Overview
This lecture covers coordination and abnormal (involuntary) movements, focusing on their neurological basis, types, clinical features, and differentiation, as well as an introduction to coordination tests.
Introduction to Movement Disorders
- Abnormal (involuntary) movements are due to lesions in the basal ganglia or extrapyramidal system.
- The basal ganglia include caudate, putamen, globus pallidus, substantia nigra, and subthalamic nucleus.
- The extrapyramidal system also involves the thalamus, red nucleus, reticular formation, inferior olivary, and vestibular nuclei.
Classification and Assessment
- Movement disorders are classified into hyperkinetic (excess movement) and hypokinetic (reduced movement, e.g., Parkinson's tremor).
- Assess location, distribution (proximal/distal), rhythmicity, speed, amplitude, relationship to activity/posture, and effect of emotions or temperature.
Types of Abnormal Movements
- Tremors: Rhythmic, oscillatory, purposeless movements, commonly affecting distal limbs; types include resting, action, essential, and intention tremors.
- Chorea: Irregular, rapid, jerky, non-rhythmic movements affecting face, limbs, and trunk; often disappears in sleep.
- Athetosis: Slow, writhing, sustained, irregular movements, usually in distal extremities; can be bilateral (double athetosis).
- Dystonia: Sustained, involuntary muscle contractions causing abnormal postures or repetitive movements; can be focal, segmental, or generalized.
- Ballismus: Violent, flinging movements, typically unilateral (hemiballismus), involving proximal limbs.
- Tics: Sudden, repetitive, non-rhythmic motor or vocal movements, often suppressible, and worsened by emotional stress.
- Myoclonus: Sudden, brief, shock-like muscle jerks, usually bilateral and arrhythmic; triggered by sensory stimuli.
Causes of Abnormal Movements
- Can be due to genetic, metabolic, drug-induced, infectious, autoimmune, or structural (lesion, trauma) causes.
- Certain drugs (e.g., anticholinergics, antipsychotics, anticonvulsants) and metabolic conditions (e.g., Wilson's disease) commonly cause movement disorders.
Coordination Testing
- Coordination is primarily a cerebellar function and is tested in children over 6 years old with adequate muscle strength.
- Upper limb tests: finger-nose, rapid alternating movement, rebound test, handwriting.
- Lower limb tests: heel-knee, cerebellar ataxia tests, Romberg, tandem walking.
Key Terms & Definitions
- Basal ganglia — Deep brain structures involved in movement control.
- Extrapyramidal system — Pathways and nuclei that modulate motor activity outside the direct corticospinal tract.
- Chorea — Irregular, rapid, involuntary jerky movements.
- Athetosis — Slow, writhing, continuous involuntary movements.
- Dystonia — Sustained muscle contractions causing twisting and abnormal postures.
- Ballismus — Forceful, flinging movements of a limb.
- Tic — Sudden, stereotyped motor or vocal movement, often suppressible.
- Myoclonus — Brief, shock-like involuntary muscle contraction.
- Tremor — Involuntary, rhythmic muscle contraction leading to shaking movements.
Action Items / Next Steps
- Review types and features of abnormal movements for differentiation in exams.
- Prepare to study cerebellar function and coordination tests in detail in the next session.