Diagnosis and treatment of idiopathic intracranial hypertension

Abstract

Objective To review and discuss the clinical presentation and treatment of idiopathic intracranial hypertension. Discussion Visual alterations and headache are the two main symptoms of idiopathic intracranial hypertension, although additional features including cranial nerve palsies, cognitive deficits, olfactory deficits and tinnitus are not uncommon. The headache associated with idiopathic intracranial hypertension frequently has a migrainous phenotype. The underlying cause of the disorder has not yet been elucidated. Several hypotheses have been postulated but none of them can explain the full clinical picture. Therapeutic options remain limited, focusing mainly on reduction in body weight and the reduction of CSF production with carbonic anhydrase inhibitors. Conclusion The accurate diagnosis of idiopathic intracranial hypertension is essential as visual deterioration due to papilledema may be irreversible. Given its phenotypic similarity and frequent overlap with chronic migraine it is essential to consider idiopathic intracranial hypertension in the diagnostic workup of chronic headache; in particular, when considering its increasing prevalence. Understanding in detail the pathophysiological mechanisms behind the associated headache would also allow study of current and future therapeutic options in a structured way.

Cerebral Venous Outflow Implications in Idiopathic Intracranial Hypertension—From Physiopathology to Treatment

“…Transient visual obscurations (TVOs ) refer to sudden loss or shadowy, fogginess, black, white, or grey vision in one or both eyes, lasting for a minute or less than 30 s, sometimes related to a change of position of the body. Increased pressure in liquid from surrounding optic nerve sheaths could compress the thin vascular small arteries and veins at this level, producing a transient ischemia of the optic nerve head [ 31 ]. While not specific for raised ICP, the daily occurrence of these symptoms without other explanation (e.g., ischemic amaurosis fugax) is much more frequently encountered in IIH patients.…”

“…Optic nerve pallor suggests that permanent injury to the optic nerve has occurred. The presence of spontaneous venous pulsations has been considered to exclude the possibility of raised ICP, however the evidence from some studies [ 32 ] proved that there are patients with lumbar puncture pressure > 30 cm H 2 O presenting spontaneous venous pulsation, so this situation does not rule out raised intracranial pressure [ 31 ].…”

“…In the baseline patient group from the Idiopathic Intracranial Hypertension Treatment Clinical Trial, the co-existence of visual field defects with a loss of visual acuity manifesting as an enlarged blind spot and inferior partial arcuate defects were described as the most frequent pathological changes, even in patients with mild disease [ 27 ]. Loss of visual acuity is generally accepted to be a feature of advanced disease, but clinicians should be aware that in some cases, we can witness a rapid development of a severe visual loss within the first four weeks from symptoms’ onset in severe cases of intracranial hypertension, prompting surgical intervention to prevent permanent visual deficits [ 31 ].…”

“…Pulsatile tinnitus [ 27 , 31 ] is another common feature of idiopathic intracranial hypertension (in more than half of patients), with two-thirds presenting bilaterally. It consists of hearing a whooshing, whistling, humming, or marching noise, continuously or synchronously with the heartbeats (pulsatile is much more frequent) and is thought to represent an auditory perception of turbulent pulsatile flow in intracranial vessels, or in case of intracranial hypertension, probably secondary to a turbulent flow in transverse venous sinus stenosis [ 26 , 31 ]. It is not specific for intracranial hypertension and also occurs due to other underlying vascular abnormalities (including arteriovenous malformations, arterial stenoses), eustachian tube dysfunction, and other benign causes, but in most cases, remains idiopathic.…”

“…The mechanisms through which ONSF reduces the optic nerve consequences of high ICP are not clear. The MRI-proven increase of optic sheath thickness and increased tortuosity of the optical nerve could lead to the idea that the ONSF exerts its action by local fistula formation between the nerve sheath and dura, with slow drainage and resorption of the excess of fluid in the orbital tissue, or a local hypertrophic scarring in the first segment of the optic nerve with a further limitation of transmission of increased pressure in the distal optic nerve and papilla [ 31 ].…”