Interplay of upper and lower motor neuron degeneration in amyotrophic lateral sclerosis

Carvalho, Mamede de; Поляков, А. Н.; Tavares, Cátia; Swash, Michael

doi:10.1016/j.clinph.2017.08.024

Cited by 5 publications

(3 citation statements)

References 17 publications

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“…Spasticity can be associated with hyperexcitability of the lower motor neuron, thereby facilitating the activation of spinal motor neurons with consequent reduced variability of firing rates, probably due to activation of inward persistent sodium currents producing a stable plateau potential (35). Decreased firing rate variability in PLS has been observed by a number of authors using an array of different neurophysiological methods (35)(36)(37)(38).…”

Section: Nerve Conduction Studies and Electromyography (Emg)mentioning

confidence: 99%

Neurophysiological features of primary lateral sclerosis

Carvalho

Kiernan

Pullman

et al. 2020

Amyotrophic Lateral Sclerosis and Frontotemporal Degeneration

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Primary lateral sclerosis (PLS) is a motor neuron disease characterized by spinobulbar spasticity, absence of progressive lower motor neuron (LMN) dysfunction and marked by a slow functional decline. Electromyography is essential to exclude significant LMN involvement, particularly in the context of distinguishing PLS from amyotrophic lateral sclerosis (ALS), given that the prognosis is substantially better, and respiratory complications are unusual, in PLS. Nevertheless, minor neurogenic changes and occasional fasciculation potentials can be observed in PLS. The most useful technique for the objective assessment of upper motor neuron (UMN) dysfunction is transcranial magnetic stimulation (TMS), which in PLS is characterized by a high cortical threshold and delayed central conduction times. TMS is sensitive to identify cortical dysfunction in PLS and might have potential for monitoring UMN function in longitudinal studies and in clinical trials. The findings of TMS need to be interpreted in the context of the clinical presentation and phenotype, particularly in the differentiation between PLS and ALS. While other neurophysiological techniques have been investigated, studies to date have tended to involve small patient cohorts and as such, their value in distinguishing PLS from ALS remains unclear.

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Section: Nerve Conduction Studies and Electromyography (Emg)mentioning

confidence: 99%

Neurophysiological features of primary lateral sclerosis

Carvalho

Kiernan

Pullman

et al. 2020

Amyotrophic Lateral Sclerosis and Frontotemporal Degeneration

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“…In addition, motor unit (MU) recruitment and the firing pattern can also be affected in the presence of ALS because they are modulated by upper and lower motor neuron activity. Carvalho and colleagues reported that MU firing rate fluctuation was reduced in patients with upper motor neuron dysfunction‐dominant diseases by n‐EMG with a slight voluntary muscle contraction 4,5 . However, the n‐EMG method is invasive and it takes a long time to obtain data from a sufficient number of MUs.…”

Section: Introductionmentioning

confidence: 99%

“…Carvalho and colleagues reported that MU firing rate fluctuation was reduced in patients with upper motor neuron dysfunction-dominant diseases by n-EMG with a slight voluntary muscle contraction. 4,5 However, the n-EMG method is invasive and it takes a long time to obtain data from a sufficient number of MUs. Also, quantification of the force level is essential on comparing MU firing rates between different subjects because firing rates are variable during sustained muscle contraction because of differences in the effort expended by subjects.…”

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confidence: 99%

Assessment of motor unit firing by high‐density surface electromyography detects motor neuronal hyperexcitable state in amyotrophic lateral sclerosis

et al. 2023

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Introduction/Aims In amyotrophic lateral sclerosis (ALS), the impact of motor neuron dysfunction on the motor unit (MU) firing pattern remains to be elucidated. The aim of this study was to clarify the characteristics of the MU firing rate and its association with clinical factors in ALS patients using high‐density surface electromyography (HDSEMG) and MU decomposition analysis. Methods Nineteen ALS patients and 20 controls prospectively underwent HDSEMG recording of the vastus lateralis muscle during ramp‐up (30% of maximum voluntary contraction) and sustained (10% of maximal voluntary contraction for 60 seconds) contractions on performing isometric knee extension. After decomposition analysis, instantaneous firing rates (IFRs) of individually identified MUs were calculated. Comparison of IFRs and clinical variables between ALS patients and controls and analysis of the correlation between individual mean IFR and clinical variables in ALS patients were performed. Results The number of identified MUs was lower in ALS patients than in controls (P = .017). Mean IFRs of MUs (i.e., mean MU firing rates) were higher in ALS patients than in controls at some force levels on ramp‐up contraction (P < .05) and at 50 to 60 seconds during sustained contraction (9.1 [ALS] vs 8.3 [controls] pulses per second; P = .036). There was no correlation between the clinical parameters and mean IFR of each patient. Discussion ALS patients had a higher MU firing rate during muscle contraction at a low force level. Noninvasive assessment of the MU firing rate by HDSEMG can detect a motor neuronal hyperexcitable state in ALS patients.

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Upper and lower motor neuron neurophysiology and motor control

Carvalho

Swash

2023

Handbook of Clinical Neurology

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Interplay of upper and lower motor neuron degeneration in amyotrophic lateral sclerosis

Cited by 5 publications

References 17 publications

Neurophysiological features of primary lateral sclerosis

Neurophysiological features of primary lateral sclerosis

Assessment of motor unit firing by high‐density surface electromyography detects motor neuronal hyperexcitable state in amyotrophic lateral sclerosis

Upper and lower motor neuron neurophysiology and motor control

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