The mechanism for the anticonvulsant effects of magnesium sulfate has not been clearly defined. The primary effect is thought to be central. Hypotheses include raising the seizure threshold by its action at the n-methyl d-aspartate (NMDA) receptor, membrane stabilization in the central nervous system secondary to its actions as a non-specific calcium channel blocker, as well as decreasing acetylcholine in motor nerve terminals [65,66]. Another theory is that it promotes vasodilatation of constricted cerebral vessels by opposing calcium-dependent arterial vasospasm, thereby reducing cerebral barotrauma