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href="/bb/neuro/neuro99">Biology 202
In the diagnosis of Tourette's Syndrome the concept of involuntary tics has become hard to define. Many patients experience a volitional aspect of the tics, "a capitulation to an internal urge for motor discharge accompanied by psychological tension and anxiety Patients who are afflicted with Tourette's syndrome can only describe their symptoms by using terms associated with the "I" function, the consciousness of self and relation to one's environment, and many of their symptoms are associated with or affect the function of their self. This can imply that what ever is causing the symptoms of Tourette's is subsequently affecting the part of the nervous system that controls the self and the "I" function.
Most of the studies done on the neuropathology of Tourette's syndrome (TS) have been focus on the basal ganglia, a group of nuclei located mostly in the diencephelon of the brain, a region beneath the cortex. This area has been classically associated with involuntary movement and tic disorders such as Parkinson and Huntington's disease. The neural circuits formed by the basal ganglia and the thalamus are critical for normal function and hypothesized to be required for the planning of movement ranging from simple to complex. Though what these pathways actually do is still very vague the basal ganglia has been found, in normal circumstances, to exert an inhibitory influence on the thalamus. Disruption of this inhibition could correspond with TS in which the making of uncontrolled and unplanned movements are involve. There is evidence that patients with Tourette's syndrome have some structural abnormalities in the region of the basal ganglia, mainly TS patients showed a comparative size reduction in the basal ganglia.
There are various different behaviors through which Tourette's syndrome presents itself. The diagnostic categories of TS depend on the presence of tics, alone, although patients with Tourette may have mental or behavioral disorders, which over shadow the severity or impairment on normal function of the tics. The tics are both motor and vocal and can be simple or very complex. The simple tics such as a repetitive eye blink shoulder shrug, head jerk, and twitch of the nose or dart of the eyes, clearing of the throat clearing and sniffing. These small movements which are normally ones done involuntarily, or primarily subconsciously are, in Tourette's patients a form of "unvoluntary movement" (1). This term is meant to convey what the testimonies of many patients suggest, that the tics are in fact responses the unpleasant feelings and the movement occurs in order to relieve this feeling. This urging feeling shows that many tics have a volitional component. In many cases tics become more severe around family members and close friends, they also have been found to decrease or disappear in the presence of stranger, at school or at work. This seems to suggest that the condition encompass social stigma, which would be lacking if the "I" function, were not present in the presentation of TS.
Complex vocal tics are particularly interesting when examining the relationship between Tourette's and the I function. Besides the similar compulsive or urging feeling that the patients have to say certain phrases repetitively these fact that these complex vocal tic, unlike some of the simpler ones which consist of noises or grunts, complex tics involve words and sentences with linguistic meaning. These tics involve aspects that have been learned, rather than simple tics such as grunts or sniffs that are innate motions, which are started at birth. For example, if TS was diagnosed at birth some of the presentations would not be found because the infant would not have the ability to string together word into sentence as an adult. This implies that whatever causes Tourette's is affected by learned speech. Perhaps the I-function, as well as the neurological causes of Tourette's, is not limited to one physiological area of the nervous system but rather spread of the various areas of the brain affecting all function of the tics.
Coprolalia, a type of complex vocal tic, many times manifests itself in socially unacceptable or obscene language such as the urge to swear or use a racial epithet, even when this is the last thing the "person" would want to do. People with coprolalia seem to be compelled be the forbidden nature of what they are saying, seemingly against their will. This shows a certain control of the illness over the self similarly to how it does in the case of the other tics, because the persons body is acting against the will of the "person." It also shows the strong environmental and learned symptoms that are involved in Tourette's. Though the urging feeling is perhaps caused by a deformation in the basal ganglia, or a change in the level of neurotransmitters in the brain, these physical aspects of the person do not "know" about the social stigma of swear word or racial slurs. These things are learned, through what is seemingly a separate area of the brain, that contain consciousness, though these cases appears to be affected by and to affect the symptoms of Tourette's Syndrome.
The word involuntary is used to describe the nature of the tics that people with TS experience, though this is not entirely accurate. People with Tourette's are rather compelled to perform the tics. This need, awareness of the syndrome, suggests that the I function is involved in the resolutions of TS. Also the use of complex and meaningful sentences and gestures as aspect of the syndrome implies that social and learned aspects of the brain contribute to Tourette's Syndrome. On the basis of these observation there seems to be a need for joint studies between psychiatry and Neurobiology in order to determine the root and the solution to Tourette's syndrome.
2) UNRECOGNIZED SYMPTOMOLOGY OF THE TOURETTE SYNDROME GENE IN THE GENERAL POPULATION , by John S. Hilkevich, Ph.D.
3)Tryptophan and Tourette's Syndrome, by Steven Wm. Fowkes
4)Tourette's Syndrome: A Model Neuropsychiatric Disorder
5)Guide to the Diagnosis and Treatment of Tourette Syndrome
6)Tourette's Syndrome Homepage
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