Idiopathic Intracranial Hypertension (IIH)

VERSION: 1.0 CREATED: January 29, 2026 REVISED: January 29, 2026 STATUS: Approved

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DIAGNOSIS: Idiopathic Intracranial Hypertension

ICD-10: G93.2 (Benign intracranial hypertension), G93.5 (Compression of brain)

CPT CODES: 85025 (CBC), 80053 (CMP), 84443 (TSH), 84703 (Pregnancy test), 89051 (CSF cell count), 84157 (CSF protein), 82945 (CSF glucose), 88104 (Cytology), 70553 (MRI brain with and without contrast + MRV), 70450 (CT head (if MRI unavailable)), 92134 (Optical coherence tomography (OCT)), 92250 (Fundus photography), 62272 (Large-volume LP), 96374 (High-dose IV acetazolamide), 96365 (IV steroids (controversial))

SYNONYMS: Idiopathic intracranial hypertension, IIH, pseudotumor cerebri, PTC, benign intracranial hypertension, BIH, primary intracranial hypertension

SCOPE: Evaluation and management of idiopathic intracranial hypertension in adults including diagnosis, medical management, and surgical interventions. Applies to ED, hospital, and outpatient settings. Excludes secondary causes of elevated ICP.

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DEFINITIONS: - Idiopathic Intracranial Hypertension (IIH): Syndrome of elevated ICP (≥25 cm H2O in adults) with no identifiable cause, normal CSF composition, and normal neuroimaging except signs of elevated ICP - Papilledema: Optic disc swelling due to elevated ICP; bilateral in most cases - Visual Field Defects: Enlarged blind spot (most common), peripheral constriction, central/cecocentral scotoma (severe) - Fulminant IIH: Rapid visual decline over days to weeks; requires urgent intervention - Frisen Scale: Grading system for papilledema (0-5); 0=normal, 5=severe with obscured vessels - Transverse Sinus Stenosis: Common imaging finding; may be cause or effect of elevated ICP

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PRIORITY KEY: STAT = Immediate | URGENT = Within hours | ROUTINE = Standard | EXT = Extended/atypical cases | - = Not applicable to this setting

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1. LABORATORY WORKUP

1A. Core Labs (Rule Out Secondary Causes)

Test	ED	HOSP	OPD	ICU	Rationale	Target Finding
CBC (CPT 85025)	ROUTINE	ROUTINE	ROUTINE	ROUTINE	Anemia (can cause papilledema); baseline	Normal
CMP (CPT 80053)	ROUTINE	ROUTINE	ROUTINE	ROUTINE	Renal function (for acetazolamide); electrolytes	Normal
TSH (CPT 84443)	-	ROUTINE	ROUTINE	-	Hypothyroidism/hyperthyroidism can cause ICP	Normal
Vitamin A level	-	ROUTINE	ROUTINE	-	Hypervitaminosis A	Normal
Pregnancy test (CPT 84703)	ROUTINE	ROUTINE	ROUTINE	-	Pregnancy considerations for treatment	Document

1B. CSF Analysis (Diagnostic LP)

Test	ED	HOSP	OPD	ICU	Rationale	Target Finding
Opening pressure	STAT	STAT	ROUTINE	-	Diagnostic criterion; ≥25 cm H2O in adults	Elevated (≥25 cm H2O)
CSF cell count (CPT 89051)	STAT	STAT	ROUTINE	-	Rule out meningitis	Normal (≤5 WBC/μL)
CSF protein (CPT 84157)	STAT	STAT	ROUTINE	-	Rule out meningitis, malignancy	Normal (≤45 mg/dL)
CSF glucose (CPT 82945)	STAT	STAT	ROUTINE	-	Rule out infection	Normal (>60% serum)
Cytology (CPT 88104)	-	ROUTINE	EXT	-	If malignancy suspected	Negative
Cultures	ROUTINE	ROUTINE	-	-	If infection suspected	Negative

1C. Extended Labs (If Secondary Cause Suspected)

