Diagnosing cervicogenic headache.

The notion that disorders of the cervical spine can cause headache is more than a century old, yet there is still a great deal of debate about cervicogenic headache (CEH) in terms of its underlying mechanisms, its signs and symptoms, and the most appropriate treatments for it. CEH is typically a unilateral headache that can be provoked by neck movement, awkward head positions or pressure on tender points in the neck. The headaches can last hours or days, and the pain is usually described as either dull or piercing. Convergence of the upper cervical roots on the nucleus caudalis of the trigeminal tract is the most commonly accepted neurophysiological explanation for CEH. In most cases, CEH is caused by pathology in the upper aspect of the cervical spine, but the type and exact location of the pathology varies substantially among individual cases. Anaesthetic blocks may be necessary to confirm the diagnosis of CEH, showing that the source of pain is in the neck. Differential diagnosis is sometimes a challenge because CEH can be mistaken for other forms of unilateral headache, especially unilateral migraine without aura. Neuroimaging and kinematic analysis of neck motion may aid in diagnosing difficult CEH.