Different Types of Fibrillation Potentials in Human Needle EMG

Partanen, Juhani

doi:10.5772/55352

Cited by 3 publications

(4 citation statements)

References 19 publications

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“…With a little searching with small needle insertions, several active spots with independently firing end plate spikes can be found, for example, in the extensor carpi radialis muscle. End plate spikes are readily differentiated from fibrillation potentials of denervated or injured muscle fibers by their firing patterns and waveform 10 , 22 , 23 . The explanation for local and propagated end plate spikes may be found if we consider that there is dynamic and static gamma motor innervation of muscle spindles.…”

Section: Discussionmentioning

confidence: 99%

Electromyography of the muscle spindle

Partanen

Vanhanen

Liljander

2022

Sci Rep

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In needle electromyography, there are two spontaneous waveforms, miniature end plate potentials and “end plate spikes”, appearing usually together. Miniature end plate potentials are local, non-propagating postsynaptic waves, caused by spontaneous exocytosis of acetylcholine in the neuromuscular junction. The prevailing hypothesis states that “end plate spikes” are propagated postsynaptic action potentials of muscle fibers, caused by presynaptic irritation of the motor nerve or nerve terminal. Using several small concentric needle electrodes in parallel with the muscle fibers, most “end plate spikes” are strictly local or propagating for 2–4 mm. At the end plate zone, there are miniature end plate potentials without “end plate spikes”. Local “end plate spikes” are junctional potentials of intrafusal gamma neuromuscular junctions of the nuclear bag fibers, and propagated “end plate spikes” are potentials of nuclear chain muscle fibers of muscle spindles. Miniature end plate potentials without “end plate spikes” at the end plate zone derive from alpha neuromuscular junctions. These findings contrast with the prevailing hypothesis. The history of observations and different hypotheses of the origin of end plate spikes are described.

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Section: Discussionmentioning

confidence: 99%

Electromyography of the muscle spindle

Partanen

Vanhanen

Liljander

2022

Sci Rep

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“…ENMG has another problem: after acute onset of the disease the proprioceptive tendon-and H-reflexes change in a few days. However, the development of pathological spontaneous activity, fibrillations and positive sharp waves, indicating axonal injury in electromyography (EMG) may take 2-3 weeks and even longer in distal muscles of the leg and foot [1]. Loss of motor units during maximal voluntary contraction may be observed soon, but more distinct changes, such as increase of duration, complexity (polyphasic and jittering waveform), and amplitude of motor unit potentials after parallel reinnervation may take several weeks and even months to develop [2].…”

Section: Introductionmentioning

confidence: 99%

Recording of Proprioceptive Muscle Reflexes in the Lower Extremity

Partanen¹,

Sompa²,

Muñoz-Ruiz³

2021

Proprioception

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Electromyography (EMG) is routinely used in diagnostics of root syndromes in the lower extremity. By studying signs of axonal damage of different root levels in the corresponding myotomes of the lower extremity and back muscles with needle EMG reveals, which of the motor roots are injured in patients with suspected root compression. But by EMG study only injuries of the anterior motor roots are diagnosed. Routine electroneuromyography does not disclose specific injury of the afferent sensory posterior roots. However, the integrity of some the posterior roots is readily studied with myotatic reflexes. We have routinely measured a proprioceptive reflex, the H-reflex of the soleus muscle with stimulation of the posterior tibial nerve, and found it to be useful in the diagnostics of the S1 root syndrome. It seems to be possible to record H-reflex of the peroneus longus muscle at the L5 level. We discuss the serious problems with volume conduction, when trials to measure proprioceptive reflexes of the L4 and L5 levels are performed. It may also be useful to record the medium latency reflexes in the area of the posterior tibial nerve, which seems to have a different reflex arch (II-afferents – β-efferents) from H-reflex (Ia afferents – α efferents). These measurements are non-invasive and not time consuming, and we hope to be able to add them for the routine ENMG diagnostics, when appropriate.

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“…However, fibrillation potentials are distinctly different from EPSs both by the wave form and by the firing properties [9]. There is also a rare type of fibrillation-like activity, 'myokymic' fibrillations, which are elicited by so-called 'giant miniature end plate potentials' [31,32]. The essential difference between EPSs and fibrillation potentials is the fact that denervation causes prolongation of the refractory period of the muscle fibre and thus the fibrillation potential cannot recur as promptly as action potential in a normal muscle fibre [33].…”

Section: End Plate Spikes Are Different From Fibrillation Potentialsmentioning

confidence: 99%

“…The essential difference between EPSs and fibrillation potentials is the fact that denervation causes prolongation of the refractory period of the muscle fibre and thus the fibrillation potential cannot recur as promptly as action potential in a normal muscle fibre [33]. This causes the relatively long minimum interpotential interval of both rhythmic and irregular fibrillation potentials [31]. On the contrary, EPSs have numerous short intervals less than 30 ms [9].…”

Section: End Plate Spikes Are Different From Fibrillation Potentialsmentioning

confidence: 99%