Repetitive Nerve Stimulation in Amyotrophic Lateral Sclerosis

Background： Nowadays, it is widely known that decremental responses in low-frequency repetitive nerve stimulation （LF-RNS） are frequently observed in patients with amyotrophic lateral sclerosis （ALS）. The pathological mechanism of this phenomenon remains unknown. This study aimed to illuminate the features of RNS in Chinese patients with ALS. Methods： Clinical and electrophysiological data of 146 probable and definite ALS patients who underwent RNS were retrospectively enrolled and analyzed. LF-RNS （3 Hz） was performed in trapezius, deltoid, abductor digiti minimi （ADM）, quadriceps femoris, and tibialis anterior. High-frequency RNS （HF-RNS, 10 Hz） was performed only in ADM. The two-sample t-test and Chi-squared test were used for statistical analysis.Results： Decremental responses to LF-RNS （≥ 10%） in at least one muscle were detected in 83 （56.8%） of the cases and were most commonly seen in trapezius and deltoid. The incidence ofdecremental response was higher in patients with upper limb onset. Incremental responses to HF-RNS （≥60%） in ADM were observed in 6 （5.6%） of the cases. In 106 muscles with decremental response, 62 （57.4%） muscles had a continuous decremental pattern, more than a U-shape pattern （37 cases, 34.3%）. Nineteen cases showed definite decrements in LF-RNS tests in trapezius, while no abnormalities were found in the electromyography and neurological examination of the sternocleidomastoid muscle, supplied by the accessory nerve as well.Conclusions： Decremental responses in the RNS are commonly observed in ALS patients. The findings regarding the trapezius indicated that some ALS onsets could be initiated by a ＂dying back＂ process, with destruction of neuromuscular junctions （NMJs） before motor neurons. Incremental responses in the ADM implied damage of the NMJs involved both the post and presynaptic membranes.

Contact heat evoked potentials in knowledge workers and unskilled labors

Background:Whether occupation has an impact on contact heat evoked potential(CHEP)results has not been investigated.In this study,we investigated the difference of CHEP parameters between knowledge workers and unskilled labors.Methods:A total of 137 healthy participants were recruited between November 20,2014 and December 31,2016.All participants underwent neurologic examination,laboratory examination,and nerve conduction studies.CHEP was performed on four body sites:the upper border of the distal third of the volar forearm,the upper border of the distal third of the lateral leg,the spinous process of seventh cervical vertebrae(C7),and the spinous process of 12th thoracic vertebrae(T12).Independent t test and nonparametric test were performed using SPSS software to compare the difference of the CHEP parameters between knowledge workers and unskilled labors.Results:The“N2 latency/height”(Z=-2.290,P=0.022)and“P2 latency/height”(Z=-2.020,P=0.043)on the volar forearm of unskilled labors significantly increased than those of knowledge workers.The“N2 latency/height”(F=6.348,P=0.016)and“P2 latency/height”(F=5.920,P=0.018)in the distal leg of unskilled labors significantly prolonged than those of knowledge workers.The N2-P2 amplitude(F=5.797,P=0.020)in the distal leg of unskilled labors significantly decreased than those of knowledge workers.Conclusions:Our study found that significantly prolonged N2 latency and P2 latency and significantly decreased N2-P2 amplitude in the distal leg and the volar forearm in unskilled labors as to knowledge workers.