Background: The relationship between childhood tic disorders and group A st
reptococcal (GAS) infections has been recently investigated by several rese
arch groups, but no systematic evaluation of laboratory indicators of GAS i
nfections has been provided.
Objective: The aim of our study was to seek clinical and laboratory evidenc
e of GAS infections in a large population of children affected with tic dis
orders.
Study design: This investigation was a case-control study: 150 consecutive
children presenting with ties were investigated for clinical and laboratory
signs of streptococcal infections on the occasion of their first neuropsyc
hiatric consultation. To compare the rate of exposition to GAS in a similar
population, a control group of 150 children without tic disorders was exam
ined during the same period.
Results: In children with ties, mean antistreptolysin O (ASO) titer (434 +/
- 338 IU) was significantly higher compared with that of control subjects (
155 +/- 126 IU); 38% of the children with ties compared with 2% of the cont
rol subjects (P < .001) had ASO titers <greater than or equal to>500 IU. Tw
enty-six children with ties (17%) had throat cultures positive for GAS, but
in all cases, only few colonies per plate were isolated. Among the strains
isolated, no prevalent T pattern or M type was observed. In children with
ties a positive correlation between ASO titers and severity of tic disorder
(measured by the Yale Global Tic Severity Scale) was found.
Conclusion: Our results suggest that children with tic disorder could be a
unique population in which GAS infection, or at least the exposure to strep
tococcal ant;gens, is correlated to the neurobehavioral disorder. Moreover,
our data indicate a relationship between the severity of tic disorder and
the magnitude of the serologic response to GAS antigens.