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In 20 normal subjects, sounds or vibrational signals were recorded from the biceps brachii muscle during voluntary isometric contraction. Fourier analysis showed presence of predominantly low frequency components with little contributions beyond 60 or 70 Hz. Relatively high amplitude peaks occurring below 20 Hz were seen in the frequency spectrum with the(More)
In 15 normal subjects, antidromic median sensory compound nerve action potentials (SCNAPs) were recorded supramaximally from the middle finger with ring electrodes, using different interelectrode recording distances. The onset latencies were identical in all recording instances. The peak latency and amplitude of the major negative deflection continued to(More)
Cortical somatosensory evoked potential (SEP) recording to lower-limb stimulation was performed on a patient to monitor surgery for scoliosis. Intraoperatively, the patient developed acute and irreversible hemorrhagic hypotension. Cortical SEPs were clearly present with systolic blood pressures in the low 50s and upper 40s (mm Hg). The potentials(More)
In 15 normal subjects, compound muscle action potentials (CMAPs) produced during electrical stimulation of the brachial plexus were obtained at a distance (far field) from their sources (upper-limb muscles). These far-field CMAPs were recorded at the forehead, neck, and tip of the middle finger and were referred to a relatively inactive region(More)
The electrode described in this paper consist of a barrel or handle with its conducting cable and a detachable stimulating tip. It is constructed of inexpensive and commercially available materials and is disposable. During the course of a stimulation study, electrode tips of different lengths or curvatures may be substituted without the need to replace the(More)
To determine the effect of recording electrode size on the compound muscle action potentials (CMAPs), maximally evoked CMAPs were obtained from the abductor digiti minimi muscle in ten normal subjects with circular-shaped surface recording electrodes of different diameters (4, 6, 8, 10, 12, and 14 mm). The electrodes were concentrically located on the same(More)
When a recording electrode is situated at a relatively far and roughly equal distance from multiple muscle action potential (MAP) sources such as the intrinsic-hand muscles (far-field recording), the individual MAPs generated by muscle fibers may contribute to the resultant compound potential with nearly equal weights depending on the orientation of the(More)