Version May 2024
INTRODUCTION — Cervical dystonia, also known as spasmodic torticollis or simply torticollis, is one of the most common adult-onset focal dystonias. It is a hyperkinetic movement disorder that manifests with varying degrees of abnormal neck posturing, neck tremor, and/or neck pain. Although generally benign, cervical dystonia can lead to significant disability if untreated, and it is often underrecognized and misdiagnosed.
The treatment of choice for cervical dystonia is botulinum toxin (BoNT) injections, which are administered into target neck muscles to cause selective denervation and relaxation of the abnormal neck posture. Oral medications are useful adjuncts in some patients, but side effects are often limiting and antidystonia effects are relatively modest. Surgical therapy with deep brain stimulation (DBS) is available for refractory cases.
This topic will review the management and prognosis of cervical dystonia in adults. Clinical features, diagnosis, and differential diagnosis of cervical dystonia are reviewed separately. Diagnosis and treatment of other forms of dystonia in children and adults are also reviewed elsewhere. (See "Cervical dystonia: Etiology, clinical features, and diagnosis" and "Etiology, clinical features, and diagnostic evaluation of dystonia" and "Treatment of dystonia in children and adults" and "Hyperkinetic movement disorders in children".)
GOALS AND APPROACH — Treatment of cervical dystonia is symptomatic and optional. The goals of therapy are to improve neck alignment and cosmetic appearance, reduce pain and other secondary complications, and minimize treatment-related side effects.
Many patients with mild symptoms may choose to forgo treatment, except when the abnormal head posturing or movement is unacceptable from a cosmetic perspective. Most patients with disabling pain and/or excessive neck movements that interfere with daily life require treatment. Treatment options include botulinum toxin (BoNT) injections, oral medications, and deep brain stimulation (DBS) for refractory cases (algorithm 1). Among these, BoNT injections are the most effective and well-tolerated treatment (see 'Efficacy' below). Oral medications have more modest effects on dystonia and are used primarily as add-on therapy or when BoNT is not practical or desired. (See 'Second-line strategies' below.)
Over time, patients may opt for a combination of treatment strategies to minimize the risk of side effects from the use of high doses of a single agent. High doses of BoNT injected to the cervical area can cause temporary dysphagia or head drop, while the dose titration of oral medications is often limited by sedation or changes in cognition. Fortunately, moderate doses are sufficient to reduce tremor and pain for most patients, and very high doses of either oral or injected medications are rarely needed for acceptable symptom control.
ROLE OF LEVODOPA TRIAL — Rare patients with young-onset cervical dystonia or a family history of parkinsonism and/or dystonia should be considered for a carbidopa-levodopa trial to exclude dopa-responsive dystonia (DRD). Patients with DRD usually exhibit a robust response to low doses of carbidopa-levodopa (levodopa <300 mg/day), and the benefit is often sustained through their lifetimes without a risk of developing motor complications or fluctuations. Details of a levodopa trial are reviewed separately. (See "Treatment of dystonia in children and adults", section on 'Levodopa trial'.)
Most patients with DRD-associated cervical dystonia will have sufficient response from levodopa to make adjunctive treatments unnecessary, although there is no contraindication to the use of levodopa with botulinum toxin (BoNT) injections or any of the second-line oral medications discussed below.
BOTULINUM TOXIN INJECTIONS — Botulinum toxin (BoNT) injections are recommended as first-line therapy for cervical dystonia in most patients. In expert hands, injections provide excellent symptom relief with minimal, if any, side effects. The effects of BoNT are temporary, and injections are repeated quarterly for sustained benefit.
BoNT injections are covered by most commercial insurances and Medicare in the United States, but the cost of this therapy may be prohibitive for patients without coverage. In such cases, oral medications are preferred. (See 'Second-line strategies' below.)
Mechanism of action — BoNT is a potent neurotoxin produced by Clostridium botulinum that causes regional muscle weakness through its action as a zinc endopeptidase that cleaves specific proteins involved in vesicular fusion. Disruption of these fusion proteins interferes with the release of acetylcholine at the neuromuscular junction, resulting in chemical denervation and flaccid paralysis of the targeted muscle.
