Functional Neurosurgery for Dystonias

Abstract

Dystonia is a term first used by Oppenheim in 1911 to describe a peculiar movement and posture disorder in children. Dystonias consist of involuntary movements with spasmodic, often painful, muscle contractions and twisting repetitive movements and/or abnormal postures. Dystonias are clasified according to several criteria [5]: Primary (previously called idiopathic torsion dystonia or dystonia musculorum deformans), that can be hereditary (most often due to DYT1 mutation on chromosome 9) or non-hereditary, or secondary dystonias due to trauma, infection, stroke, metabolic abnormality, neuroleptic-induced, etc. Dystonia is also classified according to age of onset (early or late onset) or according to involved body parts (generalized, focal, multi-focal, segmental, hemi-dystonia). The most common dystonia is cervical dystonia, even called spasmodic torticollis for which surgery has been performed since the early 20th century, with myotomies as well as intradural procedures such as sectioning of accessory nerve roots and anterior rhizotomy of C1−C2 (McKenzie and Dandy-Foerster procedures), and later on microvascular decompression of the accessory nerve roots (Jannetta procedure). These methods have yielded inconsistent results, which, together with the high risks of complications, especially concerning swallowing, have prompted a shift towards use of other more lenient techniques [2]. Cerebellar, and epidural cervical stimulation have been tried but abandoned.