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Chapter 2 – Literature Review
difficulties surround the ability to identify the pathology of ET including
varying classifications, misdiagnosis and inadequate controls (R. J. Elble,
2009; Lorenz & Deuschl, 2007). Furthermore, it is often difficult to
separate effects of co-morbidities and general aging from ET on the
neural system (Deuschl & Elble, 2009).
Pathophysiology - Neural dysfunction
Neural dysfunction can be thought of as comprising two subgroups, that
of a central and peripheral pathology. Central pathology in this review
examines alterations occurring in ET that relate to central areas such as
that of the cerebellum or inferior olive while peripheral pathology
identifies the influence of stretch reflex and motor unit entrainment in
ET.
Central pathology
ET typically exhibits a kinetic tremor of 4-12Hz (E. Louis, 2005). Various
possible sources for this oscillation have been suggested including the
cerebellarthalamocortical pathway and olivocerebellar pathway (R. J.
Elble, 2009; Pinto, Lang, & Chen, 2003).
The possible involvement of the cerebellum in the pathology of ET has
been identified through the use of imaging tools such as Positron
Emission Tomography (PET), dysfunction in tasks related to cerebellar
function (Trillenberg, et al., 2006), the disappearance of tremor after
cerebellar stroke (Pagan, Butman, Dambrosia, & Hallett, 2003) and the
use of DBS to successfully treat tremor (Jenkins, et al., 1993; Yu &
Neimat, 2008). Jenkins, et al. (1993) assessed 11 ET patients and 8
10