Nigral Iron Deposition in Common Tremor Disorders
Nina Homayoon, MD, et al
We investigated R2* relaxation rates as a marker of iron content in the substantia nigra in patients with common tremor disorders and explored their diagnostic properties.
Mean nigral R2* rates were measured in 40 patients with tremor-dominant Parkinson’s disease (PD), 15 with tremor in dystonia, 25 with essential tremor, and 25 healthy controls.
Tremor-dominant PD patients had significantly higher nigral R2* values (34.1 5.7) than those with tremor in dystonia (30.0 3.9), essential tremor (30.6 4.8), and controls (30.0 2.8). An R2* threshold of 31.15 separated tremor-dominant PD from controls with a sensitivity and specificity of 67.5% and 72%. The sensitivity and specificity for discrimination between PD and non-PD tremor patients was 67.5% and 60%.
Iron content in the substantia nigra is significantly higher in tremor-dominant PD than in tremor in dystonia, essential tremor, and controls. Because of the considerable overlap, nigral R2* cannot be suggested as a useful diagnostic tool.