Cervical Dystonia

Disease/Disorder

Definition

Cervical Dystonia (CD) is an adult-onset focal dystonia presenting with pain and involuntary cranio-cervical muscle activation leading to abnormal movements or postures (often twisting nature) affecting the head, neck, and or chin. Common presentations include Torticollis/caput Anterocollis/caput, Laterocollis/caput, Retrocollis/caput or combined postures determined by specific muscles involved.

Etiology

The recently revised recommendations for Classifications of Dystonia is based on two Axes:

• Axis I or Clinical features: Age at onset, distribution, temporal pattern, coexistence of other movement disorders or neurological manifestations
• Axis II or Etiology: Nervous system pathology, Heritability and idiopathic with several subcategories in each group ^1,2

Epidemiology including risk factors and primary prevention

Adult-onset focal dystonia is the most common form of isolated or idiopathic dystonia with CD being the most frequently documented type of focal dystonia. The reported prevalence of CD varies greatly from 2.3/100,000 to 390/100,000 with the wide ranges most likely explained by the inclusion of generalized dystonia or regional differences. Numbers are also likely under-reported due to delayed diagnosis. In focal dystonias, other than focal hand dystonia, females are more affected than males (1.4:1), with males having an earlier age of onset (39.2 vs 42.9 years). Risk factors for primary CD include certain genes (GNAL, THAP1, CIZ1, ANO3) and inherited causes such as DYT23.³

Patho-anatomy/physiology

The cause or causes of dystonia are not well established, and in many patients traditional neuroimaging studies are normal. Investigations have suggested potential causes including:

• Abnormalities in the brain sensorimotor systems as potential pathophysiologic mechanisms of dystonia.
• Damage to brain regions in the thalamus, brainstem, parietal lobe, cerebellum, and basal ganglia.
• Alterations in CNS inhibitory pathways.
• Disruptions in the various steps in dopamine synthesis or nigrostriatal dopamine neuron function ultimately affecting signaling in basal ganglia circuits.⁴

Advanced In-vivo neuro imaging, such as PET or fMRI has revealed the following abnormalities in the various types of dystonias: basal ganglia volume expansion, altered dopamine D2 levels, increase in gray matter in sensory motor cortex, abnormal levels of activity in the premotor cortices, sensorimotor cortex, and supplemental motor areas during motor tasks.⁵ These findings suggest abnormalities in structure, integration processing, and loss of inhibition mediated by GABA levels. Despite similar imaging characteristics across various forms of dystonia, differing levels of Dopamine D2 have been demonstrated between types.

As noted above, the evidence implicating specific regions of the nervous system involved is lacking and disease progression and trajectory varies

• Age of presentation
  • Adult onset (typically age 40-60 years).
  • When onset is in infancy or childhood, secondary causes should be investigated.
• Symptoms vary over time and disease progression is poorly understood but:
  • Frequently worsen with stress or excitement.
  • May improve with rest or with a geste antagoniste/sensory trick (i.e., touching cheek, ear, or back of the head) Figures 1a. 1b.
• Small percentage have spontaneous recovery. This recovery is often temporary lasting days to years with < 1% of affected individuals having permanent recovery.

 Common Patterns of Cervical Dystonia

Patients may present with simple or complex postures and or tremulous movements involving any muscle that attaches to the head and or neck region. The most common patterns of CD include torticollis, torticaput (torticaptis), laterocollis, laterocaput (laterocaptis), anterocollis, anterocaput (anterocapitis), retrocaput (retrocollis), shoulder elevation and or combinations of these postures. Figs. 1a-e  Other less common patterns can also occur, see Fig 1f.

Figure 1a Right Torticollis-torticaput

Figure 1b Right torticollis-torticaput demonstrating response to sensory trick

Figure 1c Right torticollis with contralateral sternocleidomastoid (SCM) hypertrophy

Figure 1d Left laterocaput

Figure 1e Anterocollis and anterocaput

Figure 1f Anterocollis with retrocaput

Figure 2a. Right torticollis-caput, laterocaputs with shoulder and glenoid elevation

Figure 2b R torticollis, R shoulder elevation and glenoid depression

Figure 2c Patient from figure 2a four weeks post botulinum toxin injections

Closely observing the patient’s postures and movements is key to developing a treatment plan as these symptoms can be caused by dystonia in ipsilateral or contralateral craniocervical muscle groups. (Table-1)

Table 1 Common Clinical Patterns and Muscle Involvement

Specific secondary or associated conditions and complications

Many associated conditions can cause acquired or secondary cervical dystonia including:

• Infectious: Viral encephalitis
• Metabolic: Wilson’s disease, mitochondrial
• Neurodegenerative: Parkinson’s, Huntington’s, pantothenate kinase-associated neurodegeneration
• Toxic: medication exposure (neuroleptics, anticholinergics), mitochondrial encephalopathies
• Trauma: cervical injuries, whiplash, concussion

Complications of CD include cervical spine arthritis, nerve root compression, cervical stenosis and cervical myelopathy.

