Neurosurgical treatment for writer's cramp

Treatment of focal hand dystonia: current status

BACKGROUND

Focal hand dystonia (FHD) is usually adult-onset focal dystonia that can be associated with marked occupational and functional disability leading to reduced quality of life.

METHODS

Relevant studies on treatment options for FHD, their limitations, and current recommendations were reviewed using the PubMed search until March 31, 2021. Besides, the reference lists of the retrieved publications were manually searched to explore other relevant studies.

RESULTS

and conclusion Currently, botulinum toxin has the best evidence for treatment of FHD, and 20-90% of patients experience symptomatic improvement. However, its benefit is often limited by the reduction of muscle tonus acting on the muscle spindle. Different surgical modalities that have been used to treat focal hand dystonia include lesional surgery, deep brain stimulation, and magnetic resonance-guided focused ultrasound thalamotomy. Recent studies exploring the role of behavioral techniques, sensorimotor training, and neuromodulation for the treatment of focal hand dystonia have reported good outcomes, but larger studies are required before implementing these interventions in practice.

[Role of neurosurgical management in movement disorders other than Parkinson disease]

Neurosurgical procedures are indispensable in management of various types of movement disorders (MD). Stereotactic operations that have been well established include deep brain stimulation for tremor, dystonia, and Parkinsonian symptoms. Recently the actual role of stereotactic ablative procedures such as thalamotomy and pallidotomy has been re-explored, and Vo thalamotomy shows long-term improvement of task specific focal dystonia like writer's cramp and musician's dystonia. A new less invasive treatment of tremor using MR guided focused ultrasound has started and is promising. Intrathecal administration of baclofen is also an established treatment for severe spasticity, but other ablative procedures such as peripheral neurotomy and dorsal rhizotomy are also important in spasticity treatment. It seems that most neurologists are unfamiliar, at least in Japan, with such neurosurgical procedures. However, neurologists involved in management of MD should understand the important roles of neurosurgical management of intractable MD and should refer such patients to appropriate neurosurgeons before permanent contracture and deformity develop.

[Neurosurgical management of dystonias]

Neurosurgical treatment, especially deep brain stimulation (DBS) of globus pallidum interna (GPi), is known to play a very important role in management of dystonia. GPi DBS is generally used for treatment of generalized and segmental dystonias and its efficacy is well established. However, the role of neurosurgical treatment for focal dystonia, especially task-specific focal hand dystonia (TSFHD), is not widely known. Writer's cramp (WC) and occupational cramp like musician's cramp (MC) belong to this category. I have treated more than 100 patients with TSFHD with modern stereotactic thalamotomy of the nucleus ventro-oralis (Vo). The dystonic symptoms immediately improved after making a small thermo-controlled lesioning in the Vo nucleus of the thalamus. There were no permanent complications. Stereotactic Vo thalamotomy is effective and safe for of task-specific focal hand dystonia. 25 years have passed after introduction of modern DBS, and now I think it time to discuss pros and cons of DBS and lesioning humbly and seriously. Not only DBS but thalamotomy and other neurosurgical procedures play an important role in management of dystonias.