Epilepsy Rates ‘Raised’ In Patients With Tourette’s Syndrome
Epilepsy Research U.K.
Posted Aug 28 2013

People with Tourette’s syndrome appear to have an increased risk of epilepsy, research has revealed.

Tourette’s syndrome is a neurological condition that affects around one in every 100 people and is characterised by involuntary noises and movements called ‘tics’.

The disorder often goes hand-in-hand with other conditions, including obsessive compulsive disorder (OCD), attention deficit hyperactivity disorder (ADHD) and autistic spectrum disorder (ASD).

These comorbidities, in turn, are associated with increased rates of epilepsy, but little is known about the occurrence of epilepsy in people with Tourette’s syndrome.

To address this situation, researchers at St George’s Hospital in London reviewed the medical records of 347 patients with Tourette’s syndrome, all of whom attended a specialist clinic.

Almost a quarter (23 per cent) of the study population were female and half were under the age of 17.

The researchers recorded any associated medical conditions that the patients had been diagnosed with and found that 24 per cent had OCD, 54 per cent had ADHD, ten per cent had learning difficulties and ten per cent had ASD.

Diagnoses of epilepsy were rated as ‘definite’ or ‘probable’ by a neurologist and any cases where the condition had been misdiagnosed or inappropriately suspected were excluded from the analysis.

The researchers observed that six per cent of patients with Tourette’s syndrome had been diagnosed with epilepsy, with half of these cases deemed to be definite.

On average, patients were seven years old when their seizures began and 33 per cent of epilepsy cases developed within a year of the onset of tics associated with Tourette’s.

Epilepsy did not appear to be associated with more severe Tourette’s, but patients who experienced seizures tended to have more comorbidities than those who did not.

For instance, rates of ADHD, OCD and learning difficulties were significantly higher among Tourette’s patients with epilepsy.

Similarly, rates of epilepsy were elevated among Tourette’s patients with learning difficulties and OCD.

Publishing their findings in the Journal of Neurology, Neurosurgery and Psychiatry (See Below), the study authors concluded that patients with Tourette’s syndrome “have a higher-than-expected rate of epilepsy”.

They added: “Rates are higher still in patients with various comorbidities, especially learning difficulty, and uncommon in ‘pure’ Tourette’s syndrome.”



J Neurol Neurosurg Psychiatry 2013;84:e1 doi:10.1136/jnnp-2013-306103.31
The British Neuropsychiatry Association 26th Annual General Meeting 7th–8th February 2013 Institute of Child Health, London

EPILEPSY IN TOURETTE SYNDROME
David Williams, Jeremy S Stern, Kathryn Grabecki, Helen Simmons, Mary M Robertson

Department of Neurology, Atkinson Morley's Wing, St. George's Hospital, Blackshaw Road London, SW17 0QQ, United Kingdom

Abstract
Objective Tourette Syndrome (TS) is a neurodevelopmental disorder frequently associated with comorbidities such as OCD, ADHD and autistic spectrum disorders (ASD). Tics are more common in Learning Difficulty (LD) populations. The mechanism of these associations is felt to vary for instance appearing to be more genetically based for OCD than for ADHD. The comorbid conditions seen with TS are known to be associated with increased or high rates of epilepsy. In turn, epilepsy cohorts also have high rates of neurodevelopmental and behavioural disorders. There has been little literature on epilepsy in TS.

Method
Clinical records of 347 patients with TS seen at a specialist clinic were reviewed. Associated conditions were diagnosed clinically but it was not possible to stratify LD by IQ. Epilepsy diagnoses were rated as definite or probable by a neurologist taking into account previous investigations including EEG where available, clinical descriptions and treatment. Cases where epilepsy had been inappropriately suspected or misdiagnosed were excluded.

Results
The cohort was 23% female and 50% under the age of 17 with the following comorbidities: OCD (24%), ADHD (54%), LD (10%) and ASD (10%). Epilepsy was seen in 21 cases (6%) and was felt to be definite in half of these cases. Mean age of seizure onset was 7 years and was within a year of onset of tics in 33% of the epilepsy cases. In 4-6 cases the seizures were felt to be symptomatic, in 6 were focal and in 9 had remitted. Cases with epilepsy were not more severe on Yale Global Tic Severity Scores but had more comorbidity. There was an earlier age of onset of tics and significantly higher rates of ADHD, OCD and LD with a non-significant trend for an increased rate of ASD. Looking at the figures from the other direction, patients in the TS cohort with LD and OCD had significantly increased rates of epilepsy (18.2% v. 4.8% for LD) and there were non-significant trends for ADHD and ASD.

Conclusion
Patients with Tourette syndrome have a higher than expected rate of epilepsy, and are also sometimes misdiagnosed with seizures. Rates are higher still in patients with various comorbidities, especially LD, and uncommon in “pure” TS. Seizures could be a marker for a more severe neurodevelopment syndrome, or could reflect a shared substrate. Thalamocortical dopaminergic dysfunction has been linked to seizures and there could be contributions from epileptogenesis effects of neurodevelopmental genes or drug treatment for tics.