If MRI is Negative: Proceed to Myelography
If the brain and spine MRI are negative in this patient with orthostatic headache and concerning neurological symptoms, the next step is to perform myelography (CT or digital subtraction myelography) to localize the CSF leak source, as spontaneous intracranial hypotension (SIH) remains the leading diagnosis and can exist despite negative initial MRI. 1
Diagnostic Reasoning
The clinical presentation—severe unilateral headache with orthostatic worsening, neck stiffness, and focal neurological symptoms (facial twitching, tingling, tinnitus)—strongly suggests SIH despite the migraine history. The orthostatic component is the critical distinguishing feature here.
Why Negative MRI Doesn't Exclude SIH
- Approximately 20% of SIH cases have normal brain MRI findings 1
- CSF pressure can be normal in patients with SIH, and absence of low CSF pressure should not exclude this condition 2
- The diagnosis of SIH is challenging and sometimes cannot be definitively diagnosed or excluded until full diagnostic workup with invasive imaging (myelography) has been performed 2
Next Steps Algorithm
1. Perform Myelography
The 2023 multidisciplinary consensus guideline provides clear criteria: when spine MRI is negative but clinical suspicion for SIH remains high (as in this case with orthostatic headache), proceed to myelography to identify the leak source 1.
2. Consider Non-Targeted Epidural Blood Patch (EBP)
- First-line treatment for SIH is non-targeted EBP, which should be performed as early as possible 1
- This can be both diagnostic and therapeutic—if symptoms improve after EBP, it supports the SIH diagnosis even with negative imaging
- If symptoms persist after EBP, this further justifies proceeding to myelography for targeted treatment planning 1
3. Evaluate for Alternative Diagnoses
If the full imaging workup including myelography remains negative and symptoms persist, consider SIH-mimicking conditions 2:
- Positional orthostatic tachycardia syndrome (POTS)
- Cervicogenic headaches
- New daily persistent headache syndromes
- Hemiplegic migraine (though the orthostatic component makes this less likely)
Critical Pitfalls to Avoid
Do not dismiss SIH based solely on negative MRI. The orthostatic nature of this headache is pathognomonic and demands thorough investigation. The focal neurological symptoms (facial twitching, tingling, unilateral tinnitus) could represent complications of untreated SIH, including subdural collections or venous sinus changes.
Do not delay treatment while pursuing imaging. Consider empiric non-targeted EBP while arranging myelography, as early treatment improves outcomes and prolonged untreated SIH can lead to serious complications including subdural hematomas 3.
Do not attribute all symptoms to migraine history. While this patient has a migraine history, the new presentation with orthostatic features and focal neurological symptoms represents a distinct clinical entity requiring different management.
Management Priorities
Immediate Actions:
- Arrange myelography (CT or digital subtraction) of the complete spine
- Consider trial of non-targeted EBP before or concurrent with myelography planning
- Implement conservative measures: bed rest, aggressive hydration, caffeine supplementation
- Provide symptomatic headache management 1
If Myelography Identifies Leak:
- Proceed to targeted EBP, transvenous embolization (for CSF-venous fistula), or surgical repair depending on leak characteristics 1
If Myelography Remains Negative:
- Reassess for alternative diagnoses
- Consider repeat imaging if symptoms persist
- Evaluate for POTS and other orthostatic disorders 2
The key principle is that orthostatic headache with negative initial MRI warrants invasive imaging (myelography) rather than abandoning the SIH diagnosis 1, 2.