[Idiopathic chronic dysautonomia: when should the diagnosis be made?]

Chronic autonomic disorders may complicate a wide range of conditions which can be divided into secondary, due to specific diseases, and primary, in which no cause has been determined.

We report the case of a 43-year-old woman, who presented a chronic autonomic failure, which had begun by symptomatic orthostatic hypotension. Progressively, syncopes became daily, causing considerable discomfort associated with other signs of sympathic dysfunction: unilateral Horner's syndrome, diarrhea and hypohidrosis. The autonomic involvement was confirmed by study of the cardiovascular responses to tilt-up and electrophysiological autonomic testing. Etiologic search for a chronic acquired neuropathy (diabetes, amyloidis, paraneoplastic) or an inherited neuropathy was not conclusive. After five years, dysautonomic symptoms increased, but remained isolated. The physical examination did not show other clinical abnormalities such as cerebellar, pyramidal or extrapyramidal failure in favor of a multiple system atrophy or Parkinson's disease. All these data suggest the diagnosis of a primary autonomic failure.

The diagnosis of primary autonomic failure is difficult to make because it requires that all the investigations in search of an etiology are negative and a long follow-up to be sure that dysautonomic symptoms persist isolated after many years of progression.