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.

What to Expect of Feeding Abilities and Nutritional Aspects in Achondroplasia Patients: A Narrative Review

“…ACH is known to be associated with an increased risk of obesity [4] and a major predisposition to abdominal obesity since early childhood, though the causes are still not fully understood [1,71,75]. It has been recognized as a major health problem in adults with ACH and it can worsen complications such as lumbar spinal stenosis, joint pain, or sleep apnea [76][77][78]. In their recent case-control study, Fredwall et al detected a higher prevalence of obesity with a body mass index (BMI) ≥ 30 kg/m 2 among 49 Norwegian adults with ACH, specifically 67% (n = 33/49) [79].…”

Thoracolumbar stenosis and neurologic symptoms: Quantitative MRI in achondroplasia

“…The disharmonious development of the basicranium and spinal dysplasia in achondroplasia is due to disordered endochondral ossification resulting in a small cranial base, small vertebral bodies, and early fusion of the pedicles to the vertebral bodies 3 . Hence, the narrowing of foramen magnum with obliteration of the subarachnoid space or subtle “nicking” of the posterior cord and thoracolumbar deformity with secondary spinal canal stenosis are recognized problems in patients with achondroplasia 4–6 …”

“…Although all patients with achondroplasia are predisposed to develop spinal stenosis, only about 20%‐47% of patients in adolescence or adulthood become symptomatic due to progressive spine deformity 4,6 and may require surgery 8 …”

“…3 Hence, the narrowing of foramen magnum with obliteration of the subarachnoid space or subtle "nicking" of the posterior cord and thoracolumbar deformity with secondary spinal canal stenosis are recognized problems in patients with achondroplasia. [4][5][6] In achondroplasia, the entire length of the spinal canal is reduced, as a result of small vertebral bodies, while the cross-sectional area of the spinal canal is narrowed by the shortened pedicles and the decreased interpedicular distances. 7,8 Moreover, age-related degenerative changes due to disc narrowing and bulging, in-folding and thickening of the ligamentum flavum as well as facet osteoarthritis, further contribute to the reduction of the dimensions of the spinal canal, in particular the lumbar spinal canal.…”

“…9,10 Thus, in patients with achondroplasia, spinal deformity is the combined effect of congenital dysplasia and acquired degenerative changes related to ageing 11 ; this results in progressive spinal stenosis exacerbated by a dynamic thoracolumbar kyphosis (TLK) and a compensatory lumbar hyperlordosis. 4,[12][13][14] Although all patients with achondroplasia are predisposed to develop spinal stenosis, only about 20%-47% of patients in adolescence or adulthood become symptomatic due to progressive spine deformity 4,6 and may require surgery. 8 Magnetic resonance imaging (MRI) provides a useful, noninvasive tool to evaluate spinal deformity, spinal stenosis, spinal cord compression, and intramedullary signal abnormalities.…”