Terminology

The syndrome known as pseudotumor cerebri (PTC) is generally thought of as a condition characterized by increased intracranial pressure (ICP) without evidence of dilated ventricles or a mass lesion by imaging, normal cerebrospinal fluid (CSF) content, and papilledema occurring in most cases (but not all—see later) in young, obese women without any clear explanation. The terminology used to describe this condition has changed dramatically over time and continues to change as new issues regarding its etiology are raised. The condition was probably first described by Quincke in 1897¹; however, the term pseudotumor cerebri appears to have first been used in 1914.² Subsequently, Foley suggested calling the condition “benign intracranial hypertension” because it appeared to have a much more benign neurological prognosis than increased ICP caused by a central nervous system mass lesion or infection.³ Because significant visual morbidity may result from PTC, use of the adjective “benign” is no longer considered appropriate terminology. Instead, most physicians use the term idiopathic intracranial hypertension (IIH) for cases of PTC that occur in young, obese patients and the term secondary pseudotumor cerebri for the rare cases in which a cause (e.g., drug induced) is identified.^4,5 The problem with this terminology is that a substantial percentage of patients with so-called IIH have been shown to have some degree of lateral sinus stenosis. At issue is whether the stenosis is the cause or the effect of the increased ICP. If one believes—as many do—that the stenosis is the cause of the condition, patients previously considered to have IIH but who exhibit lateral sinus stenosis may have to be put into the category of secondary PTC, even though they are otherwise identical in body habitus, age, and other features as patients without lateral sinus stenosis. This issue is discussed in more detail later. It suffices here simply to state that (1) one should not use the term pseudotumor cerebri synonymously with idiopathic intracranial hypertension, and (2) some patients previously thought to have IIH because no cause could be identified may now be considered to have a condition caused by stenosis of one or both lateral sinuses. In this chapter I use the terms pseudotumor cerebri to describe the general condition and idiopathic intracranial hypertension when discussing the condition formerly thought to have no identifiable cause but, in some cases, appears to be associated with lateral sinus stenosis. It should also be emphasized that some authors use the term pseudotumor syndrome for patients with increased ICP unassociated with ventricular dilation, evidence of cerebral edema, or an intracranial mass lesion but with abnormal CSF content. This condition occurs in some patients with aseptic, carcinomatous, or lymphomatous meningitis. This chapter deals only with patients who have true PTC, not this “pseudotumor syndrome.”

Epidemiology

PTC affects infants, children, and young adults. The idiopathic form (i.e., IIH), which represents about 90% of cases, is typically a disorder of obese females of childbearing age,⁵ but it may also occur in men and young children.⁶ The incidence of IIH varies throughout the world. Two studies in the United States estimated the incidence to be approximately 0.9 per 100,000 in the general population with a female-to-male ratio of 8 : 1.^7,8 The incidence increases to 3.5 per 100,000 in women aged 20 to 44 years and further increases to 13 per 100,000 in women who are 10% over ideal weight and 19 per 100,000 in women who are 20% over ideal weight.⁷ A recent and rapid gain in weight is associated with an increased risk for IIH in both obese and nonobese patients.^9,10 All races are affected, and there is evidence that African Americans have a worse prognosis than white individuals regardless of treatment.¹¹ Secondary PTC, which accounts for about 10% of cases, may develop at any age and occurs with equal frequency in both sexes.

Symptoms and Signs

Primary PTC (i.e., IIH) and secondary PTC produce identical symptoms and signs. Occasionally, the condition is asymptomatic and discovered during a routine ophthalmic examination when papilledema is found¹²; however, the most common symptom, as well as most often the initial symptom, is headache, which occurs in approximately 90% of cases.^4,5 The character of the headache is not specific, but it is generally different from previous headaches and is severe.^13–15 It most frequently is bifrontal or generalized, pressure-like, and often associated with neck pain.¹³ The headache usually occurs daily but may be intermittent. Many patients have migrainous features, including unilateral pain, nausea, vomiting, photophobia, and phonophobia.¹⁵ It may awaken the patient from sleep or resemble a “brain tumor headache” that is worse in the morning and aggravated when cerebral venous pressure is increased by Valsalva maneuvers (e.g., coughing, sneezing).

