There are many different causes of dystonia. Primary dystonia (also called idiopathic torsion dystonia) is a condition in which dystonia is the only clinical feature and there is no evidence of cell death of another known cause. Primary dystonia is not degenerative and in some cases is caused by genetic mutations. Dystonia may result also from exposure to certain medications, birth injuries or strokes, or as a symptom of other neurological disorders (secondary dystonia). In the latter case, it may be degenerative.