Headache caused by and symptomatic of secondary angiitis of the central nervous system. Headache is the dominant symptom of this disorder, but lacks specific features.

Diagnostic criteria:
  1. Any new headache fulfilling criterion C
  2. Secondary angiitis of the central nervous system (SACNS) (angiitis of the CNS in the presence of systemic angiitis) has been diagnosed
  3. Evidence of causation demonstrated by either or both of the following:
    1. headache has developed in close temporal relation to other symptoms and/or clinical signs of onset of SACNS
    2. either or both of the following:
      • a) headache has significantly worsened in parallel with worsening of the systemic angiitis
      • b) headache has significantly improved in parallel with improvement in the systemic angiitis resulting from steroid and/or immunosuppressive treatment
  4. Not better accounted for by another ICHD-3 diagnosis.

Headache is the dominant symptom in CNS angiitis (either primary or secondary). It is present in 50-80% of cases according to the diagnostic methods used, respectively angiography and histology. Nevertheless it has no specific features and is therefore of little diagnostic value until other signs are present such as focal deficits, seizures, altered cognition or disorders of consciousness. However, the absence of both headache and CSF pleocytosis makes CNS angiitis unlikely.

The difficulty here is two-fold: 1) diagnosing CNS angiitis in a patient known to have one of the many conditions that can cause angiitis; 2) finding the underlying condition (inflammatory, infectious, malignant, toxic) in a patient presenting with CNS angiitis.

The pathogenesis of 6.4.3 Headache attributed to secondary angiitis of the central nervous system is multifactorial: inflammation, stroke (ischaemic or haemorrhagic), raised intracranial pressure and/or subarachnoid haemorrhage.