A recent update to the modified Dandy Criteria for IIH is used for diagnosis. 

Diagnosis relies on accurately identifying papilledema and excluding secondary forms of intracranial hypertension with neuroimaging. A lumbar puncture to ensure normal cerebrospinal fluid (CSF) constituents and confirm an elevated opening pressure is also needed. 

A diagnosis of definite IIH is reached if the patient has:

•  Either papilledema or a sixth nerve palsy

•  Normal MRI/MRV imaging of the head

•  And a lumbar puncture showing an elevated opening pressure (>25 cm H2O in adults or >28 cm H2O in sedated children) with normal spinal fluid constituents

A minority (5-10%) of patients with IIH may have no papilledema. However, IIH without papilledema is frequently overdiagnosed in patients with chronic primary headache disorders who undergo a lumbar puncture because an elevated lumbar puncture opening pressure is present in 10% of normal patients. It is important to remember that chronic migraine and chronic tension-type headaches each have a prevalence of up to 3% in the general population (and each are a thousandfold more common than IIH without papilledema).  

The presence of multiple MRI features of raised intracranial pressure can assist in making an accurate diagnosis of IIH in those patients without evidence of papilledema or a sixth nerve palsy. 

The presence of three of four MRI features of intracranial hypertension is highly specific for IIH:

•  Empty sella

•  Optic nerve sheath distension

•  Posterior globe flattening

•  Transverse venous sinus stenosis

Testing/Imaging

•  MRI of the brain with and without contrast and MRV of the head should be obtained urgently to exclude an intracranial mass lesion, hydrocephalus, or cerebral venous sinus thrombosis.

•  LP should be performed after neuroimaging in order to confirm normal spinal fluid constituents (cell counts, protein, and glucose) and elevated opening pressure.

•  In patients with severe papilledema, frequent visual acuity and visual field testing (usually 24-2 or 30-2 standard automated perimetry protocols) are important to assess for response to medical therapy and need for surgical intervention. For patients with improving papilledema and vision, visual fields are monitored approximately every three months.

•  Ocular imaging modalities, including photography and optical coherence tomography (OCT), are invaluable for documenting the degree of papilledema and monitoring response to therapy.

•  Orbital B-scan ultrasound helps distinguish papilledema from pseudo-papilledema. Buried optic disc drusen may be identified as a hyper-echoic signal at the optic nerve head. Enhanced-depth OCT imaging of the optic nerve head may also identify optic disc drusen as hypo-reflective cores with adjacent hyper-reflective bands. The presence of optic nerve head drusen does not completely exclude the co-occurrence of papilledema. Clinical history and longitudinal follow-up are essential in these difficult cases.

Robert M. Mallery, MD

Assistant Professor of Neurology, Harvard Medical School

Department of Neurology, Brigham and Women’s Hospital 

Department of Ophthalmology, Mass. Eye and Ear