Inclusion criteria:  Patients diagnosed with ankylosing spondylitis Patients who have been using conventional therapy (non-steroidal anti-inflammatory drugs and/or salazopyrin) or anti-TNF therapy for more than 5 years.  Exclusion criteria:  Patients with rheumatic diseases (rheumatoid arthritis, systemic lupus erythematosus ......) Patients with other systemic diseases that can lead to neuropathy Patients who have had a known neuropathy or have taken medication that can lead to neuropathy as a side effect Patients with pacemakers