Cervical Dystonia

Definition

• Abnormal head and neck posture caused by tonic involuntary contractions in a set of cervical muscles

• Previously called: Spasmodic torticollis

Epidemiology

• M:F 1:1.2

• Can occur at any age – peak 41yrs

Aetiology/pathophysiology

• Previous thought to be psychogenic

• Dystonia – cortical origin

• Primary

o Idiopathic

o Genetic

• Secondary

o Neuroleptic medication exposure

o Trauma

Clinical

• Usually insidious onset, sometimes more sudden

• Usually plateaus after 5 years

• May have a sensory trick “geste antagoniste”

• Neck pain common (70-80%)

Classification

• Direction of movement:

o Latero-

o Retro-

o Antero-

o Torti- (rotation)

• Axis of rotation:

o Base of neck – collis

o Base of skull – caput

Treatment – Botox

• First line treatment for most patients

• First published cases 1985

• Multiple clinical trials (including RCTs)

o Improvement in dystonia rating scales of 10-50%

• Onset of effect 3-12 days, lasts ~ 3months

• Possible side effects

o Allergic reaction

o Injection site pain

o Bleeding or bruising

o Infection

o Dry mouth

o Dysphagia

o Neck pain

o Headache

o Neuropraxia

• Assessment of dystonia

o With head in relaxed position

o Attempting to hold head in neutral position

o Walking/sitting/lying

o Movement of head to different positions

o Description of pain

o Palpation of painful muscles

o Associated dystonia (arm, blepharospasm, dysphonia)

Laterocollis	Levator scapulae Scalenus anterior Scalenius medius Semispinalis cervicis Longissimus cervicis
Laterocaput	SCM Splenius capitus Splenius cervicis Trapezius Semispinalis capitis Longissimus capitis Levator scapulae
Torticollis	Ipsilateral Splenius capitus Longissimus cervicis Semispinalis cervicis OCI Contralateral Trapezius SCM Semispinals capitus Spinalis capitus
Torticaput	SCM (Contralateral) Trapezius (contralateral) Semispinalis capitis Splenius capitis Splenius cervicis Longissimus capitus Obliquus capitis inferior
Antecollis	Scalenus anterior Scalenus medius Lev scapulae Longus colli pars recta Longus collis pars obliqua inferior SCM
Antecaput	Longus capitis Longus colli pars obliqua superior Lev scap Platysma Digastric, submental
Retrocollis bilateral	Longissimus cercicis Semispinalis cervicis
Retrocaput bilateral	SCM Trapezius Semispinalis capitus Splenius capitus Splenius cervicis Obliquus capitis inferior

Specific injections

OCI	Midway between posterior SCM and dorsal midline At level of C2 (?25mm below mastoid process) 30-35mm deep

Treatment – Other

Medications

• Limited benefit in general

• Anticholinergics

o Trihexyphenidyl (Artane)

o Benztropine

• Benzodiazepines

• TCA’s (amitriptyline, nortriptyline)

Surgical

• Selective peripheral denervation

• Myectomy

• DBS (to GPI) – some benefit in limited trials