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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.

Background and Purpose: Whole-spine magnetic resonance imaging (MRI) studies, to identify structural abnormalities associated with the development of symptomatic spinal stenosis in achondroplasia., Methods: Forty-two subjects with achondroplasia were grouped into four age-related categories. Congenital spinal deformities (vertebral body and disc height, interpedicular distance), acquired spinal degenerative changes, thoracic kyphotic (TK) angle, thoracolumbar kyphotic (TLK) angle, spinal canal widths were evaluated by MRI., Results: Patients in the first three groups were asymptomatic and younger (group 1: 4.4 ± 0.78 years; group 2: 8.18 ± 0.60 years; group 3: 10.95 ± 0.93 years) than the symptomatic group (group 4: 23 ± 1.30 years). Patients showed height of vertebral bodies, whole canal width, and average lumbar interpedicular distance reduced. Discs degeneration was more pronounced in the lumbar region and in symptomatic adult patients. TK and TLK angles showed a positive correlation with age (p &lt; .05, r = .42; p &lt; .05, r = .41), whereas thoracic and thoracolumbar canal width had a negative correlation (p &lt; .05, r = -.69; p &lt; .05, r = -.58). A negative correlation between lumbar discs degeneration and canal width was found only at L1-L3 level (p &lt; .05, r = -.35). At L1-L3, the canal width cutoff value of .59 allowed the differentiation between asymptomatic and symptomatic patients (area under the curve of .966, p &lt; .0001)., Conclusion: In achondroplasia, the spinal canal narrowing, due to accelerated degenerative changes, is a predisposing factor of symptomatic lumbar spinal stenosis. Lumbar canal MRI is a helpful tool to detect the risk of the development of neurological symptoms; in adult patients, a stenosis higher than 60% of upper lumbar canal could be a critical value for the onset of neurological symptoms., (© 2022 The Authors. Journal of Neuroimaging published by Wiley Periodicals LLC on behalf of American Society of Neuroimaging.)

Purpose: To identify MRI-based quantitative craniofacial variables linked to airways narrowing and obstructive sleep apnea (OSA) development in children with achondroplasia., Methods: We evaluated skull base and midface MRI in two cohorts of children affected by achondroplasia, with (group 1) or without OSA (group 2). 3DFSPGR-T1weighted images were used to assess airways volume (nasopharynx, oropharynx, and laryngopharynx), jugular foramina (JF) and hypoglossal foramina (HF) areas, foramen magnum area, cervical cord area, and maxillary retrusion (SNA angle)., Results: Nineteen out of 27 children with achondroplasia exhibited different degrees of obstructive respiratory impairment (n.4 mild, n.8 moderate, n.7 severe), while 8 children did not show OSA. Each group was compared with age-matched controls without neuroimaging abnormalities. Both groups showed reduced nasopharynx volume, JF areas, and SNA angle, while group 1 showed also reduced oropharynx volume, ratio of FM/cervical cord areas, and HF areas (p < 0.05). A positive correlation between nasopharynx volume and SNA angle was found in both groups, while a positive correlation among upper airways volume, JF and HF areas was found only in group 1. No correlation between upper airways volume and OSA severity was found., Conclusion: In children with achondroplasia, multifaced craniofacial abnormalities contribute to airways volume reduction predisposing to sleep disordered breathing. MRI-based quantitative assessment allows the appraisal of craniofacial variables linked to the development of sleep-disordered breathing such as FM stenosis, jugular and hypoglossal foramina stenosis, and retruded maxillary position and may be a valuable tool for clinical surveillance., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: We propose an magnetic resonance imaging (MRI)-based quantitative morphovolumetric approach to the posterior cranial fossa (PCF) and craniocervical junction (CCJ) changes in achondroplastic patients investigating possible associations with ventriculomegaly and medullary compression., Methods: We analyzed MRI of 13 achondroplastic children not treated by surgery. 3D FSPGR T1-weighted images were used to analyze (1) PCF synchondroses; (2) PCF volume (PCFV), PCF brain volume (PCFBV), PCFV/PCFBV ratio, cerebellar volume, cerebrospinal fluid (CSF) spaces volume, and IV ventricle volume; (3) PCF (clivus, supraocciput, exocciput lengths, tentorial angle) and CCJ (AP and LL diameters of foramen magnum (FM)) morphometry; (4) measurements of FM and jugular foramina (JF) areas; and (5) supratentorial ventricular volume., Results: All patients showed synostosis of spheno-occipital synchondroses, eight showed synostosis of intra-occipital synchondroses, nine showed CCJ impingement on the cervical cord but only three had cervical myelopathy. Compared to controls, clivus and exocciput lengths, LL and AP diameters of FM, FM area and JF area were significantly reduced, supraocciput length, tentorial angle, PCFV, PCFBV, cerebellar volume, supratentorial ventricular system volume were significantly increased. A correlation was found between clivus length and supratentorial ventricular volume, premature closure of intra-occipital synchondroses and FM area while a trend was found between FM area and supraocciput length., Conclusion: Our analysis demonstrates a relationship between the shortening of the clivus and the ventriculomegaly. On the other hand the premature closure of PCF synchondroses, the shape, and the growth direction of supraocciput bone contribute to reduce the FM area, causing in some patients medullary compression.