INTRODUCTION — Idiopathic intracranial hypertension (IIH) is also commonly called pseudotumor cerebri. It is a disorder defined by clinical criteria that include symptoms and signs isolated to those produced by increased intracranial pressure (eg, headache, papilledema, vision loss), elevated intracranial pressure with normal cerebrospinal fluid composition, and no other cause of intracranial hypertension evident on neuroimaging or other evaluations [1].
While once called benign intracranial hypertension, to distinguish it from secondary intracranial hypertension produced by a neoplastic malignancy, it is not a benign disorder. Many patients suffer from intractable, disabling headaches, and there is a risk of severe, permanent vision loss.
Recommendations for the treatment of IIH are limited by the absence of randomized controlled trials [2]. Moreover, the natural history of untreated IIH is unknown.
This topic will discuss the prognosis and treatment of IIH. The epidemiology, pathogenesis, clinical features and diagnosis of this disorder are discussed separately. (See "Idiopathic intracranial hypertension (pseudotumor cerebri): Epidemiology and pathogenesis" and "Idiopathic intracranial hypertension (pseudotumor cerebri): Clinical features and diagnosis".)
PROGNOSIS — No prospective series describe the natural history of idiopathic intracranial hypertension (IIH). A protracted course lasting months to years appears to be common [3-6]. Generally, symptoms worsen slowly, but a subset has a more fulminant course. With treatment, there is usually gradual improvement and/or stabilization, but not necessarily recovery; many patients have persistent papilledema, elevated intracranial pressure as documented on lumbar puncture, and residual visual field deficits.
Permanent vision loss is the major morbidity associated with IIH. An early, hospital-based study that followed 57 patients for 5 to 41 years found that 24 percent developed blindness or severe visual impairment [7]. Community and clinic-based studies have found a lower rate of severe visual loss of 6 to 14 percent [8-10].
Studies have attempted to identify patients at risk of severe permanent vision loss. Significant vision loss at presentation suggests a higher risk [4,8]. Other risk factors more variably identified in studies include male gender, systemic hypertension, anemia, black race, younger age or onset in puberty, more severe obesity or recent weight gain, higher opening pressure on lumbar puncture, and severe papilledema [4,7,10-14].
A recurrence of symptoms may occur in 8 to 38 percent of patients after recovery from an episode of IIH or after a prolonged period of stability [7,15-17]. Weight gain is a common but not universal antecedent to recurrent IIH [15,18]. The time interval may be as long as several years [16].
Fulminant IIH — A subset of individuals with IIH have a more malignant or fulminant course with rapid development of vision loss within a few weeks of symptom onset [19-21]. This is generally apparent at presentation. To limit the severity of permanent vision loss, more aggressive surgical treatment measures are considered at the outset, often with temporizing measures (eg. serial lumbar punctures, lumbar drain, and/or corticosteroids) employed until surgery can be performed.
GENERAL TREATMENT AND FOLLOW-UP CONSIDERATIONS — The treatment of IIH has two major goals: the alleviation of symptoms (usually headache) and the preservation of vision.
Patients require regular follow-up visits until they stabilize. Follow-up visit intervals are individualized based on the severity, duration, and response to treatment of the clinical manifestations, but initially should be at least monthly. Each office visit should include a best corrected visual acuity, formal visual field testing, and dilated fundus examination with optic disc photographs [4].
Some patients with normal vision and minimal symptoms require no treatment other than monitoring.
Any potential agents that might cause or worsen IIH (eg, tetracycline derivatives) should be discontinued. However, this intervention alone may not be sufficient to manage IIH. (See "Idiopathic intracranial hypertension (pseudotumor cerebri): Epidemiology and pathogenesis", section on 'Medications'.)
Similarly, patients should be questioned regarding symptoms of sleep apnea; diagnostic polysomnography and treatment of sleep apnea should follow where appropriate. The association of sleep apnea and IIH is uncertain, but treatment of sleep apnea has other benefits. (See "Overview of obstructive sleep apnea in adults".)
WEIGHT LOSS — A low-sodium weight reduction program is recommended for all obese patients with IIH and appears to alleviate symptoms and signs in many but not all patients. However, studies documenting benefit are limited to observations in patients who generally receive treatment with other interventions for IIH.
