What are the symptoms and diagnostic criteria for Idiopathic Intracranial Hypertension (IIH)?

Symptoms and Diagnostic Criteria for Idiopathic Intracranial Hypertension (IIH)

Idiopathic intracranial hypertension (IIH) presents with headache, visual disturbances, papilledema, and pulsatile tinnitus, requiring diagnosis through specific clinical criteria, neuroimaging, and lumbar puncture to confirm elevated intracranial pressure. 1, 2

Clinical Presentation

Common Symptoms

• Headache: Present in nearly 50% of patients as their most debilitating symptom 2

  • Typically diffuse, progressive in severity
  • Often worse in the morning or when lying flat
  • Exacerbated by Valsalva maneuvers (coughing, straining)
  • Daily occurrence in 86% of cases 3
  • Focal in 84% and pulsating in 52% 3

• Visual Disturbances: 1, 2

  • Transient visual obscurations (unilateral or bilateral darkening of vision lasting seconds)
  • Blurred vision
  • Double vision (often from sixth nerve palsy)
  • Visual field defects

• Pulsatile Tinnitus: Whooshing sound in ears 2

• Other Symptoms: 1, 2

  • Back pain
  • Neck pain
  • Dizziness
  • Cognitive disturbances
  • Radicular pain

Physical Examination Findings

• Papilledema: Key diagnostic finding present in approximately 60% of cases 2
• Cranial nerve examination: Typically normal except possible sixth cranial nerve palsy/palsies 1
• Pupillary abnormalities: May include unequal pupils or sluggish responses 2

Diagnostic Criteria

Required Elements for Diagnosis 1, 2

1. Evidence of increased intracranial pressure:

   • Opening pressure >250 mm CSF in adults (>280 mm CSF in children or if sedated/obese)

2. Normal neuroimaging:

   • No hydrocephalus, mass, structural or vascular lesion
   • No abnormal meningeal enhancement

3. Normal CSF composition

4. Normal neurological examination (except for papilledema and possible sixth nerve palsy)

Neuroimaging Findings 2

MRI may show:

• Empty sella
• Flattening of posterior aspect of globes (56% sensitivity, 100% specificity)
• Distention of perioptic subarachnoid space
• Transverse sinus stenosis
• Intraocular protrusion of optic nerve (40% sensitivity, 100% specificity)
• Horizontal tortuosity of optic nerve
• Enlarged optic nerve sheath
• Smaller pituitary gland size

Diagnostic Approach

1. Confirm papilledema by fundoscopic examination

   • When uncertain, consult experienced clinician before invasive testing 1

2. Neuroimaging: 1

   • Urgent MRI brain within 24 hours
   • If MRI unavailable, urgent CT brain with subsequent MRI
   • CT or MR venography mandatory to exclude cerebral sinus thrombosis

3. Lumbar puncture: 1

   • Perform after normal imaging
   • Measure opening pressure in lateral decubitus position
   • Analyze CSF composition (must be normal)

Patient Classification

Types of IIH 1

• Typical IIH: Female, childbearing age, BMI >30 kg/m²
• Atypical IIH: Not female, not childbearing age, or BMI <30 kg/m²
• Fulminant IIH: Precipitous decline in visual function within 4 weeks of diagnosis
• IIH without papilledema: Meets all criteria except papilledema
• IIH in ocular remission: Previously diagnosed IIH with resolved papilledema

Pitfalls and Caveats

• Misdiagnosis is common: IIH is both underdiagnosed and misdiagnosed 2

• Delayed recognition risks: Can result in irreversible neurological damage and permanent vision loss 2

• Medication associations: Certain medications can contribute to IIH, including: 2

  • Tetracycline-class antibiotics
  • Vitamin A and retinoids
  • Steroids
  • Growth hormone
  • Thyroxine
  • Lithium

• Underlying conditions: Addison disease and hypoparathyroidism can increase risk 2

• Normal pressure readings don't exclude diagnosis: Some patients may have IIH despite pressure readings within normal range 2

• Headache relief after CSF withdrawal: Significantly more frequent in IIH patients than controls and may help confirm diagnosis 3

Remember that early recognition and prompt management are critical to prevent permanent vision loss, which is the most serious complication of IIH.