Tremor and abmormal movements
Key early features are bradykinesia or slowness of movement, resting tremor (in 70% of casesof idiopathic PD), and disturbed posture and gait. Idiopathic Parkinson's typically begins unilaterally. Arm swing is decreased, the affected shoulder may be higher or lower, and when more advanced, the affected leg may move more slowly. Later as the condition becomes more severe, both sides of the body are affected, there is postural instability, and a small stepped festinant='hurrying' gait.
Repetitive alternating movements are particularly affected, tend to decay and reduce in amplitude.
Bradykinesia can be demonstrated by piano playing movements (repetitve alternating finger movements), and by timing alternating pronation and supination movements of the hands on the thighs. Timed walk over a fixed distance is useful.
The voice may be soft, monotonous, and when severe both rapid and unclear from poor lip and tongue movement.
Postural instability can be demonstrated with the "pull test" and semi quantitated by counting the number of steps required to remain upright.
Tremor is a sinusoidal oscillation of a body part.
Tremor may be
- present at rest
- while maintaining a posture
- during movement
- or when approaching a target
Rest tremor i.e. with the limb fully supported against gravity is typical of Parkinson's disease, when it is often much worse on one side, at least initially.
Tremor on maintaining a posture is typical of physiological, drug induced, and essential tremor. This can be demonstrated by holding the hands outstretched and near the face. Characteristically tremor is worse with hands held near the mouth, leading to social embarrassment with eating and drinking. In essential tremor there is often tremor of the head, and voice.
Tremor most obvious when approaching a target is typical of cerebellar disease, and may be associated with head tremor called titubation. It is demonstrated by the finger-nose-finger test.
Tremor may also be task specific, such as when writing, which is usually considered a dystonia.
Chorea and Ballism
Important causes are rheumatic fever, the antiphospholipid antibody syndrome, and Huntington's diease.
Violent hemichorea is called hemiballism. It usually results from an infarct of the subthalamic nucleus.
Dystonia is a sustained abnormal movement which may lead to twisitng, jerking and prolonged abnormal postures. It may affect a single body part, a region, one side of teh body or be generalised. There are a wide range of causes, genetic, idiopathic, drug induced or result from structural nervous system disease or damage such as from strokes, infections, inflammation or metabolic disorders.
Myoclonus produces sudden, brief shock-like movements either from muscle contraction, or inhibition (asterixis). It may arise in the spinal cord, brainstem or cortex, and be focal, segmental, multifocal or generalised. It may be spontaneous, and repetitve, and at times regular. Cortical or BS myoclonus may be stimulus sensitive. Cortical myoclonus may be triggered bMyoclonus may be action induced.
- idiopathic known as essential, which can be hereditary.
- secondary to a wide range of nervous system disorders including encephalopathies, some drug induced, post hypoxia-ischaemia, stroke, infection, metabolic, mitochondrial disorders
Tics are repeated stereotyped movements of the face or limbs, noises or utterances, including snorts, grunts, and swearing outbursts. There is an irresistible urge to make the tic, which often can be briefly suppressed.