The sudden repetitive muscular contractions and vocalizations cataloged by Dr. Tourette are called tics. These motoric events commonly last a second or less, and represent voluntary action that may be anticipated and often suppressed. Severely affected patients, however, experience barrages of motor and cognitive impulses, which overwhelm their conscious ability to suppress. Accompanying comorbid conditions, behavioral, emotional, and academic challenges may cause greater morbidity than the tic symptoms. Generally, tics are not painful and do not occur during sleep.

Over time, as noted by Leckman and colleagues, tics tend to display a rostral to caudal progression, with eye blinking as a most common beginning. At times, the anatomic origin is limited to a few muscle groups (simple tic: eye blinking, jaw thrusting, throat clearing), or multiple organized contractions which mimic contextual speech or movement (complex tic: obscene gestures such as “the finger” [copropraxia], obscene utterances [coprolalia], or repetition of others’ speech and movement [echolalia, echopraxia]). The quality of obscene
utterances and behavior is that of a rapid usually noncontextual explosion of words or actions, not to be confused with angry or antisocial statements of a frustrated or acting out child. TS patients often experience premonitory awareness of the onset of a tic. Attempts at suppression or alteration of tics may then present as a collection of odd voluntary motions or vocalizations meant to mask the underlying episode. These behaviors may phenomenologically overlap with symptoms of obsessive—compulsive disorder (OCD) as the child repetitively takes suppressive action to relieve tic tension. This is different from the pattern noted in OCD in which the action is often accompanied by thoughts related to symmetry, counting, phobic avoidance, or ritual. For patients with tic disorders and without OCD, the behaviors are not associated with well-formed ideas; rather, there is a feeling of physical tension resulting in an ameliorative action.

Multiple classifications of tic disorders are available and overlapping in detail. The DSM-IV is selected for this text. DSM-IV divides tic disorders into three categories: TD, chronic motor or vocal tic disorder, and transient tic disorder. The diagnostic criteria are quite simple considering the complexity of this condition, and are summarized in Table 10-1. For a diagnosis of TD, vocal and motor tics must be present although not necessarily at the same time, during one year of history, without a reprieve longer than three months. For the diagnosis of chronic motor or vocal tic disorder, symptoms should be present for at least one year, without a reprieve longer than three months, but without both vocal and motor subtypes. For transient tic disorder, symptoms should be present for no longer than one year. In all categories, the onset should occur before the age of 18, and the symptoms should be severe enough to intrude on functioning.

While DSM-IV criteria focus on motor findings, TS patients frequently present with additional features of OCD, and attention-deficit hyperactivity disorder (ADHD). Thus, one should consider the triad of tics, OCD, and ADHD in all patients presenting with tics. In addition, tics are present in many children with pervasive developmental disorders (PDD), particularly those with Asperger syndrome. These and other comorbid conditions are discussed throughout this chapter, and by other authors in this text.

Jankovic has reviewed other hyperkinetic movement disorders, including stereotypic behaviors, dystonias, choreiform disorders, and myoclonus which may be confused with tics.

Stereotypic behaviors: These are repetitive actions that are complex in nature and consistent over long periods. There may be a ritualistic and/or self-soothing quality to these behaviors. For example, autistic and mentally retarded patients often rock or pace for long periods of time. Rapid hand rubbing is a common finding in this population, as well, and a prominent diagnostic finding specifically in Rett syndrome. These phenomena differ from tics in their consistency and seemingly self-soothing quality.

Dystonias: These movements are often sustained contractions that are observed as abnormal postures of the head and neck (torticollis), or extremity and are frequently painful. As a rule, tics do not cause pain, unless the frequency and intensity cause repetitive strain. Sometimes, the movements are rapid and tic-like in quality. In dystonias, however, the anatomic location is often less fluid than in tic disorders.

Choreiform disorders: This collection of disorders manifests as rapid motor movements, which may begin with “piano playing” finger movements evident upon finger extension. In severe syndromes (Huntington chorea, Sydenham chorea), fulminate total body jerking may render the patient incapacitated. The early presentation is easily confused with tics, family history (Huntington chorea), streptococcal episode (Sydenham chorea), and appropriate serum and/or genetic studies assist in the differential diagnosis.

Myoclonus: This is characterized by “lightning bolt” fast muscle contractions alternating with relaxation of large muscle groups. Myoclonic movements are also common and normal during early stages of sleep.

