Impact of hyponatremia on nerve conduction and muscle strength

Abstract

Whereas chronic mild-to-moderate hyponatremia has no impact on muscle strength, we demonstrate for the first time an impact of profound hyponatremia on nerve conduction studies. Further studies are needed to ascertain the contribution of these latter results on gait disturbances, propensity to falls and attention deficits associated with hyponatremia.

Impact of chronic hyponatremia on neurocognitive and neuromuscular function

“…Possibly, as the analysis suggested a correspondence between degree of hyponatremia and chances of normalisation after treatment, a trial with longer duration and consequent correction of hyponatremia would show a beneficial effect of serum sodium normalisation on neurocognitive and neuromuscular function. Accordingly, in the two comparable studies which showed a benefit after serum sodium correction, the time point for the second neuromuscular testing was defined as achievement of normonatremia …”

“…Possibly, as the analysis suggested a correspondence between degree of hyponatremia and chances of normalisation after treatment, a trial with longer duration and consequent correction of hyponatremia would show a beneficial effect of serum sodium normalisation on neurocognitive and neuromuscular function. Accordingly, in the two comparable studies which showed a benefit after serum sodium correction, the time point for the second neuromuscular testing was defined as achievement of normonatremia 13,24 T A B L E 3 Descriptive comparison as mean (standard deviation) according to different neuromuscular balance tests with eyes closed: force vector area (cm 2 ), orthostatic power (watts), and external muscle activity (Hz) The major strength of our study is our study design with standardised and computerised measurement methods and reproducible processes, allowing a detailed assessment of hyponatremia associated symptoms as well as neurocognitive and neuromuscular functional impairment. However, our study also has limitations.…”

“…Two further clinical studies showed an improvement of mental cognition and quality of life after normalisation of chronic hyponatremia, but did not assess the neurocognitive and neuromuscular function. Another trial failed to show an improvement in the overall neurocognitive composite scores after inducing normonatremia except for the domain of rapid motor movements, while a study using neuromuscular test showed no effect of hyponatremia correction on muscle strength but improvement in the nerve conduction tests …”

“…Another trial failed to show an improvement in the overall neurocognitive composite scores after inducing normonatremia except for the domain of rapid motor movements, 23 while a study using neuromuscular test showed no effect of hyponatremia correction on muscle strength but improvement in the nerve conduction tests. 24 The aim of this prospective case-control study was the investigation of the subclinical manifestation of chronic non profound hyponatremia on subjective well-being as well as neurocognitive and neuromuscular function in clinically unimpaired subjects by assessment before and after therapeutic short-term intervention as well as by direct comparison to healthy normonatremic volunteers.…”

Mild Hyponatremia is Associated with Low Skeletal Muscle Mass, Physical Function Impairment, and Depressive Mood in the Elderly

“…did not observe any signi cant difference in GS when the sodium concentration was increased from 127.7 ± 2.5 mmol/L to 136.1 ± 1.8 mmol/L in humans. (25) Mild hyponatremia itself is correlated with muscle strength but the level of hyponatremia may be more severe, noticeably lower than the cutoff.…”