Differential Diagnosis for IIH vs CVST

When differentiating Idiopathic Intracranial Hypertension (IIH) from Cerebral Venous Sinus Thrombosis (CVST), it's crucial to consider various factors, including clinical presentation, imaging findings, and risk factors. Here's a structured approach to the differential diagnosis:

• Single Most Likely Diagnosis:

  • IIH in patients with typical symptoms (headache, vision changes, papilledema) without focal neurological deficits, and who are often obese women of childbearing age.
  • CVST in patients presenting with sudden onset of headache, seizures, or focal neurological deficits, especially if there are risk factors for thrombosis (e.g., pregnancy, oral contraceptives, thrombophilia).

• Other Likely Diagnoses:

  • Migraine or other headache disorders, which can mimic the headache profile of IIH but typically lack papilledema.
  • Space-occupying lesions (e.g., tumors, abscesses), which can cause increased intracranial pressure and symptoms overlapping with IIH or CVST.
  • Arterial ischemic stroke, which might present with acute focal neurological deficits similar to CVST but usually has a distinct vascular territory involvement.

• Do Not Miss Diagnoses:

  • Subarachnoid hemorrhage, which can present with sudden severe headache and requires immediate diagnosis and treatment.
  • Meningitis or encephalitis, which can cause increased intracranial pressure, headache, and altered mental status, necessitating prompt antibiotic or antiviral treatment.
  • Pituitary apoplexy, a medical emergency that can cause sudden headache, visual disturbances, and altered mental status due to hemorrhage or infarction of a pituitary adenoma.

• Rare Diagnoses:

  • Pseudotumor cerebri syndrome due to other causes (e.g., vitamin A toxicity, tetracycline use), which can mimic IIH.
  • Dural arteriovenous fistulas, which are abnormal connections between arteries and veins in the dura mater and can cause symptoms similar to IIH or CVST.
  • Cerebral venous sinus thrombosis in the setting of a hypercoagulable state or due to a rare condition such as Behçet's disease, which might not be immediately considered without specific risk factors or systemic symptoms.

Each of these diagnoses requires careful consideration of the patient's clinical presentation, imaging studies (notably MRI and MR venography for CVST, and MRI for IIH to rule out other causes), and laboratory tests to guide the diagnostic process and ensure that potentially life-threatening conditions are not overlooked.