Integration of viscerosomatic sensory input at the spinal level.

The major point of this chapter is that there is evidence to support the idea that cervical headache might not only result from injured somatic structures in the neck but also occur because of interactions with visceral organs. The complex arrangement of convergent inputs from somatic and visceral afferent fibers and of the propriospinal pathways in the upper cervical segments may create an environment to precipitate such headaches (Fig. 8). It is possible that the soreness experienced in the muscles innervating the neck may not be due to direct injury but may occur as muscle hyperalgesia that is often associated with visceral pain (Giamberardino, et al., 1993). Much more research is required to understand these complex interactions before patients who suffer pain of cervical headache can be treated satisfactorily.