6.7.3 Headache attributed to reversible cerebral vasoconstriction syndrome (RCVS)

Headache caused by reversible cerebral vasoconstriction syndrome, typically thunderclap headache recurring over 1-2 weeks, often triggered by sexual activity, exertion, Valsalva manœuvres and/or emotion. Headache can remain the sole symptom of RCVS.

Diagnostic criteria:
A. Any new headache fulfilling criterion C
B. Reversible cerebral vasoconstriction syndrome (RCVS) has been diagnosed
C. Evidence of causation demonstrated by at least one of the following:

    1. headache, with or without focal deficits and/or seizures, has led to angiography (with “strings and beads” appearance) and diagnosis of RCVS
    2. headache has either or both of the following characteristics:

      a) recurrent during ≤1 month, and with thunderclap onset
      b) triggered by sexual activity, exertion, Valsalva manœuvres, emotion, bathing and/or showering

    3. no new significant headache occurs >1 month after onset

D. Not better accounted for by another ICHD-3 diagnosis, and aneurysmal subarachnoid haemorrhage has been excluded by appropriate investigations.

Reversible cerebral vasoconstriction syndrome (RCVS) is a poorly understood condition, characterized clinically by severe diffuse headaches that typically are of the thunderclap type, mimicking aneurysmal SAH. RCVS is the most frequent cause of thunderclap headache recurring over a few days or weeks. 6.7.3 Headache attributed to reversible cerebral vasoconstriction syndrome may rarely have other modes of onset: progressing rapidly over hours or more slowly over days. Headache is often the only symptom of RCVS, but the condition can be associated with fluctuating focal neurological deficits and sometimes seizures.

Angiography is, by definition, abnormal, with alternating segments of arterial constriction and dilatation (“strings and beads” appearance). However, MR-, CT- and even catheter-angiography can be normal during the first week after clinical onset. Patients with recurring thunderclap headache and a normal angiogram, but fulfilling all other criteria for RCVS, should be considered as having Headache probably attributed to reversible cerebral vasoconstriction syndrome. Brain MRI is abnormal in 30% to 80% of cases, showing various patterns of lesions including intracranial haemorrhages (convexity subarachnoid, intracerebral and/or subdural), cerebral infarctions and/or cerebral oedema corresponding to “posterior reversible encephalopathy syndrome”.

At least half of cases of RCVS are secondary, mainly postpartum and/or to exposure to vasoactive substances including illicit drugs, alpha-sympathomimetics and serotoninergic drugs. The disease is self-limiting in 1-3 months, with resolution of the headache and disappearance of the arterial abnormalities ( hence “reversible”). However, strokes due to RCVS can produce permanent impairment.