Decrease of Muscle Mass in Young Patients With Neuromuscular Disease: Assessment of Sarcopenia

Abstract

Background: Sarcopenia can be associated with the disease etiologies other than degenerative processes, such as neurologic disease including cerebral palsy, myelomeningocele, or Duchenne muscular dystrophy, even in children. Although the relationship between neurologic disease and scoliosis or ambulatory function is known, the mediators affecting scoliosis or gait function in these patients are unclear, an example might be sarcopenia. This study aimed to assess the degree of sarcopenia in young patients with neurologic diseases using computed tomography (CT), and analyze the correlation between sarcopenia and scoliosis or ambulatory function.

Methods: Pediatric and young adult patients (≤ 25 years old) who underwent whole-spine or lower-extremity CT were retrospectively included. From bilateral psoas muscle areas (PMAs) at the L3 level, the psoas muscle z-score (PMz) and psoas muscle index [PMI = PMA/(L3 height)²] were calculated. The t-test, Fisher's exact test, and logistic regression analyses were performed.

Results: A total of 121 patients (56 men, mean age 12.2 ± 3.7 years) were included with 79 neurologic and 42 non-neurologic diseases. Patients with neurologic diseases had lower PMz (P = 0.013) and PMI (P = 0.026) than patients without. In neurologic disease patients, severe scoliosis patients showed lower PMz (P < 0.001) and PMI (P = 0.001). Non-ambulatory patients (n = 42) showed lower BMI (β = 0.727, P < 0.001) and PMz (β = 0.547, P = 0.025). In non-ambulatory patients, patients with severe scoliosis also showed lower PMz (P < 0.001) and PMI (P = 0.004).

Conclusion: Patients with neurologic diseases could have sarcopenia even in young age. Psoas muscle volume was also associated with ambulatory function in these patients. Sarcopenia was more severe in severe scoliosis patients in the non-ambulatory subgroup.

Keywords: Child; Neurologic Diseases; Sarcopenia; Scoliosis.

Fig. 1. Representative images for the measurement of psoas muscle area and vertebral height on CT. (A) Psoas muscle area (green color) measured on an angle-corrected axial CT image (B) perpendicular to the L3 vertebral body at the mid L3 level. (C) L3 vertebral height was also measured on an angle-corrected sagittal CT image.

CT = computed tomography.

Fig. 2. Box plots that compare psoas muscle parameters such as the (A) PMz and (B) PMI according to neurologic disease and severe scoliosis. Sarcopenia was more severe in patients with severe scoliosis in the neurologic disease group with lower PMz (P < 0.001) and PMI (P = 0.001) being observed compared to patients with non-severe scoliosis.

PMz = psoas muscle z-score, PMI = psoas muscle index.

Fig. 3. Box plots that compare (A) PMz and (B) PMI between the ambulatory function groups. In the non-ambulatory group, psoas muscle parameters were lower in patients with severe scoliosis (P < 0.001 for PMz and P = 0.004 for PMI).

PMz = psoas muscle z-score, PMI = psoas muscle index.