Cervical Dystonia

Cervical dystonia (spasmodic torticollis) is the commonest adult focal dystonia, with involuntary neck muscle contractions causing abnormal head posture.

• Prevalence about 5 to 10 per 100,000; onset 30 to 50 years; women more affected.

• Idiopathic in most; secondary causes include dopamine blocking drugs, trauma, posterior fossa lesions, Wilson disease.

• Patterns: torticollis, laterocollis, anterocollis, retrocollis, shift; often combinations with tremor.

• Complications: neck pain (70%), cervical radiculopathy or myelopathy, depression, social avoidance.

• Head turning or tilting, shoulder elevation, tremor, neck pain, hypertrophy of sternocleidomastoid.

• Sensory trick (touching chin or cheek) reduces posturing.

• Fluctuation with stress, worse on walking or concentration, absent during sleep.

• Spontaneous remission in 10 to 20% early, rarely sustained.

• Clinical: TWSTRS scale for severity.

• Exclude structural causes (MRI brain and cervical spine if atypical, abrupt onset, neurological signs), ocular torticollis (fourth nerve palsy), Wilson disease (under 40), drug exposure, functional dystonia.

• EMG mapping and ultrasound to guide injections in complex cases.

• Genetic testing in early onset or family history.

• Botulinum toxin injections every 12 to 16 weeks into overactive muscles (typical total dose: onabotulinumtoxinA 100 to 300 units, abobotulinumtoxinA 500 to 1000 units, incobotulinumtoxinA 120 to 240 units), response in 70 to 90%; ultrasound or EMG guidance in anterocollis and deep muscles; risk of dysphagia and neck weakness.

• Oral agents (less effective): trihexyphenidyl, baclofen 10 to 20 mg, clonazepam 0.5 to 2 mg, diazepam, tetrabenazine.

• Deep brain stimulation of the globus pallidus internus for refractory disease, selective peripheral denervation as alternative.

• Physiotherapy, stretching, occupational therapy, pain management (amitriptyline, gabapentin), psychological support.

• Surgical cervical decompression if myelopathy.