This case report presents a 72-year-old man with no previous history of headache who developed a sudden onset of daily, predominantly orthostatic headache. Initial brain magnetic resonance imaging (MRI) revealed bilateral subdural hematomas and diffuse pachymeningeal thickening, suggestive of spontaneous intracranial hypotension (SIH). Although spine MRI showed no epidural fluid collection, the patient’s condition deteriorated after a minor trauma, with progression of subdural hematomas requiring neurosurgical intervention. Persistent SIH signs led to the suspicion of a cerebrospinal fluid–venous fistula (CVF), despite a first negative dynamic computed tomography (CT) myelography. A second exam—performed with the patient in the contralateral decubitus position—revealed a CVF at T10–T11, which was successfully treated with intravascular embolization. The patient made a full clinical and radiological recovery. This case highlights the complexity of diagnosing and managing SIH, particularly in the context of comorbidities and CVF. It emphasizes the importance of repeated, position-sensitive imaging and referral to specialized centers. This chapter provides a comprehensive overview of SIH pathophysiology, clinical features, complications, and treatment strategies across various healthcare settings.