Essentials of Assessment

History

Important information

• Onset: Acute vs insidious, age of onset
• Head or neck position
• Symptom history
  • Does the dystonia and or head/neck position vary during the day?
  • What factors that worsen or improve symptoms?
    • Ex fatigue vs rest, anxiety, stress, illness, sensory tricks
• Presence of pain and, numbness, or tingling
• Associated symptoms/signs
  • High ICP: Vomiting, headache, neurological deficits
  • Infection
• History
  • Trauma, infection, or fever
  • Positive family of movement disorders
• Medication exposure (i.e., anticholinergics)
• Prior treatment (benzodiazepines, baclofen, botulinum toxin, surgery)

Physical examination

Musculoskeletal: Observe/document, including photos/videos pre and post treatment (Fig. 2a, Fig. 2c) including neck/head/chin/shoulder position or postures including; head/neck; ROM, tilt rotation, flexion/extension, tremor, facial or shoulder asymmetry, atrophy/hypertrophy or weakness. Evaluation of upper and lower limbs including bony deformity, joint laxity, ROM limitations, muscular tenderness to palpation.

Neurological: DTR, muscle tone, resistance to movement (rigidity/spasticity), involuntary movements, tremulous movements, cranial/precranial nerves, primitive reflexes, numbness/tingling/weakness (i.e., brachial plexus injury), mirror dystonia, overflow movements, motor control, cognitive assessment.

HEENT: Vision screen (visual field defects or nystagmus), lymph nodes, pharyngeal inflammation

Cardiorespiratory: chest pain, tachypnea, wheezing, symmetrical thoracic cage expansion and coloration

Gastrointestinal: Difficulty swallowing, regurgitation

Integumentary: Signs of pressure or trauma

Clinical functional assessment: mobility, self-care cognition/behavior/affective state

Detailed assessment of

• Cervical Passive and active ROM using an arthrodial protractor
• Observation, photos, video of postures and movements with eyes open and closed
• Evidence of improved symptoms of dystonia after providing tactile stimulation to the affected body part, also called Sensory Trick (ST) or “geste antagoniste”
• Effects of dystonia on work capacity, participation and sleep quality
• Psychiatric comorbidities
  • Depression
  • Anxiety

Laboratory studies

No specific studies are recommended for all patients with CD. Investigation should be based on history and associated findings and may include:

• CBC along with gram stain or culture if infectious
• Medication levels
• Genetic testing
• Serum ceruloplasmin and copper levels
• Histopathologic studies of masses with fine needle aspiration cytology if imaging is inconclusive

Imaging

Imaging tests are not routinely required when evaluating patients with CD as they are not useful in helping to establish the diagnosis. However, imaging (radiographs, MRI) may be useful in some patients to evaluate for conditions that may contribute to or result from constant dystonic movements. Examples include degenerative spine disorders, spondylosis, cervical stenosis, cervical myelopathy or CNS pathology. Electrodiagnostic testing in some patients may be necessary based on presentation to rule out potential treatable causes of the patient’s symptoms.

Imaging based procedural guidance for botulinum toxin (BoNT) injections is increasingly recommended ant utilized by clinicians who treat patients with CD.

• Ultrasound (US) is the preferred imaging-based guidance method and provides information about⁶:
  • Localized anatomy, muscle location, size, depth, atrophy and rheological changes
  • Identifies safe path to target including structures to be avoided
  • May be useful in identifying involuntary movements in deep muscles
• US combined with EMG guidance is preferred by many clinicians because EMG provides additional information including
  • The presence or absence of EMG activity helps determine if the target muscle is potentially contributing to the observed dystonic movements.
  • The level of muscle activity may inform dosing
  • Presence of compensatory activation or tremulous activation

Muscle selection for BoNT injections requires an extensive knowledge of cross sectional and functional anatomy. During the procedure muscle isolation and targeting is enhanced by EMG and ultrasound studies. Clinicians must be skilled in interpreting EMG activity to discriminate between dystonic activation and antagonistic or compensatory muscle activation.^7,8,9,10 Polymyographic electromyography prior to injection has been shown to have significantly increased sensitivity and specificity relative to clinical exam alone and yield greater improvement in TWSTR, even among patients who had deteriorating response to repeat BoNT injections. Frequency analysis can also be used to differentiate dystonic firing from compensatory firing.¹¹

Supplemental assessment tools

Additional exam tools

Physical Exam:

