Pseudotumor cerebri pathophysiology
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief:
Overview
Pathophysiology
Pathogenesis
The exact pathogenesis of pseudotumor cerebri is not completely understood. Idiopathic intracranial hypertension or pseudotumor cerebri is defined by the symptoms of increased intracranial pressure without any evidence of tumor.(1uptodate)
Any theory regarding the pathophysiology of this disease should explain the following statements:
- High incidence rate in women with childbearing age
- Reduced conductance to CSF outflow(25 wall)
- Normal ventricle size and lack of hydrocephalus(26 wall)
- No evidence of cerebral edema(27 wall)
Some of the these theories are:
- Increased production of CSF and reduced resorption: Normal CSF flow involves production at the choroid plexuses and absorption at the cranial and spinal nerve root arachnoid villi and granulations. Impaired CSF absorption at the superior sagittal sinus or along the spinal nerve roots could therefore explain IIH and has been documented in 75-100% of IIH patients.[1] Permeability along the blood-CSF barrier varies, producing an increasing oncotic pressure gradient between the CSF and venous system in a rostral to caudal progression.[2] It is speculated that variations in this oncotic pressure contribute to or impede CSF absorption. The mechanism remains unclear however, since high CSF protein concentrations, as commonly found in Guillain-Barré syndrome or spinal tumors, can manifest as intracranial hypertension, whereas individuals with IIH frequently present with normal-to-low CSF protein findings.[1]
- Cerebral venous outflow abnormalities
- increased CSF outflow resistance
- obesity.(89 uptodate): Some evidences suggest that onesity can increase intra abdominal and intra cranial pressure and have a role in pathogenesis of IHH. (106 uptodate) In a study on 7 obese women with IHH it was seen that weith loss improved their symptoms.(107 uptodate) In the other hand higher level of leptin (a protein released from adipose tissue) was found in IHH patiets.(125)
- Vitamin A intoxication: There are some evidences of higher serum and CSF level of vitamin A, retinol and retinol binding protein can be related to IHH pathogenesis.(116-118)
- Sleep apnea: Sleep apnea can cause hypercarbia which can result in vasodilation and elevated intacranial pressure (74 uptodate)
- Sex hormones: In one study regarding IIH etiology which was done on 8 men with this disease, Four of them had abnormal FSH and LH level, 2 of them had estradiol abnormalities and seven of them had reduced testosterone level.(127 uptodate)
Genetics
[Disease name] is transmitted in [mode of genetic transmission] pattern.
OR
Genes involved in the pathogenesis of [disease name] include:
- [Gene1]
- [Gene2]
- [Gene3]
OR
The development of [disease name] is the result of multiple genetic mutations such as:
- [Mutation 1]
- [Mutation 2]
- [Mutation 3]
Associated Conditions
Gross Pathology
On gross pathology, [feature1], [feature2], and [feature3] are characteristic findings of [disease name].
Microscopic Pathology
On microscopic histopathological analysis, [feature1], [feature2], and [feature3] are characteristic findings of [disease name].