This 44 y/o female presented with severe headache, worse on sitting and standing and progressive in severity over two weeks. There were no focal neurologic signs on physical exam, T - 98.6°F and WBC - 9000/cc³. MRI with gadolinium enhancement was performed. Selected images shown above demonstrate meningeal thickening and enhancement. Lumbar puncture was performed. Opening pressure was <10 mm H2O. The fluid was viscous and markedly xanthochromic, protein was 200 mg/cc. There was no bacterial, fungal or TB growth. A nuclear cisternogram failed to demonstrate a site of CSF leakage. Spontaneous intracranial hypotension was diagnosed. Symptoms gradually abated over the following 6-8 weeks.