Dystonia

What is dystonia?

Dystonia is a type of neurological disorder resulting in abnormal body posture or movements resulting from sustained involuntary muscle contraction.

 

How common is dystonia?

Exact numbers are unclear, but it is considered more common that previously thought. It is frequently misdiagnosed.

 

Are there different types of dystonia?

Dystonia can be divided in types in many ways:

Based upon the areas involved:

1. Focal dystonia: When one or a small group of muscles in one body region are involved. Examples are:
   1. Eyelids: Blepharospasm
   2. Face: Hemifacial spasm
   3. Mouth or tongue: Oromandibular
   4. Larynx: Spasmodic dysphonia
   5. Neck: Cervical dystonia
   6. Hand: Writer’s cramps
   7. Foot or leg
   8. Trunk
2. Segmental dystonia: When more than one body regions are involved. Examples are:
   1. Meige syndrome: Eyes and lower face dystonia
   2. Trunk and limb
3. Multi-segmental dystonia: When multiple unrelated body segments are involved. For example, Writer’s cramps and cervical dystonia
4. Generalized dystonia: When trunk is involved with other body segments.
5. Combined dystonia: It implies that dystonia is associated with or a part of other conditions such as:
   1. Parkinsonism
   2. Myoclonus
   3. Chorea
   4. Wilson disease
   5. Hypermagnesemia
   6. Aceruloplasminemia
   7. Woodhouse-Sakati syndrome
   8. Lysosomal storage disease
   9. Disorders of purine metabolism
   10. Mitochondrial disorders
   11. Organic acidurias
   12. Aminoacidurias
   13. Disorders of biotin metabolism
   14. Neurodegenerative disorders
   15. Primary coenzyme Q10 deficiency

Based upon triggers:

1. Action dystonia: Triggered by writing, typing, walking, or certain activities or postures.
2. Circadian dystonia: Upon waking up or while going to sleep.
3. Paroxysmal dystonia: Intermittent attacks of dystonia with no obvious trigger. It usually affects children, rarely after teen years.

Based upon etiology:

1. Primary or genetic
   1. Autosomal dominant
   2. Autosomal recessive
   3. Genetic combined
2. Secondary or acquired
3. Unknown cause or idiopathic

What are secondary or acquired causes of dystonia?

1. Hypoxic brain injury
2. Hypoglycemic brain injury
3. Infectious, such as prion disease
4. Para-infectious, such as Reye syndrome
5. Toxic, such as kernicterus, CO poisoning, wasp sting, methanol, cyanide, disulfiram, manganese (from ephedrone, chronic liver disease, total parental nutrition)
6. Autoimmune, such as multiple sclerosis or anti-phospholipid antibody syndrome
7. Paraneoplastic conditions
8. Osmotic demyelinating syndrome
9. Vascular disorders
10. Traumatic brain injury
11. Space occupying brain lesion
12. Electrocution
13. Drugs, such as anti-psychotics or anti-epileptics

 

How is dystonia diagnosed?

It is diagnosed based upon history and examination. Nowadays, review of pictures and videos taken by the patient, or the family or friends can also help. Other than genetic testing that may be useful in some patients, there is no lab test available to confirm primary dystonia. There are many causes of secondary or acquired dystonia and the workup for that is tailored to an individual patient.

 

What is pseudo-dystonia?

May conditions can mimic dystonia. Some examples are:

1. Ptosis
2. Myotonia
3. Functional or psychogenic dystonia
4. Tetanus
5. Klippel Feil syndrome
6. Neck mass
7. Dupuytren contracture
8. Trigger finger
9. Carpopedal spasms

 

How is dystonia treated?

Before treatment is considered, it is important to make the exact diagnosis to see if it is of primary or the secondary type. For secondary dystonia, treatment is cause specific. Following measures are available for primary dystonia, which may not be effective in all cases:

1. Physical and/or occupational therapy
2. Some anti-epileptics like carbamazepine
3. Anti-cholinergic drugs
4. Benzodiazepines
5. Botulinum toxin injections
6. Deep brain stimulation
7. Amantadine
8. Ketogenic diet
9. Avoidance of triggers
10. Avoidance of fasting, stress, anxiety
11. Trans-magnetic stimulation
12. Brain surgery

Some patients with specific type of dystonia may also benefit from:

1. Focal dystonia: Botox is the treatment of choice.
2. Tardive dyskinesia: Anti-dyskinetic meds (valbenazine, deutetrabenazine, and tetrabenazine)
3. Dopamine responsive dyskinesia: Dopamine or levodopa, anticholinergics
4. Paroxysmal kinesogenic dyskinesia: Carbamazepine, or other antiepileptics
5. Paroxysmal non-kinesogenic dyskinesia: Benzodiazepine, gabapentin, levetiracetam
6. Paroxysmal exercise induced dyskinesia: Ketogenic diet, triheptanoin
7. Tardive akithesia: Zolpidem

For combined dystonia

1. Myoclonus and dystonia: Zonisamide, benzodiazepines
2. Parkinsonism and dystonia: Levodopa, dopamine agonists, anticholinergics
3. Spasticity and dystonia: Baclofen

 

Where can I get more information about dystonia?

American Academy of Neurology

The International Parkinson and Movement Disorder Society