Katherine Butler

Sensorimotor reorganization by proprioceptive training in musician's dystonia and writer's cramp

Objective: The sensorimotor organization (SMO) of the motor hand area is abnormal in focal hand dystonia and likely contributes to symptom manifestation. In healthy subjects SMO is changed by training with proprioceptive stimulation. Here we test whether similar interventions reverse the abnormal SMO in musicians dystonia and writers cramp. If so, they could be developed for therapeutic application. Methods: In six non-musicians, six professional musicians, six patients with musicians dystonia, and six patients with writers cramp, SMO was explored by measuring changes in short-interval-intracortical-inhibition (SICI) during short periods of hand muscle vibration before and after two training types: AttVIB, involving attention to 15 minutes vibration of the abductor pollicis brevis (APB); and AttIndex, involving attention to subtle cutaneous stimulation of the index finger. Results: In healthy non-musicians, baseline SMO is spatially differentiated: SICI is reduced in projections to the vibrated, but enhanced to the non-vibrated muscles. Here AttVIB increased and AttIndex reduced the effect of subsequent APB-vibration on SMO. In healthy musicians, baseline SMO is less differentiated. AttVIB reinstated a more differential SMO pattern while AttIndex attenuated the effect of APB vibration. In focal hand dystonia, SMO is completely dedifferentiated. AttVIB tended to restore a more differential SMO in musicians dystonia but not in writers cramp while AttIndex failed to induce any changes in both groups. Conclusion: The intervention effect depends on the pre-interventional sensorimotor organization (SMO). In focal hand dystonia, particularly in musicians dystonia, it is possible to retrain an abnormal SMO toward a more differential pattern, which has potential implications for therapy.

Regaining Motor Control in Musician's Dystonia by Restoring Sensorimotor Organization

Professional musicians are an excellent model of long-term motor learning effects on structure and function of the sensorimotor system. However, intensive motor skill training has been associated with task-specific deficiency in hand motor control, which has a higher prevalence among musicians (musicians dystonia) than in the general population. Using a transcranial magnetic stimulation paradigm, we previously found an expanded spatial integration of proprioceptive input into the hand motor cortex [sensorimotor organization (SMO)] in healthy musicians. In musicians dystonia, however, this expansion was even larger. Whereas motor skills of musicians are likely to be supported by a spatially expanded SMO, we hypothesized that in musicians dystonia this might have developed too far and now disrupts rather than assists task-specific motor control. If so, motor control should be regained by reversing the excessive reorganization in musicians dystonia. Here, we test this hypothesis and show that a 15 min intervention with proprioceptive input (proprioceptive training) restored SMO in pianists with musicians dystonia to the pattern seen in healthy pianists. Crucially, task-specific motor control improved significantly and objectively as measured with a MIDI (musical instrument digital interface) piano, and the amount of behavioral improvement was significantly correlated to the degree of sensorimotor reorganization. In healthy pianists and nonmusicians, the SMO and motor performance remained essentially unchanged. These findings suggest that the differentiation of SMO in the hand motor cortex and the degree of motor control of intensively practiced tasks are significantly linked and finely balanced. Proprioceptive training restored this balance in musicians dystonia to the behaviorally beneficial level of healthy musicians.

Focal hand dystonia affecting musicians. Part I: An overview of epidemiology, pathophysiology and medical treatments

In 1911, Oppenheim coined the term ‘dystonia’ to describe disordered motor control, characterised by an association of hypotonia and tonic muscle spasm. Focal hand dystonia is one form of this disorder, in which symptoms are often task-specific and occur during skilled movements such as writing (writers cramp) or playing a musical instrument (musicians cramp). Much research has been conducted on the pathophysiology of dystonia, but the underlying mechanisms still remain unclear. Hypotheseses about functional central nervous system alterations continue to gain more support. Scientific treatment-based publications on focal dystonia are sparse, and progress in evidence-based treatment options are necessary in order to assist this patient group. This paper will review the literature, documenting dystonia classification criteria, manifestations, pathophysiology and medical treatment techniques for musicians affected by focal hand dystonia.

Focal Hand Dystonia Affecting Musicians. Part II: An Overview Of Current Rehabilitative Treatment Techniques

Focal Hand Dystonia is a complex and difficult condition to treat. Many treatment techniques have been trialled with musicians who suffer from this condition. Current treatments include: oral medications, Botulinum toxin (BTX) injections, surgery and rehabilitative therapies. The medical-based treatments have been discussed in a prior paper, and thus rehabilitative therapy treatment options and the related clinical implications are the focus of this paper. These include: sensory re-education, sensory motor retuning, rest, splintage and limb immobilisation. Future research areas relating to focal hand dystonia and the musician are highlighted.