Formulations — In the United States, five toxins are approved by the US Food and Drug Administration (FDA) for the treatment of cervical dystonia: four type A toxins (abobotulinumtoxinA [Dysport], daxibotulinumtoxinA [Daxxify], incobotulinumtoxinA [Xeomin], and onabotulinumtoxinA [Botox]) and one type B toxin, rimabotulinumtoxinB (Myobloc). All inhibit the release of acetylcholine quanta in the neuromuscular juncture, leading to chemical denervation and flaccid paralysis of the targeted muscle.
Each product is a unique drug with regard to formulation, potency, and dosing [1]. There is little evidence to support the use of one brand over another, and product selection is generally based on clinician preference and availability. In clinical practice in the United States, BoNT-A treatment is often used as first-line therapy, while BoNT-B is usually reserved for patients who fail or do not tolerate BoNT-A treatment. (See 'Efficacy' below.)
Dosing and muscle targets — Dosing of BoNT for cervical dystonia is individualized and adjusted over time. Injections may be given under electromyographic (EMG) or ultrasonographic guidance, depending on clinical preference [2,3].
●Initial dose and titration – For patients who are toxin naïve, we start at the lower end of the dosing range for the selected toxin and then increase the dose at each subsequent treatment cycle based on response and tolerability. Once a dose is reached at which a patient has optimal response without side effects, there is no need to continue to increase the dose.
Every toxin has its own dosing schedule for muscle injection outlined by the manufacturer, and not all cervical muscles are listed in these schedules. There is no official dose conversion between toxin types [4]. Rotating brands or serotypes is not recommended unless done for practical reasons, such as insurance coverage changes.
Caution is required when treating patients with comorbid neuromuscular diseases, like amyotrophic lateral sclerosis or myasthenia gravis, as they may develop excessive weakness at doses lower than those used in other patients.
●Onset and duration of effect – The clinical benefits of injections usually take approximately one week to become noticeable, are maximum at approximately one month postinjection, and dissipate by three months (or sooner) in most patients. Data from an open-label phase 2 trial of daxibotulinumtoxinA suggest it may have a longer duration of effect [5], but results from the phase 3 trial that led to its FDA approval in 2023 for the treatment of cervical dystonia [6] have yet to be published. Real-world data should be forthcoming. (See 'Efficacy' below.)
●Target muscles for injection – The most challenging aspect of administration for cervical dystonia is the selection of the correct muscles to inject. The decision is based on the identification of the abnormal posture or postures exhibited by an individual patient, and the assumption that certain muscles are most likely to be involved in the genesis of such postures (table 1). For some patients, the main goal of treatment will be pain relief, as opposed to correction of abnormal posture. In these cases, palpation can be helpful to identify areas of spasm and pain for direct targeting [7].
A set of primary and secondary muscles to consider for injection has been proposed based on the collis-caput (Col-Cap) classification (figure 1 and table 2) of abnormal neck postures in cervical dystonia [8,9]. This new classification has not yet been widely adopted by movement disorder specialists but is included here as a new paradigm to be considered alongside standard methods to improve muscle targeting and injection efficacy. (See "Cervical dystonia: Etiology, clinical features, and diagnosis", section on 'Neck posturing'.)
Side effects — Injection site pain is common but is typically mild and transient. Besides injection site pain, side effects from injections are secondary to excessive weakness of the muscles injected (or others in its vicinity), causing head drop, dysphagia, or both. In general, injecting the sternocleidomastoid muscle close to its insertion on the mastoid, avoiding the musculature of the anterior triangle of the neck, and adhering to the dose limits for these muscles can prevent dysphagia, while limiting the dose injected to the neck extensors can prevent head drop.
Like the injection benefits, side effects dissipate spontaneously in weeks. The risk of generalized botulism should be negligible as long as maximum recommended doses are not exceeded.
