Schaaf, R.C., Miller, L.J., Seawell, D., & O’Keefe, S. ( 2003). Children with disturbances in sensory processing: A pilot study examining the role of the parasympathetic nervous system. AJOT, 57.
According to study in 1997, about 10% of children are over or under responsive to sensory stimuli to the point that it interferes with their daily lives. They may have trouble eating some types of foods, playing on playground equipment or playing with others. These problems led to decreased social skills, low self-esteem, and may lead to problems in skill development.
The purpose of this pilot study was to compare parasympathetic functions of children with sensory modulation disturbances (over or under responsiveness) and typical developing children. The parasympathetic nervous system, part of the autonomic nervous system, helps individuals adapt to changing conditions. It regulates the body's recovery from a stressful situation and returns it to normal conditions (heart rate, pulse, sweat). We hypothesized that children with sensory modulation disturbances would demonstrate difficulty in returning their bodies to a normally regulated state as measured by vagal tone, a cardiac reactivity measure.
In the study six typical children participated in this study (average age 6.2) and were the controls for this study. Nine children (average age 5.8) who had been diagnosed with sensory modulation disorder after evaluation by an experienced master clinician as and confirmed by scores < -3 standard deviations on the Short Sensory Profile were compared.
Prior to participating, informed consent was completed. Next, the parents completed the Short Sensory Profile and their questions were answered. Third, the child was escorted to our "space ship" and the Sensory Challenge Protocol was administered.
The Sensory Challenge Protocol evaluates the participants' physiological response to a series of sensory stimuli: olfactory (wintergreen oil), visual (strobe lights), auditory (tape recorded sirens), tactile (touch from ear to chin to ear with a feather), and vestibular (being slowly tipped back in a chair). Before the stimulation started, a 2-minute baseline was recorded. Next, the stimulation begins and continues for ~15 minutes. The duration of stimulation is 3 seconds with a pause of 12 or 17 seconds between each stimuli.
During the procedure, participants wear electrodes that conduct information about their heart reactivity and electrodermal responses (sweat). The heart measures were evaluating the parasympathetic system and the sweat measures were evaluating the sympathetic system, both related to the autonomic nervous system. For analysis of the vagal tone data, information was later transferred to a computer and the computer program MxEdit was used to reduce and data files.
The study found that children with sensory modulation disorder had less effective parasympathetic functions than typically developing children. A significant difference occurred in heart rate. Other factors may have affected the cardiac results such as fitness level and age. The study also evaluated power and recommended a sample size of 20 in order to detect group differences