Association between visual parameters and neuroimaging features of idiopathic intracranial hypertension

Authors: Padhye LV, Van Stavern GP, Sharma A, Viets R, Huecker JB, Gordon MO.

BACKGROUND/AIMS: Papilledema refers to optic disc swelling resulting from high intracranial pressure (ICP). The precise mechanism by which papilledema occurs remains uncertain. Although orbital neuroimaging features associated with papilledema are well-described, it is unclear whether these findings correlate with visual function. Idiopathic Intracranial Hypertension (IIH) is a condition in which the intracranial pressure is elevated with no obvious cause, causing papilledema and visual loss. The utility of papilledema and IIH neuroimaging findings as a surrogate marker for visual loss, or a predictor of visual loss, is understudied. This retrospective cross-sectional review aims to correlate parameters of visual function with orbital magnetic resonance imaging (MRI) findings.
METHODS: Patients meeting criteria for IIH who had received orbital imaging within 4weeks of examination were included. Visual parameters of papilledema grade, visual field mean deviation, and visual acuity were correlated with neuroimaging features, including optic nerve thickness, and optic nerve sheath thickness, among others. All MRI scans were reviewed by a neuroradiologist blinded to clinical status. Spearman rank correlations and t-tests were generated with SAS (v9.2).
RESULTS: Thirty five patients were included. No significant relationships were found between the main visual parameters of papilledema grade and visual field mean deviation, and MRI findings.
CONCLUSIONS: We found no significant correlation between visual parameters and imaging features of papilledema. This might indicate that MRI features may provide insight into the structural changes that occur in papilledema, but may not be helpful when making clinical management decisions for patients with IIH in particular, and papilledema in general.

Headaches Associated with Papilledema

Authors: Sergott RC.

Headaches associated with papilledema may be both life-threatening as well as vision-threatening. This review will review the following clinical features: (1) the character of headaches associated with increased intracranial pressure; (2) the visual symptoms associated with papilledema; (3) the funduscopic findings of true papilledema versus pseudo-papilledema; (4) the role of ancillary ophthalmological testing such as visual fields and spectral domain optical coherence tomography; (5) the neuro-radiological evaluation of patients with headaches and papilledema; (6) the treatment of vision-threatening papilledema.

An uncommon case of Idiopathic Intracranial Hypertension with diagnostic pitfalls

Authors: Mrfka M, Pistracher K, Schökler B, Wissa S, Kurschel-Lackner S.

We report on an unusual case of Idiopathic Intracranial Hypertension (IIH) in a woman of normal weight. Papilledema and increased intracranial pressure are symptoms of cerebral venous sinus thrombosis or idiopathic intrancranial hypertension. Because of the different treatment strategies, it is important to keep these two diseases separate. We show that the use of different imaging methods is an important tool in obtaining an effective diagnosis.

Papilledema: Are We Any Nearer to a Consensus on Pathogenesis and Treatment

Authors: Lee AG, Wall M.

Papilledema is a term generally reserved (at least in the English language use of the term) by neuro-ophthalmologists for optic disc edema due to increased intracranial pressure. The etiology for the intracranial hypertension may be known (e.g., brain tumor, meningitis, cerebral venous sinus thrombosis) or may be idiopathic (idiopathic intracranial hypertension ). IIH is a disorder that predominantly affects overweight women of childbearing age and these epidemiologic factors should offer clues to pathogenesis. The main morbidity of papilledema is visual loss and the major mechanism for permanent optic nerve damage is axoplasmic flow stasis and resultant intraneuronal ischemia. The current initial management of papilledema in IIH includes weight loss and medical therapy (e.g., acetazolamide or furosemide). Patients who fail, are intolerant to, or noncompliant with maximum tolerated medical therapy might require optic nerve sheath fenestration or cerebrospinal fluid diversion (i.e., shunting) procedures.

Space obstructive syndrome: intracranial hypertension, intraocular pressure, and papilledema in space

Authors: Wiener TC.

Humans undergo several consistent and measurable changes of fluid distribution and regulation in the course of adapting to microgravity. Recently, a syndrome of objective findings has been described by Mader et al. associated with long-duration missions, including hyperopic shifts, mildly elevated intracranial pressure, papilledema, globe flattening, choroidal folds, and other anatomic findings. Experience with venous obstructive lesions leads the author to propose a primary obstructive process, unique to or exacerbated by microgravity, acting at the level of the proximal internal jugular veins, termed Space Obstructive Syndrome (SOS). Literature, anatomy, and ultrasound observations revealed four major potential compression zones of the internal jugular vein, with Zone I between the sternocleidomastoid muscle and the carotid artery as the primary area of compression, both in 1 G in an upright position and in microgravity. Internal jugular vein compression, along with loss of gravitationally induced cranial outflow of blood in the vertebral veins and collaterals, may lead to intracranial venous hypertension with resultant facial/head and upper airway swelling, increased intraocular pressure, intracranial hypertension, and papilledema. Further study and proof of concept will necessitate ultrasound, Doppler flow study, and internal jugular vein pressure measurements on orbit in the International Space Station. If proven, SOS will give researchers opportunity for study and development of mitigation strategies such as artificial gravity systems.

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