Objective We present the case of a 48 year old woman with co-occurring synaesthesia and Tourette syndrome.

Method A 48 year old lady was referred for her Tourette syndrome. She had experienced mild typical simple motor and vocal tics from age 6, which by age 17 had improved to only a throat clearing tic. At age 44 the tic disorder gradually became more florid with multiple complex tics and intrusive non-obscene socially inappropriate behaviours. At assessment other characteristic comorbidities were identified; obsessive compulsive disorder and probably attention deficit disorder as a child. In addition symptoms of lifelong synaesthesia were elicited.

Results As is often the case, the patient was not aware that synaesthetic experiences are not common to us all. There was interaction in her symptomatology between the two conditions, probably partly driven by obsessionality. For instance, the stimulus of another person swearing leads to echocoprolalic urges that elicit the synaesthetic percept of a ginger cat which in turn precipitated the utterance of the phrase “ginger cat” instead of repeating the swear word. For each different swear word, the patient experiences a different image e.g. a pink flip-flop. When the patient smells cooking, it elicits a strong sensation of burnt apple pie which then triggers off motor and vocal tics. In noisy environments she sees swirling coloured numbers which she feels cause her to tic. A similar effect can accompany her premonitory urge to tic. Orange is an especially prominent colour in these experiences, and one of her socially inappropriate tics is to shout “ginger kids”.

Conclusion This is a unique case of Tourette syndrome coincidentally comorbid with synaesthesia with the latter interacting, provoking and being driven by tics and obsessionality. The putative neuroanatomy of colour-grapheme synaesthesia is debated (abnormal activation in visual colour association V4/V8/fusiform areas) but probably does not overlap with the proposed substrate of Tourette syndrome (basal ganglia/thalamocortical circuits). It is suggested that in this patient the interaction of the two conditions is mediated at a higher cognitive level over the four year course since the late exacerbation of her Tourette syndrome, in itself an atypical evolution.