Test	ED	HOSP	OPD	ICU	Rationale	Target Finding
Iron studies	-	ROUTINE	ROUTINE	-	Iron deficiency anemia associated	Normal
Cortisol (AM or stimulation test)	-	-	EXT	-	Adrenal insufficiency; steroid withdrawal	Normal
ANA, dsDNA (CPT 86235, 86225)	-	-	EXT	-	SLE (cerebral venous thrombosis risk)	Negative
Hypercoagulability panel	-	ROUTINE	EXT	-	If venous sinus thrombosis suspected	Normal

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2. DIAGNOSTIC IMAGING & STUDIES

2A. Neuroimaging (Required Before LP)

Study	ED	HOSP	OPD	ICU	Timing	Target Finding	Contraindications
MRI brain with and without contrast + MRV (CPT 70553)	STAT	STAT	ROUTINE	-	Before LP; rule out mass, CVT	No mass; may show empty sella, flattened globes, optic nerve sheath distension, transverse sinus stenosis	Pacemaker, metal
CT head (if MRI unavailable) (CPT 70450)	STAT	STAT	-	-	Emergent exclusion of mass	No mass, hemorrhage	None (contrast: renal)
CT venography	URGENT	URGENT	-	-	If MRV inconclusive for CVT	No venous sinus thrombosis	Renal disease; contrast allergy

2B. Ophthalmologic Studies

Study	ED	HOSP	OPD	ICU	Timing	Target Finding	Contraindications
Dilated fundoscopic exam	STAT	STAT	ROUTINE	-	All patients; before LP if possible	Papilledema grading (Frisen scale)	None
Optical coherence tomography (OCT) (CPT 92134)	-	ROUTINE	ROUTINE	-	Quantify RNFL thickness; follow progression	Baseline RNFL; monitor for atrophy	None
Automated perimetry (visual fields)	-	ROUTINE	ROUTINE	-	Detect visual field defects; monitor	Document defects; enlarged blind spot	None
Visual acuity	STAT	STAT	ROUTINE	STAT	Baseline and monitoring	20/20 or stable	None
Color vision testing	-	ROUTINE	ROUTINE	-	Optic nerve function	Normal	None
Fundus photography (CPT 92250)	-	ROUTINE	ROUTINE	-	Document papilledema; follow	Baseline; monitor	None

2C. IIH MRI Findings (Supportive but Not Diagnostic)

Finding	Significance
Empty or partially empty sella	Chronic elevated ICP
Flattening of posterior sclera	Elevated ICP transmitted to globe
Optic nerve sheath distension	Elevated ICP; perineural CSF
Vertical tortuosity of optic nerve	Elevated ICP
Transverse sinus stenosis	Common; may be cause or effect
Enhancement of optic nerve head	Active papilledema

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3. TREATMENT

3A. Weight Management (Cornerstone for Obese Patients)

Treatment	Route	Indication	Dosing	Contraindications	Monitoring	ED	HOSP	OPD	ICU
Weight loss (diet/lifestyle)	-	-	10% :: - :: - :: Target 5-10% body weight loss; improves ICP	None	Weight; symptoms; visual function	-	ROUTINE	ROUTINE	-
Bariatric surgery referral	-	-	N/A :: - :: once :: Consider if BMI >35 with comorbidities; effective for IIH	Per surgical criteria	Weight; ICP	-	-	ROUTINE	-
Nutrition/dietitian referral	-	-	N/A :: - :: daily :: Structured weight loss program	None	Progress	-	ROUTINE	ROUTINE	-

3B. First-Line Medical Therapy

Treatment	Route	Indication	Dosing	Contraindications	Monitoring	ED	HOSP	OPD	ICU
Acetazolamide (Diamox)	PO	-	500 mg :: PO :: BID :: 500 mg BID; titrate to 2-4 g/day as tolerated; IIHTT used up to 4 g/day	Sulfa allergy, severe renal/hepatic disease, hypokalemia	K+, bicarb, renal function q1-3 months; paresthesias (expected); fatigue, dysgeusia	ROUTINE	ROUTINE	ROUTINE	-
Potassium supplementation	-	-	20-40 mEq :: - :: daily :: 20-40 mEq daily; PRN based on K+ level	Renal failure, hyperkalemia	K+ levels	-	ROUTINE	ROUTINE	-

