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This is an underdiagnosed syndrome [Ducros A et al. 2007] with severe often bilateral and even daily headaches often thunderclap and possibly seizures and focal neurological deficits. The headache which is the dominant feature may wane after 1-3 hours leaving behind a 'background' headache. The headaches can persist almost daily for several weeks. Triggers are varied including sex, sneezing, urinating, defaecation, head movements and bathing. There may be associated nausea and sickness but not to the degree of migraine. It is between 2 and 10 times commoner in females. Mean age of onset is 45. So patients tend to be middle-aged women [Chen S 2010]. Most cases are seen post-partum or with exposure to vasoactive substances. There may be resultant localised subarachnoid bleeding which may be over the convexities of the cerebral hemispheres which is seen in a quarter of cases, parenchymal ischaemic stroke or haemorrhagic stroke seen in 5-10% [Ducros A et al. 2009]. The aetiology is thought to be altered cerebral vascular tone and increased sympathetic tone. The incidence of migraine matches the background population level. There appears to be some possible overlap with posterior reversible encephalopathy syndrome.

Middle aged females presenting with recurrent thunderclap headaches over a few days almost always have reversible cerebral vasoconstriction syndrome.

Precipitants range from post-partum to cannabis, cocaine, amphetamines, LSD, binge drinking, ergotamine, Nasal decongestants, SSRIs, Triptans, Nicotine patches, phaeochromocytoma and cervical dissection. This list is constantly expanding and changing as the diagnosis is increasingly recognised and diagnosed. [Ducros A et al. 2007]

Criteria for RCVS [Calabrese et al. 2007]
Acute and severe headache (often thunderclap headache) with or without focal neurological deficits or seizures
Monophasic course without new symptoms more than 1 month after clinical onset
Segmental vasoconstriction of cerebral arteries demonstrated by angiography (MRA, CTA or catheter)
Exclusion of subarachnoid haemorrhage due to a ruptured aneurysm
Normal or near normal CSF (protein <1g/l, white cells < 15/mm3, normal glucose)
Complete or marked normalisation of arteries demonstrated by a repeat angiogram (MRA, CTA or catheter) after 12 weeks, although they may be normal earlier


It is vital to exclude both SAH and Cervical dissection and CVT and Primary Angiitis of the Central Nervous System. These would be the differential of thunderclap headache and differentials for SAH.


  • CT head: initially all patient
  • LP result - see table on previous page
  • MRI T1/T2/FLAIR/GRE/DWI/ADC/MRA/MRV and Cervical T1 with fat saturation and contrast. MRI will show infarction or bleed. It may show changes of posterior reversible encephalopathy (symmetrical high signal on FLAIR) or Subarachnoid or subdural bleeding.
  • MRA or DSA: Angiography is diagnostic (DSA is superior to MRA/CTA) and shows various segmental narrowing 'string of beads' of the intracranial vessels which disappear on angiograms within 12 weeks. Vasoconstriction may be missed if angiography done too early. Vasoconstriction may not peak for several weeks after presentation. The CSF which should be done to exclude SAH is usually normal but of there is even small rise in lymphocytes it is prudent to repeat a few weeks later to demonstrate normality and exclude chronic meningitis.
  • Transcranial Doppler may be used to monitoring the cerebral vasoconstriction producing increased flow velocities. RCVS may be mistaken for Primary Angiitis of the Central Nervous System (PACNS) due to the presence of similar angiographic features of segmental narrowing of cerebral arteries.


Calcium channel blockers such as Nimodipine have been used. Other agents are under investigation. However despite substantial risks of subarachnoid haemorrhage, ischaemic or haemorrhagic stroke approximately 95% of patients have no long term neurological deficits in two large prospective series [Chen et al. 2009; Ducros et al. 2007]. The prognosis appears to be excellent.

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