Table 1

Summarised International Headache Society criteria for headache attributed to Chiari I malformation (CIM)

Diagnostic categoryCriteria
A. Headache fulfilling criterion C
B. CIM has been demonstrated (MRI—5 mm caudal descent of cerebellar tonsils OR 3 mm caudal descent of cerebellar tonsils plus crowding of subarachnoid space at craniocervical junction)
C. Evidence of causation as demonstrated by ≥2 of the following

  1. Either one or both of

    1. headache developed in temporal relation to CIM

    2. headache resolved within 3 months after successful treatment of CIM

  2. Headache has ≥1 of the following characteristics

    1. precipitated by cough or other Valsalva-like manoeuvre

    2. occipital or suboccipital location

    3. lasting <5 min

  3. Associated with other symptoms/clinical signs of brainstem, cerebellar, lower cranial nerve and/or cervical spinal cord dysfunction

D. Not better accounted for by another ICHD-3 diagnosis

  • ICHD-3, International Classification of Headache Disorders, 3rd edition.13