A 55-year-old man is brought to the office due to unusual movements of his face and extremities. He lives in a group home and was noted to be sticking out his tongue, smacking his lips, and twisting his body from side to side, actions that were disruptive to the other residents. The patient has a history of schizoaffective disorder that has been treated with risperidone, fluoxetine, and clonazepam for more than 20 years. Examination shows protruding and twisting movements of the tongue, dystonic postures of the neck, and squirming movements of the torso. Which of the following is the most likely underlying cause of this patient's symptoms?

Question

A 55-year-old man is brought to the office due to unusual movements of his face and extremities.  He lives in a group home and was noted to be sticking out his tongue, smacking his lips, and twisting his body from side to side, actions that were disruptive to the other residents.  The patient has a history of schizoaffective disorder that has been treated with risperidone, fluoxetine, and clonazepam for more than 20 years.  Examination shows protruding and twisting movements of the tongue, dystonic postures of the neck, and squirming movements of the torso.  Which of the following is the most likely underlying cause of this patient's symptoms?

Quizplus · Accepted Answer

This patient exhibits characteristic symptoms of tardive dyskinesia (TD), an involuntary movement disorder associated with dopamine-blocking agents. Characteristic movements include orofacial dyskinesias (ie, rhythmic movements of the face, lips, and tongue) and choreoathetoid movements of the trunk and extremities. TD is most commonly associated with prolonged use of antipsychotic medications and is typically seen in patients with chronic psychotic disorders. It is also common for TD to worsen or first appear following antipsychotic dose reduction or discontinuation. Although more common with first-generation antipsychotics that are potent dopamine D2 blockers, TD can also occur with second-generation antipsychotics such as risperidone. The pathophysiology of TD is thought to involve dopamine D2 receptor upregulation and supersensitivity resulting from chronic blockade of dopamine receptors. Other hypotheses include an imbalance between dopamine D1 receptor and dopamine D2 receptor effects in the basal ganglia as well as excitotoxic destruction of GABA neurons in the striatum. (Choices A) Caudate nucleus atrophy is associated with Huntington disease, an inherited progressive neurodegenerative disorder characterized by choreiform movements, psychiatric symptoms, and dementia. It is not thought to play a role in TD pathogenesis. (Choice B) Chronic use of dopamine receptor-blocking agents such as antipsychotics is associated with upregulation, not downregulation of dopamine receptors. (Choices D and E) GABA receptor upregulation and glutamate receptor supersensitivity are not thought to play a role in TD. (Choice F) Medications that inhibit serotonin reuptake (eg, fluoxetine) cause downregulation of serotonin receptors after several weeks. However, this is not associated with TD. (Choice G) The ventral tegmental area is a region in the midbrain that contains a high density of dopamine-releasing neurons, which project to the nucleus accumbens and modulate reward pathways. Ventral tegmental area atrophy is not thought to play a role in TD pathogenesis. Educational objective: Tardive dyskinesia (TD) develops in the setting of prolonged exposure to dopamine-blocking agents, which is thought to result in the upregulation and supersensitivity of dopamine receptors. TD is characterized by abnormal involuntary movements of the mouth, tongue, trunk, and extremities and can first appear during treatment or following antipsychotic dose reduction or discontinuation. References: Tardive dyskinesia and tardive dystonia with second-generation antipsychotics in non-elderly schizophrenic patients unexposed to first-generation antipsychotics: a cross-sectional and retrospective study. (http://www.ncbi.nlm.nih.gov/pubmed/25485636) Tardive dyskinesia occurring in a young woman after withdrawal of an atypical antipsychotic drug. (http://www.ncbi.nlm.nih.gov/pubmed/26492119)

A 55-Year-Old Man Is Brought to the Office Due to Unusual