Idiopathic intracranial hypertension (IIH) (also known as benign intracranial hypertension or pseudotumour cerebri) is a syndrome of signs and symptoms of increased intracranial pressure without causative mass or hydrocephalus identified.
Typical demographics involves middle aged obese females.
Presentation is usually with headaches, visual problems and papilloedema. Papilloedema may not always be present, or may be unilateral, making the clinical diagnosis less than straightforward 6. Neurological examination is usually normal, with a sixth cranial nerve palsy sometimes encountered.
Additional clinical findings include normal CSF composition with elevated opening pressure (opening pressure varies however, with a mean pressure of less the 35mmHg, with pressure waves as high as 80mmHg which last 5 to 20 minutes) 6.
Idiopathic intracranial hypertension (IIH) is a poorly understood condition. Various mechanisms have been proposed to explain the pathogenesis of BIH, including decreased cerebrospinal fluid (CSF) absorption, increased CSF production, increased intravascular volume, and increased intracranial venous pressure.1
A variety of conditions are known to be associated with IIH including:
- doxycycline 2
- chronic renal failure
- systemic lupus erythematosus (SLE)
- hypervitaminosis A (in the pediatric population)
CT / MRI
Features that support the diagnosis include 3,6:
- slit like ventricles
- prominent subarachnoid space around the optic nerves : ~ 45%
- papilloedema (flattening of the posterior sclera) seen in : ~ 80%
- vertical tortuosity of the optic nerves : ~ 40%
- enhancement of the prelaminar optic nerves : ~ 50%
- partial empty sella turcica : ~ 70%
- dural venous sinus flow decreased and compressed sinuses : assessed on CTV / MRV
These changes may be reversible 3
Treatment and prognosis
Treatment options include CSF letting, acetazolamide and lumboperitoneal shunts. In patients with progressive visual deterioration optic nerve fenestration to preserve vision.
Venous sinus stenting has also been tried 4 although it is controversial as to whether apparent venous sinus stenosis is the cause or the effect of IIH. Spontanous resolution of apparent stenosis is certainly recognised 6.
Other causes of raised ICP and papilloedema should be sought, including:
- 1. Silbergleit R, Junck L, Gebarski SS et-al. Idiopathic intracranial hypertension (pseudotumor cerebri): MR imaging. Radiology. 1989;170 (1): 207-9. Radiology (abstract) - Pubmed citation
- 2. Digre KB. Not so benign intracranial hypertension. BMJ. 2003;326 (7390): 613-4. doi:10.1136/bmj.326.7390.613 - Free text at pubmed - Pubmed citation
- 3. Zagardo MT, Cail WS, Kelman SE et-al. Reversible empty sella in idiopathic intracranial hypertension: an indicator of successful therapy? AJNR Am J Neuroradiol. 17 (10): 1953-6. AJNR Am J Neuroradiol (abstract) - Pubmed citation
- 4. Higgins JN, Cousins C, Owler BK et-al. Idiopathic intracranial hypertension: 12 cases treated by venous sinus stenting. J. Neurol. Neurosurg. Psychiatr. 2003;74 (12): 1662-6. doi:10.1136/jnnp.74.12.1662 - Free text at pubmed - Pubmed citation
- 5. De lucia D, Napolitano M, Di micco P et-al. Benign intracranial hypertension associated to blood coagulation derangements. Thromb J. 2006;4 : 21. doi:10.1186/1477-9560-4-21 - Free text at pubmed - Pubmed citation
- 6. Suzuki H, Takanashi J, Kobayashi K et-al. MR imaging of idiopathic intracranial hypertension. AJNR Am J Neuroradiol. 2001;22 (1): 196-9. AJNR Am J Neuroradiol (full text) - Pubmed citation
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