CONVERGENCE OF OCCIPITAL NERVE AND SUPERIOR SAGITTAL SINUS INPUT IN THE CERVICAL SPINAL-CORD OF THE CAT

Co-existence of facial and occipital pain may occur in occipital neura lgia, migraine and cluster headache; suggesting convergence of trigemi nal and cervical afferents. Such convergence has been shown in humans and other animals, but the site and extent of this are uncertain. In a naesthetized adult cats, the superior sagittal sinus and occipital ner ve were stimulated electrically and extracellular recordings made in t he dorsolateral area of the upper cervical cord using glass-coated tun gsten electrodes. Of 49 units in 10 cats, 33 (67%) had input from the superior sagittal sinus and the occipital nerve. Thirteen (27%) had su perior sagittal sinus input and 3 (6%) had occipital nerve input. Conv ergent receptive fields were identified mechanically in 7 units. These experiments in cats show convergent input from occipital nerve and su perior sagittal sinus on dorsolateral area units in two-thirds of case s studied. This experimental site of trigeminocervical convergence may relate to referral of pain in occipital neuralgia and other headaches .