Overview
This lecture covers the core motor and non-motor features of Parkinson's disease, focusing on clinical definitions, examination techniques, and differences from similar neurological findings.
Core Motor Features of Parkinson's Disease
- About 70% or fewer Parkinson's patients have tremor; 100% have bradykinesia (slowness of movement).
- Diagnosis requires bradykinesia plus one other symptom (tremor, rigidity, or postural instability).
- Resting tremor appears when muscles are at rest and often diminishes with voluntary movement.
- Resting tremor worsens with stress and is most commonly seen in hands, arms, legs, or jaw.
- Resting tremor is often not the most disabling symptom as it disappears with activity.
Examination of Tremor and Rigidity
- Test for resting tremor by having the patient's hands or arms completely relaxed in their lap.
- Mentally challenging tasks (like serial sevens) can bring out a resting tremor.
- Rigidity is increased resistance to passive movement that is independent of movement speed (velocity).
- Rigidity is contrasted with spasticity, which is speed-dependent and seen in upper motor neuron injuries.
- Spasticity causes a "clasp-knife" phenomenon, whereas rigidity is uniform throughout the movement.
- Cogwheel rigidity is rigidity with a superimposed tremor, while lead-pipe rigidity is smooth, consistent resistance.
Postural Instability
- Postural instability is the loss of normal upright reflexes, leading to imbalance and falls.
- Falling frequently is a major neurological red flag and suggests serious neurologic dysfunction.
- Tests for postural instability include standing from a chair, walking, turning, and the pullback test.
Non-Motor Symptoms of Parkinson's Disease
- Parkinson's also involves many non-motor symptoms that can greatly impact quality of life.
Key Terms & Definitions
- Bradykinesia — Slowness of voluntary movements, a core feature of Parkinson's disease.
- Resting Tremor — Involuntary shaking seen when muscles are not being used.
- Rigidity — Increased resistance to passive movement, independent of velocity.
- Spasticity — Increased muscle tone that is velocity-dependent, associated with upper motor neuron injuries.
- Cogwheel Rigidity — Rigidity with a ratcheting quality due to underlying tremor.
- Lead-pipe Rigidity — Continuous, uniform resistance to movement.
- Postural Instability — Loss of reflexes that maintain upright posture, leading to falls.
- Extrapyramidal — Relating to motor systems outside the corticospinal (pyramidal) tract, especially the basal ganglia.
Action Items / Next Steps
- Review the differences between rigidity and spasticity.
- Practice neurological examination techniques for tremor, rigidity, and postural instability.
- Familiarize yourself with both motor and non-motor Parkinson's symptoms for clinical application.