In systematic reviews of BoNT for cervical dystonia, adverse events that were significantly more frequent with BoNT-A compared with placebo injections were diffuse weakness/tiredness and dysphagia; other adverse events included neck weakness, dry mouth/sore throat, and voice changes/hoarseness [10,11]. These side effects are attributable to excessive weakness in injected muscles or to diffusion of toxin into nearby structures.
Efficacy — Multiple short-term randomized trials have found that chemodenervation with BoNT is more effective than placebo for the treatment of cervical dystonia [10,11].
●BoNT-A – A 2017 meta-analysis of BoNT-A treatment for cervical dystonia identified eight randomized controlled trials in a total of 1010 patients [10]. All trials evaluated a single BoNT treatment session. At week 4 after injection, BoNT treatment compared with placebo led to a reduction in the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) total score of 8.1 points (95% CI 6.1-10.1), corresponding to an average improvement from baseline of 19 percent.
More limited data on daxibotulinumtoxinA for the treatment of cervical dystonia suggest that it may have more lasting effects than other BoNT-A formulations. In an open-label phase 2 study in 37 patients with cervical dystonia, the proportion of responding patients (defined as ≥20 percent reduction in TWSTRS score) was 94 percent at week 6 and 68 percent at week 24 [5]. The median time until retreatment or loss of >20 percent of the improvement at week 4 was 25 weeks.
●BoNT-B – A meta-analysis of BoNT-B treatment for cervical dystonia identified four trials in a total of 441 patients [11]. Most had previously been treated with BoNT-A; patients with pure retrocollis or anterocollis were excluded from three of the trials. Compared with placebo, there was a clinically significant benefit for BoNT-B therapy at week 4 after injection, with a mean reduction in the TWSTRS total score of 6.8 points (95% CI 4.5-9.0). Subjective rating scales also improved.
BoNT is also more effective and better tolerated than oral medications [12,13]. This was shown in a trial in which 66 patients with cervical dystonia were randomly assigned to receive BoNT-A injections plus placebo pills or placebo injections plus trihexyphenidyl [12]. Two cycles of injections were given. At 12 weeks, TWSTRS disability scores improved more with BoNT-A than trihexyphenidyl, and the difference was similar in size to that obtained in a meta-analysis comparing BoNT-A with placebo. BoNT-A was better tolerated than trihexyphenidyl.
Toxin immunogenicity — Over time, there is a theoretical risk of development of immunogenicity and resistance to toxin effects. Although the development of neutralizing antibodies has been documented in patients receiving BoNT, it is unclear whether the antibodies lead to clinically relevant resistance.
It is hypothesized that a reduction in the number of complexing proteins can reduce the immunogenicity of BoNT products [14].
RESPONSE ASSESSMENT — Patients should be assessed at least every three months. At each visit, patients are asked to quantify the degree and longevity of symptom response and are screened for common side effects. During the examination, we look for the presence of lingering neck weakness and ascertain that the dystonic symptoms are back to their preinjection baseline.
Patients who describe refractory symptoms despite escalating toxin doses should be screened for secondary causes. This is particularly important for patients with fixed neck postures and pain that seems out of proportion for the severity of the dystonia. Cervical spine magnetic resonance imaging (MRI) is the best study to exclude underlying orthopedic pathology.
If secondary causes have been excluded, the injection paradigm should be reviewed to make sure that the muscles selected for injection are the most appropriate for the patient's symptoms and that the doses selected are adequate. Electromyographic (EMG) guidance can always help with muscle localization in patients with uncertain neck anatomy, particularly those with a history of neck surgery or in those with excess neck tissue related to body habitus.
If sufficient benefit is not achieved with botulinum toxin (BoNT) injections alone, or if side effects are dose limiting, an oral medication should be added. Patients with refractory symptoms may be candidates for surgery.
SECOND-LINE STRATEGIES
First-tier oral medications — Patients who choose not to receive injections, or who achieve suboptimal relief at the maximum dose tolerated, can try the addition of oral medications. Somnolence, fatigue, and confusion are commonly dose limiting. Lower doses of medications used in combination can, at times, spare the patient from disruptive side effects.
