Characterization of Fasciculation Potentials (FPs) in Amyotrophic Lateral Sclerosis (ALS) and Peripheral Nerve Hyperexcitability Syndromes (PNH).

This study is aimed at investigating the features of fasciculation potentials (FPs) in amyotrophic lateral sclerosis (ALS) and peripheral nerve hyperexcitability syndromes (PNH). Needle electrophysiologic examination (EMG) was performed for 5-15 muscles in the ALS and PNH patients. The spontaneous activity of fasciculations and fibrillations/sharp-waves (fibs-sw) was recorded. The distribution, firing frequency, and waveform parameters of FPs in muscles were calculated and compared. In total, 361 muscles in ALS patients and 124 muscles in PNH patients were examined, with the FP detection rates of 45.1% and 53.2%. Moreover, the ALS patients with the upper limb onset had the highest FP detection rate. Fasciculations occurred more frequently in the upper limbs than in the lower limbs in ALS and PNH. The detection rate of fibs-sw in the bulbar muscle was relatively low, which could be elevated when combining fibs-sw and FPs. Benign FPs in PNH were of smaller amplitude, shorter duration, and fewer phases/turns, compared with malignant FPs in ALS. The FP area in PNH was significantly smaller than that in ALS. The incidence of polyphasic FPs in ALS was distinctly greater than that in PNH. The firing frequency of FPs in PNH was higher than that in ALS. There was no significant difference in the amplitude, duration, phases and turns, and area of FPs between groups with and without fibs-sw in the muscles of normal strength in ALS. Conclusively, it is necessary to detect the FPs in the thoracic and bulbar muscles of patients suspected having ALS. FP parameters in ALS are significantly different from PNH.

[Myokymia].

Myokymia is one of the involuntary movements, which is characterized by undulatory muscle spasm, similar to the worm's crawl. Sometimes muscle pain, itchy sensation, dysautonomia and other symptoms are associated with it. Cases showing normal neurological findings are rare. Myokymia is caused by various diseases, such as, multiple sclerosis, hypothyroidism, Guillan-Barre syndrome and so on. Generally myokymia is classified into two types, i.e. limb myokymia and facial myokymia according to the site. On the other hand, myokymia with hyperhidrosis is known as Issacs syndrome. There are many opinions about the pathogenesis and mechanism in the myoneural junction, peripheral nerve or spinal cord, however these are not established. Further investigation of myokymia is expected.