What are the treatment options for primary dystonia?

Treatment Options for Primary Dystonia

Botulinum toxin injections are the first-line treatment for focal and segmental primary dystonia, while oral medications (particularly anticholinergics) or deep brain stimulation should be considered for generalized primary dystonia. 1, 2

Initial Diagnostic Consideration

• Every patient with childhood or early-onset limb dystonia must receive a levodopa trial first to exclude dopa-responsive dystonia, which responds dramatically to levodopa replacement therapy. 3, 4, 2
• This trial is warranted in every patient with early-onset primary dystonia without an alternative diagnosis. 2

Treatment Algorithm by Dystonia Distribution

Focal and Segmental Dystonia (Cervical, Cranial, Limb)

First-Line: Botulinum Toxin

• Botulinum toxin type A is the first-line treatment for primary cranial (excluding oromandibular) or cervical dystonia. 2
• AboBoNT-A (Dysport) and rimaBoNT-B (Myobloc) have the strongest evidence for efficacy and should be offered as first-line options for cervical dystonia. 1
• OnaBoNT-A (Botox) and incoBoNT-A (Xeomin) also have similar efficacy and should be considered. 1
• BoNT/B is not inferior to BoNT/A in cervical dystonia. 2
• Botulinum toxin is also effective for writer's cramp (writing dystonia). 2

Adjunctive Treatments

• Referral to rehabilitation specialists for comprehensive neuromusculoskeletal management is recommended. 1
• Physical therapy added to botulinum toxin injections shows potential benefit in cervical dystonia. 5
• Sensorimotor training and transcutaneous electrical nerve stimulation (TENS) may help in writer's cramp. 5
• Speech therapy added to botulinum toxin injections may benefit laryngeal dystonia. 5
• Nerve-stabilizing agents such as pregabalin, gabapentin, and duloxetine can be prescribed for pain management and spasm control. 1

Generalized Primary Dystonia

First-Line: Oral Medications

• Initiate treatment with trihexyphenidyl (an anticholinergic), titrating slowly up to a high dose. 3
• Anticholinergic drugs are a primary oral medication option for generalized dystonia. 4, 6
• Add baclofen as a second agent if trihexyphenidyl alone provides inadequate benefit. 3
• Other oral options include dopamine modulators, muscle relaxants, and other pharmacologic agents. 6

Important Caveat: A subset of patients with primary generalized dystonia will have significant and sustained clinical benefit with oral medications, so adequate trials of oral medications must be attempted prior to referral for surgery. 3

Second-Line: Deep Brain Stimulation (DBS)

• Pallidal deep brain stimulation is considered a good option for primary generalized or cervical dystonia after medication or botulinum toxin have failed. 2
• Once it is clear that medical therapies are not providing significant benefit or are not well tolerated, children with disabling generalized primary dystonia should be referred quickly for DBS. 3
• Patients with primary dystonia respond better to DBS than those with secondary dystonia. 3
• Limb and axial muscles may improve more than cranial dystonia with DBS. 3
• Shorter duration of disease may be associated with better outcomes, supporting earlier referral once medical therapy fails. 3
• DBS is less effective in secondary dystonia. 2

Specific Dystonia Subtypes

Drug-Induced Extrapyramidal Dystonia

• The recommended dosage of benztropine is 1 to 4 mg once or twice a day orally or parenterally, individualized according to patient need. 7
• In acute dystonic reactions, 1 to 2 mL of benztropine injection usually relieves the condition quickly. 7
• After acute treatment, benztropine tablets 1 to 2 mg twice a day usually prevent recurrence. 7

Paroxysmal Kinesigenic Dyskinesia (PKD)

While PKD is technically a paroxysmal dystonia syndrome rather than primary dystonia, treatment differs significantly:

• Carbamazepine (50-200 mg/day) or oxcarbazepine (75-300 mg/day) are the preferred first-line treatments, with approximately 97% of patients achieving complete or partial relief. 8
• More than 85% of patients achieve complete remission with these low doses. 8
• PKD has a dramatic response to sodium channel blockers. 8

Laryngeal Dystonia (Spasmodic Dysphonia)

• Botulinum toxin injections should be offered for the treatment of dysphonia caused by spasmodic dysphonia and other types of laryngeal dystonia. 8

Common Pitfalls to Avoid

• Do not use serial casting for fixed functional dystonia, as it has been associated with worsening symptoms and onset of complex regional pain syndrome. 8
• Avoid splinting in dystonia when possible, as it may increase attention to the affected area (exacerbating symptoms), increase accessory muscle use, promote compensatory movement strategies, cause muscle deconditioning, lead to learnt non-use, and increase pain. 8
• Do not delay DBS referral excessively in children with severe generalized dystonia once medical therapy has clearly failed, as extended periods of disability carry significant physical and emotional costs. 3
• Recognize that certain drug-induced extrapyramidal disorders that develop slowly may not respond to benztropine. 7

Treatment Goals and Outcomes

• The goals of dystonia treatment are to relieve involuntary movements, correct abnormal posture, prevent contractures, reduce pain, and improve function and quality of life. 4
• Document resolution, improvement, or worsened symptoms after treatment or observation. 8