Tactile hallucination triggered by auditory hallucination – A new phenomenon

Dear Editor, Synesthesia is the experience of a stimulus in one modality producing a sensory experience in another.[1] Reflex hallucination is a morbid form of synesthesia in which a stimulus in one modality produces a hallucination in another modality.[2] A related term is mitempfindung, where a stimulus applied in one region of the body is being felt as a tactile sensation in another region.[2,3] A 21-year-old married lady with a 2-year history of schizophrenia presented with symptom exacerbation following drug discontinuation. She was on clozapine and had discontinued medicine post delivery. Within a week of discontinuing clozapine, she started getting symptoms. On interview, she reported 2 months of fear, suspicion, and hearing a voice. She also reported pin and needle sensation in the soles of her feet while she was hearing the voice. She reported no pin and needle sensation at any other point before or during the illness. She had on mental status examination thought broadcasting, second person auditory hallucination, and running commentary hallucinations. She reported that whenever she hears a voice which she claims is of a prince speaking from Dubai (extracampine), she experiences a tactile hallucination in the soles of her feet akin to paraesthesia which starts soon after the voice commences and disappears once the voice stops. She has no tactile hallucination at other times and has no sensory deficits or paraesthesia. As she had only responded to clozapine, it was restarted and titrated to 200 mg, and as there was a decrease in symptoms, she was discharged. She was maintained on the same dose of clozapine, and as of 6 months follow-up, she still remains asymptomatic. The phenomenon whereby an auditory hallucination triggered a tactile hallucination has not been reported. The phenomenon being a hallucination in reflex from a hallucination, we tentatively use the name reflex hallucination ex hallucination. Perception is considered to be a manifestation of the intrinsic self-organization of the thalamo-cortical system.[4] There is evidence that local disruption of the thalamus causes changes in remotely connected regions of the brain like auditory and somatosensory cortex, leading to synesthesia.[5] Mitempfindung is argued to be due to reduced inhibition in an otherwise quiescent spinal pathway or thalamic nucleus.[3] Hallucinations may involve the same physiological process that mediates normal perception.[4] It is hypothesized that if sensory input is masked by excessive thalamic background activity, it results in perception being uncoupled from external physical reality. In such cases, attentional factors would dominate the content of conscious experience. This finally may manifest as reduced perceptual sensitivity and predispose to hallucinations.[4,5] The phenomenon we tentatively name as reflex hallucination ex hallucination thus far has not been reported. Thalamo-cortical dysfunction is a possible hypothesis for the genesis of all these phenomena. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.