An Easy and Practical Method for Routine, Bedside Testing of Somatosensory Systems in Extremely Low Birth Weight Infants

Abstract

This study was set out to develop and describe a novel, simple, and safe method for routine bedside testing of somatosensory system in very early preterm infants. We recorded electroencephalogram (EEG) activity after tactile stimulation of hand (palm) and foot (sole) by a soft hairbrush stimulator in extremely low birth weight infants (n ϭ 10; GA, 24 -28, recording at conceptional age 30 -32 wk) and compared with the raw EEG responses to those seen by one-or two-channel brain monitors. In every subject, single tactile stimuli produced prominent (100 -350 V) somatosensory evoked responses (SERs) that were readily identified in the ongoing EEG signal. The maximal SER was in the contralateral hemisphere at around the corresponding somatosensory representation areas. Conventional EEG filtering did significantly reduce the SERs, but they could still be identified in the routine brain monitor setting widely available in NICUs. The method described here is directly applicable to assessment of integrity of somatosensory system in the early preterm period. It needs minimal training and requires an EEG system or a brain monitor device that is available in most units. Thus, the technique is likely to open a novel window to neurologic assessment of these babies. (Pediatr Res 66: 710-713, 2009)

Evaluation of somatosensory cortical processing in extremely preterm infants at term with MEG and EEG

“…In clinical settings the median nerve stimulation is the gold standard for evaluation of the somatosensory responses and has also been extensively used for studying SII responses in adults (e.g., Hari and Forss, 1999). In the future, tactile stimuli could replace the median nerve stimuli also in the EEG recordings in the NICU as even individual tactile stimuli in preterm infants before TEA evoke prominent activity detectable in the raw EEG signal without averaging (Vanhatalo et al, 2009).…”

Preterm EEG: A Multimodal Neurophysiological Protocol

“…Recent work in both human babies [5][6][7]10 and animal models with rat pups [13][14][15] has emphasized the dominance of infraslow frequencies in the EEG. While they are readily seen with the FbEEG technique (see Fig 1 and refs 8,9), they are ignored or distorted in the conventional EEG (using an AC coupled amplifier) that permanently cuts them at the time of signal collection, because AC coupled amplifiers act as highpass (low cut) filters.…”

“…Note that all sensory responses in the young preemies have a long (several seconds) refractory period, and the responses decline rapidly with short interstimulus intervals or in the presence of other ongoing EEG activity in the sensory cortex. Hence, deliver sensory stimuli at moments when the EEG has been relatively silent for at least few seconds, which is easiest to do during quiet sleep exhibiting trace discontinue activity [4][5][6] 2. To study the visual evoked responses, give single flashes with a device integrated to the EEG system.…”

Neural body maps in human infants: Somatotopic responses to tactile stimulation in 7-month-olds

“…Some clinically-oriented EEG research with preterm infants (29 -32 weeks postconceptional age) has employed tactile stimulation of hands and feet (Milh et al, 2007;Vanhatalo et al, 2009). In these studies, brushing of the hands was associated with increased activity at lateral central electrodes presumed to overly the hand areas, while brushing of the feet was associated with increased activity at the midline central electrode, which is presumed to overly the foot area.…”