4.1.9 Movement disorders

Terms and classes

• Dyskinesia is the umbrella term for disordered movement, covering both impaired voluntary movement and unwanted involuntary movement.

• Hyperkinetic disorders are an excess of unwanted movement, such as tics, chorea, athetosis, ballismus, dystonia, myoclonus and tremor.

• Hypokinetic disorders are a poverty of movement, such as akinesia, bradykinesia and parkinsonism, and they are the opposite pole from chorea and tics.

• Tremor is the hyperkinetic movement classically described as rhythmic: a regular oscillation at a fairly constant frequency. Tics and runs of myoclonic jerks recur at irregular intervals, and chorea is not rhythmic.

• Fish groups non-adaptive motor signs into spontaneous movements, such as stereotypy, and abnormal induced movements, such as mitgehen, which exist only because the examiner or surroundings act on the patient.

Examining movement

Describe the onset, timing against medicines, distribution, rhythm, speed, amplitude, symmetry, variability and functional impact before giving the movement a label.

Mannerism and stereotypy

• Mannerism is an odd, bizarre or stylised way of performing an otherwise normal voluntary, goal-directed action.

• Stereotypy is a repetitive, regular, patterned, purposeless movement, posture or utterance with no goal, seen in chronic schizophrenia and catatonia.

• The components of a stereotypy are ordinary acts, and the abnormality lies in their frequency and rigidity.

• A stereotypy can be briefly suppressed, like a tic, but no premonitory urge comes before it and no relief follows.

A mannerism keeps the purpose of the action; a stereotypy has none. Neither term alone identifies the cause.

Tics

• Tic is a brief, non-rhythmic movement or vocalisation preceded by a rising premonitory urge that the tic relieves.

• A tic can be held back for a time, at the cost of a rebound burst afterwards. Tics often wax and wane.

• The urge may be absent or unrecognised in young children, so it need not be demonstrable in every child.

• Copropraxia is the involuntary making of obscene or offensive gestures, a complex motor tic seen in a minority of people with Tourette syndrome.

• Coprolalia is the vocal counterpart, also present in only a minority, and coprophagia is eating faeces.

• A compulsion is told from a tic because it is usually linked to a feared consequence or a rule, though the two overlap.

• A stereotypy is often more rhythmic and prolonged than a tic.

Myoclonus

• Myoclonus is an abrupt, brief, shock-like involuntary jerk that cannot be suppressed and has no premonitory urge.

• Myoclonus arises in the cortex, brainstem or spinal cord, and touch, sound or startle may provoke it.

• Causes include epilepsy, metabolic disease, hypoxia and drug toxicity.

• Startle-sensitive myoclonus with rapidly progressive dementia and ataxia suggests Creutzfeldt-Jakob disease.

• Hypnic jerk (sleep start) is a single sudden whole-body jerk at sleep onset, often with a sensation of falling. It is normal and becomes more frequent with sleep loss, caffeine and stress.

Chorea, athetosis, ballismus and dystonia

• Chorea cannot be suppressed and has no inner urge. Athetosis is its slow counterpart.

• Motor impersistence, such as inability to keep the tongue out, together with a family history points to Huntington's disease as the cause of chorea.

• Sydenham's chorea is chorea appearing weeks after a streptococcal throat infection, with emotional lability, as part of rheumatic fever.

• Tetrabenazine is the licensed drug for Huntington's chorea: a monoamine-depleting vesicular monoamine transporter 2 (VMAT2) inhibitor that reduces presynaptic dopamine release from depleted vesicular stores.

• Kernicterus damages the basal ganglia, especially the globus pallidus; it and perinatal hypoxia cause athetoid or dyskinetic cerebral palsy.

• Hemiballismus cannot be suppressed and is absent in sleep.

• Dystonia usually eases or disappears in sleep.

Tremor

Tremor is classified by the state in which it appears (rest, posture, action, approach to a target) and by the signs that accompany it.

• Rest tremor is present in a relaxed, supported limb, is damped by voluntary movement of that limb, and is brought out by mental load or by moving another body part.

• Postural, physiological and essential tremors are present during activity.

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• Lithium at therapeutic long-term levels causes an enhanced physiological tremor, not essential tremor.

• In severe lithium toxicity the tremor becomes coarse and slow, around 2 Hz. New coarse tremor with ataxia, vomiting or confusion needs urgent assessment for toxicity.

• Valproate, antidepressants, bronchodilators and thyroid medicines also enhance tremor.

• Benzodiazepines suppress physiological tremor by enhancing inhibition by gamma-aminobutyric acid (GABA).

• Functional tremor is recognised by positive signs: abrupt onset, variable frequency, and pausing when the patient is distracted by a mental task or a task for the other hand.

• Entrainment is a tremor taking on the rhythm tapped by the other limb, which no organic tremor does.

Parkinsonism and raised tone

• Akinesia is reduced movement and difficulty starting it.

• Bradykinesia is slowness with decrement on repetitive movement, such as finger taps that shrink. It is the cardinal and obligatory sign, and parkinsonism cannot be diagnosed without it.