Medically supervised weight loss programs or surgically induced weight reduction (eg, gastric banding or gastric bypass procedures) may be necessary in morbidly obese patients. Case series of IIH patients undergoing gastric surgery report improvement of IIH symptoms and signs including papilledema, headache, tinnitus, and cerebrospinal fluid (CSF) pressure [27-30]. These findings were observed over one to three years after surgery and were associated with mean weight loss of 45 to 58 kg. (See "Surgical management of severe obesity".)
These uncontrolled observations provide limited support for weight loss as a treatment for IIH. Because weight loss takes some time to achieve, other treatments for IIH are generally required at the same time.
Weight gain may be a risk factor for recurrence of IIH. (See 'Prognosis' above.)
Weight loss also has other health benefits. (See "Overview of therapy for obesity in adults", section on 'Benefits of weight loss'.)
MEDICATIONS — Medical treatments include carbonic anhydrase inhibitors, loop diuretics, and corticosteroids.
Carbonic anhydrase inhibitors — Carbonic anhydrase inhibitors are believed to reduce the rate of cerebrospinal fluid production [31]. Acetazolamide is the usual first line treatment for IIH. However, evidence supporting its efficacy is mostly observational. Lowering of CSF pressure with acetazolamide has been documented in IIH patients who underwent continuous ICP recordings [32]. Case series suggest that in patients who can tolerate it, acetazolamide is successful in managing symptoms and stabilizing vision in 47 to 67 percent of patients [33-35]. In addition, in a long-term follow-up study of 54 patients, the average treatment duration for acetazolamide was 14 months [17]. While recurrent episodes of IIH occurred in 38 percent over a mean 6.2 years of follow-up, no recurrences occurred in the setting of ongoing acetazolamide treatment.
In adult patients, we usually start with 500 mg twice per day and advance the dose as required and tolerated by the patient. Although doses of up to 2 to 4 g per day can be administered, many patients develop dose limiting side effects at higher levels. In young children, the recommended starting dose is 25 mg/kg per day with a maximum dose of 100 mg/kg or 2 g per day [33]. The sustained release formulation (Diamox sequels) may be better tolerated by patients who are intolerant of generic acetazolamide, but are substantially more expensive.
Although a sulfa allergy is reported to be a relative contraindication to acetazolamide use, there is little clinical or pharmacologic basis for this recommendation. A true cross-reaction between sulfonamide antimicrobials and the sulfa moiety in acetazolamide and furosemide is unlikely [36]. Before prescribing acetazolamide to patients who report a sulfa allergy, we discuss the risks and benefits of treatment considering the nature of the adverse reaction comprising the reported sulfa allergy. For patients who have had major adverse reactions (eg, Stevens-Johnson syndrome, anaphylaxis), we usually consider that the risk precludes the use of acetazolamide. Allergy consultation or other desensitization protocols may be considered in these patients, but we have not employed these. (See "Sulfonamide allergy in non HIV-infected patients".) However, if the previous sulfa-related reaction was minor, we usually proceed with acetazolamide treatment. We treated 27 patients who had a reported sulfa allergy (excluding those that reported a severe adverse reaction) with acetazolamide; only two patients suffered urticaria, and there were no severe allergic cross-reactions to sulfa [36].
Other medication side effects of acetazolamide include digital and oral paresthesias, anorexia, malaise, metallic taste, fatigue, nausea, vomiting, electrolyte changes, mild metabolic acidosis, and kidney stones. These are usually dose-related. Monitoring of electrolytes is suggested during acetazolamide treatment.
Pregnancy, particularly the first 20 weeks, is often considered a relative contraindication to the use of acetazolamide, which is classified by the FDA as category C for pregnancy risk (table 1). Teratogenic effects have been reported with high doses in animals and a single case of a teratoma was seen in humans [5,37]. If we consider that the benefit of acetazolamide use outweighs potential risks, we do use it in pregnant women after discussion with the patient and the obstetrician and obtaining informed consent. Treatment options are somewhat limited in pregnancy as caloric restriction and the use of other diuretics are also relatively contraindicated during pregnancy [38-40].