In 1998, Swedo and colleagues wrote about a series of patients who suffered OCD and/or tics in the context of documented infection with group A beta hemolytic streptococcus (GABHS). These researchers hypothesized GABHS induced immune-mediated injury to the basal ganglia. This was consistent with the pathophysiology of Sydenham chorea (OCD in Sydenham’s patients initiated this research), and these patients were added to the “pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection” (PANDAS) spectrum. Recent research, however, found that “no correlation was identified between clinical exacerbations and autoimmune markers.” Their work looked at antineuronal antibodies
and cytokines and utilized diagnostic criteria for PANDAS outlined by Swedo and others. While this controversy continues, PANDAS should be considered in the following situations: DSM-IV diagnosis of a tic disorder or OCD; prepubertal onset; episodic presentation with abrupt onset and gradual spontaneous reduction of symptoms (“saw tooth” symptom pattern); subtle neurologic findings; choreiform movements, handwriting deterioration; GABHS infection temporally during symptom exacerbation. Further considerations in the differential diagnosis of tics are summarized in Table 10-2.

Multiple studies have supported a high co-occurrence of TS and ADHD. On average, 50% of TS patients meet criteria for ADHD, and 30% to 40% of children diagnosed with ADHD
have tics or TS. Children with both disorders have a much greater risk of conduct disorder, depression, and overall dysfunction, than children with TS only. Children with TS and ADHD also suffer much higher rates of cognitive disturbances and learning disabilities (LD) than children with TS alone whose rates of LD approach normal controls.

Phenomenologic, neurologic, and genetic overlap of TS and OCD has led many investigators to suggest that these two syndromes are part of the same illness. OCD is a condition in which patients describe unwanted disturbing, intrusive and often nonsensical worries, accompanied by behaviors which are meant to temporarily diminish their emotional discomfort. At times, OCD patients will describe sudden intrusive thoughts and equally sudden reactive behaviors. Patients with tics often report or are aware of cognitive or emotional elements to their movement symptoms. Some TS patients will describe “thought tics” which are different from obsessions as the thoughts are instantaneous, and may not be associated with anxiety or with a desire to carry out a behavior. Interestingly, selective serotonin reuptake inhibitors (SSRIs) effectively treat OCD, but not tics. Conversely, alpha-2a agonists treat tics but not OCD. Overall, history gathering and examination will assist in differentiating obsessions, compulsions, and tics.

Children with TS may experience substantial social stigma due to the overt symptoms of their illness. For some children, social avoidance and anxiety may lead to avoidance of public places, or public performance. Social phobia and performance anxiety are common in this population, either as primary or secondary conditions.

A number of authors have documented the co-occurrence of tic disorders and ASD. ASD patients have a host of movement disorders including stereotypies which are at times difficult to differentiate from tics. The clustering of ADHD, tics, OCD, and ASD suggest the variable expression of shared underlying neurodevelopmental anomalies.

Tourette syndrome is pervasive in family systems; the rate of TS in relatives of affected individuals is 10% to 15% and the rate of tics approximates 20%. Family studies reveal that the TS concordance rate in monozygotic (MZ) twins is greater than in dizygotic (DZ) twins reaching 70% versus 9% concordance for TS and 77% versus 23% concordance for chronic motor tics respectively. Importantly, however, the rate of concordance in DZ twins is higher than in the general population, and the severity of illness within MZ pairs is variable. Mutations involving the SLITRK1 gene have clearly been identified in a small number of people with Tourette syndrome. This gene involves functions within the neurocircuitry attributed to TS. Recent analyses of this gene’s role are complicated by various technical challenges. The definitive contribution of mutations at SLITRK1 and other loci continue under active study. TS certainly involves an interplay of genetic and epigenetic influences leading to various phenotypic outcomes.

Severe maternal nausea, low birth weight, and forceps delivery are statistically associated nonspecific findings in patients with TS, as well as with many other neuropsychiatric conditions. Clinically, stress may herald the onset and exacerbate symptom intensity in affected patients.

The neurochemical and anatomic abnormalities in tic disorders are not definitively determined. Postmortem studies are rare, as this is not a fatal syndrome, and severe symptoms in many individuals dissipate early in life. Harris and Singer note that analysis of parallel disease models (Huntington, Parkinson, Sydenham chorea), lesion studies, neuroimaging studies, animal models, and limited neuropathologic and empiric findings support a primary disturbance in the corticostriatothalamocortical circuitry (CSTC) and limbic system. This “motor-limbic interface” is represented in Figure 10-1.

Cortical and subcortical structures interact normally to produce desired movement (voluntary cortical discharges), affect, and cognition. Primary neurotransmitters in the system include gamma-amino-butyric-acid (GABA), glutamate, dopamine, acetylcholine, enkephalin, substance P, and other protein messengers.

The balance of stimulation and inhibition provides smooth wanted movement. In TS, abnormalities in the complex cycling cascade of dopaminergic neuronal functions and influences
are believed to be central in causation and potential intervention. Cross activation of the limbic system may account for dysregulation of affect and control of rage in some patients, as well as the premonitory sensations and subjective experiences of tic episodes and interepisode states. Dysfunction in the striatum is also associated with the pathogenesis of OCD, ADHD, and an aspect of the neuropathology of Asperger syndrome (sensorimotor gating).