Medication use in cervical dystonia is largely an extrapolation of known benefit of certain drugs in the management of other forms of dystonia. The three medications most often used for cervical dystonia in adults in descending order of efficacy are clonazepam, trihexyphenidyl, and baclofen.
●Clonazepam – Clonazepam, a long-acting benzodiazepine, works by amplifying transmission through gamma-aminobutyric acid (GABA) receptors [15]. In general, clonazepam seems most effective in patients with mild cases of dystonia [16]. A total dose of 1.5 mg/day divided in three doses is often well tolerated but may not be sufficient to control all dystonic symptoms.
●Trihexyphenidyl – Anticholinergics can be helpful in the treatment of cervical dystonia, but adults (unlike children) are rarely able to tolerate doses over 20 mg/day, which limits utility. Anticholinergics are thought to work by blocking muscarinic acetylcholine receptors in the basal ganglia [15], and they have been used in the management of dystonia for decades [17]. Dosing and titration are the same as in other forms of dystonia and are reviewed separately. (See "Treatment of dystonia in children and adults", section on 'Oral medications'.)
Supporting evidence specifically in patients with cervical dystonia is limited and consists primarily of observational studies published before the advent of therapeutic botulinum toxin (BoNT). Across reports, the percentage of adults with a positive response to trihexyphenidyl ranged from 37 to 42 percent [18-22]. The mean required dose was approximately 24 mg/day. Side effects of dry mouth, blurry vision, and forgetfulness often led to treatment discontinuation, especially in older adults. As discussed above, trihexyphenidyl was less effective and not as well tolerated as BoNT in a comparative trial [12]. (See 'Efficacy' above.)
●Baclofen – Baclofen is a GABA receptor agonist that is frequently used in the treatment of dystonia, particularly in patients with associated spasticity [15], and has been studied mainly in oromandibular and generalized dystonia [16]. Oral baclofen can be used safely and as tolerated in patients with cervical dystonia up to 80 mg/day. Dosing and titration are the same as in other forms of dystonia and are reviewed separately. (See "Treatment of dystonia in children and adults", section on 'Oral medications'.)
There may be an emerging role for intrathecal baclofen in the management of refractory cervical dystonia. One report described significant improvements in Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) scores in two patients with cervical dystonia refractory to oral and injectable treatments and who underwent high-cervical (C1-3) continuously infused intrathecal baclofen [23].
Second-tier oral medications — The use of vesicular monoamine transporter type 2 (VMAT2) inhibitors is reserved for patients who fail first- and second-line interventions.
VMAT2 inhibitors are potent dopamine-depleting agents that can cause sedation, parkinsonism, and suicidal depression. Newer VMAT2 inhibitors hold the promise of providing robust symptomatic relief with a better side effect profile; whether they are efficacious in the treatment of dystonic symptoms has not been established yet, however.
●Tetrabenazine – Tetrabenazine is a catecholamine depleter used for symptomatic treatment of several movement disorders, including tardive dyskinesia and Huntington chorea. Data to support a role for tetrabenazine in the treatment of cervical dystonia are limited. In a single-center study of 27 patients with anterocollis, two patients used tetrabenazine for more than a year at a dose of 75 mg/day [24]. The report described a sustained response without side effects. One of the patients had failed BoNT injections. In another report, tetrabenazine was effective in treatment of both myoclonus and dystonia in two patients with myoclonus-dystonia due to sarcoglycan epsilon (SGCE) pathogenic variants [25].
●Deutetrabenazine – Deutetrabenazine is a newer VMAT2 inhibitor, which is an isotopic isomer of tetrabenazine in which some hydrogen atoms have been replaced with deuterium. According to the manufacturer, this chemical change translates into a more favorable side effect profile than tetrabenazine, without any loss in efficacy. An open-label study to define the safety, tolerability, and clinical activity of deutetrabenazine in adults with dystonia (including cervical dystonia) is in progress (NCT04173260).