• Palpation of muscles to identify hypertrophy
• When infantile onset congenital torticollis (CMT) is suspected as the cause of an abnormal neck position in an adult (rather than CD) assessment clues may include
  • Symptoms present from infancy/childhood
  • The presence of a pseudotumor or “olive” in the SCM muscle.
  • SCM muscle atrophy rather than hypertrophy.
  • Asymmetry of the face and head for plagiocephaly.
  • History of congenital hip dysplasia which increases the likelihood of CMT.¹²

Early prediction of outcomes

N/A

Environmental

A few case-control studies suggest a relationship between prior neck-trunk trauma and CD. Additional studies report a higher incidence of idiopathic scoliosis in patients with CD compared to controls and that individuals with a history of cervical trauma were more likely to develop adult-onset CD.¹³

Social role and social support system

The physician should inquire about the patient’s function and impact of CD on ADLs, domestic, avocational and vocational responsibilities, and participation in social/family activities. Educating the patient’s family on the impact of CD to enhance their understanding of the condition is important for providing support to the patient.

Professional issues

Some studies have shown higher levels of social isolation/phobia, anxiety, and depression in patients with CD. Further investigation and research is warranted into the etiology of these symptoms and their contribution to the functional limitations and quality of life of patients with CD.^13,14

Rehabilitation Management and Treatments

Available or current treatment guidelines

The treatment of choice for the vast majority of patients with CD, regardless of etiology or pattern, is injection of botulinum toxin (BoNT). Other interventions or medications may be considered and or offered to patients who fail to respond to BoNT.

• BoNT:
  • Both BoNT serotype-A (abobotulinumtoxinA, incobotulinumtoxinA, onabotulinumtoxinA) and serotype-B (rimabotulinumtoxinB) carry US FDA approval for treatment of CD. FDA approvals for additional products are likely. BoNT- A is reported to have a slightly better side effect profile compared to B.
  • Formulating an individualized treatment plan for a patient is part science, part art and requires that clinicians identify, then accurately inject the muscles most likely to be contributing to the problem.
  • BoNT dosage should be based on evidence from studies, physician experience and patient response to prior treatment
  • When performing BoNT injections most expert clinicians recommend the use of instrumented or supplemental guidance rather than relying solely on palpation and surface anatomy alone. Instrumented guidance options include EMG, ultrasound (US) or US + EMG.9
    • The first author prefers performing BoNT injections for CD using US + EMG where US identifies the target muscle depth, location, structures to avoid, a safe path to the target, and injectate location and EMG helps identify whether a target muscle is active. Fig.3a,3b,3c

Figure 3a Short Axis B-mode US Image Demonstrating Relationship of Phrenic Nerve, SCM & anterior scalene muscles

Figure 3b Short Axis B-mode US image, Interscalene Triangle

Figure 3c Short axis color doppler image, SCM, longus colli and capitis

• Other treatments:
  • Oral medications: A trial of L-dopa is recommended for patients with suspected genetic causes of dystonia including CD. In general, the use of oral medications is typically limited to patients whose symptoms are not adequately managed with BoNT alone. Oral medication options include anticholinergics, dopaminergic or dopamine blocking agents. A positive response to oral medications is low and/or variable and often limited by side effects. Oral medications can also be used in between BoNT injections which is typically performed every 3 months.
  • Surgical Procedures
    • Deep Brain Stimulation (DBS): Stimulation of the globus pallidus internus or subthalamic nucleus is an “off-label” indication for DBS. It may be effective for some patients with intractable CD. However, while the efficacy and safety profile of DBS is well described for “on label” indications additional studies are required to establish this for CD.
    • Deafferentation surgery which was performed in past decades is now uncommonly recommended.
  • Physiotherapy: Physiotherapy (PT) is often utilized as an adjunctive treatment modality in combination with botulinum neurotoxin. There is limited data that shows that PT alone provides significant improvement for patients with CD; however, multiple randomized controlled trials have demonstrated benefit of the combination of BoNT and PT to BoNT alone. More research is indicated to determine clear and specific recommendations regarding PT in the treatment of CD.¹⁵
  • Bracing: Soft cervical collars are not helpful in patients with CD because they are rapidly compressed by the involuntary postures. Also, patients often report being “choked” by a collar. Some patients report benefit from part-time use of a rigid collar for specific activities (watching TV, reading, cooking).
• In patients with acquired or secondary CD, treatments should focus on the underlying cause or causes.¹⁶

At different disease stages

• The vast majority of patients with CD are diagnosed when the condition is chronic, not during the acute or sub-acute phase
• CD is typically a chronic condition and rarely resolves. However, a patient’s symptom severity and pattern of muscle involvement may vary or change over time. Therefore, frequent reassessments are needed to provide optimal treatment of the patient’s and to assess for secondary problems such as contractures, cervical spine degeneration and new onset neurological problems such as myelopathy or radiculopathy.

