Brainstem in Machado-Joseph disease: atrophy or small size?

Area of Science:

• Neuroscience
• Genetics
• Neurology

Background:

• Machado-Joseph disease (MJD), a common hereditary spinocerebellar degeneration, results from CAG repeat expansion in the MJD1 gene.
• MJD is characterized by infratentorial structure atrophy, with known correlations between atrophy and CAG repeat length.

Purpose of the Study:

• To longitudinally investigate the changing course of brainstem size in individuals with genetically confirmed MJD.
• To differentiate regional atrophy progression within the infratentorial structures.

Main Methods:

• Longitudinal magnetic resonance imaging (MRI) of seven genetically confirmed MJD cases over 4.5-10.6 years.
• Measurement of midsagittal areas of infratentorial structures, including the pontine base, cerebellum, midbrain, and pontine tegmentum.

Main Results:

• Progressive atrophy was observed in the pontine base and cerebellum, significantly correlating with patient age.
• The midbrain and pontine tegmentum showed atrophy that did not significantly progress over the observation period.
• These findings suggest that atrophy in the midbrain and pontine tegmentum may be an early feature, potentially preceding symptom onset.

Conclusions:

• Regional differences in atrophy progression exist within the infratentorial structures in Machado-Joseph disease.
• The distinct progression patterns likely reflect underlying differences in the neuropathological course of MJD affecting various brainstem regions.