Dystonia

Dystonia is a neurological movement disorder in which sustained muscle contractions cause twisting and repetitive movements or abnormal postures.[1] The disorder may be inherited or caused by other factors such as birth-related or other physical trauma, infection, poisoning (e.g. lead poisoning) or reaction to drugs, particularly neuroleptics.[1].

Causes

The causes of dystonia are not yet known or understood; however, they are categorized as follows on a theoretical basis:

Primary dystonia is suspected to be caused by a pathology of the central nervous system, likely originating in those parts of the brain concerned with motor function, such as the basal ganglia, and the GABA (gamma-aminobutyric acid) producing Purkinje neurons. The precise cause of primary dystonia is unknown. In many cases it may involve some genetic predisposition towards the disorder combined with environmental conditions.

Secondary dystonia refers to dystonia brought on by some identified cause, usually involving brain damage, or by some unidentified cause such as chemical imbalance. Some cases of (particularly focal) dystonia are brought on after trauma, are induced by certain drugs (tardive dystonia), or may be the result of diseases of the nervous system such as Wilson's disease.

Environmental and task-related factors are suspected to trigger the development of focal dystonias because they appear disproportionately in individuals who perform high precision hand movements such as musicians, engineers, architects and artists.

Treatment

Treatment has been limited to minimizing the symptoms of the disorder as there is yet no successful treatment for its cause. Reducing the types of movements that trigger or worsen dystonic symptoms provides some relief, as does reducing stress, getting plenty of rest, moderate exercise, and relaxation techniques. Various treatments focus on sedating brain functions or blocking nerve communications with the muscles via drugs, neuro-suppression or denervation. All current treatments have negative side effects and risks.

Physicians may prescribe a series of different medications on a trial basis in an effort to find a combination that is effective for a specific patient. Not all patients will respond well to the same medications. Drugs that have had positive results in some patients include anti-Parkinsons agents Trihexyphenidyl, Trihexyphenidyl-Hydrochloride(PAKISONAL), muscle relaxers (Valium), keppra, and beta-blockers including "off-label" uses for some blood pressure medications.

Drugs such as anticholinergics, which act as inhibitors of the neurotransmitter acetylcholine, may provide some relief. Clonazepam, an anti-seizure medicine, is also sometimes prescribed. However, for most sufferers their effects are limited and side effects like mental confusion, sedation, mood swings and short-term memory loss occur.

Botulinum toxin injections into affected muscles have proved quite successful in providing some relief for around 3–6 months, depending on the kind of dystonia. Botox injections have the advantage of ready availability (the same form is used for cosmetic surgery) and the effects are not permanent. There is a risk of temporary paralysis of the muscles being injected or the leaking of the toxin into adjacent muscle groups causing weakness or paralysis in them. The injections have to be repeated as the effects wear off and around 15% of recipients will develop immunity to the toxin. There is a Type A and Type B toxin approved for treatment of dystonia; often those that develop resistance to Type A may be able to use Type B.[5]

Surgery, such as the denervation of selected muscles, may also provide some relief; however, the destruction of nerves in the limbs or brain is not reversible and should only be considered in the most extreme cases. Recently, the procedure of deep brain stimulation (DBS) has proven successful in a number of cases of severe generalised dystonia.[6] DBS as treatment for medication-refractory dystonia, on the other hand, may increase the risk of suicide in patients. Unfortunately, reference data of patients without DBS therapy are lacking.[7]

One type of dystonia, dopamine-responsive dystonia, can be completely treated with regular doses of L-DOPA in a form such as Sinemet (carbidopa/levodopa). Although this doesn't remove the condition, it does alleviate the symptoms most of the time.

In the case of Oculogyric crisis, benadryl may be administered with excellent results. Symptoms subside in a matter of minutes.

A baclofen pump has been used to treat patients of all ages exhibiting muscle spasticity along with dystonia. The pump delivers baclofen via a catheter to the thecal space surrounding the spinal cord. The pump itself is placed in the abdomen. It can be refilled periodically by access through the skin.[8]

Physical therapy can sometimes help with focal dystonia. A structured set of exercises is tailored to help the affected area.

Some focal dystonias have been proven treatable through movement retraining in the Taubman approach, particularly in the case of musicians. However other focal dystonias may not respond and may even be made worse by this treatment.

In the case of a acute dystonic reaction,

Diphenhydramine (Benadryl) 25–50 mg IV push is often used in the prehospital and Emergency Department setting to relieve to muscle contractions associated with dystonic reactions. Although an antihistamine, diphenhydramine also possesses some anticholinergic properties. Although diphenhydramine (Benadryl) is used to treat this reaction, it is not an allergic reaction to the medication. The patient should be informed of this distinction.[2]