7.1.1 Headache attributed to idiopathic intracranial hypertension (IIH)

Previously used terms:

Headache attributed to benign intracranial hypertension (BIH); pseudotumor cerebri; meningeal hydrops; serous meningitis.

Description:

New headache, or a significant worsening of a pre-existing headache, caused by and accompanied by other symptoms and/or clinical and/or neuroimaging signs of idiopathic intracranial hypertension (IIH), with typical features suggestive of IIH.

Diagnostic criteria:
  1. New headache, or a significant worsening1 of a pre-existing headache, fulfilling criterion C
  2. Both of the following:
    1. idiopathic intracranial hypertension (IIH) has been diagnosed2
    2. cerebrospinal fluid (CSF) pressure exceeds 250 mm CSF (or 280 mm CSF in obese children)3
  3. Either or both of the following:
    1. headache has developed or significantly worsened1 in temporal relation to the IIH, or led to its discovery
    2. headache is accompanied by either or both of the following:
      • a) pulsatile tinnitus
      • b) papilloedema4
  4. Not better accounted for by another ICHD-3 diagnosis5,6.
Notes:
  1. ”Significant worsening” implies a two-fold or greater increase in frequency and/or severity in accordance with the general rule on distinguishing secondary from primary headache.
  2. IIH should be diagnosed with caution in those with altered mental status.
  3. For diagnostic purposes, CSF pressure should be measured in the absence of treatment to lower intracranial pressure. CSF pressure may be measured by lumbar puncture performed in the lateral decubitus position without sedative medications or by epidural or intraventricular monitoring. Because CSF pressure varies during the course of a day, a single measurement may not be indicative of the average CSF pressure over 24 hours: prolonged lumbar or intraventricular pressure monitoring may be required in cases of diagnostic uncertainty.
  4. Papilloedema must be distinguished from pseudopapilloedema or optic disc oedema. The majority of patients with IIH have papilloedema, and IIH should be diagnosed with caution in patients without this sign.
  5. 7.1.1 Headache attributed to idiopathic intracranial hypertension may mimic the primary headaches, especially 1.3 Chronic migraine and 2.3 Chronic tension-type headache; on the other hand, these disorders commonly coexist with IIH.
  6. 8.2 Medication-overuse headache should be excluded in patients lacking papilloedema, abducens palsy or the characteristic neuroimaging signs of IIH.
Comments:

Idiopathic intracranial hypertension (IIH) most commonly occurs in obese females of childbearing age (who are also the most likely to be misdiagnosed with IIH).

7.1.1 Headache attributed to idiopathic intracranial hypertension lacks specific features, and commonly resembles 1. Migraine or 2. Tension type headache. Daily occurrence is not required for diagnosis.

Relief of the headache after cerebrospinal fluid (CSF) removal is supportive of the diagnosis but not on its own diagnostic: it may be seen in patients with other headache types (sensitivity 72% and specificity 77% for 7.1.1 Headache attributed to idiopathic intracranial hypertension).

Neuroimaging findings consistent with the diagnosis of IIH include empty sella turcica, distention of the perioptic subarachnoid space, flattening of the posterior sclerae, protrusion of the optic nerve papillae into the vitreous and transverse cerebral venous sinus stenosis.