Idiopathic Intracranial Hypertension vs. Pseudotumor Cerebri: Diagnosis and Treatment
Idiopathic Intracranial Hypertension (IIH) and Pseudotumor Cerebri are the same condition, characterized by elevated intracranial pressure without evidence of structural lesions, hydrocephalus, or abnormal CSF composition. 1
Diagnostic Criteria
The diagnosis requires all of the following:
- Papilledema (swelling of the optic disc)
- Normal neurological examination (except for possible sixth cranial nerve palsy)
- Normal brain parenchyma on neuroimaging (no mass, hydrocephalus, or abnormal meningeal enhancement)
- Normal CSF composition
- Elevated lumbar puncture opening pressure >280 mm CSF in children (>250 mm CSF if not sedated/obese) or >250 mm H₂O in adults 1
Neuroimaging Findings
MRI of the head and orbits is the preferred imaging modality, showing:
- Posterior globe flattening (56% sensitivity, 100% specificity)
- Intraocular protrusion of the optic nerve (40% sensitivity, 100% specificity)
- Horizontal tortuosity of the optic nerve (68% sensitivity, 83% specificity)
- Empty sella
- Flattening of posterior globes
- Distention of perioptic subarachnoid space
- Transverse sinus stenosis 1, 2
Classification
IIH is classified into several subtypes:
- Typical IIH: Female, reproductive age, BMI >30 kg/m²
- Atypical IIH: Not female, not reproductive age, or BMI <30 kg/m²
- Fulminant IIH: Rapid visual decline within 4 weeks of diagnosis
- IIH without papilledema: Meets all criteria except papilledema
- IIH in ocular remission: Previously diagnosed IIH with resolved papilledema 1
Treatment Algorithm
1. First-Line Treatment: Weight Loss (for BMI >30 kg/m²)
2. Medical Management
Acetazolamide: First-line medication
Topiramate: Alternative if acetazolamide not tolerated
- Added benefit of weight loss and migraine prophylaxis 2
3. Surgical Interventions (for progressive visual loss despite medical therapy)
- Optic nerve sheath fenestration: For severe or progressive visual loss
- CSF diversion procedures: Ventriculoperitoneal or lumboperitoneal shunting
- Venous sinus stenting: For cases with venous sinus stenosis 2
Monitoring and Follow-up
- Frequency depends on severity of papilledema and visual field status
- Each follow-up should include:
- Visual acuity assessment
- Pupillary examination
- Formal visual field testing
- Dilated fundus examination
- BMI calculation 2
Special Considerations
Secondary Causes to Rule Out
- Cerebral venous thrombosis (requires CT or MR venography)
- Medications: tetracyclines, vitamin A/retinoids, steroids, growth hormone, thyroxine, lithium
- Endocrine disorders: Addison disease, hypoparathyroidism 1, 2
Headache Management
- Headache in IIH should be treated separately from papilledema management
- May require specific migraine prophylaxis 2
Pregnancy
- Requires multidisciplinary approach
- Acetazolamide may be used if benefits outweigh risks 2
Red Flags Requiring Urgent Intervention
- Rapidly worsening visual acuity or visual fields
- New or worsening diplopia
- Severe intractable headaches
- Altered mental status 2
Important Clinical Pearls
- IIH is both underdiagnosed and misdiagnosed
- Incidence is increasing (2.4 per 100,000 within the last decade)
- Most common in overweight women of reproductive age
- IIH can occur with normal CSF pressure in rare cases, so papilledema with typical symptoms should raise suspicion even with normal pressure 5
- The PLIHS (Pre-Lumbar puncture Intracranial Hypertension Scale) can help identify patients likely to have elevated CSF pressure 6
Remember that untreated papilledema can lead to progressive, irreversible visual loss and optic atrophy, making early diagnosis and treatment crucial for preserving vision 7, 3.