The second most common symptom of PTC is transient visual loss. Typical transient obscurations of vision (TOVs) are reported by about 70% of patients.^4,5 They may be unilateral or bilateral and generally last only a few seconds. They are thus quite different from the TOVs experienced by patients with carotid artery or cardiac valvular disease, which typically last at least 15 minutes. The TOVs occurring in patients with PTC are often precipitated by a change in posture (e.g., bending over, arising from a stooped position) or rolling the eyes. In some patients, TOVs occur 20 to 30 times a day. The visual loss may be partial or complete. TOVs indicate the presence of optic disc swelling, usually severe, but are not a sign of a poor prognosis. They probably reflect transient ischemia of the optic disc caused by the papilledema.

A small percentage of patients with PTC complain of visual loss that may be characterized as an enlarged dark spot in the temporal visual field. This is caused by enlargement of the physiologic blind spot as a result of severe papilledema. Tunnel vision and central visual loss may occur in more chronic cases¹³ or acutely from ischemic optic neuropathy.¹⁶ The visual loss in patients with PTC may also arise from local associated ocular causes, such as macular hemorrhage, exudates, or accumulation of subretinal fluid.^17,18

Diplopia, reported by approximately 40% of patients, is usually horizontal and results from unilateral or bilateral abducens nerve paresis, a nonlocalizing feature of increased ICP.^4,5 Rarely, there is vertical diplopia from trochlear nerve paresis, oculomotor nerve paresis, or skew deviation.¹⁹

Pulsatile tinnitus is not uncommon in patients with PTC, although such patients rarely mention this symptom unless asked directly about it. Frequently described as a whooshing sound, hearing a heartbeat in the head, or a high-pitched noise, pulsatile tinnitus is thought to reflect flow disturbances within the cerebral venous system.^13,20 It may be unilateral or bilateral and is often more prominent at night or in quiet surroundings.

Focal neurological deficits in patients with PTC are extremely uncommon, and their occurrence should make one consider alternative diagnoses²¹; however, patients with chronic PTC are more likely to be anxious or depressed or feel that they have a worse quality of life than age-matched control subjects.^9,10,22 Cognitive deficits are less well substantiated and may be a manifestation of headache-related concentration difficulties, depression, or anxiety.²²

Papilledema is the diagnostic hallmark of PTC and is present in almost all patients.^4,5 The papilledema of PTC is identical with that in patients with other causes of increased ICP. It is almost always bilateral and symmetrical (Fig. 150-1), but it may be asymmetric or, occasionally, unilateral (Fig. 150-2).²³ Several grading systems for papilledema have been proposed over the years. The system most commonly used is the Frisén system, which separates the appearance of the optic disc into stages ranging from normal appearance (stage 0) to very severe papilledema (stage 5) (Table 150-1 and Fig. 150-3).²⁴ The importance of this grading system cannot be overemphasized because it—along with color vision assessment and visual field testing—is crucial in determining the appropriate management of any patient with papilledema, particularly a patient with PTC. It should also be noted that PTC may occur without papilledema, but it is uncommon and the diagnosis should be made with caution in such a setting, preferably only after continuous CSF pressure monitoring.²⁵

FIGURE 150-1 A and B, Bilateral, symmetrical papilledema in a patient with pseudotumor cerebri.

FIGURE 150-2 A and B, Bilateral, asymmetric papilledema in a patient with pseudotumor cerebri.

TABLE 150-1 Papilledema Grading System (Frisén Scale)

From Frisén L. Swelling of the optic nerve head: a staging scheme. J Neurol Neurosurg Psychiatry. 1982;45:13-18.

FIGURE 150-3 Stages of papilledema according to the Frisén grading scale. A, Very early papilledema (Frisén stage 1). B, Early papilledema (Frisén stage 2). C, Moderate papilledema (Frisén stage 3). D, Marked papilledema (Frisén stage 4). E, Severe papilledema.

As with papilledema from other causes, loss of central visual acuity is uncommon in patients with PTC unless they have sustained severe damage to the optic nerves or there is an intraocular cause, such as macular hemorrhage or exudates, all of which should be easily visible with an ophthalmoscope. Instead, the visual dysfunction usually begins with visual field defects similar to those that occur in patients with glaucoma (Fig. 150-4). Thus, loss of central acuity in a patient with PTC who has severe papilledema and no evidence of an intraocular cause for the loss of vision indicates an advanced process, requires immediate and aggressive treatment, and confers a poor prognosis for recovery, even if urgent therapy is undertaken immediately.

