Idiopathic intracranial hypertension

Abstract

Idiopathic intracranial hypertension ((IIH) is characterized by increased cerebrospinal fluid pressure of unknown cause. It is predominantly a disease of women in the childbearing years. Although the cause of IIH remains obscure, it has become clear that loss of visual function is common and patients may progress to blindness if untreated. Diagnosis should adhere to the modified Dandy criteria and other causes of intracranial hypertension sought. IIH patient management should include serial perimetry and optic disc grading or photography. The proper therapy can then be selected and visual loss prevented or reversed. Although there are no evidence-based data to guide therapy, there is an ongoing randomized double-blind controlled treatment trial of IIH investigating diet and medical therapy.

Figure 1

Magnetic resonance venogram showing smooth-walled venous stenoses of the transverse sinus, characteristic of idiopathic intracranial hypertension.

Figure 2

Frequency in percent of symptoms in IIH and a control group. TVO - transient visual obscurations, ICN - intracranial noises. Reprinted with permision.

Figure 3

characteristic “C-shaped halo” with a temporal gap surrounding the disc of early of (Frisén grade 1) papilledema.

Figure 4

With grade II papilledema the halo becomes circumferential.

Figure 5

Grade III papilledema is characterized by Loss of major vessels as they leave the disc (arrow).

Figure 6

Grade III papilledema is characterized by Loss of major vessels on the disc.

Figure 7

Grade V has the criteria of Grade IV plus partial or total obscuration of all vessels on the disc.

Figure 8

A typical inferonasal step defect (arrow) of early optic disc edema in IIH.

Figure 9

Grades of visual loss in IIH found by grading the visual field examinations and then averaging the values from within each grade.

Figure 10

Relationship of VF loss by mean threshold value and papilledema grade.

Figure 11

Gross pathologic specimen of optic nerve (central core), optic nerve sheath and arachnoid trabeculations in between (from Sergott et. al.73) Note the well-developed series of arachnoid trabeculations and the fully unfolded optic nerve sheaths.

Figure 12

Treatment algorithm for idiopathic intracranial hypertension. Visual loss does not include enlargement of the blind spot unless it is compromising vision. Optic nerve sheath fenestration is preferred over steroids.