[Delayed-onset dystonia due to asphyxia in the perinatal period]

The phenomenon of delayed-onset dystonia following presumed "static" brain injuries was described after stroke and head trauma. Burke et al. described a different category of secondary dystonia, where perinatal injury (asphyxia) caused minimal or no immediate neurological deficit, with the delay of years before dystonia emerged. This type of dystonia following perinatal injury has been termed "delayed onset dystonia due to static encephalopathy of childhood". According to the definition of dystonia, we were able to select 5 patients with the aetiologic diagnosis of perinatal asphyxia from the group of 347 out- and inpatients (1.4%) treated for various types of dystonia at the Movement Disorders Department (Institute of Neurology, CCS, Belgrade) from November 1986 to November 1994. At onset of dystonia the mean age of patients was 13.2 years (range from 10 to 17), with combined initial involvement of the arm and neck in 3 patients. The period from the onset of the disease to the maximum severity lasted 8.2 years (range from 4 to 14), resulting in segmental brachial dystonia in 3, hemidystonia and generalized dystonia in one patient each (Table 1). The adverse perinatal events are described in Table 2. Three of our patients had delayed achievements of developmental milestones. All patients were regularly schooled and had preserved intellectual capacities, except the patient 3 whose achievements were below average (IQ = 86). Different drugs were administered (Table 3), but moderate effects were achieved only with trihexyphenidyl in two patients (daily doses of 24 mg and 30 mg, respectively), and baclofen (80 mg p.d.) in one patient. In this study we describe 5 new patients who fulfilled the criteria for the diagnosis of delayed-onset dystonia due to perinatal asphyxia (Tables 1 and 2). We accepted the approach of Saint-Hilaire et al. to suggest a relationship between perinatal asphyxia and later occurrence of dystonia in our 5 patients. However, coincident occurrence of a primary dystonia with a static encephalopathy of childhood due to perinatal asphyxia cannot be excluded. This phenomenon of delayed appearance of dystonia was also described in other forms of static cerebral injury; i.e. stroke, head trauma or anoxic brain damage. Interestingly enough, age at the time of anoxia or brain insults seemed to be crucial for the development of dystonia: those who suffer acute brain insults during childhood or early life are more likely to develop dystonia than the older patients. Therefore, the "static" nature of encephalopathy induced by perinatal asphyxia is questionable. Finally, this study strengthens the suggestion that perinatal asphyxia can lead to delayed-onset dystonia, and, since "some of these patients closely resemble cases of idiopathic torsion dystonia, the prior occurrence of asphyxia should be used as a criterion of exclusion for that diagnosis".