Pseudotumor cerebri (PTC), also known by the name idiopathic intracranial hypertension (IIH), is a disorder with increased intracranial pressure (ICP) and associated headaches, papilledema, vision changes, or pulsatile tinnitus in the setting of normal imaging and cerebrospinal fluid (CSF) studies. It mainly affects overweight women of child-bearing age, however women of all ages, men, and children of both sexes may also be affected. There are multiple hypotheses about the etiology of PTC including decreased CSF absorption and/or increased CSF production. Regardless of the etiology, this disorder can become debilitating and may lead to permanent vision loss. Thus timely diagnosis and treatment is a must.
The primary etiology is an accumulation of cerebrospinal fluid (CSF) either through decreased resorption and/or increased production; this leads to an elevated intracranial pressure, the source of the associated symptoms and signs. There is no proven cause for either the decreased resorption or increased production (hence the term idiopathic intracranial hypertension); however, descriptions of the proposed mechanisms are under the pathophysiology section.
The condition most commonly affects women aged 20-44 years with an annual incidence of 19.3/100,000 in those who weigh 20% or more than their ideal body weight. The annual incidence in all women aged 15 to 44 years is 3.5 per 100,000. The annual incidence of PTC in the general populace is 0.9 per 100,000. It disproportionately affects women, and when considering only post-pubertal patients, 90% of all cases occur in females. A positive relationship exists between the female sex, elevated BMI, and risk of PTC.
Children of both genders are affected equally before puberty (defined as an age of under 12 years old). Obesity less commonly correlates with the pre-pubertal patient. Males aged 12 to 15 years have an annual incidence of 0.8 per 100,000; females aged 12 to 16 years have an annual incidence of 2.2 per100,000.
Proposed mechanisms involve the vascular, hormonal, and cellular systems.
Vascular: One of the most common radiologic findings, transverse sinus stenosis, suggests a vascular component. However, the consensus is that this is likely secondary to the increased pressure rather than the cause of the increased pressure; this results in a feed-forward cycle that is relieved by removal of CSF. Hormonal: Aldosterone excess (associated with obesity and PCOS) commonly correlates with PTC and is suggested to affect the mineralocorticoid receptor of the choroid plexus leading to increased CSF production. Unfortunately, this has not yet achieved validation.
Cellular: Increased outflow resistance to CSF has been demonstrated in multiple experimental studies and is the leading theory for causation of PTC. The outflow resistance could be due to an effect of estrogen or retinoic acid (both elevated by increased adiposity) on epithelial cells leading to less outflow of CSF. Finally, the predilection of PTC for younger populations could be explained by decreased CSF production with aging. Approximately 600 milliliters is produced daily but decreases with increasing age.
The classic historical findings include:
The classic physical exam findings include:
Patient evaluation of those presenting with signs and symptoms of PTC includes neuroimaging, lumbar puncture with opening pressures and CSF analysis, ophthalmoscopy, visual acuity testing, perimetry testing, and complete blood count (CBC).
Complete blood count
Diagnosis involves utilization of the Modified Dandy Criteria :
1. Signs and symptoms of increased ICP
2. The absence of localizing findings on neurologic examination
3. The absence of deformity, displacement, or obstruction of the ventricular system with otherwise normal neurodiagnostic studies, except for evidence of increased cerebrospinal fluid pressure (greater than 200 mm water). Abnormal neuroimaging apart from empty sella turcica, optic nerve sheath with filled out CSF spaces, and smooth-walled non-flow-related venous sinus stenosis or collapse should lead to another diagnosis.
4. Awake and alert
5. No other causes of increased intracranial pressure present with CSF opening pressure of 20cm to 25 cm water, required at least one of the following:
The mainstays of medical treatment include:
For cases refractory to medical treatment, surgery can be an option:
The differential diagnosis for PTC includes etiologies that can lead to elevated ICP.
The disease prognosis depends on several factors including:
It is not uncommon for this condition to cause symptoms for from months to years even with prompt treatment. Some patients will have continued papilledema, increased ICPs, and even residual visual field deficits.
The most concerning complication of PTC is permanent vision loss because of compression of the optic nerve secondary to elevated intracranial pressure. Other complications are mainly related to side effects from treatment of the disease.
Pseudotumor cerebri/idiopathic intracranial hypertension more commonly affects women of child-bearing age and the obese. The symptoms involve headaches, vision loss (transient or persistent), pulsatile tinnitus (a whooshing sound in the ears), and/or diplopia (blurry or double vision). Treatment involves weight loss paired with medications that can reduce production of cerebrospinal fluid such as acetazolamide or reduce overall body fluids such as loop diuretics (furosemide, chlorthalidone). In severe cases steroids and/or surgery are an option.
Deterrence can involve:
Pseudotumor cerebri/idiopathic intracranial hypertension is a disease that can be missed or misdiagnosed given its overlapping features with many other disease processes. Therefore, it is essential for the diagnosing physician to work closely with neurology, ophthalmology, and radiology to provide patient-centered, evidence-based care. Nurses should be aware of pupillary changes that often occur with an elevation of intracranial pressure - a prompt referral to a neurologist/neurosurgeon is necessary when the patient has unequal pupils, papilledema and/or focal neurological deficits.
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