Abstract
Objective: To evaluate the characteristics of F-wave in spinocerebellar ataxia type 3 (SCA3) patients and preclinical carriers of SCA3 gene mutation (PreSCA3), and explore the relationship between disease severity and F-wave parameters and evaluate F-wave parameters as potential biomarkers for monitoring of disease progression in SCA3.Methods: We performed F-wave recordings in median, ulnar and tibial nerves of 39 SCA3 patients, 20 PreSCA3, and 27 healthy controls, and compared F-wave parameters between them.Results: In all nerves studied, the mean F-wave amplitude, maximum F-wave amplitude, and F/M amplitude ratio were significantly increased in the SCA3 patients in comparison with the normal controls. And the minimal F-wave latency of SCA3 patients was significantly prolonged and the F-wave persistence (%) was significantly decreased in the median nerve. For the PreSCA3, the maximum F-wave amplitude was significantly higher than normal controls for both median, ulnar, and tibial nerves. The mean F-wave amplitude and F/M amplitude ratio in all nerves were comparable between PreSCA3 and normal controls. The frequency of giant F-wave and frequency of patients with giant F-wave were similar between PreSCA3 and SCA3. The values of F/M amplitude ratio in both median, ulnar, and tibial nerves were correlated positively with disease severity and disease duration.Conclusion: Significant F-wave abnormalities occur in patients with SCA3, even in PreSCA3. F-wave may therefore reveal subclinical alterations and provide objective parameters for evaluating the progression of SCA3.
Highlights
Spinocerebellar ataxia (SCA) type 3 is caused by cytosine-adenine-guanine (CAG) repeat expansions in ATXN3 gene, which represents the most prevalent subtype of SCAs in China [1]
The CAG repeat size was comparable between SCA3 and preclinical carriers of SCA3 mutation (PreSCA3)
The presence of hyperreflexia was found in 79.5% of SCA3 and 5% of PreSCA3
Summary
Spinocerebellar ataxia (SCA) type 3 is caused by cytosine-adenine-guanine (CAG) repeat expansions in ATXN3 gene, which represents the most prevalent subtype of SCAs in China [1]. Gait ataxia is the usual chief complaint, other distinguishing clinical features include eye movement abnormalities [2], pyramidal signs, peripheral neuropathy, and extrapyramidal manifestations [3]. Previous studies have demonstrated that peripheral neuropathy was highly. Motor axons were damaged in a pattern resembling motor neuron disease [6]. F-wave, as the late response following peripheral electrical stimulation of the motor fibers, results from backfiring of antidromically activated motor neurons, which could effectively supplements the conventional nerve conduction studies [7]. F-wave latency has been proven as valuable marker of conduction property of motor axons. Decreased F-wave amplitude and persistence, prolonged F-wave latency, and F-wave chronodispersion were certified as signs of damage in the lower motor neuron [8, 9]
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