Objective The worldwide prevalence of Tourette's syndrome (TS) is well established at around 1% of school children in community studies, but little is known about the frequency of severe cases resistant to medical treatment. This subset of patients has taken on new significance due to the emergence of deep brain stimulation (DBS). We screened a specialist clinical cohort to identify this group.
Method Data was acquired from the case records of 329 patients of all ages attending the St. George's Tic Disorder clinic. Disease severity and resistance to pharmacological treatment were defined as per published European Society for the Study of Tourette Syndrome guidelines, i.e. Yale Global Tic Severity Score (YGTSS) >35 and resistance to three drug treatments including a typical and an atypical neuroleptic. Clinical records were reviewed for adherence 13 points in the guideline.
Results 14 out of 329 patients (4.3%) were deemed both severe and refractory to pharmacological treatment and had a mean YGTSS of 38.7. The small number in this group precluded statistical analysis of patient characteristics compared to the control group. No patients fulfilled all ESSTS guideline criteria although two patients in the cohort had already had DBS and one other had been assessed for DBS but improved substantially with a further medication choice (Topiramate).
Conclusion Patients in this group are the public face of TS. Their population prevalence is unknown but they are likely to over-represented in clinical cohorts although other individuals may have withdrawn from society and medical care. Even in this tertiary specialised clinic cohort fewer than 5% would be likely to be suitable for DBS given it remains a procedure for the severest cases. Current guidelines for patient selection have been drawn up in the era of a semi-experimental technique and are likely to evolve. Published criteria that that have been waived on compassionate grounds in this and other cohorts are minimum age recommendations (>25 years) and full access to behavioural therapies.