6.4: Unruptured vascular malformation

Unruptured aneurysms and AVMs may also produce headache. When the headache pattern is completely stereotyped throughout life, strong suspicion should be raised as to the possibility of an arteriovenous malformation rather than migraine with aura (Troost et al., 1979) Sentinel headaches (see above) are reported to occur in about 50 percent of patients days to weeks preceding subarachnoid hemorrhage from berry aneurysm (Day and Raskin, 1986). About half such headaches are reported to be abrupt in onset and severe and have been believed to be due to an initial leak due to partial rupture. Such patients should probably be evaluated with arteriography even if the cerebrospinal fluid does not disclose blood as Day and Raskin (Carlow, 1987) have documented that thunderclap headache episodes may occur as symptoms of an unruptured aneurysm.

Periodic headache, sometimes ipsilateral to the angioma, occurs in 5 to 25 percent of patients with AV malformations (Aminoff, 1986; Bruyn, 1984). Classic Migraine may be simulated in these patients, and may cease after rupture or surgical resection (Troost et al, 1979; Katah and Luessenhop, 1980). Because the prevalence of migraine in the general population is substantial, it remains uncertain whether the headaches associated with vascular anomalies are coincidentally or causally related. In large series of patients with migraine, diagnostic studies do not show angiomas or aneurysms, whether the headache pattern is strictly unilateral or not (Lees, 1962).

Bruyn (1984) used epidemiologic data on angiomas and migraine in the Netherlands to show convincingly that the concurrence of the two conditions is probably not fortuitous. Raskin (1988) has seen a large number of such patients and has treated them with proton beam irradiation, embolization, and surgical extirpation. Following irradiation, as the angioma slowly clots off and shrinks, head pain also gradually diminishes in many, but by no means all, patients. Following embolization, the malformation may dramatically disappear on angiography and headache may also abruptly subside. There is little doubt at present that intracerebral AV malformations may generate migraine-like symptoms. However, intractable headache may continue to be a problem after treatment has totally eradicated a vascular anomaly, so that the relationship between the two disorders remains puzzling and fascinating. Raskin (1988) has treated 12 patients with cerebral angiomas and intractable headache with repeated doses of intravenous dihydroergotamine (DHE) on an 8-hourly schedule and all became headache-free within 48 hours. Many of these patients’ headache problems are solved by approaching them therapeutically as having "migraine" (Raskin, unpublished observations). This suggests that perturbation of forebrain projections from the midbrain raphe by the regional ischemia produced by these anomalies (Homan et al, 1986) may underlie the mechanism of migraine-like symptom production.

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