Abnormal Involuntary Movements / Tics

Dystonias

Sustained or intermittent abnormal repetitive movements or postures from altered muscle tone. May be focal (one body part) or generalised (whole body); can be secondary to antipsychotics. Highly disabling — functional/social impairment and quality-of-life impact comparable to multiple sclerosis or Parkinson’s disease, but often under-recognised — average time to diagnosis for cervical dystonia in one Australian cohort was 6.8 years.

Identifying dystonia: look for a “null point” (movement quietens when the affected area is positioned toward the direction of pull) and a “sensory trick” (tactile/proprioceptive input, e.g. touching the affected body part, diminishes the movement).

Focal dystonias

• Cervical dystonia — the most common focal dystonia (~5/100,000, mean onset 49 years, 74% female). Torticollis ± laterocollis/anterocollis/ retrocollis, usually with neck pain. Differentials: musculoskeletal neck pain, trochlear nerve palsy with compensatory head tilt.
• Blepharospasm — uncontrolled eyelid closure, especially in bright light; onset typically 5th–6th decade, women ~3× more affected. Differentials: eyelid-opening apraxia (progressive supranuclear palsy, in the elderly), Tourette syndrome, psychogenic blinking, dry eyes (in younger patients).
• Oromandibular dystonia — jaw/tongue/mouth grinding, grimacing; disrupts speech and swallowing. May be secondary to Wilson’s disease, Huntington’s disease, neuroacanthocytosis, or drug-induced (tardive dyskinesia).
• Meige syndrome — combined blepharospasm and oromandibular dystonia.
• Hemifacial spasm — a peripheral nerve disorder (not dystonia): starts around the eye (orbicularis oculi) and spreads to the rest of one side of the face; twice as common in women; usually from vascular compression of the facial nerve at the brainstem. Can mimic facial tics or focal seizures.
• Spasmodic dysphonia — laryngeal muscle dystonia; adductor type (vocal cord over-adduction) causes a strained, tremulous, harsh voice; abductor type causes hypophonic whispering. May include dystonic cough, intermittent stridor, paroxysmal hiccups.
• Task-specific dystonia — writer’s/golfer’s cramp and musician’s dystonia, affecting a specific skilled task.

Treatment

Botulinum toxin A (BoNT) injection into affected muscle groups is first-line for cervical dystonia, blepharospasm and hemifacial spasm — PBS- funded for these three indications only. BoNT is administered by a neurologist with movement-disorder expertise (refer for diagnostic confirmation first); EMG or ultrasound guidance can improve targeting, particularly for cervical dystonia. Benefit lasts 3 months before re-injection is needed (neuromuscular junction recovery). Spasmodic dysphonia, oral mandibular dystonia and task-specific dystonia have a weaker evidence base and are not PBS-funded ($400/vial out-of-pocket). Other non-PBS indications include sialorrhoea/hyperhidrosis in Parkinson’s disease; tics of Tourette syndrome, parkinsonian resting tremor and essential tremor need further evidence before routine use.

Tics

Sudden, repetitive, non-rhythmic motor movement or vocalisation — commonly eye-blinking or throat clearing.

• Children: psychological support with habit reversal training can be effective.
• Socially disabling in an adult: clonidine 25mcg BD, increasing to 50–75mcg BD over 2 weeks (child dose 1mcg/kg).
• Severe or drug-refractory cases: refer to a specialist.