Sensory aspects of movement disorders

Abstract

Movement disorders, which include disorders such as Parkinson's disease, dystonia, Tourette's syndrome, restless legs syndrome, and akathisia, have traditionally been considered to be disorders of impaired motor control resulting predominantly from dysfunction of the basal ganglia. This notion has been revised largely because of increasing recognition of associated behavioural, psychiatric, autonomic, and other non-motor symptoms. The sensory aspects of movement disorders include intrinsic sensory abnormalities and the effects of external sensory input on the underlying motor abnormality. The basal ganglia, cerebellum, thalamus, and their connections, coupled with altered sensory input, seem to play a key part in abnormal sensorimotor integration. However, more investigation into the phenomenology and physiological basis of sensory abnormalities, and about the role of the basal ganglia, cerebellum, and related structures in somatosensory processing, and its effect on motor control, is needed.

Figure 1. Alleviating manoeuvres

(A) The patient has near-complete resolution of her right torticollis by lightly touching the right side of her face. (B) The patient’s anterocollis improves when attempting to balance a heavy book on her head. (C) The blepharospasm in this patient is alleviated by lightly touching his eyebrow and by wearing yellow tinted goggles.

Figure 2. Characteristics of urge phenomena in Tourette’s syndrome

These charts represent the localisation and descriptive quality of the sensory urge in a survey of 50 patients. Data from Kwak and colleagues.

Figure 3. Topography of sensations in restless legs syndrome

The frequency and distribution of sensory symptoms associated with restless legs syndrome. Figure reproduced from Karroum and colleagues, by permission of the Society for Neuroscience.

Figure 4. Subcortical and cortical pathways for motor control

This diagram of the basal ganglia and cerebellum shows pathways involved in sensorimotor integration. The blue pathway is that described by Bostan and Strick. D1 and D2=dopamine receptors. GPe=globus pallidus pars externa. GPi=globus pallidus pars interna. SNr=substantia nigra pars reticularis. STN=subthalamic nucleus. PC-ML=posterior column-medial lemiscus.