Postural Tremors

Tremor can be observed in every individual. Its amplitude and frequency are dependent on mechanical as well as neural components, and can be modified by disease. The objective of this chapter is to discuss the specific characteristics of postural tremor in healthy persons and in different pathologies. Postural tremor deserves attention since limbs are rarely completely at rest. Accordingly, postural tremor may provide important information about the state of the system. Furthermore, in some pathologies, postural and rest tremor may present different characteristics. Identifying the origins of postural tremor and its relationship with rest tremor characteristics may be helpful for diagnostic purposes. We will discuss the possible origins of those tremor oscillations, as well as current controversies. While we acknowledge that tremor, either physiological or pathological, can be observed in the lower limbs, head and even trunk just as often as in the upper limbs, this chapter will focus on finger or hand tremor. More specifically, we will compare some of the most common postural tremors with their resting tremor equivalents. Physiological tremor (PT), enhanced physiological tremor (EPT) and essential tremor (ET) will be discussed. We will also consider the possible link between these different types of postural tremors. Finally, we will discuss postural tremor in the context of Parkinson’s disease (PD) and its possible relation to ET.