Dystonia can be focal, segmental, multifocal, generalized, or hemidystonia.
Focal dystonia is localized to a specific part of the body. Overall upper limb is more commonly involved in
focal dystonia than lower limb and since it starts from hand,
focal hand dystonia (
FHD) is a more accepted terminology.
Writer's cramp and musician
dystonia are commonest types of
FHD. Typically this
dystonia is task specific, but in some patients this specificity may be lost over a period of time. Segmental or generalized
dystonia may also start as
FHD, so a detailed clinical assessment is required, which should be supplemented by relevant investigations. Treatment includes oral medications, injection
botulinum toxin, neurosurgery including neurostimulation, and rehabilitation. Role of injection
botulinum toxin has been extensively studied in
writer's cramp patients and found to be effective; however, selection of muscles and techniques of injection are crucial in getting best results.