What is Tardive Dyskinesia?
Tardive dyskinesia is a neurological condition and a type of dyskinesia characterized by involuntary repetitive muscle movements. The meaning of the word "tardive" is delayed, and the meaning of "dyskinesia" is abnormal movement. The cause of Tardive Dyskinesia is long-term use and increased dosage of anti-psychotic medicines.
Causes of Tardive Dyskinesia
The primary cause of Tardive Dyskinesia is prolonged or chronic use of neuroleptic drugs that are prescribed for psychiatric conditions. Sometimes they can also be prescribed for neurological problems. Infants and children can develop this condition as a side effect of medicines used for treating gastrointestinal problems. Neuroleptic drugs act by blocking the receptors of the body for dopamine; which is a neurotransmitter associated with controlling the brain’s pleasure centers. Dopamine also plays role in the motor function of the body. The exact mechanism of how or why tardive dyskinesia occurs is unclear. It is, however, believed to occur as a result of prolonged blocking of these receptors.
Some of the neuroleptic drugs, which are responsible for causing Tardive Dyskinesia include: Prochlorperazine, amoxapine, compazine, metoclopramide, haloperidol, flunarizine, fluphenazine, trifluoperazine hydrochloride and chlorpromazine.
It often usually takes months to years for tardive dyskinesia to develop from the use of neuroleptics, however, in some cases, this disorder can also develop in a matter of few weeks. Rarely, drugs containing selective serotonin reuptake inhibitors (SSRIs), lithium and norepinephrine reuptake inhibitors (SNRIs) may also cause tardive dyskinesia; or can cause other syndromes, which are clinically difficult to differentiate.
Risk Factors for Tardive Dyskinesia
- Elderly individuals are also at a higher risk for developing Tardive Dyskinesia.
- Smoking increases the risk of tardive dyskinesia, especially for those patients who also are being treated with antipsychotic medications.
- Individuals suffering from diabetes mellitus or organic brain injuries are at an increased risk for developing Tardive Dyskinesia.
- Women are more prone to develop Tardive Dyskinesia.
- African Americans and Africans tend to have increased rates of Tardive Dyskinesia.
- Patients suffering from severe neurological side effects from antipsychotic medicines are also more prone to developing Tardive Dyskinesia.
- Genetic risk factors also exist for Tardive Dyskinesia.
Signs & Symptoms of Tardive Dyskinesia
Tardive dyskinesia patients experience involuntary random movements of the tongue, face, lips or jaw, which produces symptoms such as:
- Puckering, smacking or pursing of the lips.
- Protrusion or thrusting of the tongue.
- Grimacing expressions of the face.
- Rapid or excessive blinking of the eyes.
- Repetitive chewing movements.
- Sometimes, Tardive Dyskinesia can also affect the arms, fingers, trunk and legs resulting in either movements that are rapid and jerking in nature or movements that are slow and writhing in nature.
- In some cases, where the legs are affected, patient will have difficulty in walking.
- Tardive dyskinesia patient can also have respiratory symptoms, such as grunting during breathing or difficulty in breathing.
Diagnosis of Tardive Dyskinesia
Tardive Dyskinesia is often misdiagnosed as some mental condition instead of a neurological disorder, as a result of which neuroleptic drugs are prescribed leading to worsening of the condition and further disabling of the patient. This also leads to decrease in the survival period of the patient.
Tardive dyskinesia resembles other movement disorders, such as Huntington's disease, Parkinson's disease, cerebral palsy, dystonia and Tourette syndrome, which makes it a bit difficult to diagnose.
Abnormal Involuntary Movement Scale (AIMS) is a test which helps in detecting tardive dyskinesia in patients who are taking neuroleptic drugs. This test helps in tracking the severity of symptoms over a period of time During the AIMS test, the patient is asked to perform a variety of movements such as extending and flexing arms, opening the mouth and walking around. The physician gauges the involuntary movements occurring in the patient’s body on a five-point scale. These involuntary movements includes movement of lips, face (cheeks, eyebrows, forehead), tongue, jaw, upper extremities (hands, arms, fingers and wrists) and lower extremities (ankles, legs, toes and knees), shoulders, neck and hips. The overall severity of the movements is also assessed and whether the patient is aware of these movements and if they cause any discomfort or pain.
Treatment of Tardive Dyskinesia
As of now, there are no FDA approved drugs for treatment of Tardive Dyskinesia. Treatment of Tardive Dyskinesia otherwise differs from patient to patient. Firstly, the doctor will minimize the dosage or discontinue the use of the culprit neuroleptic drug and an alternative medication is prescribed instead. In some cases, patients may continue to have tardive dyskinesia even after stopping the offending medication, which is known as irreversible tardive dyskinesia. Xenazine is the only medication that has been approved by the FDA for specifically treating tardive dyskinesia. Other medications can also help with the symptoms of Tardive Dyskinesia and these include benzodiazepines, clozapine and Botox injections.
There are other treatments also that are being studied for treating Tardive Dyskinesia.
Prevention of Tardive Dyskinesia
The dosage of neuroleptic medicines should be the lowest and effective dose possible. The neuroleptic medicine should be taken for the shortest duration possible. If the patient is suffering from schizophrenia, which is a chronic psychosis condition, the doctor must maintain balance, as increased dosages of neuroleptic medication help in prevention of recurrent psychosis. Tardive dyskinesia can be present for some months even after the offending drug has been stopped or it can even become a permanent condition, which is then known as Irreversible Tardive Dyskinesia. It is also recommended to prescribe atypical antipsychotics than typical antipsychotics if needed, as these have lesser neuromotor side effects and also carry a lower risk of developing Tardive Dyskinesia.