Secondary dystonias

The various forms of dystonia can be divided into two broad groups: primary dystonias and secondary dystonias. Primary dystonias are genetic (or believed to be genetic) in origin, whereas secondary dystonias result from apparent outside factors and can be attributed to a specific cause such as exposure to certain medications, trauma, toxins, infections, or stroke.

Secondary dystonia is dystonia that develops mainly as the result of environmental factors that provide insult to the brain. Spinal cord, head, and peripheral injury are also recognized contributors to dystonia. Other examples of secondary dystonias include levodopa-induced dystonia in the treatment of parkinsonism; acute and tardive dystonia due to specific drugs such as dopamine receptor blocking agents; and dystonias associated with cerebral palsy, cerebral hypoxia, cerebrovascular disease, cerebral infections and postinfectious states, stroke, encephalitis, brain tumor, and toxins such as manganese, cyanide, and 3-nitroproprionic acid.

Many secondary dystonias are dystonias associated with approximately 50 neurological and metabolic diseases. Many of these diseases are genetic. This category includes diseases such as corticobasal degeneration, pantothenate kinase deficiency (aka Hallorvorden-Spatz), Huntington’s disease, Wilson’s disease, Leigh’s disease, and juvenile parkinsonism.

A number of secondary dystonias do not present as pure dystonia, but with a mixture of other neurologic features, such as parkinsonian features like slowness of movement (bradykinesia) and rigidity.

Causes of Secondary Dystonia
It is well established that dystonia is brought about by secondary causes such as drug exposure, head and peripheral trauma, and other disorders. Studies also suggest that insults such as trauma may trigger or exacerbate symptoms in individuals who have a genetic predisposition to dystonia. Research continues to better understand these various manifestations of dystonia.

Diagnosis of Secondary Dystonia
Many of the ascribed causes of secondary dystonia are based on historical information or subtle characteristics of the symptoms, and have no diagnostic, radiologic, serologic, or other pathologic trademark.

Treatment of Secondary Dystonia
Treatment for secondary dystonias that are attributed additional neurological or metabolic disorders is usually directed by the specific requirements of that disorder.

Oral medications are often the mainstay of treatment for secondary dystonia. Although there is no single drug that helps an overwhelming number of individuals, there are several that may be of benefit. These oral medications include levodopa, trihexyphenidyl, clonazepam, and baclofen (oral and intrathecal—especially for dystonia and spasticity). Medications may be taken in combination.

Botulinum toxin injections may be used to treat specific body parts that may be affected, such as the neck, jaw, hands, or feet.

Several surgical techniques may be appropriate for select individuals who do not respond to medications and botulinum toxin injections. These may include ablative surgeries such as pallidotomy and thalamotomy, intrathecal baclofen, and deep brain stimulation. The specific characteristics of the disease or condition that is causing the dystonia may preclude an individual from selects surgical procedures for dystonia, or present alternative surgical options.

Complementary therapies may be explored, particularly physical therapy, aquatic therapy, and regular relaxation practices.

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