Hallmark features of disordered movement include:
1) Impaired postural reflexes that would normally contribute to balance (either during movement or while stationary).
2) Diminished or slowed movements (hypokinesia/bradykinesia).
3) Excessive involuntary movements (hyperkinesia).
4) Uncoordinated or unsteady movements (ataxia).
4 types of involuntary movements
1) Tremor
2) Chorea
3) Athetosis
4) Ballismus
What are tremors?
- Alternating contraction of opposing muscles
- Forms of tremor are varied and hence have differing causes. Some tremors are effectively benign, whereas others reflect significant pathology
What is chorea?
- involves brief, purposeless, irregular jerky movements of body parts
- Voluntary behaviors (e.g., walking) may be affected, as choreatic movements become disruptive. The expression of successive choreatic movements resembles dancing – hence the term “chorea”
Most common reason for Chorea
often stemming from basal gangliar disease
Describe Athetosis
comprises continuous slow writhing of body parts
Most common reason for Athetosis
often related to basal gangliar pathology
Describe Ballismus
“Flinging” and rotatory movements involving the limbs are characteristic.
Most common reason for Ballismus
Causal lesions often affect the subthalamus, which contributes to basal gangliar function
What differentiates Hypokinesia in Lower vs Upper motor lesions
- Lower motor neurons or the neuromuscular junction can be implicated, with hypokenesis presenting as flaccid
paralysis. - Lesions of upper motor neurons, which often yield elevated muscular tone and hence hyperreflexia.
What causes hypokinesia in Parkinson’s?
- Dysfunction involves modulatory/regulatory circuits
- The basal ganglia are not regulated normally by the mesencephalic substantia nigra.
- correlates with impaired initiation of movement, rigidity, poor postural reflexes and slowing of movement (i.e., bradykinesia).
- Perhaps paradoxically, patients expressing Parkinson disease and hence hypokinesia/bradykinesia often exhibit resting tremor
What type of interactions between Sensory and motor systems cooperate to maintain equilibrium?
o Some sensory-motor interactions are largely reactive.
o Other such interactions involve predictive or anticipatory circuitry.
Decorticate posture
- a cerebral lesion affecting the corticospinal and corticobulbar systems with sparing of motor centers of the brainstem.
- In such cases, the disinhibited red nucleus of the midbrain increases tone of the flexor muscles of the upper limbs, while pontine and medullary motor centers (in the absence of cerebral influence) independently promote extension
of the legs. - The posture, if not tonically expressed, may be elicited by noxious stimuli.
Decerebrate posture
- the muscle tone of the arms favors extension (resulting from the loss of red nuclear output).
- Remaining disinhibited brainstem motor centers continue promoting extension of the legs.
- The posture, if not tonically expressed, may be elicited by noxious stimuli.
What is Station?
The ability of the patient to stand steadily with the feet together
How is Gait assessed?
- The patient attempts to walk in a straight path (usually in the absence of special visual cues such as lines on the floor).
-The task may be repeated while the patient walks in tandem (heel-to-toe) or preferentially on either the heels or the toes. - The ability of the patient to turn smoothly while
reversing direction should be assessed.
Categories of tremors
1) Resting tremor- typically becomes more apparent when the patient is otherwise motionless (i.e., at rest).
2) Intention (kinetic) tremor becomes apparent with purposeful movement (e.g., reaching for a glass).
3) Essential tremor (benign familial tremor) commonly prompts misdiagnoses of cerebellar or Parkinson disease, as it can resemble intention or resting tremor.
4) Postural tremor may arise only when a particular posture is assumed (e.g., when the arms are outstretched with the palms up.
In what syndrome is a resting tremor seen?
- Parkinson disease, although not all patients will exhibit the phenomenon
- The resting tremor may diminish at later stages of the disease.
What causes intention(kinetic ) tremor?
Cerebellar lesions
Describe intention tremor
- Tremor becomes apparent with purposeful movement (e.g., reaching for a glass).
- The amplitude of the intention tremor tends to increase as the affected body part approaches the target in space.
Hallmark motoric manifestations of Parkinson’s disease
- resting tremor
- bradykinesia
- Facial Masking
- Rigidity
- Loss of Postural Reflexes
- Parkinsonian Gait
- Loss of Habituation to Glabellar Stimulation
- Speech
What are the Prodromal manifestations of Parkinson’s?
o Hyposmia
o Autonomic dysfunction - Erectile, Cardiac and GI
o Rapid eye movement sleep disorder- Maintenance or breakthrough of muscular rigor during dream
sleep
What does Hyposomia indicate?
Indicates degeneration of olfactory bulbs
What does the Rapid eye movement sleep disorder indicate?
Reflects pontine degeneration
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