AXIS I
3. TEMPORAL PATTERN

Temporal aspects include:

1. Manner of onset (acute or insidious).  Dystonia can emerge over a short period of time and remain relatively static thereafter. Dystonia can also progress rapidly over a few hours or days, it can progress more slowly over many years, or it can progress in a stepwise fashion¹.   Even when an etiologic diagnosis cannot be reached, it is important to follow patients because new problems may arise that point to the cause. For example, some patients may present with what appears to be an isolated focal dystonia of the hand or foot, but signs of parkinsonism may develop months or years after onset. In an older adult, this evolution may point to Parkinson disease, where 10% to 15% of patients present with isolated dystonia of the arm or leg.26 Alternatively, this evolution could point to one of the atypical parkinsonian disorders for which the frequency of dystonia is even higher¹.
2. Short-term variations in symptoms (diurnal, intermittent, or action induced)
3. Longer-term variations in overall severity (static or progressive)².

Dystonia phenomenology can evolve with disease progression or display momentary or daily variability in relation to voluntary actions, external triggers, compensatory phenomena, alleviating manoeuvres (gestes antagonistes) or the patient’s psychological state³.

There are four different patterns:

1.            Persistent
Dystonia that persists to approximately the same degree throughout the day.

2.            Action-specific
Dystonia that occurs only during a particular activity or task.

3.            Diurnal fluctuations
Dystonia fluctuates during the day, with recognizable circadian variations in occurrence, severity and phenomenology.

4.            Paroxysmal
Sudden self-limited episodes of dystonia usually induced by a trigger with return to pre-existing neurological state.

Paroxysmal dystonia is a specific entity, where the same trigger on different occasions might or might not induce an attack, and needs to be distinguished from dystonia which is always triggered by the same activity or action (ie task-specific dystonia).

In addition, the clinical presentation may vary over time, and this is particularly common in conditions in which dystonia is part of a syndrome (ie combined dystonia). For example, patients with SCA17 may present with a purely dystonic syndrome, which is followed by ataxia and other signs consistent with spinocerebellar ataxia. Similarly, patients with early-onset Parkinson disease frequently manifest initially with dystonia.