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.

Headache caused by idiopathic intracranial hypertension (IIH), usually accompanied by other symptoms and/or clinical signs of IIH. It remits after normalization of cerebrospinal fluid pressure.

Diagnostic criteria:
A. Any headache fulfilling criterion C
B. Idiopathic intracranial hypertension (IIH) has been diagnosed, with CSF pressure >250 mm CSF (measured by lumbar puncture performed in the lateral decubitus position, without sedative medications or by epidural or intraventricular monitoring)
C. Evidence of causation demonstrated by at least two of the following:

    1. headache has developed in temporal relation to IIH, or led to its discovery
    2. headache is relieved by reducing intracranial hypertension
    3. headache is aggravated in temporal relation to increase in intracranial pressure

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

Idiopathic intracranial hypertension (IIH) most commonly occurs in young obese women.

IIH should be diagnosed with caution in those with altered mental status and in patients with CSF pressure below 250 mm CSF. In some patients, especially children, an opening pressure of up to 280 mm CSF is normal, but, for most, an opening pressure above 280 mm CSF should be considered elevated.

Body-mass index is only weakly related to CSF pressure, and a mildly elevated CSF pressure should not be dismissed in obese patients.

CSF pressure varies when lumbar epidural pressure monitoring is done for one hour or more, so a single measurement performed within minutes may not be indicative of the average CSF pressure over 24 hours. Diagnostic CSF pressure measurement should be made when the patient is not receiving treatment to lower the intracranial pressure. 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.

Although the majority of patients with IIH have papilloedema, IIH without papilloedema has been observed. Other symptoms or signs of IIH include pulse-synchronous tinnitus, transient visual obscurations, neck or back pain and diplopia. 7.1.1 Headache attributed to idiopathic intracranial hypertension (IIH) lacks specific features. It is frequently described as frontal, retro-orbital, “pressure like” or explosive; migraine-like headache may also occur.