Primary trochlear headache and other trochlear painful disorders.

The trochlear region is a source of distinct pain that may give rise to specific primary pain disorders (primary trochlear headache), but also modulate other pre-existing headache disorders such as migraine. The sensory innervation of this region, by a branch of the ophthalmic division of the trigeminal nerve, may explain the modulatory influence of the nociceptive afferents of this region over migraine headache. We propose the term "trochlear migraine" to refer to the coexistence of strictly unilateral migraine and ipsilateral trochleodynia, with the improvement of migraine being dependent on the resolution of the trochleodynia. Trochleitis is an inflammatory trochleodynia, being frequently idiopathic and rarely secondary to usually immunologic and rheumatologic disorders. We postulate that nociceptive afferents from the inner part of the orbit may sustain the activation of trigeminal neurons, thus sensitizing or exacerbating migraine. Decreasing the possible wind-up induced from this nociceptive afferent stimulation may be effective in controlling headache.