Biomedical subjects

William S Pease

Publications and source records attributed to William S Pease.

3 recordsLinked to original sources

PubMed2005

A novel technique for recording from the serratus anterior.

OBJECTIVE: To design an electrodiagnostic technique by which to accurately record the serratus anterior compound muscle action potential (CMAP). DESIGN: Observational study. SETTING: Academic electromyography laboratory. PARTICIPANTS: Fifteen healthy volunteers. INTERVENTIONS: The long thoracic nerve was stimulated by using a standard bipolar surface electrode in the axilla, just anterior to the midaxillary line. The serratus anterior CMAP was recorded by using a self-adhesive, 8.0 x 0.5 cm, ring electrode as the E1 placed across the serratus anterior interdigitations starting at the nipple level. A self-adhesive, motor (1 x 1 cm) electrode was used as E2 and placed over the seventh rib. A standard self-adhesive ground electrode was placed over the inferior region of the latissimus dorsi. MAIN OUTCOME MEASURES: Distal motor latency (DML), and CMAP amplitude and duration. RESULTS: After removing 2 outliers, the results are reported as the mean +/- 1.96 standard deviations. Right long thoracic DML was 2.2+/-1.0ms and the left was 2.3+/-0.9ms, with a side-to-side mean difference of 0.3+/-0.4ms. The right serratus CMAP amplitude was 3.8+/-3.9mV and the left was 3.9+/-3.7mV, with a side-to-side mean difference of 0.6+/-1.2mV. Statistical analysis did not reveal a significant side-to-side difference for DML or CMAP amplitude. Both sides were combined to form a single set of trials for DML and CMAP amplitude. The mean DML became 2.2+/-0.7ms, and the CMAP amplitude was 3.5+/-1.9mV. The CMAP duration was 14.5+/-4.3ms on the right and 14.5+/-4.1ms on the left. A significant, positive correlation existed between height and DML ( P <.02). The 95% confidence intervals for DML and CMAP amplitudes were 2.1 to 2.5ms and 1.5 to 3.1mV, respectively. CONCLUSIONS: Our latency, side-to-side comparisons and amplitude data were consistent with other motor nerve conduction findings in the literature. Stimulating the long thoracic nerve in the axilla will provide a reliable technique to aid in the diagnosis and treatment of long thoracic neuropathy.

Action Potentials↗

PubMed2003

Large-array surface electromyography in low back pain: a pilot study.

STUDY DESIGN: A large-array surface electromyography device was used to collect data from healthy pain-free persons and from those with acute or chronic low back pain. Images of regional muscle electromyographic activity were assessed visually, and maximum root mean square values were compared statistically. OBJECTIVE: To determine whether data differs by patient type. SUMMARY OF BACKGROUND DATA: Whereas there is a good understanding of the anatomy and psychosocial aspects of low back pain, there is a need to understand better the physiology of low back pain. METHODS: Large-array surface electromyography data were collected from the low back muscles of 201 participants over a 3-month period using a 63-electrode fixed array and a standardized protocol. Color images representing the voltage root mean square difference of each electrode pair were created. Three images from each of three positions (standing upright, standing in 20 degrees of trunk flexion, standing holding weights) were collected from each participant. Serial studies were performed on the acute population over a 6-week follow-up period. RESULTS: Images of regional muscle activity from 92.7% of normal controls (n = 163) showed symmetrical activity. Patients with acute (n = 13) or chronic (n = 25) low back pain had multifocal and/or asymmetrical patterns. Symmetrical patterns returned in the three patients whose acute pain resolved during the study. Maximum root mean square values were higher among patients with acute (P = 0.03) and chronic (P = 0.04) pain than among control subjects. CONCLUSIONS: Large-array surface electromyography produced data from patients with back pain that differed from data on subjects without back pain. This method may be useful in evaluating patients with low back pain.

Acute Disease↗

PubMedDate not supplied

Surface and wire electromyographic. Recording during fatiguing exercise.

Electromyographic (EMG) signals are routinely recorded during assessments of biomechanic activity for ergonomic and medical purposes. Surface and intramuscular electrodes (i.m.) are employed by different researchers and there is a continuing need to understand the indications for each. This research evaluated the reproducibility of the shift of the frequency content of the EMG signals during fatiguing exercise using simultaneous recording with these two electrode types. Using healthy adult volunteers, EMG recordings from the vastus lateralis (VL) and anterior tibial (AT) were made during repeated isokinetic exertions causing fatigue. The median power frequency (MPF) was calculated for a 0.5 sec sample of data taken during each concentric contraction. Test-retest, and multiple day repeat testing were performed to exclude the effects of training and fatigue upon the data. Surface electrode recordings demonstrated better reliability testing with values of 0.54 for VL and 0.68 for AT, while simultaneous i.m. recordings were -0.90 and 0.47, respectively. This finding of greater reliability, combined with the ease of use of surface electrodes suggest that they should be preferred for most studies of EMG analysis of muscle fatigue.

Adult↗