Dystonia new

Dystonia is an extrapyramidal disorder characterized by repetitive muscle contractions leading to abnormal postures and movements. Treatment includes non-pharmacological approaches, various oral medications, botulinum toxin injections, and deep brain stimulation for severe cases.

2024-01-06 17:52:00 - Editor

Overview of Dystonia:

Dystonia is a reversible extrapyramidal movement disorder which is characterised by repetitive muscle contractions resulting in abnormal postures, limb movement or both. Dystonia is usually worsened by voluntary movement. Dystonia may be Focal or generalised. Focal dystonia include blepharospasm, laryngeal, DYT-GNAL, cervical, hand and limb dystonia. Sometimes, dystonia may be combined with myoclonus, Parkinsonism or dyskinesia. (1, 2)

Non-Pharmacological Treatment for Dystonia:

The treatment of dystonia is often symptomatic, with no curative therapies available. Non-pharmacological treatment includes relaxation training, transcutaneous electrical nerve stimulation and/or percutaneous dorsal column stimulation. Occupational therapy is very important. Additionally, speech therapy can offer communication aids to patients with laryngeal dystonia. (3)

Pharmacological Therapy Options:

Pharmacological therapy options include levodopa, other oral medications, botulinum toxin injection, investigational therapy and/or surgery. For generalised dystonia, Levodopa is suggested. Patients who do not respond to levodopa can be treated with other oral medications, botulinum toxin injection or deep brain stimulation (DBS) in severe refractory cases. For focal dystonia botulinum toxin is suggested. DBS of the GPi is for cases not responding to botulinum toxin. (2, 4)

Levodopa for Dystonia:

Levodopa is effective to control dystonia especially for dopa responsive dystonia (DRD). The usual dose is ranging from 100-750 mg daily. The response rate with levodopa is 15%. Levodopa can be either used alone or in combination with carbidopa (peripheral decarboxylase inhibitor) at 25/100 mg to take one-half tablet two to three times daily with meals; is effective to control DRD. (4, 5)

Other Oral Medications:

Other oral medications include anticholinergic agents, such as, trihexyphenidyl (1mg twice daily) which is effective in the management of torsion dystonia. (6)

VMAT2 Inhibitors:

Also, VMAT2, such as, tetrabenazine which is a vesicular monoamine transporter type 2 (VMAT2) inhibitor are effective. These agents combine both monoaminergic depletion and dopamine antagonist effects. Evidence from case series suggests that tetrabenazine (12.5mg daily) is beneficial in dystonia. (7)

Additional Oral Medications:

As well as that, Baclofen (40-80mg daily) was associated with improvement in 18% of patients with dystonia as per trial results. Finally, clonazepam (1.5-6 mg) was reported to control the disease. (8, 9)

Botulinum Toxin for Dystonia:

Botulinum toxin acts by induce cleavage of zinc endopeptidase protein involved in vesicular fusion. Botulinum toxin is very effective to treat focal dystonia including cervical dystonia and blepharospasm, and generalised dystonia not responding to oral medications. Two serotypes are available including botulinum toxin type A (BoNT-A) (1.25 to 2.5 units IM) and botulinum toxin type B (BoNT-B) (2,500 to 5,000 units IM). (10)

Investigational Therapies:

Investigational therapy includes transcranial magnetic stimulation and gene therapy. Transcranial magnetic stimulation works through repetitive, low frequency transcranial stimulation and could enhance cervical and hand dystonia. Gene therapy inhibits the targeted messenger RNA and gene silencing mediated by viral RNAi. It is particularly effective to treat DYT-GNAL dystonia. (11, 12)

Surgical Treatment for Severe Dystonia:

Surgical treatment is reserved for severe dystonia which fail treatment with pharmacological agents and botulinum toxin injection. The mainstay of surgical intervention is DPS of the internal segment of globus pallidus. (13)

References

More Posts