Otherwise known as a “spinal tap”, this test allows collection of a small sample of the fluid that bathes your brain and spinal cord, known as cerebrospinal fluid or CSF. Changes in this fluid can help in the diagnosis of a number of neurologic disorders including some associated with Sjögren’s syndrome. The test involves placing a thin needle in your lower back while you are lying on your side. The needle is inserted in between the bony building blocks (vertebrae) of the spine into the spinal canal. The area of the needle entry is first numbed with an anesthetic. Potential risks of the lumbar puncture include residual soreness of the back at the site of the procedure (this can last several days), shooting pain down the legs at the time of the procedure (this resolves when the needle is removed) and an occasionally severe headache that can last several days and require additional treatment.