Axons that are demyelinated cannot conduct as well. Cells called oligodendroglial cells form myelin around segments of axons. Each segment may be as long as several millimeters in length. Also, the axons are usually partially remyelinated after injury. The conduction deficit depends on the extent of demyelination and remyelination.

 Demyelination may stop or slow down conduction. More important, it may prevent the conduction of a train of impulses. Axonal information is often coded in bursts of action potentials. Demyelinated axons may be able to support one impulse but not a rapid train of impulses.

 Demyelination can also reduce the safety factor of conduction. In other words, an impulse has a smaller chance of getting through a demyelinated zone. Demyelination or abnormal myelination reduces the amount of information that an axon can pass through.