Topiramate is an antiepileptic drug that inhibits carbonic anhydrase activity. Its efficacy in the treatment of migraine headaches and its association with weight loss are features that make it an attractive potential therapeutic option in IIH. Case reports and one small unblinded study suggest that topiramate appears to have a similar efficacy to acetazolamide with regard to visual field improvement and symptom relief [41-45]. However, further study is needed before this can be considered a first-line treatment for IIH.
Other carbonic anhydrase inhibitors, such as methazolamide (Neptazane), can also be used in acetazolamide-intolerant patients. We occasionally have had apparent success with these agents.
Loop diuretics — Furosemide (20 to 40 mg per day for adults and 1 to 2 mg/kg per day in children) may be a useful adjunctive therapy to acetazolamide in IIH [33]. In one report of eight children treated with combined therapy of acetazolamide and furosemide, all had a rapid clinical response with resolution of papilledema, reduction in the mean CSF pressure after the first week of treatment, and normalization of CSF pressure within six weeks of starting therapy [46].
The same considerations discussed above regarding sulfa allergy and acetazolamide also apply to furosemide. We, after discussion of risk and benefits with patients, use furosemide in patients whose prior reactions have not included Stevens Johnson syndrome, anaphylaxis, or other severe reactions. Among 21 such patients treated with furosemide, no allergic reactions were noted [36].
Corticosteroids — Although corticosteroids (eg, prednisone) have been recommended for IIH, we avoid the use of corticosteroids in IIH for the following reasons [47]:
In the setting of acute visual loss, a short course of intravenous corticosteroids may be useful as a temporizing measure prior to surgical intervention in IIH. One case series describes successful use of methylprednisolone (250 mg four times a day for five days followed by an oral taper) in conjunction with acetazolamide and ranitidine in four patients with IIH and severe, acute visual loss [20]. We and others suggest not using corticosteroids for long-term management of IIH [48].
Other treatments
Headache prophylaxis — Patients with IIH can continue to have headaches despite improvement in papilledema and visual function. Medications used in the prophylactic treatment of migraine headaches are often used for headache management in IIH, if other treatments described above are not effective in this regard [52]. The choice of agent is influenced by the propensity of some of these medications (eg, valproate, tricyclic antidepressants) to produce weight gain. If these medications are employed, careful monitoring of weight is recommended. (See "Preventive treatment of migraine in adults".)
Analgesic overuse or rebound headaches may be common in patients with IIH [52-54]. Efforts should be made to avoid and treat this condition. (See "Headache syndromes other than migraine", section on 'Medication overuse headache'.)
SERIAL LUMBAR PUNCTURES — Although serial lumbar punctures have been advocated for the treatment of IIH, we do not generally recommend this treatment for the following reasons [55]:
However, serial lumbar punctures can be a useful temporizing measure as a prelude to surgery or in patients who are pregnant who wish to avoid medical therapy [39,40,56].
SURGERY — Patients with IIH who fail, are intolerant to, or are non-compliant with maximum medical therapy and have intractable headache or progressive visual loss appear to benefit from surgical intervention. Potential indications for surgical therapy include [47]:
While deteriorating vision (as suggested by an abnormal visual acuity or worsening visual field deficits) is a universally accepted indication for surgical intervention, other potential considerations need to be balanced against the inherent risks of the surgical procedures and the uncertainties regarding their efficacy.
The two main surgical procedures in IIH are CSF shunting procedures and optic nerve sheath fenestration. While not a surgical procedure per se, venous stenting will also be discussed in this section as an invasive treatment option for IIH. These treatments have not been compared in a single population. Indirect comparisons of their efficacy in case series are challenged by different indications considered for intervention and different outcome measures used.
Shunting — CSF shunting procedures include ventriculoperitoneal (VPS) or lumboperitoneal shunt (LPS). Uncontrolled observations report that these can relieve headache, diplopia, papilledema, and visual loss in patients with IIH [57-62]. However, reported outcomes are mixed, some report that 95 to 100 percent achieve stabilization or remission of visual problems [57-60,63], while others note that vision continued to worsen in up to 32 percent [61]. While headache relief appeared to occur in almost all patients soon after shunting, in one case series, the benefit was not universally sustained, with nearly half of patients having recurrent severe headaches within three years of surgery, despite a working shunt [64].
