Reduction of evoked potential measurement time by a TMS320 based adaptive matched filter

In some clinical centres, somatosensory evoked potentials are used for the assessment of neurological function during surgical procedures on the spine. As these potentials are heavily contaminated in background noise, ensemble averaging coupled with invasive instrumentation is routinely used to enhance the signal. However, this procedure is very time consuming, often taking several minutes. In this paper, an adaptive matched filter has been used to dramatically reduce this measurement time to around 20 seconds, even when employing non-invasive surface electrodes. This filter has been implemented in real-time by using a TMS320C25 digital signal processor and results are presented for signal acquisition both at the L1-T12 and T5-T6 spinal levels. In addition, the adaptive nature of this filter allows the tracking of slowly changing parameters within the evoked potential with time.