FIGURE 150-4 A-E, Progression of visual field defects in papilledema with corresponding appearance of the optic disc.

Postpapilledema optic atrophy occurs in untreated or inadequately treated patients after a variable period, usually several months, but occasionally within weeks of the onset of symptoms (Fig. 150-5). Some patients have persistent chronic papilledema without visual deterioration or optic atrophy. Postpapilledema optic atrophy in patients with PTC usually develops symmetrically, but just as papilledema may be asymmetric, so postpapilledema optic atrophy can be asymmetric. In some patients a pseudo–Foster Kennedy syndrome develops that is characterized by postpapilledema optic atrophy in one eye and papilledema in the other (Fig. 150-6).²⁶

FIGURE 150-5 Progression from fully developed papilledema to postpapilledema optic atrophy. A, Left fundi showing severe papilledema. C and D, Two weeks later, the optic disc is less swollen but pale. E and F, Four months later, the disc is diffusely pale, the retinal vessels are sheathed, and the nerve fiber layer is absent.

FIGURE 150-6 A and B, Foster Kennedy syndrome consisting of papilledema in one eye and postpapilledema optic atrophy in the other in a patient with pseudotumor cerebri.

Diagnosis

The diagnosis of both IIH and secondary PTC requires that there be no intracranial or spinal mass, no evidence of hydrocephalus, documented increased ICP, and normal CSF contents.^4,5 Thus, the diagnosis cannot and should not be made without neuroimaging and a lumbar puncture (LP).

Secondary Pseudotumor Cerebri

IIH is a diagnosis of exclusion that occurs primarily in young obese women and, occasionally, in obese men with no evidence of any underlying disease^4,5,35,36; however, about 10% of cases of PTC are associated with a number of different conditions. Suspicion of a secondary cause of PTC is heightened in prepubertal children, men, nonobese women, and otherwise typical patients with rapidly progressive visual loss that does not respond to treatment. Secondary causes of PTC include (1) impairment or obstruction of cerebral venous sinus drainage by intrinsic or extrinsic lesions, (2) endocrine and metabolic dysfunction, (3) exposure to exogenous drugs and other substances, (4) withdrawal of certain drugs, and (5) systemic illnesses.^4,5,35,36 It is important to realize that although many conditions have been reported to be associated with PTC, relatively few are likely to be true associations. Tables 150-2 to 150-5 list the best substantiated and most frequently observed ones.

TABLE 150-2 Causes of Obstruction/Impairment of Cerebral Venous Drainage Associated with Secondary Pseudotumor Cerebri

TABLE 150-3 Endocrine and Metabolic Disturbances Associated with Pseudotumor Cerebri

TABLE 150-4 Exogenous Substances Whose Exposure, Ingestion, or Withdrawal Has Been Associated with Pseudotumor Cerebri

TABLE 150-5 Systemic Illnesses Associated with Pseudotumor Cerebri

Complications

The natural history of PTC is variable. In some cases it is a self-limited condition; in others, ICP remains elevated for many years, even if the systemic and visual symptoms resolve. In still other patients, the condition resolves but then recurs months to years later or a stable condition suddenly worsens.³⁷ The most feared complication of PTC is permanent visual loss. In one long-term study performed before the era of modern neuroimaging, 57 patients with a diagnosis of PTC were monitored for 5 to 41 years.³⁸ Severe visual impairment occurred in one or both eyes in 14 patients (24.5%), and in 7 patients the visual loss occurred months to years after the initial symptoms appeared. In more than 80% of the patients in this study, CSF pressure remained elevated, regardless of the treatment that the patients had received. In a more recent prospective study of 50 patients treated for IIH, visual acuity was worse than 20/20 in 13%.¹³ The effects of even self-limited PTC on the visual system may be catastrophic. PTC produces significant visual impairment in approximately 25% of patients and permanent visual field abnormalities in most patients.^4,5,13

Pathophysiology

Although the mechanism by which ICP is increased may be clear in some cases of secondary PTC, the reason that the ventricles do not dilate is not. Furthermore, even the mechanism by which ICP becomes increased may be unclear, not only in cases of IIH but also in cases of secondary PTC such as those that are drug induced. There is certainly no evidence of brain edema by either standard MRI or diffusion tensor imaging.^39,40 Similarly, assessment of the plasma levels of ghrelin—a hormone that appears to be involved in the regulation of body weight—found no difference between obese patients with and without evidence of IIH.⁴¹ Most evidence points to decreased absorption of CSF with increased cerebral blood volume; however, despite the progress in our understanding of IIH, Fishman’s comment that there are “more speculations than data available” remains applicable.⁴²