In addition, the rate of complications from shunting is high. Shunt failure requiring revision is the most common complication of lumboperitoneal shunts and occurs in 48 to 86 percent of patients, with a few patients requiring multiple (10 to 38) shunt revisions [57-61,64]. In rare cases, shunt failure is accompanied by visual loss that can be rapid and severe [65]. Other common complications include shunt infection, abdominal pain, back pain, radicular pain, operative complications, and cerebrospinal fluid leak with low pressure [57-61,66,67]. Rare complications include cerebellar tonsillar herniation and syringomyelia, subdural and subarachnoid hemorrhage, and bowel perforation [66,68,69].
More recently developed technologies using advanced imaging as well as endoscopic operative techniques have improved the ability of surgeons to place catheters in the ventricles of patients with IIH who do not have ventricular enlargement. Case series suggested that ventriculoperitoneal catheters may be less prone to shunt obstruction than lumboperitoneal shunts [64,70-72]. However, the risks for low pressure, infections, and other complications were similar to lumboperitoneal shunts and requirements for shunt revision remained substantial at 40 to 60 percent.
We consider shunting with caution in IIH. However, it remains an option for patients who have failed other treatment approaches. Some patients who don't respond to optic nerve fenestration have been reported to have a clinical response to shunting [73].
Optic nerve sheath fenestration — Optic nerve sheath fenestration (ONSF) can stabilize or improve visual loss due to papilledema in IIH [74-85]. There is more extensive documentation of the benefit on visual function for ONSF as compared to shunting and venous stenting [63].
In one of the largest published case series summarizing 158 operations in 86 patients, visual acuity stabilized or improved in 94 percent, while visual fields stabilized or improved in 88 percent [85]. These results are consistent with aggregated data from other smaller case series [63,74-78,81-84]. Patients with a less severe and a shorter duration of visual abnormality have better visual outcomes after ONSF [86,87].
Preservation of vision is the primary goal of ONSF. While some patients experience headache relief after ONSF, many do not [74,85]. ONSF has been associated with improvement in patients with deteriorating vision loss despite a working shunt [79,81,85]. ONSF also appears to be safe and effective in children [80,88].
Complications of ONSF occur in as many as 40 to 45 percent of patients [83,85,89,90]. Most, but not all, of these are transient and nondisabling. The more common complications include:
ONSF may fail after initial benefit, requiring repeat surgery in 7 to 32 percent of eyes, depending in part on the duration of follow-up; failure may occur within months or after several years [77,82,85]. Repeat surgery appears to have a similar benefit to the original [86].
ONSF appears to be an effective procedure in patients who fail medical therapy and in our experience is preferable to CSF shunting for patients experiencing progressive vision loss.
Venous stenting — Venous stenting is a new and somewhat controversial treatment option for IIH. Its use results from the observation that many patients with IIH have apparent stenoses of the transverse venous sinus or other cerebral veins; although whether this is a primary or secondary phenomenon is uncertain. (See "Idiopathic intracranial hypertension (pseudotumor cerebri): Epidemiology and pathogenesis", section on 'Intracranial venous hypertension'.)
Three case series describe three centers' experience with venous stenting in patients with IIH who had apparent venous sinus obstruction on cerebral venography [91-93]. The effects on vision were not consistently documented and follow-up was often limited. Some patients had had prior ONSF and/or shunting. The benefit was described as follows:
There were no significant complications in any of these patients, although transient post procedure symptoms (headache lateralized to treated side, partial hearing loss, unsteadiness) were common. Also, two patients were treated with thrombolytic therapy when an intraluminal thrombus was noted to develop postoperatively, despite anticoagulation treatment [92].
We feel that further documentation of clinical benefit from venous stenting is required before this becomes a routine part of IIH treatment [94].
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SUMMARY AND RECOMMENDATIONS — The major morbidity associated with IIH is loss of vision, although persistent headaches are also a source of disability and lost quality of life. Treatment recommendations for IIH are based on uncontrolled observations. There are no clinical trials that have documented the effects of treatments in IIH.
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