What is the next best step in managing a 30-year-old female patient with progressively worsening headaches over 7 months, who improved on prednisone (corticosteroid) and experiences worsening symptoms when in a supine position, with normal laboratory results and no prior imaging studies?

Urgent Brain MRI with Contrast is Mandatory

This patient requires immediate brain MRI with contrast to evaluate for idiopathic intracranial hypertension (pseudotumor cerebri) or other space-occupying lesions, followed by lumbar puncture with opening pressure measurement if imaging shows no mass effect. 1, 2

Clinical Red Flags Present

This 30-year-old female presents with multiple concerning features that mandate urgent neuroimaging:

• Progressive worsening over 7 months - this pattern suggests increasing intracranial pathology rather than benign primary headache 3, 2
• Positional worsening when supine - classic for elevated intracranial pressure, as lying flat increases ICP 1, 4
• Improvement on prednisone - suggests inflammatory or pressure-related pathology that responds to corticosteroids 1
• Young female demographic - fits the classic profile for idiopathic intracranial hypertension (pseudotumor cerebri), which predominantly affects overweight women of childbearing age 1

Diagnostic Algorithm

Step 1: Obtain MRI Brain with Contrast Immediately

• MRI is superior to CT for detecting structural lesions, offering higher resolution without radiation exposure 2
• Include MR venography (MRV) to evaluate for venous sinus stenosis or thrombosis, found in approximately 52% of pseudotumor cerebri cases 1
• Look specifically for:
  • Bilateral distended optic nerve sheaths 1
  • Empty sella sign 1
  • Flattening of posterior globes 1
  • Venous sinus stenosis 1
  • Mass lesions, hydrocephalus, or structural abnormalities 2

Step 2: Lumbar Puncture with Opening Pressure (if MRI shows no mass)

• Opening pressure >250 mm H₂O confirms elevated intracranial pressure and defines the need for urgent intervention 1
• Remove CSF during the procedure to reduce pressure to 50% of opening pressure or 200 mm H₂O, whichever is greater 1
• Send CSF for cell count, protein, glucose, Gram stain, and culture to exclude infectious meningitis 3
• Normal CSF analysis (no organisms, normal white cell count) distinguishes IIH from infectious causes 1

Step 3: Fundoscopic Examination

• Assess for papilledema, which is present in nearly 90% of IIH cases and is a key diagnostic finding 1
• Papilledema indicates urgent need for pressure-lowering intervention to prevent permanent vision loss 1

Why Imaging Cannot Be Delayed

The guideline evidence is clear that neuroimaging should be considered in patients with progressively worsening headache 3. While the 2002 US guidelines note that imaging may not be warranted for typical migraine with normal examination 3, this patient has:

1. Atypical features (positional worsening, progressive course over months) 3, 2
2. Response to steroids suggesting inflammatory or pressure pathology 1
3. No prior imaging despite 7 months of worsening symptoms 2

The American College of Radiology specifically recommends neuroimaging for new-onset headache patterns with atypical features such as positional worsening 4.

Management After Diagnosis

If Idiopathic Intracranial Hypertension is Confirmed:

• Weight loss is highly effective in putting IIH into remission and should be strongly encouraged 1
• Acetazolamide is first-line medical therapy (not prednisone for chronic management) 1
• Where there is evidence of declining visual function, acute surgical management (optic nerve sheath fenestration or CSF shunting) to preserve vision is indicated 1
• Neurosurgical consultation for CSF shunting may be needed if medical therapy fails 1

Regarding Continued Prednisone Use:

Do not continue prednisone as chronic therapy without a definitive diagnosis. 5 While prednisone may provide symptomatic relief, it:

• Masks underlying pathology without treating the cause 5
• Carries significant risks with prolonged use (HPA axis suppression, Cushingoid features, infection risk) 5
• Is not indicated for chronic IIH management 1
• Should be tapered gradually if used long-term to avoid withdrawal 5

Critical Pitfall to Avoid

Do not assume this is migraine or tension headache and continue symptomatic treatment without imaging. 3, 2 The combination of progressive worsening, positional component, and steroid responsiveness in a young female strongly suggests elevated intracranial pressure. Delayed diagnosis of IIH can result in permanent vision loss from chronic papilledema. 1

Do not overlook venous sinus thrombosis as a secondary cause of elevated ICP, especially if the patient is on oral contraceptives or has other prothrombotic risk factors. 1