There are numerous forms of body distortions and out-of-body experiences reported in the neurological literature but this is the first case I’ve found of someone who experienced tics that seemed to occur in external objects.
These more commonly appear as almost irresistible repetitive movements that the person feels compelled to complete, but occasionally they can appear as what are known as ‘sensory tics’ which are repetitive sensations such as feelings of pressure, tickle, warmth, cold, or other abnormal sensation in skin, bones, muscles, and joints.
In this case, however, the sensations felt as if they were appearing in external objects:
A 34-year-old man dated the onset of his symptoms to age 5 when he developed a compulsion to bite down on cups and glasses. The drive was so irresistible that he once shattered a glass in his mouth. He later began having painful repetitive neck extension and shoulder shrugging. During childhood, he first noticed itchy or pressure sensations, usually deep in a joint, but sometimes on the skin, in his hands, feet, and arms. The sensations eventually spread. For a period of time, the inside of his knees and ankles were particularly affected and the sensation could only be relieved by banging his ankles together. Noises including grunts, sniffs, and loud shouts began during early adolescence. A period of coprolalia was present briefly. The tics came to involve the entire body. He had associated difficulty concentrating, compulsions, and obsessions. He was given a trial of clonidine without relief. He was never tried on other medications.
The patient characterizes his motor tics as voluntary movements performed in response to the ‚Äúitchy‚Äù feeling. Although he can partially suppress tics in any given location, suppression enhances the feeling that he must move another body area. He frequently has the urge to repeat what others say to him but can usually suppress it. Beginning during childhood and persisting through adulthood, the patient noticed that the itchy sensations preceding motor tics could arise in other people or in objects.
The extracorporeal sensations are associated with the need to scratch or touch the itchy item in a particular way. External sensations most frequently arise in angles, corners, and points of objects such as elbows, the edges of tables, or the edge of his computer screen. Out-of-body sensations are more likely if the patient is touching an object but can also arise without direct contact. When younger, the patient would act on the accompanying urge and would scratch his sister‚Äôs elbow. He is able to resist touching other people.
Disembodied sensations are not uncommon after neurological difficulties (for example, a recent case study of a person with epilepsy reported a feeling of complete disembodiment) and can even be induced in you and me, as the ‘rubber hand illusion‘ demonstrates.
In this case, however, it isn’t clear exactly how the Tourette’s syndrome is triggering the feeling that the sensations appear in other objects, although it does suggest that our self-other boundary is not as iron-clad as we sometimes like to believe.
Link to PubMed entry for case study.