Synonyms: pseudotumour cerebri, benign intracranial hypertension
Raised intracranial pressure in the absence of a mass lesion or of hydrocephalus. It is often idiopathic. Idiopathic intracranial hypertension (IIH) appears to be due to impaired cerebrospinal fluid (CSF) absorption from the subarachnoid space across the arachnoid villi into the dural sinuses.
IIH is common in obese women and can lead to significant visual impairment.Prompt recognition and treatment are needed to prevent potentially permanent visual changes including partial or total blindness.
- It most frequently occurs in obese women of childbearing age.
- A study in Sheffield found:
- An incidence of 1.56 per 100,000 per year for men and 2.86 per 100,000 per year for women.
- The incidence of IIH in obese women was 11.9 per 100,000 per year.
- The prevalence of IIH was calculated as 10.9 per 100,000 (85.7 per 100,000 in obese women).
- It mostly occurs in young obese females in their third or fourth decade.
- There is an increased risk in women with menstrual irregularity.
- Female-to-male ratio is between 3:1 to 8:1.
- Up to 90% of patients are overweight.
- In women it may coincide with recent weight gain, fluid retention, the first trimester of pregnancy and the postpartum period.
Known associations include:
- Endocrine: adrenal insufficiency, Cushing's syndrome, hypoparathyroidism, hypothyroidism and hyperthyroidism.
- Medication: cimetidine, corticosteroids, danazol, isotretinoin, levothyroxine, lithium, minocycline, nalidixic acid, nitrofurantoin, tamoxifen, tetracycline, ciclosporin, levonorgestrel implant, pancreatin, recombinant and natural human growth hormone, vitamin A in infants.
- Miscellaneous: polycythaemia vera, iron-deficiency anaemia, chronic kidney disease, systemic lupus erythematosus, Lyme disease.
- Headache tends to be the first symptom: generalised throbbing is worst first thing in the morning and last thing at night. It is relieved on standing (consistent with raised intracranial pressure). It is also aggravated by straining, coughing or a change in position. In many cases, the headache may be mild, nonspecific and have been present for many weeks or months.
- Gradual visual field defects; moderate or gross bilateral papilloedema without significant focal intracranial signs. Transient reduction of vision ('greying out') on bending or stooping, halo or a short episode of visual Catherine wheel flashes, persistent blurring, scotoma or horizontal diplopia may also occur.
- Nausea, vomiting, drowsiness.
- Less commonly, diplopia due to VI cranial nerve palsy.
- Other causes of headache, including cerebral tumours and malignant hypertension.
- Other causes of papilloedema.
- Other causes of visual disturbance.
These are primarily to exclude any other possible cause of raised intracranial pressure.
- Recommended blood tests include: FBC, ESR, iron studies, antinuclear antibodies, coagulation studies.
- Screening for Lyme disease is recommended in patients who have a history of exposure to Lyme disease in areas of endemic disease.
- CT or MRI scanning: the ventricles, in contrast to hydrocephalus, are normal or reduced in size.
- Visual field charting: enlarged blind spot and peripheral field construction.
- Lumbar puncture, if not contra-indicated by clinical features and pressure measurement. Monitor intracranial pressure if in doubt as to the diagnosis.
There is currently no consensus on the management of IIH. Management is initially medical with weight reduction if obese and diuretic therapy. CSF diversion surgery may be required (eg, for visual disturbance).
- The aim of treatment is the relief of symptoms of raised intracranial pressure and the prevention of progressive optic nerve damage.
- Weight reduction is advisable if obese.
- Treatment of underlying condition; stopping any causative medication.
- The intracranial pressure may be controlled by serial lumbar puncture.
- For acute treatment, prednisolone to relieve headache and papilloedema.
- In mild chronic disease, acetazolamide or other diuretics are effective at lowering the intracranial pressure. Acetazolamide appears to be the most effective agent for lowering intracranial pressure.
Surgical intervention may be considered if other measures are ineffective. Surgical options include:
- Optic nerve sheath fenestration (decompression).
- CSF diversion (lumbo-peritoneal or ventriculo-peritoneal shunt).
- Intracranial venous sinus stenting has also been investigated. Stent placement to remove obstruction to venous outflow has been proposed as a treatment option for patients with IIH refractory to medical treatment.
Bariatric surgery (weight loss surgery) may be an effective treatment for IIH in obese patients.
- IIH is not known to be associated with any specific effect on mortality.
- Response to treatment is generally good but recurrent attacks occur in up to one third of patients.
- Relapse and remission of symptoms are common.
- There is a significant threat to sight.Varying degrees of permanent visual loss occurs in up to 50% and significant disability in 10%.
Further reading and references
; Idiopathic intracranial hypertension. Lancet Neurol. 2006 May5(5):433-42.
; Idiopathic intracranial hypertension. Curr Pain Headache Rep. 2007 Feb11(1):62-8.
; Idiopathic intracranial hypertension: Diagnosis, monitoring and treatment. Rev Neurol (Paris). 2012 Oct168(10):673-83. doi: 10.1016/j.neurol.2012.07.018. Epub 2012 Sep 14.
; The incidence and prevalence of idiopathic intracranial hypertension in Sheffield, UK. Eur J Neurol. 2011 Oct18(10):1266-8. doi: 10.1111/j.1468-1331.2011.03372.x. Epub 2011 Mar 22.
; Reversible benign intracranial hypertension in a child with hyperthyroidism. J Pediatr Endocrinol Metab. 2008 Nov21(11):1099-101.
; The laboratory profile in idiopathic intracranial hypertension. Neurol Sci. 2015 Jul36(7):1189-95. doi: 10.1007/s10072-015-2071-y. Epub 2015 Jan 18.
; Lyme disease-related intracranial hypertension in children: clinical and imaging findings. J Neurol. 2016 Jan 6.
; The syndrome of pseudotumour cerebri and idiopathic intracranial hypertension. Curr Opin Neurol. 2011 Feb24(1):12-7. doi: 10.1097/WCO.0b013e328341f94a.
; Idiopathic intracranial hypertension and visual function. Br Med Bull. 200679-80:233-44. Epub 2007 Jan 22.
; Not so benign intracranial hypertension. BMJ. 2003 Mar 22326(7390):613-4.
; Acetazolamide for the treatment of idiopathic intracranial hypertension. Expert Rev Neurother. 201515(8):851-6. doi: 10.1586/14737175.2015.1066675. Epub 2015 Jul 7.
; Update on the surgical management of idiopathic intracranial hypertension. Curr Neurol Neurosci Rep. 2014 Mar14(3):438. doi: 10.1007/s11910-014-0438-8.
; Unilateral transverse sinus stenting of patients with idiopathic intracranial hypertension. AJNR Am J Neuroradiol. 2010 Apr31(4):645-50. doi: 10.3174/ajnr.A1890. Epub 2009 Nov 26.
; Bariatric surgery for the treatment of idiopathic intracranial hypertension. J Neurosurg. 2011 Jan114(1):34-9. doi: 10.3171/2009.12.JNS09953. Epub 2010 Jan 22.
; Interventions for idiopathic intracranial hypertension. Cochrane Database Syst Rev. 2005 Jul 20(3):CD003434.