Bone Health in Pediatric Charcot-Marie-Tooth (CMT) Patients: The Baseline Experience in a Multidisciplinary Neuromuscular Program at a Pediatric Tertiary Care Center

Abstract

Purpose/Aims

Adults with CMT have increased fracture risk, but data in children is lacking. We examine current bone health data in CMT at Lurie Children's Hospital (LCH) to inform clinical care, optimize bone health, and improve long- term morbidity and fracture risk.

Rationale/Background

Poor pediatric bone health increases lifelong risk of osteoporosis, with associated morbidity and mortality. CMT, the most common chronic peripheral neuropathy in childhood, is genetically and clinically heterogeneous, with milder, demyelinating (CMT-D), and more severe, axonal (CMT-A) subtypes.

Presentation includes distal leg weakness or deformity, mobility or balance issues, and muscle cramping. There are no disease-modifying therapies in children; early recognition, symptomatic care, and rehabilitation are critical.

Brief Description of the Undertaking/Best Practice

Retrospective chart review of 38 patients (pts) with CMT seen at LCH from 2012-22 revealed 21 pts (age 7-24 years(y)) who had Dual-energy X-ray Absorptiometry (DXA). Lumbar (LS) and total body less head (TBLH) bone mineral density (BMD, g/cm2) were measured (GE/Lunar iDXA). DXA Z-scores, ambulatory status, scoliosis, fracture, vitamin D supplementation, and 25OH vitamin D (25OHD) levels were assessed.

Outcomes achieved/documented

Seventeen pts had CMT-D; 4 had CMT-A. 18 pts were weight bearing (WB). The 2 non-WB (NWB), and 1 WB with assistance pts all had CMT-A. 3 pts had scoliosis (1 was NWB; 2 had CMT-D). 2 pts had a history of 1 fracture (not vertebral). 16 took supplemental vitamin D; 13 had 25OHD results, 1 was < 20 ng/ml. Pts were 5- 17y at initial DXA and had 1-7 DXA's completed. At initial DXA, 3 had low BMD (TBLH) (9, 12, 15y). One NWB pt later developed low LS BMD, and another with initial normal BMD had low BMD at 9y (NWB). Three pts with low BMD had CMT-A. Patients with fracture and low 25OHD had normal BMD, and 1 pt with scoliosis had low BMD.

Conclusions

Patients with CMT-A had a more severe phenotype and associated bone health measures in this cohort (3 NWB, and 3 with low BMD). Guidelines for pediatric CMT recommend improving muscle strength to slow progression of weakness, without specific bone health recommendations. Given the peripheral nature of CMT, DXA of lateral distal femur or distal 1/3 radius, or peripheral quantitative computed tomography (pQCT) may more accurately characterize bone health status. This study was limited by small sample size and 17/38 pts did not have DXA data. The LCH Neuromuscular program (neurologists, dietitians, physical and occupational therapists, and bone health specialists), seeks to monitor pts with CMT longitudinally, assessing 25OHD, calcium status, and BMD serially, to optimize bone health and prevent fractures and long-term morbidity.