Relationship of spasticity to soft tissue body composition and the metabolic profile in persons with chronic motor complete spinal cord injury

Abstract

Background/objective: To determine the effects of spasticity on anthropometrics, body composition (fat mass [FM] and fat-free mass [FFM]), and metabolic profile (energy expenditure, plasma glucose, insulin concentration, and lipid panel) in individuals with motor complete spinal cord injury (SCI).

Methods: Ten individuals with chronic motor complete SCI (age, 33 +/- 7 years; BMI, 24 +/- 4 kg/m2; level of injury, C6-T11; American Spinal Injury Association A and B) underwent waist and abdominal circumferences to measure trunk adiposity. After the first visit, the participants were admitted to the general clinical research center for body composition (FFM and FM) assessment using dual energy x-ray absorptiometry. After overnight fasting, resting metabolic rate (RMR) and metabolic profile (plasma glucose, insulin, and lipid profile) were measured. Spasticity of the hip, knee, and ankle flexors and extensors was measured at 6 time points over 24 hours using the Modified Ashworth Scale.

Results: Knee extensor spasticity was negatively correlated to abdominal circumferences (r = -0.66, P = 0.038). After accounting for leg or total FFM, spasticity was negatively related to abdominal circumference (r = -0.67, P = 0.03). Knee extensor spasticity was associated with greater total %FFM (r = 0.64; P = 0.048), lower % FM (r = -0.66; P = 0.03), and lower FM to FFM ratio. Increased FFM (kg) was associated with higher RMR (r = 0.89; P = 0.0001). Finally, spasticity may indirectly influence glucose homeostasis and lipid profile by maintaining FFM (r = -0.5 to -0.8, P < 0.001).

Conclusion: Significant relationships were noted between spasticity and variables of body composition and metabolic profile in persons with chronic motor complete SCI, suggesting that spasticity may play a role in the defense against deterioration in these variables years after injury. The exact mechanism is yet to be determined.

Figures

Figure 1

A frame of the timeline of the study during the first visit at the laboratory and the second visit at the GCRC. Time points are numbered MAS (1) to MAS (6).

Figure 2

The average of spasticity scores of (a) hip, (b) knee, and (c) ankle flexors and extensors over the course of 24 hours. Hypertonicity was more in the extensor skeletal muscle groups compared with the flexors. A pattern of increased hypertonicity was detected in the morning because of immobilization and late administration of their oral baclofen dose.

Figure 3

Mean ± SD of %FM and %FFM using lunar DEXA for the measurement of regional and total body composition.

Figure 4

Inverse relationships between knee extensors spasticity and %FM in (a) gynoid (r  =  −0.65, P  =  0.047) and (b) total body (r  =  −0.65, P  =  0.03) and indices of FM to FFM in (c) trunk (r  =  −0.69, P  =  0.025) and (d) total body (r  =  −0.65, P  =  0.04).

Figure 5

The relationship between FFM-total body (kg) and RMR (kcal/d; r  =  0.89; P  =  0.0001).