Monitoring

Progressive loss of visual function most often develops in patients with PTC in a manner similar to that occurring in patients with chronic open-angle glaucoma in that field defects are usually the first manifestation, followed by progressive visual field constriction, color vision loss, and finally, loss of central vision.^4,5 Thus, once patients complain of reduced visual acuity or “tunnel vision,” they are, as noted earlier, in need of rapid, aggressive intervention because they have advanced disease that will result in permanent visual dysfunction if not treated immediately and that may remain permanent even if treatment is initiated immediately. In addition, the tempo of visual loss in patients with PTC may be rapid or slowly progressive.¹⁶ Conversely, most visual deficits associated with papilledema are reversible if ICP is lowered before severe visual loss or optic nerve ischemia develops.^43,44 Thus, it is imperative that patients be monitored by an ophthalmologist who can assess the best-corrected visual acuity, color vision, visual fields by quantitative static or kinetic perimetry, and severity of papilledema so that appropriate and timely intervention can be performed before permanent visual dysfunction occurs. In addition to standard clinical testing, stereo color photographs of the optic discs obtained on a regular basis are helpful in providing the examiner with objective evidence of the appearance of the optic discs. Although some authors recommend monitoring patients with PTC with devices to measure the thickness of the peripapillary nerve fiber layer,⁴⁵ we have not found such techniques to be particularly useful.

The intervals between clinical assessment of patients with PTC must be individualized. At disease onset, some patients require an evaluation every 1 to 2 weeks until a pattern of progression or stability is established. Other patients can be examined every 1 to 3 months without fear that they will lose vision in the interim, and patients with stable vision and mild or moderate papilledema may need to be examined only every 4 to 12 months. Most patients may be monitored clinically by following their visual status rather than by LP, and once it is established that the results of neuroimaging studies are normal, subsequent scans are not helpful in assessing the patient’s status. There is evidence that puberty is a risk factor for a less favorable visual outcome than that in prepubertal, teenage, or adult persons.⁴⁶ There is also evidence that African Americans are more likely than white individuals to experience severe visual loss regardless of access to care, duration of symptoms, visual status at the time that treatment is begun, or the type of treatment¹¹ and that severe visual loss is twice as likely to develop in men as in women.⁴⁷ Thus, it would appear appropriate to monitor pubescent children, men, and all African American patients very closely and to initiate treatment earlier in the course of the disorder in these groups than in others.

Treatment

Most patients with PTC require concurrent management from more than one physician. A neurologist, ophthalmologist, primary care physician, and neurosurgeon may be involved in the patient’s care. The primary responsibility for coordinating the patient’s treatment is generally relegated to the neurologist or neuro-ophthalmologist; good communication among providers is crucial for a successful outcome. The approach to treatment depends on several factors, including the presence and severity of symptoms such as headache, the degree of visual loss at initial examination, the rate of progression of visual loss, the presence of an identifiable underlying cause (e.g., medication induced, venous sinus thrombosis, Chiari malformation), and detection of factors known to be associated with a poorer visual prognosis (e.g., African American heritage, pubescent child, male gender, high-grade papilledema with macular edema).

Regardless of the cause, the primary goals of treatment in patients with PTC are preservation of vision and alleviation of symptoms. Treatment of PTC in adults and children is similar. In asymptomatic patients with mild papilledema, close observation without specific therapy may be undertaken once an underlying cause is excluded. If a secondary cause is identified, it should be treated appropriately. For example, implicated exogenous agents should be discontinued, obstructive sleep apnea treated, and Chiari malformations decompressed (Fig. 150-7).^48,49 Although treating the underlying condition usually produces improvement, it may also be necessary to use other medical and surgical treatments specifically directed at controlling ICP, at least as temporizing measures.

FIGURE 150-7 Resolution of papilledema after posterior fossa decompression in a patient with a Chiari malformation in the setting of otherwise typical pseudotumor cerebri. Before the decompression, the patient had undergone unsuccessful bilateral subtemporal decompression and optic nerve sheath fenestration. A and B, Bilateral papilledema. C, Sagittal magnetic resonance image showing a Chiari malformation. D and E, Appearance of the optic disc after decompression of the malformation.

