Fasciculation potentials: Still mysterious

Motor unit firing pattern: evidence for motoneuronal or axonal discharge origin?

In neuromuscular diseases, a fasciculation origin is disputed. In some reports, it was suggested that motor unit firing pattern alone is evidence for motoneuronal or axonal fasciculations; namely interspike intervals of approximately 5 ms (doublet intervals) provide evidence for the axonal firing. To clarify the reliability of the suggestion, we compared doublet intervals originated in motoneurons and their axons in healthy humans. For this aim, the H-reflex and M-response of single motor units were elicited during gentle voluntary muscle contractions. Peri-stimulus time histograms allowed reliable judgment about a doublet origin: motoneuronal (at the H-reflex latency) or axonal (at the M-response latency). Significant difference between motoneuronal and axonal doublet intervals was absent. It was concluded that doublet interval alone cannot be the reliable criterion for an axonal firing origin; additional evidences are needed for this conclusion, for example, the appearance of the F-wave. The approach may be used as an additional estimation of mechanisms underlying motor unit diseases.

Innervation zones of fasciculating motor units: observations by a linear electrode array

This study examines the innervation zone (IZ) in the biceps brachii muscle in healthy subjects and those with amyotrophic lateral sclerosis (ALS) using a 20-channel linear electromyogram (EMG) electrode array. Raster plots of individual waveform potentials were studied to estimate the motor unit IZ. While this work mainly focused on fasciculation potentials (FPs), a limited number of motor unit potentials (MUPs) from voluntary activity of 12 healthy and seven ALS subjects were also examined. Abnormal propagation of MUPs and scattered IZs were observed in fasciculating units, compared with voluntarily activated MUPs in healthy and ALS subjects. These findings can be related to muscle fiber reinnervation following motor neuron degeneration in ALS and the different origin sites of FPs compared with voluntary MUPs.

Spike sorting paradigm for classification of multi-channel recorded fasciculation potentials

BACKGROUND

Fasciculation potentials (FPs) are important in supporting the electrodiagnosis of Amyotrophic Lateral Sclerosis (ALS). If classified by shape, FPs can also be very informative for laboratory-based neurophysiological investigations of the motor units.

METHODS

This study describes a Matlab program for classification of FPs recorded by multi-channel surface electromyogram (EMG) electrodes. The program applies Principal Component Analysis on a set of features recorded from all channels. Then, it registers unsupervised and supervised classification algorithms to sort the FP samples. Qualitative and quantitative evaluation of the results is provided for the operator to assess the outcome. The algorithm facilitates manual interactive modification of the results. Classification accuracy can be improved progressively until the user is satisfied. The program makes no assumptions regarding the occurrence times of the action potentials, in keeping with the rather sporadic and irregular nature of FP firings.

RESULTS

Ten sets of experimental data recorded from subjects with ALS using a 20-channel surface electrode array were tested. A total of 11891 FPs were detected and classified into a total of 235 prototype template waveforms. Evaluation and correction of classification outcome of such a dataset with over 6000 FPs can be achieved within 1-2 days. Facilitated interactive evaluation and modification could expedite the process of gaining accurate final results.

CONCLUSION

The developed Matlab program is an efficient toolbox for classification of FPs.

Efficacy of hypnosis-based treatment in amyotrophic lateral sclerosis: a pilot study

BACKGROUND

Amyotrophic lateral sclerosis (ALS) and its devastating neurodegenerative consequences have an inevitably psychological impact on patients and their caregivers: however, although it would be strongly needed, there is a lack of research on the efficacy of psychological intervention. Our aim was to investigate the effect of hypnosis-based intervention on psychological and perceived physical wellbeing in patients and the indirect effect on caregivers.

METHODS

We recruited eight ALS volunteers patients as a pilot sample for an hypnosis intervention and self-hypnosis training protocol lasting 1 month. Anxiety and depression level was measured in patients and caregivers at pre and post treatment phase. Quality of life and perceived physical symptoms changes were also investigated in patients.

RESULTS

One month pre-post treatment improvement in depression, anxiety, and quality of life was clearly clinically observed and confirmed by psychometric analyses on questionnaire data. Moreover, decreases in physical symptoms such as pain, sleep disorders, emotional lability, and fasciculations were reported by our patients. Improvements in caregiver psychological wellbeing, likely as a consequence of patients psychological and perceived physical symptomatology improvement, were also observed.

CONCLUSION

To the best of our knowledge, even if at a preliminary level, this is the first report on efficacy psychological intervention protocol on ALS patients. The findings provide initial support for using hypnosis and self-hypnosis training to manage some ALS physical consequences and mainly to cope its dramatic psychological implications for patients and, indirectly, for their caregivers.