Typical idiopathic intracranial hypertension Optic nerve appearance and brain MRI findings

Jonathan A. Micieli, MD

Valérie Biousse, MD

A 24 year old African American woman is referred for bilateral optic disc edema after visiting an optometrist to update her glasses. She is asymptomatic Her past medical history is significant for obesity (BMI 39.1) Visual acuity is 20/20 OD, 20/20 OS There is no relative afferent pupillary defect Color vision is 14/14 correct Ishihara plates OU

Figure 1.

Right eye Left eye

Figure 1.

Right eye Left eye

There is bilateral optic disc edema in both eyes. There are peripapillary wrinkles (also known as Paton’s lines) in both eyes (red arrow). The left eye also has pseudodrusen (blue arrow),

which are small discrete refractile bodies seen in patients with longstanding papilledema

Figure 2.

An OCT (optical coherence tomography) image of the optic disc is shown on the left to highlight the peripapillary wrinkles in the right eye.

The wrinkles are commonly seen with optic disc edema. As the disc swells, it displaces the retina causing it

to form a series of folds concentric to the edge of the optic disc

Figure 3.

Left eye Right eye

24-2 SITA-Fast Humphrey visual fields

Figure 3.

Left eye Right eye

Although there are a high number of false positives, visual fields appear normal with only mildly enlarged blind spots

The patient has bilateral optic disc edema and preserved visual function, suggesting

papilledema, which is optic disc edema due to raised intracranial pressure (ICP)

An MRI of the brain without and with contract and MRV of the head with contrast

were ordered to assess for any intracranial process (mass, hydrocephalus,

leptomeningeal enhancement) or venous sinus abnormality (thrombosis, dural fistula

or stenosis) that may lead to elevated ICP

Figure 4.

Sagittal T1 MRI of the brain without contrast Axial T2 FLAIR MRI of the brain without contrast Coronal T2 MRI of the brain without contrast

Figure 5.

MRV of the brain is shown here

Figure 6.

Sagittal T1 MRI of the brain without contrast shows a partially empty sella. There is intrasellar herniation of arachnoid mater and CSF (yellow), which flattens the pituitary gland (red) in the sella turcica (blue). This is the most common MRI finding seen in idiopathic intracranial hypertension. It is also seen in other causes of elevated ICP and may also be seen in the normal population

Patient with a partially empty sella Example of a normal appearing sella

Figure 7.

Mid-sagittal T1 MRI of the brain shows caudal displacement of the cerebellar tonsils. A line (red in the IIH patient and yellow in a normal control) is drawn from the basion to the opisthon defining the foramen magnum.

Sagittal T1 MRI shows mild tonsillar herniation Normal sagittal T1 MRI shown for comparison

Axial T2 FLAIR MRI shows flattening of the posterior globes in this patient (red arrow)

Normal axial T1 MRI shown for comparison

Flattening of the posterior globes may be seen in patients with elevated intracranial pressure and is due to a change in the pressure gradient between the perioptic CSF spaces and the intraocular pressure

Figure 8.

Figure 9.

Coronal T2 MRI shows distention of the CSF spaces around the optic nerves

Example of a normal coronal T2 MRI shown for comparison

Figure 10.

MRV of the brain shows narrowing of the distal transverse sinuses, which is another common finding in patients with idiopathic intracranial hypertension

A lumbar puncture was performed in the left lateral decubitus position and showed: Opening pressure of 39 cm of H2O Nucleated cells: 0 Red blood cells: 2 Protein and glucose within normal limits

The patient was diagnosed with idiopathic intracranial hypertension (IIH) according

to the modified Dandy criteria.

Modified Dandy criteria required for the diagnosis of IIH:

A) Papilledema

B) Normal neurological examination except for cranial nerve abnormalities

C) Neuroimaging: normal brain parenchyma without evidence of structural lesion

or venous sinus thrombosis

D) Normal CSF composition

E) Elevated lumbar puncture opening pressure (> 25 cm of H2O in adults)

She was prescribed acetazolamide and was started on a diet and weight loss

program under the guidance of her primary care physician

Presentation 3 months after presentation 6 months after presentation 1 year after presentation

Figure 11.

OD

OS

Presentation 3 months after presentation

6 months after presentation

1 year after presentation

Figure 12.

OD

OS

OS OD OD OD OD OS OS OS

Her optic disc edema resolved over a period of 1 year with weight loss and acetazolamide, which was discontinued

Summary points: ● Papilledema is defined as optic disc edema due to elevated intracranial pressure

and usually has preserved visual function (unless there is macular edema from severe disc edema or optic atrophy from longstanding papilledema)

● Classic MRI findings in IIH include a partially empty sella, flattening of the

posterior globes, distention of the CSF space around the optic nerves, tonsillar hernitation, skull base meningoencephaloceles, and distal transverse sinus stenosis without any evidence of an underlying structural lesion

Empty sella

Flattening of posterior globes Distention of CSF space

Distal transverse sinus stenosis