Repeater F‐waves are signs of motor unit pathology in polio survivors

Abstract

Introduction The purpose of this study was to determine whether F‐waves reveal electrophysiological features of anterior horn cells in polio survivors. Methods Forty‐three polio survivors and 20 healthy controls underwent motor nerve conduction studies of the median and tibial nerves bilaterally, including sampling of F‐waves elicited by 100 stimuli and the determination of motor unit number estimation (MUNE). Results A significant increase in abnormally stereotyped (“repeater”) F–waves and a reduction of F‐wave persistence were observed in both nerves in the polio group as compared with the control group. Repeater F‐waves had a negative correlation with MUNE. Conclusions These trends in F‐wave persistence and repeater F‐waves after motor unit loss are characteristic findings in polio survivors. Repeater F‐waves are a sign of motor unit pathology. Muscle Nerve 51 :680–685, 2015

Differences in Dysfunction of Thenar and Hypothenar Motoneurons in Amyotrophic Lateral Sclerosis

“…The difference in the percentage of upper limb onset between groups 1 and 2 may underlie a different pattern of disease progression between the two groups. The estimated number of motor units and CMAP amplitudes are useful parameters for evaluating motoneuron loss, whereas the F-wave may be a direct probe of dysfunction or instability in anterior horn cells (Hachisuka et al, 2015 ). The F-wave persistence is related to the number of LMNs and motoneuron excitability (Schiller and Stalberg, 1978 ; de Carvalho et al, 2002 ; Argyriou et al, 2006 ).…”

“…The F-wave persistence is related to the number of LMNs and motoneuron excitability (Schiller and Stalberg, 1978 ; de Carvalho et al, 2002 ; Argyriou et al, 2006 ). The proposed mechanisms underlying repeater F-waves are increased excitability in particular anterior horn cells, decreased excitability in some motoneurons, or motoneuron loss (Schiller and Stalberg, 1978 ; Petajan, 1985 ; Peioglou-Harmoussi et al, 1987 ; Hachisuka et al, 2015 ). As motoneurons are lost, repeater F-waves from individual motoneurons may be recognized more easily; however, it has been argued that the low frequency of backfiring of individual motoneurons makes the mechanism rather unlikely (Chroni et al, 2012 ).…”

“…Conversely, the combination of the decreased mean F-wave amplitude and the increased F/M amplitude ratio in the APB emphasizes the preferential involvement of the APB in ALS. Repeater F-waves indicate pathological changes in motor units (Hachisuka et al, 2015 ). The significant increase in the number of repeater F-waves in the APB may imply a greater degree of hyperexcitability within the spinal motoneurons innervating the APB (Fang et al, 2015 ).…”

“…The F-wave is a late and low-amplitude response that reflects antidromic activation of motoneurons (Pastore-Olmedo et al, 2009 ). F-waves may provide an independent measure of segmental motoneuron excitability (Fisher, 1992 ; Milanov, 1992 ; Hachisuka et al, 2015 ). The primary purpose of this study was to examine the differences in dysfunction between spinal motoneurons innervating the APB and ADM in ALS using F-waves.…”

Clinical and Physiological Significance of F-Wave in Spinocerebellar Ataxia Type 3

“…The CMAP amplitude are useful parameters for evaluating motor neuron loss, whereas the F-wave may be a direct probe of dysfunction or instability in upper motor neurons disorder (22). These results indicate that this estimate probably reflects the significance of F-wave parameters in SCA3.…”