3C. Second-Line/Adjunctive Medical Therapy

Treatment	Route	Indication	Dosing	Contraindications	Monitoring	ED	HOSP	OPD	ICU
Topiramate	-	-	25 mg :: - :: BID :: 25 mg BID; titrate to 50-100 mg BID; also promotes weight loss	Nephrolithiasis, glaucoma, pregnancy	Weight; cognitive effects; metabolic acidosis	-	ROUTINE	ROUTINE	-
Furosemide (add-on)	PO	-	20-40 mg :: PO :: daily :: 20-40 mg daily; if acetazolamide insufficient alone	Sulfa allergy (cross-reactivity uncommon), severe dehydration	K+, renal function	-	ROUTINE	ROUTINE	-

3D. Headache Management

Treatment	Route	Indication	Dosing	Pre-Treatment Requirements	Contraindications	Monitoring	ED	HOSP	OPD	ICU
Acetazolamide (treats underlying cause)	-	-	N/A :: - :: per protocol :: Per above	-	Per above	Per above	-	ROUTINE	ROUTINE	-
Analgesics (acute)	-	-	N/A :: - :: PRN :: NSAIDs, acetaminophen PRN; avoid opioids	-	NSAID: GI/renal issues	Limit use to prevent MOH	ROUTINE	ROUTINE	ROUTINE	-
Migraine prophylaxis (if comorbid)	-	-	N/A :: - :: per protocol :: Topiramate (dual benefit); beta-blockers, amitriptyline	-	Per medication	Per medication	-	-	ROUTINE	-

3E. Therapeutic Lumbar Puncture

Treatment	Route	Indication	Dosing	Contraindications	Monitoring	ED	HOSP	OPD	ICU
Large-volume LP (CPT 62272)	-	-	20-40 mL :: - :: - :: Remove 20-40 mL CSF; immediate symptom relief	Mass lesion, coagulopathy, infection at site	Headache, symptoms; temporary benefit	URGENT	URGENT	ROUTINE	-
Serial LPs (CPT 62272)	-	-	N/A :: - :: per protocol :: Bridge to surgery or when medical therapy insufficient	Same	Same; not long-term solution	-	ROUTINE	ROUTINE	-

3F. Surgical Interventions (Vision-Threatening or Refractory)

Treatment	Route	Indication	Dosing	Contraindications	Monitoring	ED	HOSP	OPD	ICU
Optic nerve sheath fenestration (ONSF)	-	-	N/A :: - :: once :: Incision in optic nerve sheath; protects vision; does not reduce ICP	Severe optic atrophy (relative)	Visual fields, acuity post-op	-	URGENT	ROUTINE	-
CSF shunting (VP or LP shunt)	-	-	N/A :: - :: once :: Ventriculoperitoneal or lumboperitoneal shunt; reduces ICP and headache	Infection, peritoneal pathology	Shunt function; revision rate high (50%+)	-	URGENT	ROUTINE	-
Venous sinus stenting	-	-	N/A :: - :: per protocol :: Stent transverse sinus stenosis; emerging therapy	No significant stenosis; venous anatomy	ICP; stent patency; headache	-	ROUTINE	ROUTINE	-

3G. Fulminant IIH (Urgent Vision Loss)

Treatment	Route	Indication	Dosing	Contraindications	Monitoring	ED	HOSP	OPD	ICU
High-dose IV acetazolamide (CPT 96374)	IV	-	500 mg :: IV :: q6h :: 500 mg IV q6h initially	Per above	K+, bicarb	STAT	STAT	-	-
Emergent therapeutic LP	-	-	N/A :: - :: daily :: Large-volume LP; may repeat daily	Mass lesion, coagulopathy	Symptoms, vision	STAT	STAT	-	-
Urgent surgical referral	-	-	N/A :: - :: once :: ONSF or shunt within days	Per procedure	Vision	STAT	STAT	-	-
IV steroids (controversial) (CPT 96365)	IV	-	250 mg :: IV :: q6h :: Methylprednisolone 250 mg IV q6h; short-term bridge only; can worsen IIH long-term	Contraindicated for maintenance	Glucose; short-term only	STAT	STAT	-	-

