Tourette syndrome (TS) is a neurological condition characterized by tics, which are sudden, involuntary, and repetitive movements (motor tics) or vocal sounds (vocal tics). For parents observing a newborn or young infant, the sudden, often jerky movements common in this age group can raise concerns about an early-onset tic disorder. Understanding the typical developmental timeline of TS is the first step in addressing this parental anxiety.
The Onset Window for Tourette Syndrome
Tourette syndrome is overwhelmingly a disorder of childhood onset, and it virtually never manifests during infancy. The average age of onset is typically around six years old, commonly ranging between ages five and ten. Onset must occur before age 18.
It is extremely rare for tics to begin before age three, and onset before 18 months is not consistent with Tourette syndrome. The neurological systems required for the complex motor and vocal behaviors that define tics are still developing in the first year of life.
Clinical criteria require the presence of multiple motor tics and at least one vocal tic that have persisted for more than one year. Because symptoms must be present for a full year, a formal diagnosis of TS is almost never made in a child younger than four years old.
Early Indicators of Tourette Syndrome
When Tourette syndrome appears in the typical onset window of early childhood, the first signs are generally subtle. The earliest tics are almost always simple motor tics, involving a limited number of muscle groups, most frequently in the head and neck area.
Common first tics include rapid eye blinking, head jerking, or shoulder shrugging. These movements are brief, involuntary, and repetitive, but they often start mildly and may be mistaken for habits. Vocal tics, such as throat clearing, sniffing, or grunting, typically appear later than motor tics.
A significant feature distinguishing true tics in older children is the “premonitory urge,” a distinct, uncomfortable sensation that precedes the tic. Individuals describe this as a building tension or pressure that is temporarily relieved only by performing the tic. Infants and very young children cannot experience or communicate this complex sensory phenomenon, confirming why TS is not a condition of infancy.
Differentiating Common Infant Movements from Tics
The movements parents observe in infants are almost always normal phenomena related to an immature nervous system. Benign sleep myoclonus involves sudden, brief jerks of the limbs or trunk that occur only as the baby is falling asleep or during sleep. These movements cease immediately upon waking and are a common feature of early development.
The Moro reflex, or startle reflex, is often mistaken for a tic. This reflex causes the infant to suddenly throw out their arms and legs and then pull them back in, usually in response to a loud noise or a sudden change in position. This protective reflex typically disappears by four to six months of age.
Normal infant movements are usually rhythmic, linked to a state of arousal, or part of a predictable developmental reflex. Tics, in contrast, are non-rhythmic, tend to occur in bursts, and are not tied to a specific sleep or reflex state.
Repetitive actions, such as head shaking or head banging, are common developmental behaviors known as stereotypies. They are distinct from tics because they are often self-soothing and can be briefly interrupted by distraction.
Parents should be reassured that these observed twitches and jerks are typically a sign of the brain and motor system maturing. While tics are suppressible for a short time in older children, normal infant movements, such as sleep myoclonus, are not suppressible at all. If an infant’s movements are concerning, especially if they are sustained, rhythmic, or accompanied by other symptoms like lethargy, a pediatrician can assess them.