Advances in imaging of brain abnormalities in neuromuscular disease

Abstract

Brain atrophy, white matter abnormalities, and ventricular enlargement have been described in different neuromuscular diseases (NMDs). We aimed to provide a comprehensive overview of the substantial advancement of brain imaging in neuromuscular diseases by consulting the main libraries (Pubmed, Scopus and Google Scholar) including the more common forms of muscular dystrophies such as dystrophinopathies, dystroglycanopathies, myotonic dystrophies, facioscapulohumeral dystrophy, limb-girdle muscular dystrophy, congenital myotonia, and congenital myopathies. A consistent, widespread cortical and subcortical involvement of grey and white matter was found. Abnormalities in the functional connectivity in brain networks and metabolic alterations were observed with positron emission tomography (PET) and single photon emission computed tomography (SPECT). Pathological brain changes with cognitive dysfunction seemed to be frequently associated in NMDs. In particular, in congenital muscular dystrophies (CMDs), skeletal muscular weakness, severe hypotonia, WM abnormalities, ventricular dilatation and abnormalities in cerebral gyration were observed. In dystroglycanopathy 2I subtype (LGMD2I), adult patients showed subcortical atrophy and a WM periventricular involvement, moderate ventriculomegaly, and enlargement of subarachnoid spaces. Correlations with clinical features have been observed with brain imaging characteristics and alterations were prominent in congenital or childhood onset cases. In myotonic dystrophy type 2 (DM2) symptoms seem to be less severe than in type 1 (DM1). In Duchenne and Becker muscular dystrophies (DMD, BMD) cortical atrophy is associated with minimal ventricular dilatation and WM abnormalities. Late-onset glycogenosis type II (GSD II) or Pompe infantile forms are characterized by delayed myelination. Only in a few cases of oculopharyngeal muscular dystrophy (OPMD) central nervous system involvement has been described and associated with executive functions impairment.

Keywords: MRI; brain; imaging; muscular dystrophy.

Figure 1.

47-year-old male affected by myotonic dystrophy type 1 (with a sister affected by the same pathology) with moderate cognitive involvement, (MIRS) = 3, first symptoms onset at age 26 years, CTG = 413, expansion class = E2. (a) Marked white matter change abnormality around frontal horn detected in a FLAIR brain MRI scan (red arrow). Left ventricle appears larger than right. (b) In the temporopolar area at the level of insula marked changes of white matter with major involvement on the left side (red arrow). In brain stem, there is marked atrophy of quadrigeminal bodies and atrophy of pons on the left side (green box). The third ventricle is dilated. CTG, Cytosine-Thymine-Guanine; FLAIR, fluid-attenuated inversion recovery; MIRS, muscular impairment rating scale; MRI, magnetic resonance imaging.

Figure 2.

Brain MRI of a patient with CMD. Axial T2 images show evidence of severe white matter abnormalities, pachygyria in the occipital lobes and ventricular enlargement. CMD, congenital muscular dystrophy; MRI, magnetic resonance imaging.