Secondary signal change and an apparent diffusion coefficient decrease of the substantia nigra after striatal infarction.

BACKGROUND AND PURPOSE Diffusion-weighted imaging can depict secondary signal change of the substantia nigra of patients with ipsilateral striatal infarction via a decrease in the apparent diffusion coefficient (ADC). Clinical predictors of this phenomenon remain unclear. METHODS We assessed 98 stroke patients with acute ischemic lesions in the hemilateral basal ganglia, external capsule, or internal capsule. The ADC values of the bilateral substantia nigra obtained from a follow-up MRI, various clinical factors, and patients' outcome were analyzed. Nineteen patients who underwent a follow-up MRI within 3 days were excluded from analysis because none of them demonstrated a significant ADC change of substantia nigra. RESULTS Of 79 patients, 21 (26.6%) revealed a decreased ADC in the substantia nigra. Ischemic lesions in the globus pallidus (odds ratio 12.90) and the presence of emboligenic diseases (odds ratio 6.95) were independent predictors for an ADC decrease in the substantia nigra. The clinical outcome 3 months after stroke onset was not different between patients with an ADC decrease and patients without. CONCLUSIONS A reduction of ADC in the substantia nigra after acute striatal infarction was more frequently observed when the globus pallidus was affected or when the patient had emboligenic diseases, however, did not necessarily relate to the patient's clinical outcome.