Conditional Computer Analysis of the Onset-to-Onset Duration of Spikes from the Electromyographic Interference Pattern of Extraocular Muscles

Abstract

A new type of analysis of the electromyographic spike obtained from the full interference pattern of extraocular muscles is introduced. It entails the use of a computer for the measurement and statistical analysis of the duration of onset-to-onset from one spike to the next one and the onset-to-onset immediately preceding it. The lateral, medial and superior recti muscles were examined in 13 subjects, of whom 7 were healthy, 3 were suffering from ocular myopathy and 3 from infranuclear neuropathy. Sharp, well-defined differences between healthy, myopathic and neuropathic lesions were found. The technique is simple, rapid and accurate. Its value is enhanced by the fact that no area of overlap was encountered between the 3 basic types of muscle examined. The parameter, and its statistical analysis, appears to be an additional and reliable tool in the interpretation of electromyography (EMG), especially of value in subclinical, incipient or doubtful clinical conditions involving eyeball motility.

Electromyographic Investigation of Extraocular Muscles in Vestibular Nystagmus Evoked by Caloric Stimulation

“…It has, for an EOM, an unusually pro longed duration, a very high amplitude, never seen even in the most forceful agonist gaze, and an almost pure diphasic shape, without peaks within the spike. The latter finding indicates an almost complete summation of all the firing motor units, since peaks, denoting asynchronous superposition of action potentials, would otherwise have been noted [2]. These specific outbursts have also been noted by Bjork [1], and we completely agree with him that the antagonist activity in nystagmus is similar to that of a single saccadic move-ment.…”

Motor Unit Activity Extracted from the Electromyographic Full Interference Pattern of Extraocular Muscles

“…The shape of AP, which may greatly contribute to a proper interpretation of EMG, requires analysis of literally thousands of spikes in order to obtain statistically significant histograms [17].…”

Analysis of surface EMG spike shape across different levels of isometric force

“…Myopathic patients experience a loss of muscle fibers so they must increase both MU recruitment and firing rates, which results in less synchronous MU firing patterns. These patients have an increase in MSA, MNPPS, and MSF (Magora and Gonen, 1970;Muro et al, 1982;Latash, 1988a,b). The recruitment of higher threshold MUs also results in an increase in MSS (Vittasalo and Komi, 1975;Komi and Viitasalo, 1976).…”

“…derived from several sources: analysis of the indwelling EMG IP from myopathic and neuropathic patients (Magora and Gonen, 1970;Muro et al, 1982;Latash, 1988a,b), computer modeling of SEMG activity (Yao et al, 2000) and surface detected motor unit action potentials (MUAPs) (Vittasalo and Komi, 1975;Komi and Viitasalo, 1976). For example, patients with neuropathic lesions have higher rates of MU synchronization and exhibit an increase in MSA and MSD and a decrease in MNPPS and MSF (Magora and Gonen, 1970;Muro et al, 1982;Latash, 1988a,b).…”

“…For example, patients with neuropathic lesions have higher rates of MU synchronization and exhibit an increase in MSA and MSD and a decrease in MNPPS and MSF (Magora and Gonen, 1970;Muro et al, 1982;Latash, 1988a,b). Modelling work has demonstrated that the superposition of synchronized MUAPs can increase the amplitude and slope of the resulting potential (Yao et al, 2000).…”