Electrical Perceptual Threshold Testing - validation study

Study Design : Prospective experimental Objectives : To investigate inter-rater and intra-rater reliability of electrical perceptual threshold (EPT) testing in assessing somatosensory function in healthy volunteers. Setting: Spinal Injuries Unit, Royal North Shore Hospital, Sydney, NSW, Australia Methods: Cutaneous electrical stimulation of 4 dermatomes at American Spinal Injuries Association (ASIA) sensory key points (C3, T1, L3, S2) was performed on 40 control subjects. The lowest ascending stimulus intensity at which sensation was perceived was recorded as the EPT. Mean EPT values for each dermatome, as determined by 2 testers at two time points, were examined and plotted against a normative template. Differences and associations between intra- and inter-rater measurements, and left-right measurements were investigated. EPT results for 2 people with spinal cord injuries were also examined. Results : EPT measurements from left and right sides, obtained from the two time points and two testers, were found to be strongly associated, with the exception of left and right side measurements at the S2 dermatome. No significant differences in the mean EPT for tester or time period were found. The intra- and inter-rater reliability was good for all dermatomes tested. Mean EPT measurements fell within the range of a normative template at each of the 4 dermatomes tested. Conclusion : EPT is an objective, reproducible and quantifiable method of assessing sensation in a control group. However, caution should be applied in certain dermatomes such as S2 where there was large variation between left and right side measurements. Sponsorship : New South Wales Office of Science and Medical Researc

Development of auditory sensitivity in the inferior colliculus of the tammar wallaby (Macropus eugenii)

The Australian tammar wallaby, a macropod marsupial, is now the subject of established investigations into the development of the visual and somatosensory systems (e.g., Waite et al., 1991, 1994; Mark and Marotte, 1992). Recently, we have commenced studies of the development of the auditory system. The particular advantage of the marsupial preparation is that much of its development occurs both slowly and ex utero, the young being carried and suckled in a pouch, so that access is available at very early stages of development. We have now established the timetable for the first appearance and the properties of the scalp-recorded, auditory brainstem response (ABR) in developing wallabies, in several cases monitoring the ABR in longitudinal studies (Cone-Wesson, Hill and Liu, in prep.). Following its first appearance as a simple biphasic wave, in a preparation at around 120 days of pouch life, the ABR progressively becomes more complex, with an increased number of distinct peaks, as the animal matures. A likely reason for the elaboration of the ABR with development is the progressive onset of function in auditory brainstem nuclei, which are candidates as generators of discrete evoked potentials that may sum in the form of the ABR. The present study is concerned with the development of function in the prominent auditory centre, the inferior colliculus (IC). In marsupials, this major midbrain structure receives afferent connections from the more-peripheral auditory nuclei (Aitkin, 1986). The development of the IC has been studied in several mammalian species, rat (Altman and Bayer, 1981), cat (Aitkin and Reynolds, 1975; Moore, 1980), bat (M#x00F6;ller et al., 1978) and rhesus monkey (Cooper and Rakic, 1981), however, little information is available on development of the IC in marsupials (Aitkin et al., 1995)

Electrical Perceptual Threshold Testing - validation study

Study Design : Prospective experimentalObjectives : To investigate inter-rater and intra-rater reliability of electrical perceptual threshold (EPT) testing in assessing somatosensory function in healthy volunteers.Setting: Spinal Injuries Unit, Royal North Shore Hospital, Sydney, NSW, AustraliaMethods: Cutaneous electrical stimulation of 4 dermatomes at American Spinal Injuries Association (ASIA) sensory key points (C3, T1, L3, S2) was performed on 40 control subjects. The lowest ascending stimulus intensity at which sensation was perceived was recorded as the EPT. Mean EPT values for each dermatome, as determined by 2 testers at two time points, were examined and plotted against a normative template. Differences and associations between intra- and inter-rater measurements, and left-right measurements were investigated. EPT results for 2 people with spinal cord injuries were also examined.Results : EPT measurements from left and right sides, obtained from the two time points and two testers, were found to be strongly associated, with the exception of left and right side measurements at the S2 dermatome. No significant differences in the mean EPT for tester or time period were found. The intra- and inter-rater reliability was good for all dermatomes tested. Mean EPT measurements fell within the range of a normative template at each of the 4 dermatomes tested.Conclusion : EPT is an objective, reproducible and quantifiable method of assessing sensation in a control group. However, caution should be applied in certain dermatomes such as S2 where there was large variation between left and right side measurements.Sponsorship : New South Wales Office of Science and Medical Researc