Diagnosing Dystonia

Tuesday, 19 November, 2002

Dystonia is a neurological movement disorder characterized by involuntary muscle contractions, which force certain parts of the body into abnormal, sometimes painful, movements or postures. Dystonia can affect any part of the body including the arms and legs, trunk, neck, eyelids, face, or vocal cords. If dystonia causes any type of impairment, it is because muscle contractions interfere with normal function. Features such as cognition, strength, and the senses, including vision and hearing are normal.

While dystonia is not fatal, it is a chronic disorder and prognosis is difficult to predict. Dystonia is one of the least known movement disorders, though its impact on patients' quality of life can be as severe as Parkinson's disease and MS. Dystonia is the third most common movement disorder worldwide and affects as many as 2,000 people in New Zealand. There is currently no cure for dystonia, but treatments are available. These include drug therapy, injections of botulinum toxin, and surgery, all of which can enable people with dystonia to live a full life.

Brief History of Dystonia Dystonia, like many other chronic neurological disorders, was recognized as a distinct entity only relatively recently. Even before the term "dystonia" was coined, people with the syndrome were being reported explicitly in the literature. In 1911, Hermann Oppenheim, a Berlin neurologist who wrote a leading textbook of neurology, was impressed with the variation in muscle tone seen in a neurologic syndrome that he had encountered in several young boys. He coined the term "dystonia" to indicate that "muscle tone was hypotonic at one occasion and in tonic muscle spasm at another, usually, but exclusively, elicited upon volitional movements." The term was widely accepted and has been used by neurologists ever since, even though throughout time, the definition changes.

In addition to alteration of muscle tone, Oppenheim also described twisted postures associated with the muscle spasms affecting limbs and trunk, bizarre walking with bending and twisting of the torso, rapid and sometimes rhythmic jerking movements, and progression of symptoms leading eventually to sustained fixed postural deformities. In 1944, Ernst Herz, from analysis of cinematographic and electromyographic recordings, regarded slow sustained postures as the best definition for dystonia. In 1962, New Zealander and Harvard Professor Derek Denny-Brown of Boston City Hospital expanded upon this definition and defined dystonia as a fixed or relatively fixed attitude. One problem with using only sustained postures for the definition of dystonia is that it allows all types of abnormal postures to be called dystonia, such as fixed postures that could develop from a stroke. Another problem is that these definitions do not take into account the other types of abnormal movements seen in the disorder. In February, 1984, a committee consisting of members of the Scientific Advisory Board of the Dystonia Medical Research Foundation developed the following definition: "dystonia is a syndrome of sustained muscle contractions, frequently causing twisting and repetitive movements, or abnormal postures."

What are the symptoms?

Generalised dystonia usually begins with limbs, especially the foot and the arm, and affects the whole of the body. It occurs mainly in children but can begin in adulthood.

  • Usually childhood onset
  • Begins in arm or leg
  • Trunk affected
  • Can respond well to L-Dopa (dopa-Responsive Dystonia)

Focal dystonias Cervical dystonia (or spasmodic torticollis) affects the neck muscles, turning the head to one side or pulling it forwards and backwards

  • Muscle spasms causing the neck to pull, turn or jerk
  • Head starts to rotate, tilt or be pulled forwards or backwards during conversations or other activities
  • Head tremor may be present
  • Pain may be present

Blepharospasm affects the muscles of the eyelids, causing them to close unexpectedly and remain closed for long periods

  • Abnormal, frequent blinking
  • Spasmodic closure of eyelids
  • Grimacing on closure of eyelids
  • Irritation and discomfort in the eyes and eyelids
  • Light sensitivity or sensitivity to wind
  • Family history of abnormal blinking may exist

Writer's cramp (and other task specific dystonias, e.g. typist's cramp) affect the hand and finger muscles, making writing or other fine hand movements slow and painful

  • Difficulty writing
  • Hand cramps
  • Pain present

Laryngeal dystonia (or spasmodic dysphonia) involves the muscles that control the vocal chords. The voice sounds either strained and hoarse or low and breathy

  • Strained, forced speech
  • Whispering speech
  • Persistent, no obvious cause

Oromandibular dystonia affects the muscles in the jaw, lips and tongue, making the jaw grind or holding it open or shut. This particularly affects eating and speaking

  • Muscle contractions, forcing mouth to shut or pull open
  • Distorted speech
  • Difficulty in swallowing