History
IIH predominantly affects overweight females of childbearing age. In the landmark study of this disorder, the Idiopathic Intracranial Hypertension Treatment Trial (IIHTT), women accounted for 97% of case. [21] These patients typically present with symptoms related to increased ICP and papilledema. These can include headache (84%), transient visual obscurations (68%), pulse synchronous tinnitus (52%), subjective decrease in vision (32%) and horizontal diplopia (18%). [1] Other symptoms may include dizziness (51%), photophobia (48%), neck pain (42%) and radicular pain (19%). [22] In order to ensure that the diagnosis is limited to IIH, a detailed medical and medication history should be taken focused on symptoms suggestive of obstructive sleep apnea, [23] exogenous substances, and underlying systemic/neurological disorders.
Symptoms of elevated intracranial pressure
The presenting headaches typically are nonspecific and vary in type, location, and frequency. Pain generally is described as being diffuse, worse in the morning, and exacerbated by the Valsalva maneuver. In a large case series, men were less likely than women to report headache (79% vs 89%; P = 0.01). [24]
Trials that assessed headache-related disability found significant patient-reported quality-of-life implications in the physical, mental, and visual domains. [25, 26]
Patients who present with double vision most frequently complain of horizontal displacement of the images. While horizontal diplopia has been reported to occur in 18% of patients, curiously, only a minority are found to have a VI palsy.
Pulsatile tinnitus or pulse synchronous tinnitus is a common symptom. Due to its unusual nature it must be elicited by direct questioning as patients may not readily admit to its occurrence. It can be heard in 1 or both ears, as a pulsing synchronous rhythm that may be exacerbated by the supine or bending position. Its underlying pathophysiology has not been definitively determined.
Symptoms of papilledema
Transient visual obscurations occur in 68% of patients. The disturbance can last up to 30 seconds and is described as a dimming or "graying out" of vision in 1 or both eyes. These obscurations may be predominantly or uniformly orthostatic (ie, developing with standing up or bending over) and can be precipitated by bright light or eye movement. Visual obscurations are not predictive of visual loss or correlated with degree of elevated ICP.
Progressive loss of peripheral vision in 1 or both of the eyes may be noted. Typically, the vision field loss begins insidiously in the nasal inferior quadrant and can progress to overall constriction with subsequent involvement of the central visual field.
Blurring and distortion (ie, metamorphopsia) of central vision is caused by macular wrinkling and subretinal fluid extension from the swollen optic disc.
Sudden visual loss can occur due to a retinal vascular occlusive event, ischemic optic neuropathy or an intraocular hemorrhage secondary to peripapillary subretinal neovascularization related to chronic papilledema.
Physical Examination
Vision
Upon presentation, visual acuity is usually normal in all but the most fulminant cases. Patients who present with poor visual acuity are to be assessed and treated on an emergent basis.
Color vision
Color vision is not usually affected in early to moderate cases of IIH.
Ocular motility examination
Occasionally, limited abduction of 1 or both eyes results from increased ICP. This false-localizing CN VI palsy typically resolves with the lowering of the ICP.
Fundus examination
The most significant physical finding in patients with IIH is bilateral disc edema due to increased ICP.
Papilledema varies from patient to patient and is indistinguishable from optic nerve swelling caused by intracranial space-occupying lesions. In more pronounced cases of disc swelling, macular involvement with subsequent edema and diminished central vision may be present. High-grade and atrophic papilledema and subretinal hemorrhage are poor visual prognostic signs. In some cases, the disc swelling is asymmetric; in the IIHTT, 7% of papilledema cases were asymmetric. [27] In rare instances, the appearance of the optic nerve is relatively normal. Risk of permanent visual loss is higher with more severe papilledema. [28]
Peripapillary flame hemorrhages, venous engorgement, and hard exudates are features consistent with acute papilledema. Telangiectatic vessels on the disc surface, optociliary shunt veins (which exit the disc at its margin), and optic disc pallor are associated with chronic papilledema. The severity of papilledema can be assessed using the Frisen grade. The grading scale is 0 to 5, with 0 being no papilledema and 5 being severe edema with obscured vessels on the surface of the optic nerve head. Unfortunately, in day to day clinical use, the Frisen grading of papilledema is not practical as it is subject to inter and intra observer variability.
Left optic disc with moderate chronic papilledema in a patient with idiopathic intracranial hypertension (pseudotumor cerebri). Paton lines (arc-shaped retinal wrinkles concentric with the disc margin) are seen along the temporal side of the optic nerve head.
Right optic disc with postpapilledema optic atrophy in a patient with idiopathic intracranial hypertension (pseudotumor cerebri). Diffuse pallor of disc and absence of small arterial vessels on surface are noted, with very little disc elevation. The disc margin at the upper and lower poles and the nasal border is obscured by some residual edema in the nerve fiber layer and secondary gliosis that persists despite the resolution of acute edema.
Visual fields
Static perimetry is the foundation of determining the impact of IIH on the visual function of IIH patients. Goldmann-type kinetic perimetry and computerized static perimetry are both options for testing the visual field. However, while Goldmann-type kinetic perimetry provides reliable information concerning the most peripheral parts of the visual field, the testing is highly operator-dependent and the use of this device has become practically obsolete. Although static perimetry usually does not test beyond 30° of eccentricity, it is less operator-dependent and far more readily available in the modern clinical setting. Despite the presence of reliability indices that the static perimetry software provides, performance failures were quite commonly noted in the IIHTT. [29] It is important to have serial visual fields in close succession to avoid overcalling treatment failures when in fact the visual field defects may be due to so called "performance failures".
In the IIHTT, there was an overall depression of the visual field with progressive loss linked to increased eccentricity. [30] Untreated or inadequately treated papilledema will eventually lead to clinically significant visual loss. Although almost all patients present with enlarged blind spots during their initial perimetry, uncontrolled papilledema results in progressive peripheral visual field constriction or nerve fiber bundle defects.
Typically, the first sign of incipient papilledema related optic neuropathy is constriction of the inferior nasal quadrant of the visual field with a border reflecting the nasal horizontal midline (nasal step). This starts in the most peripheral points in the visual field (ie, 50° from fixation) and progresses inward.
The central visual field is affected only in end-stage chronic papilledema.
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Left optic disc with moderate chronic papilledema in a patient with idiopathic intracranial hypertension (pseudotumor cerebri). Paton lines (arc-shaped retinal wrinkles concentric with the disc margin) are seen along the temporal side of the optic nerve head.
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Right optic disc with postpapilledema optic atrophy in a patient with idiopathic intracranial hypertension (pseudotumor cerebri). Diffuse pallor of disc and absence of small arterial vessels on surface are noted, with very little disc elevation. The disc margin at the upper and lower poles and the nasal border is obscured by some residual edema in the nerve fiber layer and secondary gliosis that persists despite the resolution of acute edema.
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Most common early visual field defect in papilledema as optic nerve develops optic atrophy is inferior nasal defect, as shown in left eye field chart (left side of figure). Shaded area indicates defective portion of field. Note sharp line of demarcation between defective lower nasal quadrant and normal upper nasal quadrant along horizontal midline. This is characteristic of early papilledema optic atrophy and is referred to as nasal step or inferonasal step.
