Mal di testa cervicogenico

Cervicogenic headache and the trigeminocervical convergence

Cervicogenic headache is pain referred to the head from a source in the cervical spine. Unlike other types of headaches, cervicogenic headache has attracted interest from disciplines other than neurology, in particular manual therapists and interventional pain specialists, who believe that they can find the source of pain among the joints of the cervical spine. https://pubmed.ncbi.nlm.nih.gov/19747657/

Clinical criteria for the diagnosis of cervicogenic headache are: (https://pubmed.ncbi.nlm.nih.gov/11472384/)

▶︎ 1 Unilateral headache without side-shift

▶︎ 2 Symptoms and signs of neck involvement: pain triggered by neck movement or sustained awkward posture and/or external pressure of the posterior neck or occipital region; ipsilateral neck, shoulder, and arm pain; reduced range of motion

▶︎ 3 Pain episodes of varying duration or fluctuating continuous pain

▶︎ 4 Moderate, non-excruciating pain, usually of a non-throbbing nature

▶︎ 5 Pain starting in the neck, spreading to oculo-fronto-temporal areas

▶︎ 6 Anaesthetic blockades abolish the pain transiently provided complete anaesthesia is obtained, or occurrence of sustained neck trauma shortly before onset

▶︎ 7 Various attack-related events: autonomic symptoms and signs, nausea, vomiting, ipsilateral oedema and flushing in the peri-ocular area, dizziness, photophobia, phonophobia, or blurred vision in the ipsilateral eye

Satisfying criteria 1 and 5 qualifies for a diagnosis of possible cervicogenic headache. Satisfying any additional three criteria advances the diagnosis to probable cervicogenic headache.

The mechanism underlying the pain involves convergence between cervical and trigeminal afferents in the trigeminal nucleus caudalis (TNC). (https://pubmed.ncbi.nlm.nih.gov/15062532/)

In this nucleus, nociceptive afferents from the C1, C2, and C3 spinal nerves converge onto second-order neurons that also receive afferents from adjacent cervical nerves and from the first division of the trigeminal nerve (V1), via the trigeminal nerve spinal tract. This convergence has been shown anatomically and physiologically in laboratory animals. (https://pubmed.ncbi.nlm.nih.gov/11403743/, https://pubmed.ncbi.nlm.nih.gov/12077000/, https://pubmed.ncbi.nlm.nih.gov/12821523/, https://pubmed.ncbi.nlm.nih.gov/18494984/)

Piovesan and colleagues describe the trigeminocervical convergence mechanisms under different clinical scenarios. (https://pubmed.ncbi.nlm.nih.gov/38388233/)

A. Nociceptive silence. In healthy individuals, innocuous stimuli that could trigger headaches in patients with migraine (fasting, sleep disturbances) or cervicogenic headache (neck movement, external pressure) do not activate the nociceptive centers.

B. Migraine premonitory phase. Up to 88% of migraineurs report symptoms lasting up to 48 h before the headache and aura. Symptoms and neuroimaging studies suggest the involvement of the hypothalamus (fatigue, yawning) and sensory pathways such as the TNC (neck discomfort, shaded in gray). The activation of nociceptive pathways (ascending), subject to the modulation of centers such as the hypothalamus and periaqueductal gray (descending), seems to be part of the mechanism. (https://pubmed.ncbi.nlm.nih.gov/30074545/)

C. Migraine headache phase. The activation of the trigeminovascular system marks this phase. Nociceptive sensitive structures (meninges, vessels) can originate inputs that travel through V1. The trigeminal tract then projects to the second-order neurons of the TNC and upper spinal cord. This convergence probably accounts for migraine pain in trigeminal (usually frontotemporal, indicated in yellow) and non-trigeminal (occipital and suboccipital) areas. Finally, diffuse projections exist through the entire pain matrix (hypothalamus, thalamus, S1).

D. Cervicogenic headache. Conversely, neck structures (joints, vertebrae) can generate nociceptive stimuli transmitted via C1-3. The projections terminate in the upper spinal cord as well as the TNC. This mechanism possibly mediates the pain felt in the anterior (V1) and posterior (C1-3) areas following stimuli in the neck.

V1: 1st branch of the trigeminal nerve; V2: 2nd branch of the trigeminal nerve; V3: 3rd branch of the trigeminal nerve; C1-3: 1st, 2nd and 3rd cervical nociceptive roots; GG: gasserian (trigeminal) ganglion; TNC: trigeminal nucleus caudalis; Hyp: hypothalamus; Th: thalamus; S1: primary sensory cortex.