, MRRA, Inc. This company manufactures “brush” optodes that sample easily through hair and increase the sensitivity tenfold over the regular fiber bundle. Proof of concept studies using these brush optodes were conducted December 2014 and established critical proof of concept regarding stimulus intensity response relationships.
The cortical activation in the somatosensory cortex is clearly detected with a sub-threshold C-fiber specific neurostimulation. There is significant NIRS response at very weak stimulation current, and the data suggest there is a linear dose-response relationship between stimulation and NIRS signal. Our very preliminary results from the experiments of December 2014, where we enrolled 35 subjects and used the brush optodes, are encouraging. Here we sought to determine if we could discern an intensity response relationship using the newly constructed system. The initial preliminary analysis shows contralateral activations for both electrical stimulation and finger tapping, with corresponding smaller ipsilateral deactivations. The activations switch sides for left- versus right-handed subjects. These findings are consistent with the expected physiologic response.