Cervical dystonia: from pathophysiology to pharmacotherapy.
BACKGROUND
Dystonia is a chronic disorder characterised by an aberration in the control of movement. Sustained co-contraction of opposing agonist and antagonist muscles can cause repetitive and twisting movements, or abnormal postures. Cervical dystonia (CD), often referred to as spasmodic torticollis, is a type of focal dystonia involving the muscles of the neck and sometimes the shoulders.


METHODS
This systematic review collates the available evidence regarding the safety and efficacy of a range of treatments for CD, focusing on their effectiveness as shown by double-blinded, randomised controlled trials.


RESULTS
Our review suggests that botulinum toxin type A (BTA), botulinum toxin type B (BTB) and trihexyphenidyl are safe and efficacious treatments for CD. Evidence shows that botulinum toxin therapies are more reliable for symptomatic relief and have fewer adverse effects than trihexyphenidyl. When comparing BTA to BTB, both are found to have similar clinical benefits, with BTA possibly having a longer duration of action and a marginally better side effect profile. BTB is also safe and probably just as efficacious a treatment in those patients who are unresponsive or have become resistant to BTA.


CONCLUSIONS
The current evidence shows that the pharmacological management of CD relies on BTA and BTB, two agents with established efficacy and tolerability profiles.
Michael Trimble Neuropsychiatry Research Group, Department of Neuropsychiatry, BSMHFT and University of Birmingham, Birmingham, UK.
Sejal
S
Patel
Davide
D
Martino
D001905:Botulinum Toxins / Q000009:adverse effects / Q000627:therapeutic use*; D019274:Botulinum Toxins, Type A / Q000009:adverse effects / Q000627:therapeutic use*; D006801:Humans; D018727:Muscarinic Antagonists / Q000009:adverse effects / Q000627:therapeutic use; D009465:Neuromuscular Agents / Q000009:adverse effects / Q000627:therapeutic use; D014103:Torticollis / Q000188:drug therapy* / Q000503:physiopathology*; D014282:Trihexyphenidyl / Q000009:adverse effects / Q000627:therapeutic use
D018727:Muscarinic Antagonists; D009465:Neuromuscular Agents; C096323:rimabotulinumtoxinB; D014282:Trihexyphenidyl; D001905:Botulinum Toxins; D019274:Botulinum Toxins, Type A