With regard to cerebrovascular diseases causing head pain, the extracranial temporal and occipital arteries, when involved in giant cell arteritis (cranial or “temporal” arteritis), give rise to severe, persistent headache, at first localized on the scalp and then more diffuse. Most strokes caused by vascular occlusion do not cause head pain. However, with occlusion or dissection of the vertebral artery, there may be pain in the upper neck or postauricular area; basilar artery thrombosis causes pain to be projected to the occiput and sometimes to the forehead; and the ipsilateral eye and brow, and the forehead above it are the most common sites of projected pain from dissection of the carotid artery and occlusion of the stem of the middle cerebral arteries. Expanding intracranial aneurysms of the posterior communicating or distal internal carotid arteries very often cause pain projected to the eye. The distinctive headache caused by aneurysmal rupture is mentioned below and in a separate section later in the chapter.
Infection or blockage of paranasal sinuses is accompanied by pain over the affected maxillary or frontal sinuses. Usually it is associated with tenderness of the skin and cranium in the same distribution. Pain from the ethmoid and sphenoid sinuses is localized deep in the midline behind the root of the nose or occasionally at the vertex (especially with disease of the sphenoid sinus). The mechanism in these cases involves changes in pressure and irritation of pain-sensitive sinus walls.
With frontal and ethmoidal sinusitis, the pain tends to be worse on awakening and gradually subsides when the patient is upright; the opposite pertains with maxillary and sphenoidal sinusitis. These relationships are believed to disclose their mechanism; pain is ascribed to filling of the sinuses and its relief to their emptying, induced by the dependent position of the ostia. Bending over intensifies the pain by causing changes in pressure, as does blowing the nose and air travel, especially on descent, when the relative pressure in the blocked sinus rises. Sympathomimetic drugs, such as phenylephrine hydrochloride, which reduce swelling and congestion, tend to relieve the pain. However, the pain may persist after all purulent secretions have disappeared, probably because of persistent inflammation of the membranes, or blockage of the orifices and dissipation of air from the blocked sinus, so called vacuum sinus headaches.
Headache of ocular origin, located as a rule in the orbit, forehead, or temple, is of the steady, aching type and tends to follow prolonged use of the eyes in close work. However, cranial pain is too frequently attributed to ocular causes, particularly if the external appearance of the sclera and conjunctiva are normal. The main faults are hypermetropia and astigmatism (rarely myopia), which result in sustained contraction of extraocular as well as frontal, temporal, and even occipital muscles. In the uncommon and overemphasized circumstance of a refractive error causing headache, correction rapidly ameliorates the headache. Traction on the extraocular muscles or the iris during eye surgery evokes pain. Patients who develop diplopia from neurologic causes or are forced to use one eye because the other has been occluded by a patch often complain of frontal headache. Another mechanism is involved in iridocyclitis and in acute angle closure glaucoma, in which raised intraocular pressure causes steady, aching pain in the region of the eye, radiating to the forehead. When acute angle closure glaucoma causes headache, the sclera is invariably red. Dilating the pupil risks precipitating angle closure glaucoma, a situation that can be reversed by the administration of pilocarpine 1 percent drops.