Transcranial sonography in neurodegeneration with brain iron accumulation disorders.

Background: Transcranial Sonography is a non-invasive technique that has been used as a diagnostic tool for a variety of neurodegenerative disorders. However, the utility and potential application of this technique in NBIA disorders is scarce and inconclusive.

Methods: In this cross-sectional retrospective case-control study, the echogenicity of Substantia Nigra (SN), Lentiform Nucleus (LN), and Diameter of the Third Ventricle (DTV) were assessed by TCS in genetically confirmed NBIA patients referring to the movement disorder clinic. The normal echogenicity area of SN was defined based on the 90th percentile of an age-and-gender-matched control group. NBIA patients underwent neurologic examination at each visit, but their brain magnetic resonance imaging and demographics were extracted from electronic records.

Results: Thirty-five NBIA patients of four subtypes with a mean disease duration of 10.54 years and 35 controls were enrolled. The normally defined SN echogenicity in controls was 0.23 cm. DTV and SN echogenicity areas were significantly higher in patients compared to the controls (P = 0.002 and < 0.001, respectively). Around 85% and 63% of the patients showed LN and SN hyperechogenicity at least on one side, respectively. Disease duration was positively correlated with DTV (r = 0.422, p = 0.015). Cases with Pantothenate Kinase Associated Neurodegeneration (n = 23) also had significantly higher DTV and SN echogenicity area compared to the controls.

Conclusion: Despite most NBIA patients displayed increased DVT and higher SN and LN hyperechogenicity than healthy controls, the discriminatory role of TCS on different NBIA subtypes remains to be determined.