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4. OTHER RECOMMENDATIONS

4A. Referrals & Consults

Recommendation	ED	HOSP	OPD	ICU	Indication
Neuro-ophthalmology	URGENT	ROUTINE	ROUTINE	URGENT	All patients; diagnosis, monitoring, management
Neurology	-	ROUTINE	ROUTINE	-	Headache management; atypical cases
Neurosurgery	URGENT	URGENT	ROUTINE	URGENT	Fulminant IIH; shunt evaluation
Interventional neuroradiology	-	ROUTINE	ROUTINE	-	Venous sinus stenting evaluation
Ophthalmology	URGENT	ROUTINE	ROUTINE	URGENT	If neuro-ophthalmology unavailable
Bariatric surgery	-	-	ROUTINE	-	Obese patients; BMI >35
Nutrition/dietitian	-	ROUTINE	ROUTINE	-	Weight loss counseling

4B. Medication Review (Discontinue IIH-Associated Drugs)

Medications to Avoid/Discontinue
Vitamin A and retinoids (isotretinoin, tretinoin)
Tetracyclines (doxycycline, minocycline)
Growth hormone
Lithium
Corticosteroid withdrawal (taper slowly if on steroids)
Levonorgestrel (controversial)

4C. Patient/Family Instructions

Recommendation	ED	HOSP	OPD
IIH is a chronic condition requiring ongoing monitoring	-	ROUTINE	ROUTINE
Weight loss is critical for long-term management	-	ROUTINE	ROUTINE
Take acetazolamide as prescribed; stay hydrated	-	ROUTINE	ROUTINE
Report new visual symptoms immediately (blurred vision, double vision, vision loss)	ROUTINE	ROUTINE	ROUTINE
Report worsening headache, nausea/vomiting, pulsatile tinnitus	ROUTINE	ROUTINE	ROUTINE
Avoid medications that can worsen IIH (vitamin A, tetracyclines)	-	ROUTINE	ROUTINE
Keep all ophthalmology appointments; visual field testing is critical	-	ROUTINE	ROUTINE
IIH Research Foundation (ihrfoundation.org) for resources	-	-	ROUTINE

4D. Pregnancy Considerations

Recommendation	ED	HOSP	OPD
Acetazolamide: Category C; discuss risks/benefits; some use in 2nd/3rd trimester	-	ROUTINE	ROUTINE
Topiramate: Category D; contraindicated in pregnancy	-	ROUTINE	ROUTINE
Weight management critical before conception	-	-	ROUTINE
Serial LPs may be used in pregnancy if needed	-	ROUTINE	ROUTINE
Surgical intervention if vision-threatening	-	URGENT	-
Vaginal delivery generally safe; avoid prolonged Valsalva	-	ROUTINE	ROUTINE

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5. DIFFERENTIAL DIAGNOSIS

Alternative Diagnosis	Key Distinguishing Features	Tests to Differentiate
Cerebral venous thrombosis	Acute headache; hypercoagulable state; may have focal signs	MRV, CT venography
Meningitis (infectious or carcinomatous)	Fever, meningismus, abnormal CSF	CSF analysis, cultures, cytology
Intracranial mass (tumor, abscess)	Focal signs; mass on imaging	MRI with contrast
Hydrocephalus	Enlarged ventricles; gait, cognition changes	MRI/CT
Medication-induced ICP elevation	History of causative medication	History; resolve after discontinuation
Sleep apnea	Nocturnal headaches; daytime somnolence; may coexist	Sleep study
Systemic hypertension (hypertensive encephalopathy)	Severely elevated BP; may cause papilledema	BP measurement
Optic neuritis	Unilateral vision loss; pain with eye movement; no papilledema initially	MRI orbits; OCT
Hypervitaminosis A	History of vitamin A/retinoid use	Vitamin A level
Anemia (severe)	Can cause papilledema without true ICP elevation	CBC

