Main Difference – Dystonia vs Tardive Dyskinesia
Dyskinesia is a set of disorders characterized by excessive and unusual involuntary movements of muscles which include chorea, dystonia, myoclonus, tremor, and paroxysmal tardive (late-onset type) dyskinesia. Dystonia and tardive dyskinesia share several similar features since both involve movements of the head, arms, legs, hand, feet, lips, and tongue. Therefore, it is highly important to identify the clinical signs and symptoms, characteristically owned by each condition, in order to single-out the etiology and decide on the necessary mode of treatments. The main difference between Dystonia and Tardive Dyskinesia is that Dystonia is a state of abnormal muscle tone resulting in muscular spasm and abnormal posture whereas Tardive Dyskinesia is a neurological disorder characterized by involuntary movements of the face and jaw.
This article explains,
1. What is Dystonia? – Definition, Types, Signs and Symptoms, Causes, Diagnosis and Treatment
2. What is Tardive Dyskinesia? – Definition, Signs and Symptoms, Causes, Diagnosis and Treatment
3. What is the difference between Dystonia and Tardive Dyskinesia?
What is Dystonia
Dystonia is defined as a movement disorder which involves involuntary, and usually painful, spasms and muscle contractions which can induce abnormal movements and postures.
There are 2 major types of Dystonia known as focal or generalized dystonia. Focal dystonia refer to involuntary movements, taking place in a single part of the body, which often includes blepharospasm (upper facial), spasmodic torticollis (cervical), and writer’s cramp. Generalized dystonia typically involve the trunk, one or both legs, and another body part.
Other minor types of dystonia include Meige’s syndrome (spasms of the jaw muscles when opening and closing of the mouth) and spasmodic dystonia which can result in impairment of speech due to spasms of laryngeal (throat) muscles.
As far as the etiology of dystonia is concerned, it can either be inherited or acquired due to an underlying primary cause like Parkinsonism. Inherited causes of dystonia are very rare and may include Dopa-responsive dystonia, idiopathic tension dystonia, and x-linked dystonia-Parkinsonism where acquired causes mainly include various medications.
The severity of muscular movements caused by dystonia will often fluctuate with symptoms which will worsen during illnesses, stress, vigorous activities, and postural changes in the body. Patients will also experience signs and symptoms such as leg dragging, foot cramps, involuntary pulling of the neck, uncontrollable blinking and disturbances in speech.
Even though there is no exact single test to confirm dystonia, a routine evaluation including electrolyte levels, full blood count, peripheral smear, thyroid hormone profile, Serum Calcium, Magnesium, copper and Ceruloplasmin levels, liver profile, erythrocyte sedimentation rate, VDRL test, Electroencephalogram, CT scan and MRI of the brain will help to establish an accurate diagnosis.
The primary objective of the treatment includes eliminating the root cause for tardive dystonia which can either be a drug or another underlying primary disorder. Tapering off or complete discontinuation of neuro-epileptic drugs which is the commonest cause for most of the cases of Dystonia is highly encouraged.
The main pharmacological treatment for Dystonia is the usage of dopamine-depleting agents or dopamine receptor blockers like neuroleptics. The recently introduced Botulinum toxin also has a beneficial effect on improving the involuntary muscle movements whereas deep brain stimulation has become the hallmark of surgical therapy for severe disabling dystonia which does not respond to medical interventions.
What is Tardive Dyskinesia (TD)
Also known as late-onset dyskinesia, Tardive Dyskinesia is defined as a group of movement disorders, characterized by hyperkinetic involuntary movements which involve a mixed manifestation of orofacial dyskinesia, chorea, tics, and/or athetosis. The main characteristic feature of affected individuals is known to be orofacial dyskinesia, which usually begins with a slow and mild tongue movement followed by exaggerated lips and tongue movements. Furthermore, mild to moderate symptoms can gradually progress into unusual chewing movements, blinking, bulging cheeks, grimacing, arching eyebrows, and blepharospasm.
The main etiology for Tardive Dyskinesia is thought to be medications like neuroleptics and antipsychotic drugs which are usually used for psychiatric or neurodevelopmental disorders such as schizophrenia, schizoaffective disorder, and bipolar disorder. A positive family history and genetics are also known to be playing an important role in the predisposition of this condition.
Although it can be diagnosed by a complete clinical history and a thorough physical examination, there is no FDA-approved treatment for Tardive Dyskinesia. However, Benzodiazepines, dopamine-depleting drugs like Tetrabenazine, VMAT2 inhibitors like Reserpine have found to be effective in some individuals.
Difference Between Dystonia and Tardive Dyskinesia
Dystonias are spasms taking place in individual or groups of muscles which can either be sustained or intermittent, sudden or slow, painful or painless. Being able to affect any voluntary muscle in the body including vocal cords, these movements of can appear very unusual and abnormal to those who are around.
On the other hand, Tardive Dyskinesias are a set of late-onset involuntary and hyperkinetic movements of various types which mostly occur randomly and rhythmically, appearing bizarre and unusual to others.
Image Courtesy:
“Dystonia2010” By James Heilman, MD – Own work (CC BY-SA 3.0) via Commons Wikimedia
“DeGaper” (Public Domain) via Commons Wikimedia
