What are the other Names for this Condition? (Also known as/Synonyms)

• Headache Attributed to CM1
• Headache due to Chiari Malformation Type I
• Headache due to CM1

What is Headache Attributed to Chiari Malformation Type I? (Definition/Background Information)

• Headache Attributed to Chiari Malformation Type I (CM1) is a headache disorder that occurs secondary to Chiari malformation type I, which is a condition in which a portion of the brain, called the cerebellar tonsils, slips down through the opening at the base of the skull (a defect termed herniation). This puts pressure on the spinal cord and the brainstem resulting in associated signs and symptoms
• Due to this, occipital or suboccipital lobe headaches that are triggered by coughing and Valsalva-like maneuver develops. These mild-to-severe intensity headaches are often of short durations, typically lasting 5 minutes or less. In most cases, on successful treatment (including surgical decompression, if needed) of Chiari malformation type I, a remission of the headaches within 3 months is noted
• Depending on the degree of herniation and severity of CM1, apart from recurrent headaches, the other signs and symptoms noted may include neck pain, walking with a gait, dizziness, speech and swallowing difficulties, vision disturbances, and numbness and tingling sensation

The criteria for diagnosis of Headache Attributed to Chiari Malformation Type I (CM1) as outlined by the International Headache Society (IHS) is given below:

• Chiari malformation type I (CM1) has been demonstrated
• Any headache fulfilling the criterion below

Evidence of causation demonstrated by at least two of the following:

• Either or both of the following:
  • Headache has developed in temporal relation to the CM1 or led to its discovery
  • Headache has resolved within 3 months after successful treatment of the CM1
• Headache has one or more of the following three characteristics:
  • Precipitated by cough or other Valsalva-like maneuver
  • Occipital or suboccipital location
  • Lasting less than 5 minutes
• Headache is associated with other symptoms and/or clinical signs of brainstem, cerebellar, lower cranial nerve and/or cervical spinal cord dysfunction

Not better accounted for by another ICHD-3 diagnosis.

(Source: International Headache Society Classification ICHD-3, London, United Kingdom)