Coordination of care

There is no universal treatment algorithm for all patients or CD subtypes and CD management must be individualized. It is critical that clinicians first establish the correct diagnosis including potential reversible causes. The next step is recognizing the clinical pattern and establishing a treatment plan including BoNT injection pattern and dose.²

Patient & family education

Patients should be reassured that CD is a treatable condition and most patients will have symptomatic improvement with BoNT therapy. They should be referred to the Dystonia Medical Research Foundation and other sites for education and support. They should also be advised that illness, stress, and pain may increase symptoms.^17,18,19

Measurement of treatment outcomes including those that are impairment-based, activity participation-based and environmentally-based

• The Pain Numeric Rating Scale (PNRS) can be used to monitor pain improvement post treatment. – Single item questionnaire ranking pain 0-10
• The Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) is the most widely used evaluation scale for CD. It can be measured at baseline and prior to subsequent toxin injections.²⁰ It is a numeric scale ranging from 0-85 with three components: severity of dystonia (0-35), disability scale (0-30), and a pain scale (0-20). The original TWSTRS scale²⁰ has been revised (TWSTRS-2) and a TWSTERS-Pscyh is also available, see supplementary materials.^{20, 21}
• In 2015 the Comprehensive Cervical Dystonia (CD) Rating scale (CCDRS) was released. Included are a revised version of the TWSTRS-2, the TWSTRS-PSYCH a previously validated scale the Cervical Dystonia Impact Profile (CDIP-58)
• Unified Dystonia Rating Scale (UDRS)
• 24 question Cervical Dystonia Questionnaire (CDQ-24)²²

*Develop a practice specific pre/post injection tool with a standardized list of questions to keep consistent evaluation at your clinic.

Translation into Practice:  practice “pearls”/performance improvement in practice (PIPs)/changes in clinical practice behaviors and skills

Clinical Pearls:

• Recognizing the patient’s clinical pattern is the first step in establishing a treatment plan.
• Muscles can only move a structure to which they are attached. Examples of patterns/potential target muscles;
  • Muscles attached to the cervical spine move the neck, not the head and vice versa; 
    • Anterocollis: dystonia in the scalenes, longus colli, SCM (when acting bilaterally)Anterorcaput: typically caused by dystonia in the longus capitis.Combined anterocollis/caput: longus colli/capitis, scalenes. (Fig. 1e)Anterocollis + Retrocaput: Bilateral SCM (Fig. 1f)
  • Muscles which are attached to different locations of the same bone may have different actions. Example; the scapular attachments of trapezius (lateral) and levator scapula (medial/superior) lead to different actions/movements
    • Trapezius: shoulder elevation + glenoid elevation Fig. 2a
    • Levator scapulae: shoulder elevation + glenoid depression
• Pre and post treatment photos/videos are essential as they help establish the pattern and response to treatment Figures 2a. 2c.
• Supplemental guidance with EMG will enhance identification of muscles requiring treatment. The use of US provides useful information including depth and location and safe path to the target. Many expert clinicians recommend combined US+EMG guidance.

Figure 2a. R torticollis, laterocaput/collis with shoulder and glenoid elevation

Figure 2b R torticollis, shoulder elevation and glenoid depression

Cutting Edge/Emerging and Unique Concepts and Practice

• Microcurrent Therapy
  • Low-intensity current applied superficially
  • Multiple studies showed efficacy of shorter treatment duration and improved ROM when used in conjunction with therapeutic exercise and ultrasound
• Soft tissue mobilization
• Kinesiology Taping (KT)
  • Stretchable tape supporting muscles providing sensory feedback
  • Mixed findings on KT efficacy when used as a supplemental intervention.
• Shear wave Elastography as a potential diagnostic aid
• Dry Needling/Acupuncture
• Other Investigative Injectable Agents
• RFA/Laser/ECSWT

Gaps in the Evidence-Based Knowledge

Additional studies are required to establish:

• The cause or causes of idiopathic CD
• Efficacy of DBS and or disease modifying therapies
• Whole genome sequencing on CD patients may point to more specific mutations related to CD

References

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Original Version of the Topic

Katharine Alter, MD, Kevin J Cipriano, MD, Jared D Astrow, DO, Rajit Banerjee, BS. Cervical Dystonia. 5/7/2021

Author Disclosures

Jared A Stowers MD
Nothing to Disclose

Derek Day MD
Nothing to Disclose

Katharine E Alter MD
Catalyst Medical Education, Honoraria, Faculty, CME courses
Cleveland Clinic Foundation, Honoraria, Faculty, CME courses
Paradigm Medical Education, Honoraria, Faculty, CME courses
AANEM, Honoraria, Faculty, CME courses
Springer/Demos Medical Publishing, Royalties, Author