Quantitative Sensory Testing and Occipital Nerve Stimulator

The primary aim of this study is to assess the reversibility of a range of psychophysical markers of pain processing in patients with chronic migraine or cluster headache before and after ONS insertion and comparing to patients having a general anaesthetic (GA) for a non-painful aetiology at Barts Health NHS Trust. We will also compare with healthy volunteers not undergoing surgery. To establish whether pain perception alters in patients with chronic migraine/cluster headache having ONS using questionnaires and compare to patients having a general anaesthetic for a non- painful procedure D \& C at Barts Health NHS Trust. Are pain markers (Glutamate, TGF-B1) altered with ONS?