Impairment of motor skills in children with achondroplasia—usefulness of brain and cranio-cervical junction evaluation by quantitative magnetic resonance imaging: a case-control study

Abstract

Background Most infants and children with achondroplasia show delayed motor skill development; however, some patients may have clinical consequences related to cranio-cervical junction stenosis and compression. Purpose To assess, using brain magnetic resonance imaging (MRI), quantitative variables linked to neuromotor impairment in achondroplasic children. Material and Methods In total, 24 achondroplasic children underwent pediatric neurological assessment and were grouped in two cohorts according to relevant motor skill impairment. Achondroplasic children with (n=12) and without (n=12) motor symptoms were identified, and brain MRI scans were quantitatively evaluated. 3D fast spoiled gradient echo T1-weighted images were used to assess: supratentorial intracranial volumes (SICV); supratentorial intracranial brain volume (SICBV); SICV/SICBV ratio; posterior cranial fossa volume (PCFV); posterior cranial fossa brain volume (PCBFV); PCFV/PCFBV ratio; ventricular and extra-ventricular cerebrospinal fluid (CSF) volumes; foramen magnum (FM) area; and jugular foramina (JF) areas. Results In both groups, SICV/SICBV ratio, supratentorial ventricular and extra-ventricular space volumes were increased while SICBV was increased only in the asymptomatic group ( P < 0.05). PCFV/PCFBV ratio, IV ventricle, infratentorial extra-ventricular spaces volumes were reduced ( P < 0.05) in the symptomatic group while PCFBV was increased only in the asymptomatic group ( P < 0.05). Foramen magnum (FM) area was more reduced in the symptomatic group than the asymptomatic group ( P < 0.05) but no correlation between FM area and ventriculomegaly was found ( P > 0.05). Conclusion Evaluation of the FM area together with infratentorial ventricular and extra-ventricular space volume reduction may be helpful in differentiating patients at risk of developing motor skill impairment. Further investigation is needed to better understand the temporal profile between imaging and motor function in order to propose possible personalized surgical treatment.