Idiopathic Intracranial Hypertension (IIH) Clinical Presentation

Updated: May 17, 2017
  • Author: Mark S Gans, MD; Chief Editor: Andrew G Lee, MD  more...
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Presentation

History

Patients with idiopathic intracranial hypertension (IIH) usually present with symptoms related to increased intracranial pressure (ICP) and papilledema, including headache, transient visual obscurations, and diplopia due to unilateral or bilateral abducens nerve (cranial nerve [CN] VI) palsy. Rarely, patients presenting with increased ICP with related optic nerve edema may be asymptomatic. Nonspecific symptoms may include dizziness, nausea, vomiting, photopsias, retrobulbar pain, and pulse-synchronous tinnitus. [2]

Symptoms of elevated intracranial pressure (ICP)

Headaches are recorded in almost all IIH patients. [55] They are typically nonspecific and vary in type, location, and frequency. The pain is generally described as being diffuse, worsening in the morning and being exacerbated by the Valsalva maneuver.

Patients who present with double vision most frequently complain of horizontal displacement of the images. Horizontal diplopia is a symptom of a false-localizing CN VI palsy. Vertical diplopia is rare, but it has been reported.

Pulsatile tinnitus may be reported. This is a rhythmic sound, heard in one or both ears, with a pulsing synchronous rhythm that may be exacerbated by the supine or bending position.

Radicular pain (usually in the arms) is an uncommon symptom.

Symptoms of papilledema

Transient visual obscurations occur in most patients. The disturbance can last up to 30 seconds and is described as a dimming or blackout of vision in one or both of the eyes. These obscurations may be predominantly or uniformly orthostatic (ie, developing with standing up or bending over).

Progressive loss of peripheral vision in one or both of the eyes may be noted. Typically, the vision loss starts in the nasal inferior quadrant and is followed by loss of the central visual field (possibly affecting visual acuity) and, finally, loss of color vision.

Blurring and distortion (ie, metamorphopsia) of central vision is caused by macular wrinkling and subretinal fluid spreading from the swollen optic disc.

Sudden visual loss is due to intraocular hemorrhage secondary to peripapillary subretinal neovascularization related to chronic papilledema.

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Physical Examination

The most significant physical finding in patients with IIH is bilateral disc edema secondary to the increased ICP.

This 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 in addition to subretinal hemorrhages are poor visual prognostic signs. In some instances, the disc swelling is asymmetric; in rare instances, the appearance of the optic nerve is relatively normal.

If left untreated, chronic disc swelling eventually leads to clinically significant visual loss. Although 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 (eg, nasal depression, nasal steps, and arcuate scotomas).

The central visual field is affected in end-stage chronic papilledema. Sudden loss of central vision may result from an associated anterior ischemic optic neuropathy, a vascular occlusion, or an associated subretinal neovascular membrane.

Diplopia in patients with IIH is invariably due to unilateral or bilateral CN VI palsy. These CN palsies diminish with the lowering of the ICP. Occasionally, patients with diplopia present with oculomotor or trochlear nerve palsy. In rare instances, vertical diplopia is due to a skew deviation.

Visual function testing

Visual function tests—in particular, ophthalmoscopy (funduscopy), visual field assessment, and ocular motility examination—are the most important parts of the neurologic examination for diagnosing and monitoring patients with IIH.

Ophthalmoscopy

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 (see the images below). The severity of papilledema is 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 disc and leaving the disc. This grading scale correlates with optical coherence tomography (OCT) findings of retinal nerve fiber layer thickness. [56]

Left optic disc with moderate chronic papilledema 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 atroph 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. Disc margin at upper and lower poles and nasally is obscured by some residual edema in nerve fiber layer and gliosis that often persists even after all edema has resolved.

Visual field assessment

The first sign of incipient postpapilledema optic atrophy 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 (see the image below).

Most common early visual field defect in papillede 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.

Formal visual field testing should be conducted in patients with suspected IIH. Goldmann-type dynamic perimetry and computerized automated Humphrey-type static perimetry are both options for testing visual field. While Goldmann-type dynamic perimetry provides reliable information concerning the most peripheral parts of the visual field, the results of the test are operator-dependent. Although Humphrey-type static perimetry usually does not test beyond 30° of eccentricity, it is less operator-dependent. Thus, Humphrey-type static perimetry is the recommended test for more reliable long-term follow-up. [57]

Visual acuity is usually normal until significant peripheral visual field loss with progressive postpapilledema optic atrophy has occurred.

Color vision is usually tested in the office with color-confusion type plates, most commonly the Ishihara or Hardy-Rand-Rittler (HRR) plates. Unlike visual acuity testing, it is not sensitive in picking up early postpapilledema optic atrophy, because color perception is concentrated in the central visual field.

Ocular motility examination

Occasionally, limited abduction of one or both of the eyes results from increased ICP. This is termed false-localizing CN VI palsy. It can usually be observed as the patient follows the examiner’s hand to the right and the left with both eyes.

Typically, the involved eye does not move fully outward, leaving some white sclera showing lateral to the cornea on the involved side in comparison with the other side. The speed of the abducting movement also is usually less in the paretic eye than in the normal eye. Some patients with full abduction still show some sclera; therefore, when using this sign demonstrating asymmetry between the eyes in abduction is important.

Diplopia testing is another way to detect even a low-grade CN VI paresis. The patient is told to look at a focal light source (eg, a penlight or Finnoff head), preferably placed more than 3 m away. Either a red glass or a Maddox rod is placed in front of the patient’s right eye. The Maddox rod creates an image of a vertical red line when the patient views a focal light source through it.

In a positive test for limited abduction, the red image (the focal light or line) is displaced to the right of the light in the patient’s view (ie, homonymous or uncrossed diplopia). This indicates that the visual axes are convergent with respect to one another (esotropia, relative weakness of the lateral rectus muscle or muscles, or CN VI palsy).

Alternate cover testing also may reveal a slight corrective saccade when the other eye is covered in patients with CN VI palsies.

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Complications

The only severe and permanent complication of IIH is progressive blindness from postpapilledema optic atrophy. As optic nerve axons die, the apparent degree of papilledema may diminish, giving a false sense of improvement. For this reason (and others), the patients must be monitored with frequent visual field examinations.

The earliest visual loss is in the peripheral fields (outside 30°). For reasons that are not clear, the earliest field loss tends to be in the inferior nasal quadrant. Visual acuity and color vision are not affected until late in the disease, when the peripheral visual field isopters are quite contracted.

Occasionally, a patient may develop an acute loss of vision due to ischemic optic neuropathy or a retinal vascular occlusion associated with the papilledema.

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