Role of deep brain stimulation — Deep brain stimulation (DBS) is well studied in the treatment of advanced Parkinson disease and refractory essential tremor, but its role in the treatment of dystonia (and particularly cervical dystonia) is less clear. Nonetheless, limited evidence supports a role in selected patients with treatment-refractory severe cervical dystonia.
DBS is a neurosurgical procedure in which a pulse generator delivers electric stimulation to deep structures within the brain via a stereotactically implanted electrode. The traditional DBS target for cervical dystonia is the internal globus pallidus (GPi) [26].
Supporting evidence includes a randomized, sham-controlled trial of GPi DBS in 62 patients with BoNT-refractory cervical dystonia. After three months of active versus sham stimulation in all 62 implanted patients, the active stimulation group had lower TWSTRS severity scores (between group difference 3.8 points, 95% CI 1.8-5.8) and lower disability scores [27]. The most common procedural or stimulation-related adverse effects were dysarthria (seven patients, 11 percent) and involuntary movements (six patients, all but one related to active stimulation).
The subthalamic nucleus (STN) is also being explored as a target. Successful bilateral STN DBS was reported in two patients with treatment-refractory cervical dystonia [28]. Interestingly, the benefits happened immediately in these patients, as opposed to the delayed benefit that is expected in patients undergoing GPi DBS.
DBS may have a role in the treatment of refractory tardive cervical dystonia as well. In a report of eight patients with tardive dystonia (all of whom had neck involvement and variable compromise of other regions) who underwent GPi DBS, patients had rapid improvement in blepharospasm and more delayed improvement in other areas; arm dystonia improved within 18 months and leg, neck, or trunk symptoms improved within 48 months [29]. Three of eight patients had substantial improvement at the first-month follow-up visit [29].
PROGNOSIS — Cervical dystonia is an important source of disability; left untreated, it can have a substantial impact on health and quality of life.
Natural history — Cervical dystonia is a lifelong condition in most patients. Spontaneous remission has been reported in up to 10 percent of patients, mostly within the first five years of diagnosis [30,31].
Symptoms are progressive in a subset of patients despite botulinum toxin (BoNT) therapy. In a single-center cross-sectional study of 74 patients with cervical dystonia, the median age of onset was 45 years, and two-thirds of the patients were female [32]. The mean time elapsed from first symptom to the start of BoNT therapy was 5.9 years, and the mean duration of BoNT therapy was 9.9 years. Based on questionnaires, approximately one-third of patients reported new or worsening symptoms (eg, pain, increased muscle tone and spasms, reduced mobility of the head and neck) at follow-up compared with their pre-BoNT state. Longer time to initiation of BoNT correlated with worse outcomes. Confidence in these findings is limited by the retrospective nature of the study.
Focal dystonia also carries a risk of spread to contiguous body regions. In data from the ongoing Natural History Project database of the Dystonia Coalition, among 286 patients with isolated focal dystonia initiating in the neck, 24 (8.4 percent) demonstrated signs of spread over time, most commonly to the hand [33]. The mean time to first spread was 3.5 years. Spread to the neck was common in individuals presenting with focal hand or laryngeal dystonia. In a separate study, older age (>50 years) was identified as a risk factor for spread [34].
Disability and complications — Patients with cervical dystonia are at risk for a range of adverse outcomes, particularly when left untreated. Adequate symptom control with BoNT injections likely reduces these risks, but not all patients have access to first-line therapy.
●Employment and productivity – Cervical dystonia affects middle-aged adults near the peak of their economically productive life. Severe cases can lead to disability, with inability to maintain meaningful employment [35]. In two Finnish studies, cervical dystonia was associated with diminished working capacity and earlier retirement age compared with that of otherwise healthy adults [36,37].
●Quality of life – In a single-center cross-sectional study of 200 patients with cervical dystonia who were actively receiving treatment, patient-reported pain, disability, and, most prominently, mood disorder were important factors affecting quality of life [38]. Dystonia severity as assessed by the treating neurologists did not correlate with quality of life. In a separate study of 19 patients with mild cervical dystonia, psychiatric symptoms (anxiety in 58 percent and depression in 42 percent) were associated with increased risk of cervical dystonia-related disability [39].
