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Other Movement Disorders

The different types of abnormal movements:

  • Tremor – Oscillatory, typically rhythmic and regular

  • Dystonia – Sustained, twisting and frequently repetitive with prolonged abnormal postures. dystonic movements repeatedly involve the same group of muscles i.e. are patterned.

  • Chorea – Involuntary, irregular, purposeless, nonrhythmic, abrupt, rapid, unsustained movements that seem to flow from one body part to another.

  • Myoclonus – Sudden, brief, shock-like involuntary movements caused by muscular contractions (positive myoclonus) or inhibitions (negative myoclonus e.g. asterixis seen in liver disease)

  • Tics – Abrupt sudden isolated movements. consists of abnormal movements (motor tics) or abnormal sounds (phonic tics).


Tremor

Types - Resting (PD), Postural, Intention (Cerebellar), Functional


A functional tremor is a fine, low amp, high frequency tremor that's exacerbated by stress, metabolic/endocrine disorders (thyroid, hypocalcaemia), and drugs (nicotine, thyroxine, steroids, caffeine).

Dystonia

This is a syndrome of sustained muscle contractions that produces abnormal postures or repetitive movements involving different distributions.


Adult-Onset Focal Dystonia - Most common type of primary focal dystonia, and is typically a Cervical dystonia


Writer’s cramp - Form of dystonia, with a typical onset in 20s-30s. Characterised by abnormal posture only when writing, and not with other movements.

“A person with medication induced dystonia” © James Heilman, MD CC BY 3.0 (https://creativecommons.org/licenses/by/3.0/)

It can be easy to confuse dystonia with akathisia and tardive dyskinesia. These are the main ways each present:

N.B. Procyclidine is an antispasmodic and antimuscarinic drug that can cross the BBB and treat these extrapyramidal disorders.


Chorea

Primary - Caused by:

  • Neurodegeneration – Huntington’s Disease

  • Wilson’s disease

  • Benign hereditary chorea


Secondary - Caused by:

  • Sydenham’s chorea

  • SLE

  • Drug-induced

Drawing of boys afflicted with rheumatic chorea - https://commons.wikimedia.org/wiki/File:Boys_afflicted_with_rheumatic_chorea.jpg

Post-hypoxic Myoclonus

Acute - Usually within 48 hours after hypoxic insult in a deeply comatose patient, and indicates a poor prognosis


Chronic - Known as Lance-Adams Syndrome, and is where there's intentional myoclonus several days after hypoxic brain insult. Characterised by clonic movements, triggered by intentional action or external stimuli, and relieved at resting or during sleep.



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