Chemo can alter electrolyte levels, one that I can think of that could cause twitching.spasms is magnesium, this electrolyte can also causes cardiac dysrhythmias when severely low. Ask your MD to check a magnesium level. Our oncolgist did not check magnesium levels weekly, however he did give magnesium in IV fluids that were given to my husband weekly. If receiving
Erbitux and chemo then the risk of low magnesium can increase. When my husband started having the spasms I did request a magnesium check and it was slightly low, but this did not happen until about the 4th week into treatment, and he was also getting
Erbitux. It can not hurt to ask.Good luck to you and your sister.