Effects of Lithium on Electromyographic Recordings in Man

Abstract

(1) EMG investigations in 17 female manic-depressive patients under longterm treatment with lithium salts showed a reduction of the maximal motor nerve conduction velocity (NCV) and of the duration of isolated potentials (IPs) in six cases. These changes, however, were not clearly due to the influence of lithium only. Psychopathology, additional medication, and other variables may have been also responsible for these findings. (2) NCV and IPs as well as the concentration of electrolytes in serum and RBC were determined in seven healthy volunteers before, during, and after lithium administration. NCV was significantly decreased and the duration of IPs slightly increased after l week of lithium intake. The magnesium serum concentration increased steadily during the experimental period. (3) Thus, the possibility cannot be excluded that symptoms of fatigue and muscular weakness in lithium-treated patients might be caused at least partially by changes of the peripheral nervous-muscular function.

Plasma and Erythrocyte Concentrations of Lithium

“…In agreement with Girke et al (1975), we have found a slight decrease in m.c.v. and increase of M-response duration during Li treatment.…”

“…So we have combined the measurements of serum Li with measurements of RBC Li concentration. Moreover we have carried out correlative studies by EMG (Girke et al, 1975;Pinelli et al, 1972) or EEG investigations (Zakowska-Dabrowska and Rybakowski, 1973;Johnson et al, 1970;Watanabe et al, 1973;Platman and Fieve, 1969).…”

Severe Generalized Polyneuropathy in Lithium Intoxication

“…The great discrepancy between the high incidence of NCV changes in patients under lithium therapy [3] and the rare occurrence of severe polyneuropathy in lithium intoxication is another evidence to support our sugges tion. However, more clinical observations and/or further animal experiments are needed to prove our hypothe sis.…”

“…We make a hypothesis that some undetermined factors other than a high serum lithium level are essential to trigger the development of overt polyneuropathy in lithium intoxication. In view of the proposal raised by Girke et al [3], i.e. that NCV changes in patients under lithium therapy are not clearly due to the influence of lithium only, we have more con fidence to believe that a high serum lithium level is not the only etiological factor for a severe polyneuropathy.…”

“…Slowing of motor NCVs has been reported in one third of manic-depressive patients under lithium therapy and in normal volunteers receiving lithium [3], while polyneuropathy is rarely seen in lithium intoxication. Pamphlett and Mackenzie [8] suggested that mild pe ripheral neuropathy may be overlooked in lithium intox ication because of dramatic central nervous system (CNS) damage.…”