Chapter 10 - Motor system examination

Questions

Define the following terms:

spasticity, rigidity, hemiparesis/plegia, bradykinesia, paraparesis/plegia, upper motor neurons, lower motor neurons, internal capsule, chorea, athetosis, dystonia, hemiballism, tic, fasciculation.
Spasticity is a resistance to passive movements that is greatest at the initiation of motion (particularly of a rapid movement). It is often a sign of overactive muscle stretch reflexes.
Hemiparesis/plegia is paralysis or paresis (weakness) of one side of the body.
Rigidity is a smooth resistance to passive movement that occurs throughout the range of motion and usually results from extrapyramidal disorders such as Parkinson's disease.
Bradykinesia is a pathological slowing of motor performance often seen with Parkinson's disease and parkinsonism.
Paraparesis/plegia is paralysis or paresis of both lower extremities.
Upper motor neurons are the principal descending motor pathways for voluntary movement, including the corticospinal and corticobulbar tracts (and some other associated tracts).
Lower motor neurons are the anterior horn motor neurons and their axons that extend through the ventral nerve root and the peripheral nerves to reach the neuromuscular junction.
The internal capsule is the primary locus through which the upper motor neuron (corticospinal and corticobulbar) pathways descend.
Chorea is a purposeless, involuntary, random twitching movement.
Athetosis is a purposeless, involuntary writhing movement.
Dystonia is an involuntary, sustained twisting position of the body or a body part (torticollis, for example, when it involves the head).
Hemiballism a repeated, involuntary, flinging or flipping movement of a part of the body on one side, usually due to damage to the subthalamic nucleus.
Tic is a rapid movement, tending to be repeated in the same pattern over and over.
Fasciculation is an involuntary twitching of individual motor units, usually visible as a rippling of the skin but not resulting in any actual movement of the body part.

10-1. Describe the course of "upper motor neurons".

Answer 10-1. Upper motor neurons (corticospinal and corticobulbar tracts) arise in the motor cortex, traverse the internal capsule, cerebral peduncle and pyramids of the brain stem.

10-2. Over what functions do the upper motor neurons exert the greatest control (what movements are most affected by damage)?

Answer 10-2. They are mostly involved in control of distal movements (such as hand and fingers). Proximal functions (such as shoulder shrug) have bilateral control.

10-3. Where are sites of potential lesions producing lower motor neuron signs and symptoms?

Answer 10-3. Lower motor neuron damage can be anywhere along the pathway from the anterior horn motor neuron, ventral root, plexus or peripheral nerve.

10-4. What are the features of lower motor neuron damage?

Answer 10-4. Lower motor neuron damage results in decreased reflex and usually atrophy. It may also produce fasciculations.

10-5. What is the significance of fasciculations?

Answer 10-5. Diffuse, persistent and extensive fasciculations suggests motor neuron disease or damage (transient fasciculations are common and benign if unaccompanied by weakness or reflex change).

10-6. What are the characteristics of peripheral nerve damage?

Answer 10-6. Effects of nerve damage are most often seen distally, reflexes are affected early and atrophy is often present.

10-7. What are the characteristics of muscle disease?

Answer 10-7. Symptoms are usually most evident proximally, there is no sensory loss, reflexes only affected late and atrophy is not severe.

10-8. What are the characteristics of basal ganglia disease?

Answer 10-8. Muscle tone, postures, and patterned movements are most affected. Parkinsonism is common, with bradykinesia, difficulty initiating movements, delayed postural reflex responses and rigidity. Abnormal movements at rest are common: resting tremor, chorea, athetosis, dystonia and hemiballism.

10-9. What are the characteristics of cerebellar disease?

Answer 10-9. There are usually a variety of problems with coordination of voluntary actions, there may be trunkal ataxia (drunken gait) and muscle tone may be variably affected. Reflexes may be decreased or pendular.