Tearing without pain after trigeminal root section for cluster headache.

The cranial autonomic symptoms (CAS) in patients with cluster headache (CH) are considered to occur as a result of intense ophthalmic division pain. Five CH patients underwent transection of the trigeminal nerve root but continued to experience periodic CAS without pain, whereas another five patients continued to experience typical cluster headaches. These findings confirm that CH is generated by a central pacemaker and the pain may be expressed without activation of the peripheral trigeminovascular network.