A CSF leak occurs when the fluid that surrounds the brain and spinal cord escapes through a tear or hole in the dura mater, the protective membrane. This can result from trauma, surgery, or less commonly, a structural defect. Symptoms often include a headache that worsens when upright and improves when lying down, along with possible nasal drainage of clear fluid if the leak is through the nose. Treatment depends on the cause and may involve bed rest, hydration, and caffeine, or surgical repair