• Parkinsonism is diagnosed clinically by bradykinesia plus at least one of rest tremor or rigidity. General slowness alone is not enough.

• The commonest presenting feature of idiopathic Parkinson's disease is a unilateral rest tremor.

In an immobile patient, look for rigidity and decrement with a relevant drug (drug-induced parkinsonism), a mood syndrome with slowed thought (depressive retardation), or other catatonic signs (catatonic immobility).

Gait, cerebellar signs and restless legs

• Absence of falls alone does not establish a functional gait disorder.

• Abnormal limb coordination on bedside testing with normal power and sensation localises to the cerebellum.

• Cerebellar signs affect coordination, tone, eye movement and speech, whereas micrographia and lead-pipe rigidity are basal ganglia signs.

• Restless legs syndrome is an unpleasant leg sensation with an urge to move, brought on by rest, relieved by movement, worse in the evening and disruptive of sleep.

• Low serum ferritin (iron deficiency) is the main reversible driver of restless legs, because brain iron is needed for dopamine synthesis.

Medicine-induced movement disorders

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• Oculogyric crisis is a form of acute dystonia: sustained upward deviation of the eyes with neck extension.

• Marked one-sided asymmetry of rest tremor, rigidity and bradykinesia points to idiopathic Parkinson's disease rather than drug-induced parkinsonism, even soon after an antipsychotic is started.

• Tardive dyskinesia worsens soon after a dose reduction because the drug had partly masked it. Raising the dose masks the movements rather than resolving them, and they may persist.

• Neuroleptic malignant syndrome is fever, lead-pipe rigidity, fluctuating consciousness and labile blood pressure, with very high creatine kinase from muscle breakdown.

• Neuroleptic malignant syndrome typically follows rapid escalation of a high-potency antipsychotic in a dehydrated patient.

Akathisia

• Akathisia shows as rocking, fidgeting, pacing or repetitive leg movements, but distress can be severe with little visible movement, so ask directly.

• Aripiprazole is a recognised cause of akathisia despite its low overall extrapyramidal rate.

• Psychomotor agitation is purposeless overactivity driven by anxiety without any felt inner urge to move, and that urge is what marks akathisia. The two may coexist.

• Mistaking akathisia for worsening psychosis can lead to harmful dose escalation.

• Treatment options are reducing the dose, switching, or adding propranolol after checking contraindications.

Functional movement disorders

• Diagnose a functional movement disorder from positive findings (inconsistency, distractibility, entrainment) interpreted by an experienced clinician. Normal imaging alone is not enough.

• Patients experience the symptoms as involuntary, and inconsistency does not mean fabrication or malingering.

• Functional and other neurological disorders can coexist.

Catatonia

Catatonia is a syndrome of psychomotor signs, associated with mood disorders, psychosis, autism, neurological and medical disease and some withdrawal states. It includes mannerisms and stereotypies.

Spontaneous signs

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• Mutism is the most frequent catatonic sign among psychiatric inpatients on the Bush-Francis Catatonia Rating Scale, within a common cluster of immobility, staring, withdrawal, posturing and negativism.

• Psychiatric stupor is told from coma by unimpaired consciousness, and patients can often recall the episode afterwards.

• Depression is the most frequent cause of stupor among psychiatric inpatients.

• Schnauzkrampf is classically linked with schizophrenia, and Fish classes it as a stereotyped posture.

Signs elicited by the examiner

• Posturing is a posture the patient adopts; an imposed posture that is then held implies waxy flexibility.

• Catalepsy is a passively induced posture held against gravity; waxy flexibility is slight, even resistance to repositioning. Both are catatonic signs in ICD-11.

• Automatic obedience is exaggerated cooperation with spoken instructions, whereas echopraxia imitates the examiner's movements.

• Gegenhalten resists only passive movement, whereas negativism also resists instructions.

Signs that are not catatonic

• Chorea, tremor, akathisia, asterixis, micrographia and Bleuler's ambivalence belong to other disorders and are not part of catatonia.

• Cataplexy is an abrupt, emotion-triggered loss of muscle tone with preserved awareness, a feature of narcolepsy type 1 (loss of hypocretin neurones). It is not a catatonic sign, unlike the sound-alike catalepsy.

Assessment and treatment

• Check physiology, hydration, nutrition, bladder function and the underlying illness, and prevent aspiration, thrombosis, pressure injury, contractures, renal injury and rhabdomyolysis.

• Fever with autonomic instability raises concern for malignant catatonia or neuroleptic malignant syndrome, and dopamine-blocking drugs can worsen catatonia.

• Delirium and catatonia can coexist, so preserved consciousness does not absolutely separate them.

• Lorazepam challenge, commonly 1 to 2 mg parenterally with monitoring, supports diagnosis and treatment. A response is not specific, and no response does not exclude catatonia.

• Specialist benzodiazepine or electroconvulsive therapy treatment may be needed promptly.

Rating scales