A CSF leak does not always show up on an MRI. The best test is the beta-2 transferrin, if you can get a fluid sample. Those who have a CSF leak sometimes experience fluid dripping out of their nose when they lean forward, and can obtain a sample this way. The sample is time sensitive, and is only good for about 4 hrs. at room temperature, or 3 days if refrigerated. Other tests may include a CT with contrast dye, or a pledget test. Also, you can try increasing your caffeine intake to see if this temporarily helps to alleviate some of your symptoms. Although caffeine is contraindicated in those with PCS, it is recommended for individuals with a CSF leak as it helps to increase the volume of cerebrospinal fluid.