For patients in whom TD is suspected, dark rings at the outer edges of the irises might be Kayser-Fleischer rings due to copper deposition in the cornea (Descemet membrane). In some patients, slit-lamp examination is necessary to visualize the rings. This finding, together with the patient's age and symptoms, raises concerns about Wilson disease, an uncommon autosomal recessive disorder of copper metabolism characterized by hepatic and extrapyramidal symptoms (EPS).
In Wilson disease, copper accumulates in multiple organs, most importantly the brain and liver, leading to a variety of clinical presentations: neurologic symptoms, liver failure, and psychiatric manifestations. Wilson disease should be considered as a differential diagnosis to TD in patients younger than 50 years who have movement disorders: tremors, reduced dexterity, choreiform movements, dystonia, rigidity, and/or dysarthria. Psychiatric features occur in 10%-25% of patients and can precede the movement disorder. When Wilson disease is suspected, serum copper and ceruloplasmin levels should be checked, brain MRI should be performed, and an ophthalmologic consultation should be conducted. Results of a brain MRI in Wilson disease may demonstrate the classic "face of the giant panda" sign in the midbrain on T2-weighted images.
If a patient with hyperkinesia resembling TD has cognitive changes, Huntington disease, an autosomal dominant disorder, should be considered.
If hyperkinesia is focal (ie, affecting one limb), and especially if it co-occurs with other focal neurologic deficits (eg, asymmetric reflexes, hemiparesis), imaging should be performed to exclude a structural brain lesion.
Hudson-Stahli lines and Ascher intrastromal corneal rings are clinically insignificant ophthalmologic findings and are not part of the differential diagnosis for TD.
Learn more about the differential diagnosis of TD.
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Cite this: Matthew Swan, James Robert Brasic. Fast Five Quiz: How Much Do You Know About Tardive Dyskinesia? - Medscape - Apr 22, 2022.