Trigeminal autonomic cephalalgia (TAC) is the name for a type of primary headache that occurs with pain on one side of the head in the trigeminal nerve area and symptoms in autonomic systems on the same side, such as eye watering and redness or drooping eyelids. TACs include

Cluster headache
Paroxysmal hemicrania (chronic or episodic)
Short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT)
Short-lasting unilateral neuralgiform headache attacks with cranial autonomic symptoms (SUNA)
Long-lasting autonomic symptoms with hemicrania (LASH)TACs can be differentiated by the length and frequency of recurrence of the headaches.Treatment for TACs varies depending on the exact type, but can include medication such as Indomethacin (in the case of chronic paroxysmal hemicrania) or acute and prophylactic therapy (in the case of cluster headache). == References ==
That influence will be electrotonic; depolarization of the surrounding field will induce a partial depolarization
of the pacemaker cells. Therefore, appropriate diagnosis of modulated parasystole relies upon the construction of a “phase response curve” as theoretical evidence of modulation of the ectopic pacemaker cycle length by the electrotonic activity generated by the sinus discharges across the area of protection. In this case, the timing of the arrival of the electronic stimulus will serve to delay or advance the subsequent pacemaker activation. In this case, the coupling intervals between the manifest ectopic and sinus discharges will be either fixed or variable, depending on the cycle length relations between the two pacemakers. See also
Extrasystole

References
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ventricular parasystole
atrial parasystole