The first step in successfully treating chorea is making the correct diagnosis.
A thoughtful approach to the diagnosis and treatment of the multiplicity of chorea types was presented by Pichet Termsarasab, MD, a practicing neurologist in Cleveland Heights, Ohio, at the 21st International Congress of Parkinson’s Disease and Movement Disorders in Vancouver, BC, on Sunday, June 4.
Termsarasab began by stressing that making a correct diagnosis is the first step in successfully treating a chorea.
Choreas are characterized by random, flowing movements, Termsarasab said, and have a wide range of causes and may be acquired or genetic. Examples of acquired choreas include hemichoreas caused by toxoplasmosis of the central nervous system.
Genetic forms include the chorea of Huntington’s disease (HD) and benign hereditary chorea, a pediatric syndrome that may affect the brain, lungs, and thyroid.
The life stage during which a chorea appears often provides a clue about its cause. Some choreas, such as Sydenham’s chorea, first appear in childhood. Others, like the chorea of HD, first appear in adulthood. These associations make the time course of the appearance of a chorea an important consideration in making a correct diagnosis.
Termsarasab then shared a few general principles of treatment, first recommending that clinicians address easily controllable causes of chorea before considering drug therapy. One such cause is hyperglycemia, which is especially common in Asian women with poorly controlled diabetes, he said. Choreas may also develop in patients at the other end of the blood glucose scale, such as those with severe non-ketotic hypoglycemia.
Systemic lupus erythematosus (SLE) may also cause chorea and is easily treated with corticosteroids. This point illustrates the importance of keeping autoimmune disease in mind in the differential diagnosis, Termsarasab said.
Termsarasab added that if a specific cause can’t be identified and treated, symptomatic treatment has an important role. However, clinicians must “treat the patient and not just the condition,” he stressed.
In keeping with this philosophy, Termsarasab recommended asking, “Does the patient need treatment?” If symptoms are mild and not disabling, treatment may not be needed, he explained.
He added that pharmacologic agents may work pre-synaptically or post-synaptically. Available pre-synaptic agents include reserpine, tetrabenazine, deutetrabenazine, and valbenazine.
He noted that the US Food and Drug Administration (FDA) approved tetrabenazine in 2008 for the treatment of choreas associated with HD. On April 4 of this year the FDA approved deutetrabenazine (Austedo) for the treatment of choreas associated with HD, and it approved valbenazine (Ingrezza) for the treatment of tardive dyskinesia a week later.
Termsarasab added that deutetrabenazine’s approval was based on a study by the Huntington’s Disease Study Group published in JAMA Neurology in 2016, and valbenazine’s was based on results of the KINECT 3 study.
Although deutetrabenazine is based on tetrabenazine, its molecular structure differs, Termsarasab said. This difference makes deutetrabenazine more stable and gives it a longer half-life. He added that these features also promote compliance because deutetrabenazine’s smaller peaks make it less sedating than tetrabenazine.
Post-synaptic agents include amantadine and antipsychotic agents. However, Termsarasab cautioned that antipsychotic agents may induce parkinsonism in patients with chorea.
With regard to dosing, Termsarasab noted that chorea can plateau with time, so “patients don’t need to be on same dose forever.”
To sum up, he said that high-quality evidence supporting the use of these symptomatic agents is limited, and additional well-designed studies are needed.