Abstract
A-wave was observed in patients with motor neuron disease (1). However, data on the characteristics and clinical significance of A-waves in patients with amyotrophic lateral sclerosis (ALS) have been scarce. The F-wave studies of 83 patients with ALS and 63 normal participants which were conducted previously at the Department of Neurology in Peking Union Medical College Hospital were retrospectively reviewed to determine the occurrence of A-waves in ALS. A-waves occurred more frequently in ALS patients than in normal controls. For the median and peroneal nerves, the frequencies of nerves with A-waves and frequencies of patients with A-waves were comparable between the ALS patients and normal controls. For the ulnar and tibial nerves, the frequencies of nerves with A-waves and frequencies of patients with A-waves were significantly increased in the ALS patients compared with those of the normal participants. Disease progression rate was slower in the ALS patients with A-waves (0.73 ± 0.99) than that in the ALS patients without A-waves (0.87 ± 0.55, P = 0.007). No correlations were found between the amplitudes of F-waves with A-waves and those of A-waves in the ulnar nerves (r = 0.423, P = 0.149). No correlations were found between the persistence of F-waves with A-waves and the persistence of A-waves in the ulnar nerves as well (r = 0.219, P = 0.473). The occurrence of A-waves may indicate dysfunction of lower motor neurons and possibly imply a relatively slower degenerative process.
Highlights
A-waves are compound muscle action potentials that follow the M-wave with a constant shape and latency, which are detected during F-wave studies [2]
The present study aimed to investigate the occurrence and characteristics of A-waves in amyotrophic lateral sclerosis (ALS) patients
Though the frequency of A-waves increased with age, ages were comparable between normal control participants and ALS patients in the present study
Summary
A-waves are compound muscle action potentials that follow the M-wave with a constant shape and latency, which are detected during F-wave studies [2]. The term A-waves has been used in a more general manner for abnormal late responses that are not axon reflexes and are recorded in motor nerve conduction studies using supramaximal stimuli [2, 3]. A-wave is a relatively common finding during routine F-wave studies using standard stimulation and recording techniques. It was proposed that A-waves were indicator of dysfunction of peripheral nerves, especially of generalized and demyelinating origin [3, 4]. A-Wave in ALS presence of A-waves in demyelinating neuropathies, especially in Guillain–Barré syndrome. It was reported that A-wave could be observed in patients with motor neuron disease [1], though demyelination is the crucial underlying pathophysiologic correlate of supramaximally stimulated A-waves [4]. The present study aimed to investigate the occurrence and characteristics of A-waves in ALS patients
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