When treatment of PTC is required, either medical or surgical treatment may be appropriate and may even be used in combination. Unfortunately, no single treatment is always completely effective. Current practice patterns regarding the treatment of patients with PTC are based largely on case series and clinical experience; there are no randomized trials that have prospectively assessed the effectiveness of treatment in patients with this disorder. Additionally, all drugs currently used to treat patients with PTC are used “off-label.”

Surgical Procedures

Surgery is performed when patients initially have severe optic neuropathy or when other forms of treatment have failed to prevent visual loss. It is not recommended for the treatment of headaches alone. At one time, subtemporal decompression was the procedure of choice, but this has generally been replaced by various operations to divert CSF or by optic nerve sheath fenestration (ONSF).⁶⁷ The decision whether to proceed with a CSF diversion procedure or ONSF depends largely on the local resources available. There is more information available regarding the risks and benefits of ONSF than shunts in patients with PTC.^67,68 Thus, although one may argue that shunting treats the primary pathology of PTC,⁶⁷ the risks and benefits of each procedure must be considered for each patient. Although it appears from one retrospective study that ventriculoatrial and ventriculoperitoneal shunts are more effective than ONSF in alleviating headache and just as effective in decreasing ICP and preserving or improving vision,⁶⁹ most attempts at comparisons are confounded by differences in surgical technique and assessment of outcomes, the retrospective nature of the data, and underreporting of adverse events. In addition to shunt procedures and ONSF, attention has recently focused on the role of cerebral venous sinus stenting for the treatment of PTC in patients who have evidence of lateral or sigmoid sinus stenosis (see later).

Cerebrospinal Fluid Diversion Procedures

In the past, most neurosurgeons preferred to perform a lumboperitoneal shunt procedure for patients in whom surgery was thought to be warranted. The results are generally quite good with respect to visual preservation or improvement and resolution of headache^67,70,71; however, these shunts often malfunction, with at least one revision required within a year after placement, and a Chiari malformation can develop in some patients, particularly children.^70,72 Most of the malformations are asymptomatic or cause minor neurological manifestations, but fatal tonsillar herniation after lumboperitoneal shunting for PTC has been reported.⁷³ Now that stereotactic devices are available for the placement of intracranial devices, many surgeons prefer to perform either a ventriculoperitoneal or a ventriculoatrial shunt procedure for PTC because both are quite effective in relieving headache and lowering ICP in patients with PTC and have less likelihood of failure.^67,69,74,75 In the rare instance in which neither a lumbar nor a ventricular site is available, a shunt can be placed in the cisterna magna.⁷⁶ Although this type of shunt results in reduction of ICP, it is associated with a high complication rate. Indeed, all shunt procedures may be complicated by a variety of problems, including spontaneous obstruction of the proximal or distal ends of the shunt, excessively low pressure, infection, and migration of the distal end of the catheter resulting in chest or abdominal pain.^69–72

Optic Nerve Sheath Fenestration

ONSF (also called “optic nerve sheath decompression”) is a procedure in which the optic nerve just posterior to the globe is exposed and several slits or some other type of opening is made in the dura and arachnoid sheaths of the nerve to allow CSF to escape, thus decompressing the nerve. Both lateral and medial approaches are used, almost all of which incorporate an operating microscope.^68,77–80

Successful ONSF results in resolution of papilledema on the operated side and occasionally on the other, with bilateral improvement in visual function in many cases.^68,78,80 The procedure immediately reduces pressure on the nerve by creating a filtration site that controls the intradural pressure surrounding the orbital segment of the optic nerve.⁸¹ Although the procedure is usually quite effective in reducing pressure on the optic nerve and some patients report substantial improvement in headaches after ONSF, most studies show no effects of ONSF on ICP,^82,83 and it is thought that the decrease in papilledema and the subsequent visual improvement or stabilization result from a local decrease in optic nerve sheath pressure rather than from a generalized decrease in ICP.^82,83 In contrast, one study showed persistently decreased CSF pressure after ONSF as assessed by repeated LP for 3 years after the procedure.⁸⁴ The mechanism of the long-term effectiveness of ONSF may be fibrous scar formation between the dura and optic nerve, thus creating a barrier that protects the proximal optic nerve from the effects of increased ICP.

