Basal Ganglia TIC Disorder

The basal ganglia, a group of nerve cells located in the mid-brain, are largely responsible for learning and motor control. Basal ganglia work with other parts of the brain to help make decisions and to call up and perform well-coordinated voluntary movements. Malfunction of the basal ganglia may cause motor tics, which are sudden, repeated, uncontrollable movements of muscle groups, or vocal tics-sounds that are made involuntarily.

Causes

• Basal ganglia tic dysfunction may be caused by abnormal regulation of dopamine, a chemical in the brain that helps transmit nerve impulses. Over-activity of dopamine reduces the ability of the basal ganglia to inhibit behavior, often resulting in tics. Although no single gene has been pinpointed, susceptibility to tic disorders appears to be genetic. In some instances, tic disorders may be caused by using recreational drugs or prescription medications, most notably, cocaine or stimulants.

Symptoms

• Tic disorders present a wide spectrum of symptoms that can range from minor disruptions to severe impairment of daily life. Symptoms usually begin before the age of 18, and include sudden, involuntary, repetitive movement or gestures such as eye blinking or arm flapping, or vocalizations such as grunting or coughing. Some sufferers can briefly control the symptoms for short periods of time. The resulting stress, however, makes the tics more severe when they are eventually released.

Categories

• There are several different types of tic disorders. Transient tic disorders begin in childhood, but they are temporary, lasting only for several weeks or months. These tics are more noticeable during stressful or emotional times. In contrast, the duration of chronic tic disorders is many years. The most serious type of tic disorder is called Tourette syndrome—or TS. With TS, both motor and vocal tics appear at some time during the illness. The tics are more intense and long-lasting and they cause significant impairment in daily functioning.

Diagnosis

• There are no objective tests to diagnose tic disorder, but brain imaging studies may be performed to rule out other illnesses that mimic tic disorders. A clinical diagnosis is made by observing the symptoms, studying the history of the symptoms and collecting information about other family members who may have the disorder, as it has been determined that the tendency to develop tics is genetic.

Treatment

• Treatments are available to help manage symptoms of tic disorder, but there is no cure. Counseling, biofeedback and relaxation techniques may help to relieve stress, resulting in tic reduction. Habit reversal training helps increase the awareness of tics and helps develop strategies to respond to them. Medications that help block dopamine are an option, and in severe cases, deep brain stimulation may be used.