More spontaneous activity

1. What are complex repetitive discharges (CRDs)?
2. What is ephaptic transmission?
3. What are myotonic discharges?
4. What are fasciculations?
5. What are myokymic discharges?

Answers:
1. CRDs are high frequency discharges originating from a principle pacemaker that causes a group of muscle fibers to fire in near synchrony, spreading through through ephaptic transmission. There is a regular interval between each discharge and within each discharge with abrupt start and stop, resembling the sound of a motor boat.
2. Ephaptic transmission is a process of lateral transmission of activity between injured axons.
3. Myotonic discharges are single muscle fiber APs triggered by needle movement, percussion, or voluntary contraction. The rhythm waxes and wanes, sounding like a dive bomber.
4. Fasciculations are spontaneous discharges resulting in intermittent muscle fiber contraction and are pathological when assoc with fibs or PSWs. The hallmark is irregularly firing motor unit.
5. Myokymic discharges are groups of MUAPs firing repetitively, associated with a clnical myokymia, presenting as slow continuous muscle fiber contractions (rippling over the skin). It is semiregular between discharges and within discharges, sounding like marching soldiers.