Second edition

03.qxd 3/10/08 9:32 AM Page 72
Abnormal movements
3.1 Tremor 72
3.2 Myoclonus 75
3.3 Motor tics 77
3.4 Chorea 78
3.5 Athetosis 81
3.6 Ballism 82
3.7 Dystonia 83
3.8 Parkinsonism 87
3.1 TREMOR
Tremor is a more or less rhythmic oscillatory movement,
most commonly seen in the upper extremities, which
occurs secondary to the rapidly alternating contraction of
agonist then antagonist muscles.
Clinical features
From a clinical point of view, it is most useful to distinguish
three different types of tremor, namely postural, rest,
and intention; other types (e.g., Holmes’ tremor) also
occur and are discussed later in this chapter, but are far less
common.
Postural tremor is most apparent when the patient
maintains a posture, as for example by extending the arms
straight forward, with the fingers outstretched and slightly
spread apart. This tremor typically occurs at a frequency
of from 6 to 10 Hz, and ranges in amplitude from a fine
tremor (which may be almost unnoticeable to casual
inspection) to a coarse tremor (which may effectively preclude
even the simplest of activities, such as bringing a cup
of water to the lips). Some authors also refer to this tremor
as an ‘action’ tremor, in that it occurs when the patient
takes an ‘action’, for example by extending the arms. Not
all authors are in agreement with this term, however, and
it is not used further here.
Rest tremor, as the name indicates, is seen when the
involved extremity is at rest as, for example, when, with the
patient seated, the hands are resting in the lap. This tremor
occurs at a frequency of from 3 to 5 Hz and is typically ‘pillrolling’
in character, in that the oscillatory activity of the
thumb, sweeping back and forth in proximity to the ventral
3
3.9 Akinesia 91
3.10 Akathisia 92
3.11 Catatonia 93
3.12 Asterixis 96
3.13 Mirror movements 97
3.14 Pathologic startle 98
References 99
surface of the fingers, resembles the movements one would
make if one were rolling a pill back and forth in one’s hand.
Intention tremor comes to light during finger-to-nose
testing. To perform this, ask the patient to extend the upper
extremity, with the index finger extended out, and then to
bring the index finger in to touch the nose. Normally, the
movement is smooth throughout; when intention tremor is
present, however, an oscillatory movement develops as the
index finger closes in on the target. Some authors refer to
this as a ‘kinetic’ tremor, indicating that it appears with
movement; however, this term has not gained currency and
the term ‘intention’ is used in this text.
Other tremors, far less common, include ‘task-specific’
tremors, orthostatic tremor, ‘rabbit’ tremor, Holmes’ tremor,
and ‘wing-beating’ tremor.
‘Task-specific’ tremors resemble postural tremors; however,
they only appear when the patient is engaged in a specific
activity, such as writing, throwing darts, etc.
Orthostatic tremor (Heilman 1984), as the name suggests,
occurs when patients stand up. This is a rapid tremor
of the lower extremities, which patients often describe as a
sense of quivering, which may cause a sense of unsteadiness
or even cause patients to fall. As this tremor may be
invisible, it is necessary to palpate the inner aspects of the
patient’s thighs immediately after the patient stands up to
assess its presence.
‘Rabbit’ tremor is a rest tremor confined to the jaw and
presents an appearance similar to that of a rabbit chewing.
Holmes’ tremor, named after Gordon Holmes who first
described it in 1904, is a slow frequency tremor (at a rate of
from 2 to 4 Hz) of the upper, and occasionally lower, extremity,
with rest, intentional, and postural components. The
appearance of this tremor with sustained posture may be
quite remarkable, with a rolling, sinuous motion of the upper