Influx of calcium ions into neurons is another way of saying hypocalcemia (which is low calcium in the blood), so they are the same (causing seizures). Influx of Ca ions into neurons deplete the Ca ions in the blood. I'm not sure of the exact mechanism, but it could have something to do with either the Na/Ca (Sodium/Calcium) exchange pumps at the neuronal membrane, pumping Ca into cells (therefore causing hypocalcemia), in exchange for pumping Na out of the neurons.