●Headaches – Headaches are a common comorbidity of cervical dystonia. In approximately half of patients, headaches improve with BoNT injections, suggesting that they are related to the dystonia itself [40].
●Degenerative spine disease – Prolonged exposure to frequent neck movements can accelerate degenerative processes of the cervical spine. The reported prevalence of orthopedic and neurologic spine complications in patients with cervical dystonia ranges from 20 to 40 percent, most commonly cervical spine degeneration, spondylosis, disk herniation, vertebral subluxations and fractures, radiculopathies, and myelopathies [41]. Surgical correction is required in severe cases [42,43].
SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Dystonia in children and adults".)
SUMMARY AND RECOMMENDATIONS
●Goals of treatment – Cervical dystonia is a hyperkinetic movement disorder characterized by abnormal neck posturing, tremor, and pain. Goals of therapy are to improve neck alignment, reduce pain and other secondary complications, and minimize treatment-related side effects. (See 'Goals and approach' above.)
●Criteria for treatment – Treatment is symptomatic and optional. Many patients with mild symptoms choose to forgo treatment, except when abnormal head posture or movement is unacceptable from a cosmetic perspective. Most patients with disabling pain or excessive neck movements that interfere with daily life require treatment. (See 'Goals and approach' above.)
●Role of levodopa trial – A trial of carbidopa-levodopa is appropriate in rare patients with atypical presentations (eg, young-onset, diurnal variation, parkinsonism, family history) to evaluate for dopa-responsive dystonia (DRD). (See 'Role of levodopa trial' above.)
●First-line therapy – For most patients with cervical dystonia who are selected for treatment, we recommend treatment with botulinum toxin (BoNT) injections (Grade 1B). Oral medications for dystonia have only modest efficacy at doses that are tolerable in adults, and BoNT injections are more effective and better tolerated (algorithm 1). (See 'Botulinum toxin injections' above and 'Efficacy' above.)
•Formulation – There is little evidence to support the use of one brand of BoNT over another, and product selection is generally based on clinician preference and availability. In the United States, five toxins are approved for treatment of cervical dystonia: abobotulinumtoxinA, daxibotulinumtoxinA, incobotulinumtoxinA, onabotulinumtoxinA, and rimabotulinumtoxinB. (See 'Formulations' above.)
•Administration – BoNT should only be given by clinicians trained in treating cervical dystonia. Injection sites and dosing are individualized based on neck posture classification (table 1), cervical muscle anatomy, and treatment goals (posture correction, pain relief, tremor suppression). (See 'Dosing and muscle targets' above.)
The clinical benefits usually take approximately one week to become noticeable, peak at one month postinjection, and dissipate by three months. Injections are given quarterly for sustained benefit.
•Side effects – Injection site pain is common but is typically mild and transient. Excessive weakness in or near injected muscles can lead to temporary head drop and/or dysphagia. Risks are minimized by limiting the dose injected to the sternocleidomastoid and neck extensor muscles and avoiding, when possible, injecting the muscles of the anterior triangle of the neck. (See 'Side effects' above.)
●Second-line therapy – Oral medications that can be tried as adjunctive treatment or in isolation include clonazepam, trihexyphenidyl, and baclofen. Among these, we suggest clonazepam first in most patients (Grade 2C). All can cause sedation or confusion, and side effects are often dose related. (See 'First-tier oral medications' above.)
●Refractory disease – Selected patients with refractory severe dystonia may be candidates for deep brain stimulation (DBS) surgery. The internal globus pallidus (GPi) has been the preferred surgical target, but other targets may be as effective (eg, bilateral subthalamic nuclei [STN]). (See 'Role of deep brain stimulation' above.)
●Prognosis – Cervical dystonia is a chronic disease. Remissions have been reported but are rare. Untreated, cervical dystonia can lead to orthopedic neck changes with limitation in range of motion, cervical radiculopathy, chronic pain, and disability. (See 'Natural history' above and 'Disability and complications' above.)
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