The risks associated with ONSF, although low, are nevertheless significant. They include infection, transient or permanent diplopia, and transient or permanent loss of vision from central retinal artery occlusion or ischemic optic neuropathy.^67,68 In addition, a substantial percentage of patients require repeated ONSF. Although a second procedure is technically much more difficult and never as effective as the first, most adults and children have stabilization or improvement of vision after ONSF.^67,68,78,80

Venous Sinus Stenting

As noted earlier, it is clear that occlusion of the cerebral venous sinuses can produce increased ICP and papilledema; however, it was previously assumed that there was no role of venous disease in the etiology of PTC. Recently, several groups using ICP monitoring devices have documented high pressures in the venous sinuses in typical cases of PTC.^85,86 These sometimes appear to be secondary to central venous hypertension, but they more often appear to be the result of focal stenotic lesions in the lateral sinuses obstructing cranial venous outflow.^87,88 This has led an increasing number of investigators to suggest that undetected intracranial venous hypertension may, in fact, be the substrate for all cases of PTC,⁸⁶ although others have argued that at least in some cases, the venous hypertension is the effect rather than the cause of elevated ICP because after removal of CSF, the apparent venous sinus stenosis may resolve.^85,89,90 I agree with Corbett and Digre that considering venous hypertension as the cause of the elevated ICP in IIH does not explain why the condition has a disproportionate predilection for young women, why the few men in whom IIH develops are less likely than women to be obese, or why children in whom IIH develops are even less likely to be obese.⁹¹ In addition, I also agree that other conditions that result in increased venous pressure, such as various forms of cardiac disease, are not typically associated with IIH. Nevertheless, the concept of venous sinus stenosis as a cause of PTC has been strengthened by the results of several groups that have found persistence of lateral sinus stenosis after normalization of ICP in patients with presumed IIH.⁹² In addition, other groups have performed stenting in patients with PTC in whom the usual investigations failed to reveal a cause of the raised ICP but catheter venography showed an area of stenosis with a significant pressure gradient across it in one or both lateral sinuses, after which the majority have shown an immediate reduction in ICP to normal with resolution of papilledema and improvement in visual function (Fig. 150-8).^93–96 As with other procedures, stenting is not without potential and occasionally fatal complications and, in my opinion, should be reserved for patients with clear-cut lateral sinus stenosis with evidence by manometry of a significant pressure gradient across the area of stenosis.

FIGURE 150-8 Resolution of papilledema after stenting of the lateral sinus in a patient with lateral sinus stenosis in the setting of otherwise typical pseudotumor cerebri. A and B, Bilateral papilledema. C, Catheter angiogram showing stenosis of the right lateral sinus. D, Appearance of the lateral sinus after stenting. E and F, Appearance of the optic discs after lateral sinus stenting.

Special Circumstances

Prognosis

Most patients in whom the diagnosis of PTC or IIH is made before severe constriction of the visual field or loss of the central field has occurred and in whom appropriate treatment is initiated have an excellent visual prognosis (Fig. 150-9).^5,43,44 In many of these cases, the visual field and sometimes visual acuity and color vision improve once ICP is lowered and the papilledema resolves. Indeed, even patients with severe papilledema associated with substantial visual field defects may experience improvement. Having said this, it is clear that the worse the visual function when treatment is begun, the less likely the patient is to experience visual improvement, and even patients in whom treatment appears to be initiated early in the course of the disorder may experience progressive visual loss. As noted earlier, this appears to particularly be the case in pubescent children,⁴⁶ in men,⁴⁷ and in African Americans¹¹ and is not related, at least in African Americans, to access to care, duration of symptoms, visual status at the time of treatment, or type of treatment.

FIGURE 150-9 Resolution of papilledema after medical therapy in a patient with idiopathic intracranial hypertension and a normal structure of the venous sinuses. A and B, Moderate papilledema at initial evaluation. The patient had normal visual acuity and color vision, but the visual fields showed substantial enlargement of the blind spots. C and D, Three months after beginning therapy with acetazolamide, the optic discs are no longer swollen. The patient’s visual acuity, color vision, and visual field are normal in both eyes.

Patients with IIH whose symptoms and signs have resolved nevertheless have a risk for recurrence months to years later, particularly if they gain weight over a short period.^10,37 Similarly, patients with IIH whose symptoms and signs have been stable for months to years may experience worsening, again often associated with rapid weight gain.³⁷ Thus, all patients with IIH should be told of these risks and should be observed closely or at least be told to contact their physician should they experience a recurrence or worsening of their symptoms or signs.