Idiopathic intracranial hypertension

doi:10.1016/S1474-4422(06)70442-2

The Lancet Neurology

Volume 5, Issue 5, May 2006, Pages 433-442

https://doi.org/10.1016/S1474-4422(06)70442-2 Get rights and content

Summary

Idiopathic intracranial hypertension is common in obese women and can lead to significant visual impairment. First described more than 100 years ago, the cause of the disorder remains unknown. Despite a multitude of proposed links, the aetiology has never been established. Impairment of cerebrospinal-fluid reabsorption is the most likely underlying pathophysiological cause of the raised pressure, but this notion has yet to be proven. Cerebral venous sinus abnormalities associated with the disorder need further exploration. Although the major symptoms of headache and visual disturbance are well documented, most data for disease outcome have been from small retrospective case series. No randomised controlled trials of treatment have been done and the management is controversial. The importance of weight loss needs clarification, the role of diuretics is uncertain, and which surgical intervention is the most effective and safe is unknown. Prospective trials to examine these issues are urgently needed.

Introduction

Idiopathic intracranial hypertension occurs most commonly in overweight women and is encountered by most neurology and ophthalmology departments on a regular basis. Far from being benign, the condition causes blindness in 10% of cases; indeed, most affected patients show a degree of visual loss.1, 2, 3 The association with obesity suggests that the incidence will increase as the population in the developed world gains weight. Despite this theory, very little is known about the disorder. The cause is undetermined and treatments lack any convincing evidence base. This review will summarise current knowledge of the cause, differential diagnosis, and pathophysiology of idiopathic intracranial hypertension, drawing attention to dilemmas in treatment and the need for well-designed prospective trials.

Section snippets

Definitions

Idiopathic intracranial hypertension is the clinical syndrome of raised intracranial pressure, in the absence of space-occupying lesions or vascular lesions, without enlargement of the cerebral ventricles, for which no causative factor can be identified. Serous meningitis and pseudotumour cerebri were the terms previously used for idiopathic intracranial hypertension. In 1937, diagnostic criteria for intracranial pressure without brain tumour were first published by Dandy,⁴ and in 1955 Foley⁵

Epidemiology

In the USA, Durcan⁷ reported the annual incidence of idiopathic intracranial hypertension in the general population of Iowa to be 0·9 per 100 000 and in Louisiana to be 1·07 per 100 000. A prospective longitudinal study in Benghazi, Libya, reported an annual incidence of 2·2 per 100 000.⁸ In Hokkaido, Japan, only two cases were identifed from the study in 1993, of a population of around 5·8 million, giving an incidence for that year of 0·03 per 100 000.⁹ The incidence of idiopathic intracranial

Associated conditions

Apart from female sex and obesity there are no proven associations in idiopathic intracranial hypertension. Whether the raised intracranial pressure is a result of, or occurs by chance in association with, the factor in question is important to establish.

Mechanisms of raised intracranial pressure

The pathophysiology underlying the raised intracranial pressure is unclear. Hypotheses have developed around the main determinants of CSF pressure.

Clinical features

Patients with idiopathic intracranial hypertension can be asymptomatic, but more commonly they complain of the symptoms listed in panel 3. Headache is consistently the most common symptom, occurring in 68–98% of patients3, 8, 13 and featuring as the presenting complaint in many.⁷ Headache seems to be less common in children than in adults with the disorder.⁷⁰ Headache can fluctuate and be progressive or permanent. The pain may have similarities to migraine and tension-type headache⁷¹ or show

Investigations

Idiopathic intracranial hypertension is a diagnosis of exclusion. Although there are no pathognomonic radiological signs in the disorder, empty sella turcica and variable diminution in ventricular size have been reported, although the latter is debated.⁷⁵ CT became the investigation of choice until it was superseded by MRI. Posterior scleral flattening (relative to the normal curvature of the globe), prelaminar enhancement of optic nerves, vertical tortuosity of the orbital optic nerves, and

Management

There have been no sufficiently large studies of any treatment modality in idiopathic intracranial hypertension so the evidence base for management decisions is poor. A Cochrane systematic review in 2005 did not find any randomised controlled trials of treatments for the disorder.⁸⁴ The aim of treatment is to halt or prevent visual loss. Current practice includes a combination of medical therapy, advice for weight reduction where appropriate, and surgical intervention for severe cases. Repeated

Outcome

For most patients, idiopathic intracranial hypertension lives up to its old name as a benign condition, without impairment of vision in the long term. However, a small but significant number of patients with idiopathic intracranial hypertension follow a more aggressive course. Blindness has been shown to occur in at least one eye in 8–10% of patients3, 75 and some sustained loss of vision has been reported in almost half of patients in some studies1, 2, 8, 104 (table). No consistent

Future developments

Many questions remain unanswered about idiopathic intracranial hypertension. Its association with female sex and obesity is striking and its co-occurrence with symptoms of hormonal dysfunction intriguing. Although only a few overweight people develop idiopathic intracranial hypertension, the well-recognised increasing trend towards obesity in today's society suggests that the incidence is likely to increase. Despite the large numbers of people affected, especially obese women of childbearing

Search strategy and selection criteria

References for this review were identified by searches of MEDLINE and PubMed from 1955 to February 2006, with the terms “idiopathic intracranial hypertension”, “benign intracranial hypertension”, “pseudomotor cerebri”, and “otitic hydrocephalus”. Additionally, we identified early references by hand searches of journals. Only papers published in English were reviewed. The final reference list was generated on the basis of originality and relevance to the topics covered in the review.

References (104)

K Radhakrishnan et al.
Epidemiology of idiopathic intracranial hypertension: a prospective and case-control study
J Neurol Sci
(1993)
J Galvin et al.
Clinical Characterisation of idiopathic intracranial hypertension at the Detroit medical centre
J Neurol Sci
(2004)
CJ Glueck et al.
Idiopathic intracranial hypertension, polycystic-ovary syndrome, and thrombophilia
J Lab Clin Med
(2005)
GS Cinciripini et al.
Idiopathic intracranial hypertension in prepubertal pediatric patients: characteristics, treatment, and outcome
Am J Ophthalmol
(1999)
AM Chiu et al.
Minocycline treatment and pseudotumor cerebri syndrome
Am J Ophthalmol
(1998)
CF Dogulu et al.
Idiopathic intracranial hypertension in cystinosis
J Pediatrics
(2004)
MC Brodsky et al.
Magnetic resonance imaging in pseudotumor cerebri
Ophthalmology
(1998)
PN Sylaja et al.
Differential diagnosis of patients with intracranial sinus venous thrombosis related isolated intracranial hypertension from those with idiopathic intracranial hypertension
J Neurol Sci
(2003)
AG Lee et al.
The use of acetazolamide in idiopathic intracranial hypertension during pregnancy
AmJ Ophthalmol
(2005)
GT Liu et al.
High-dose methylprednisolone and acetazolamide for visual loss in pseudotumor cerebri
Am J Ophthalmol
(1994)

LN Johnson et al.

The role of weight loss and acetazolamide in the treatment of idiopathic intracranial hypertension (pseudotumor cerebri)

Ophthalmology

(1998)

JT Banta et al.

Pseudotumor cerebri and optic nerve sheath decompression

Ophthalmology

(2000)

J Corbett et al.

Visual loss in pseudotumour cerebri

Arch Neurol

(1982)

F Rowe et al.

Assessment of visual function in idiopathic intracranial hypertension: a prospective study

Eye

(1998)

M Wall et al.