Dystonia

Dystonia

Slow involuntary sustained or intermittent contractions of muscle  repetitive involuntary twisting, writhing or squeezing movements and abnormal postures. Initially appear as part of a voluntary movement. Usually worsen with anxiety and stress. Movements are patterned and repetitive (other hyperkinetic disorders are not). Usually able to suppress the movement by gently touching the affected area. Parkinsonism and drug induced are the commonest cause of secondary dystonia.

Classification can be based on:
1) Aetiology:
• Idiopathic/primary
• Familial
• Sporadic
Secondary
Dystonia plus/heredodegenerative diseases
2) Age at onset:
• Childhood
• Adolescent
• Adult onset
3) Distribution
• Focal (one body part)
• Segmental (one or more continuous body segment)
• Multifocal
• Generalised

Aetiology:
Idiopathic or primary: result of faulty gene if dystonia is only symptom (eg mutation of DYT-1 gene)
Secondary to, eg, multiple sclerosis, Wilson’s disease, stroke, trauma, drugs (eg haloperidol, metaclopramide).

Primary inherited dystonia:
• dystonia is the only neurological manifestation; familial and nonfamilial forms
• eg Oppenheim’s dystonia – DYT1 gene implicated; mean age of onset is 12.5 yrs; 95% begin in one arm or leg  spreads to neck; if begins in one leg progression to generalised dystonia is common; if starts in leg  twisting of limb when walking (running may be normal), unusual stepping may be present, may have difficulty placing heel on ground (especially if distal muscles involved), at rest foot is often plantarflexed and inverted; if starts in arm  dystonia interferes with writing
• eg Non-DYT1 primary dystonia – affects cranio-cervical region; most are focal or segmental in distribution

Focal/segmental dystonia:
Involves one area of the body.
eg cervical dystonia (spasmodic torticollis); blepharospasm (eye lids); foot dystonia; laryngeal dystonia

Case report of 13 year old girl who developed a persistent abnormal posture of one foot and involuntary movements of the foot consisting of slow forced eversion of the foot and more rapid, irregular jerks of the foot and slight tremor in toes. It was not possible to move the foot to a normal position as passive movement increased involuntary movements. A diagnosis of idiopathic segmental dystonia was made .

Adult onset sporadic dystonia:
• most common form of dystonia
• Craniofacial dystonia (Meige’s syndrome):
• blepharospasm and oromandibular dystonia (sometimes cervical dystonia)
• Spasmodic torticollis:
• most common form of focal dystonia; mostly females in 4th or 5th decade
• asymmetric abnormal involuntary movement of neck muscles, abnormal postures of neck and shoulders -–can be painful
• social stimatisation is of concern (eg driving not possible)
• Writer’s cramp:
• dystonic spasm induced by a specific task (eg writing)  develop uncontrollable tight grip with wrist flexion

Childhood-onset idiopathic torsion dystonia (ITD):
Characteristically starts as an involuntary spasm of muscles of leg or arm (inversion of one foot is common) – usually around age 10 (80%<15yrs). Perinatal and development history are normal. Reflexes are normal. Disappears during sleep. Dystonia later spreads to all of limb, then other parts of body (20% remain localised). Dystonia eventually becomes fixed with deformity. Eventually need a wheelchair as the dystonia impairs ambulation.Secondary dystonia: Can be due to drugs (dopamine antagonists, antidepressives, antihistamines, stimulants); vascular disease (basal ganglia infarction or haemorrhage); neoplasms; head trauma; anoxia; meningitis; toxins (eg dioxin); Wilson’s disease; Parkinson’s; Huntington’s disease. Also can have dementia, ataxia, spasticity, weakness, eye movement dysfunction. Onset of dystonia is usually at restTreatment: Often unsatisfactory – first try to identify cause; anticholinergic drugs; levadopa & carbidopa; botulinum toxins into involved muscle (blocks release of acetylcholine); surgical thalamotomy; physical therapy may help some.http://www.printgraphics.net.au/myfiles/In_Motion_April_2015/index.html#30

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