6. MONITORING PARAMETERS

Parameter	ED	HOSP	OPD	ICU	Frequency	Target/Threshold	Action if Abnormal
Visual acuity	STAT	Daily	Every visit	STAT	Ongoing	Stable or improving	Escalate treatment
Visual fields (perimetry)	-	Daily (if fulminant)	q1-3 months	-	Per risk	Stable or improving	Escalate treatment
Papilledema grade (Frisen)	STAT	Daily	Every visit	STAT	Ongoing	Improving or resolved	Continue treatment
OCT (RNFL thickness)	-	Baseline	q3-6 months	-	Per schedule	Stable; no atrophy	Indicates chronic damage
Weight	-	Weekly	Every visit	-	Ongoing	Decreasing (if obese)	Reinforce; consider bariatric
Potassium	-	Daily initially	q1-3 months	-	On acetazolamide	>3.5 mEq/L	Supplement
Bicarbonate	-	Daily initially	q1-3 months	-	On acetazolamide	>18 mEq/L	May need dose reduction
Creatinine	-	Baseline	q3-6 months	-	On acetazolamide	Stable	Adjust dose if impaired
Headache severity	ROUTINE	Daily	Every visit	-	Ongoing	Improving	Optimize treatment

7. DISPOSITION CRITERIA

Disposition	Criteria
Outpatient management	Mild-moderate symptoms; stable vision; reliable follow-up
Admit to hospital	New diagnosis with significant papilledema; fulminant IIH; progressive vision loss; unable to tolerate oral medications
ICU admission	Rarely needed; severe headache requiring IV therapy; post-operative monitoring
Neuro-ophthalmology follow-up	q2-4 weeks initially; q1-3 months when stable
Urgent follow-up	Any decline in vision; worsening headache; medication intolerance

8. EVIDENCE & REFERENCES

Recommendation	Evidence Level	Source
Acetazolamide effective for IIH	Class I, Level A	IIHTT (Idiopathic Intracranial Hypertension Treatment Trial)
Weight loss improves IIH	Class II, Level B	Multiple studies; IIHTT secondary analysis
ONSF protects vision in IIH	Class III, Level B	Case series; observational data
CSF shunting reduces ICP and headache	Class III, Level B	Case series; high revision rate noted
Venous sinus stenting emerging therapy	Class III, Level C	Growing evidence; case series
Modified Dandy criteria for diagnosis	Expert consensus	Friedman et al., 2013
Topiramate as adjunct with weight loss benefit	Class III, Level C	Observational data

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DIAGNOSTIC CRITERIA (Modified Dandy Criteria - Friedman 2013)

Required for IIH Diagnosis: 1. Papilledema 2. Normal neurologic exam (except CN VI palsy allowed) 3. Neuroimaging: Normal brain parenchyma; no meningeal enhancement; no venous thrombosis (MRV required); may show empty sella, flattened globes, optic nerve sheath distension 4. Normal CSF composition 5. Elevated opening pressure: ≥25 cm H2O in adults (≥28 cm H2O in children) 6. No other cause of intracranial hypertension identified

IIH Without Papilledema (IIHWOP): - Diagnosis possible if unilateral or bilateral CN VI palsy present - Or if ALL of: typical headache, elevated OP, normal CSF, supportive MRI findings - Requires more stringent exclusion of secondary causes

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NOTES

• IIH typically affects young obese women (BMI >30); male IIH exists but consider secondary causes more carefully
• Vision loss is the most important outcome; headache is common but not the priority
• Papilledema can cause permanent optic atrophy if untreated
• Acetazolamide is first-line; titrate to maximum tolerated dose (up to 4 g/day)
• Weight loss is critical for obese patients; even 5-10% loss can significantly improve IIH
• Fulminant IIH (rapid vision loss over days to weeks) is a neuro-ophthalmic emergency
• ONSF protects vision but does not reduce ICP or headache
• Shunts reduce ICP and headache but have high revision rates (up to 50%+)
• Venous sinus stenting is emerging as effective for selected patients with significant stenosis
• Pregnancy: IIH can develop or worsen; treatment options limited; close monitoring essential
• Discontinue medications that can cause/worsen IIH (vitamin A, tetracyclines, etc.)
• Long-term follow-up required; IIH can recur, especially with weight gain

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CHANGE LOG

v1.0 (January 29, 2026) - Initial template creation - IIHTT evidence incorporated - Modified Dandy criteria included - Full surgical options (ONSF, shunt, venous stenting) - Fulminant IIH section - Pregnancy considerations - IIH-associated medications to avoid