What are the Dandy criteria for diagnosing idiopathic intracranial hypertension (IIH)?

Dandy Criteria for Diagnosing Idiopathic Intracranial Hypertension (IIH)

The Dandy criteria for diagnosing idiopathic intracranial hypertension require the presence of signs and symptoms of increased intracranial pressure, elevated cerebrospinal fluid pressure with normal composition, normal neuroimaging without evidence of hydrocephalus or mass lesions, and no other identifiable cause of intracranial hypertension. 1, 2

Modified Dandy Criteria Components

• Signs and symptoms of increased intracranial pressure (headache, papilledema, transient visual obscurations, pulsatile tinnitus, visual blurring, and horizontal diplopia) 1, 2
• No localizing neurological findings except for possible sixth cranial nerve palsy/palsies 3
• Normal brain imaging showing no evidence of hydrocephalus, mass, structural or vascular lesion, and no abnormal meningeal enhancement 3
• Normal CSF composition on lumbar puncture 3, 1
• Elevated lumbar puncture opening pressure (measured in lateral decubitus position) 3
• No other identifiable cause of intracranial hypertension 1, 4

Diagnostic Approach

Neuroimaging Requirements

• Urgent MRI brain within 24 hours; if unavailable within 24 hours, then urgent CT brain with subsequent MRI brain if no lesion identified 3, 1
• CT or MR venography is mandatory to exclude cerebral sinus thrombosis within 24 hours 3, 1
• Neuroimaging may show characteristics of raised intracranial pressure (empty or partially empty sella, increased optic nerve tortuosity, enlarged optic nerve sheath, flattened posterior globe/sclera, intraocular protrusion of optic nerve head, and transverse sinus stenosis), but these are not pathognomonic of IIH 1, 2

Clinical Examination

• Papilledema is the hallmark finding in IIH and should be documented (present in 81.96% of patients in one study) 1, 4
• Cranial nerve examination should be performed, with typically no cranial nerve involvement other than possible sixth nerve palsy/palsies 3
• If other cranial nerves or pathological findings are involved, alternative diagnoses should be considered 3, 1

Lumbar Puncture

• Following normal imaging, all patients with papilledema should have a lumbar puncture to check opening pressure and ensure CSF contents are normal 3
• The lumbar puncture opening pressure should be measured in the lateral decubitus position 3

Patient Classification

• Typical IIH: Patients who are female, of childbearing age, and have a BMI greater than 30 kg/m² 3, 1
• Atypical IIH: Patients who are not female, or not of childbearing age, or who have a BMI below 30 kg/m² (these patients require more in-depth investigation) 3, 1
• Fulminant IIH: Patients meeting the criteria for a precipitous decline in visual function within 4 weeks of diagnosis of IIH 3
• IIH without papilledema: A rare subtype where patients meet all other criteria of definite IIH in the absence of papilledema 3, 1

Common Pitfalls and Caveats

• Unilateral papilledema can occur in IIH, though bilateral presentation is more common 5
• Headache presentation in IIH can be highly variable and may mimic other primary headache disorders, making clinical diagnosis challenging 1, 6
• IIH without papilledema is a rare subtype that meets all other criteria for IIH but lacks papilledema, making diagnosis more difficult 1, 7
• Symptoms may wax and wane over time, making definitive diagnosis difficult 7
• In infants, diagnosis is challenging as they cannot verbalize typical IIH-related symptoms such as positional headaches, diplopia, or pulsatile tinnitus 8
• Rare presentations like complete ophthalmoplegia have been reported and should not exclude the diagnosis if other criteria are met 9