INTRODUCTIONPatients with Pompe disease (PD) have a total (infantile form) or partial (late-onset form) deficiency of the lysosomal enzyme acid alpha-glucosidase [1]. The deficient enzymatic activity causes a progressive and debilitating glycogen accumulation, leading to progressive muscular weakness and easy fatigability. Enzyme replacement therapy (ERT) is given to correct the enzyme defect.. The objective of this study was to check whether in these patients the standing stability improves following ERT.METHODSSix male adults with late-onset PD (36,3±19,8 yrs; 179±12,6 cm; 81,7±14,3 kg) took part in this study. The dosage of ERT was 20 mg/kg patient body weight and the treatment is given at regular intervals, intravenously, once in a fortnight. Each participant was asked to stand on a force platform for 50 s performing single trials of bipedal quiet stance with 3 feet configurations: 1) feet parallel with 20 cm mediolateral-interfoot distance (ML-IFD); 2) feet parallel with 10 cm ML-IFD; 3) feet 30°extra-rotated with the heels together. For each configuration the postural task was performed either with open-eyes (OE) or closed-eyes (CE).The patients were evaluated 2 days pre and 5 days post the ERT. Center of Pressure (COP) trajectories were obtained and 2 types of assessment tools were used: stability-related parameters including the total Sway Path (tSP), which accounts for the entire length of body sway, the Sway Path in antero-posterior (SP AP) and medio-lateral (SP ML) directions, the Root Mean Square (RMS AP and RMS ML), that gives a measure of postural sway variability, and the 95% confidence ellipse area (AREA); the parameters to evaluate the postural control structure included the Mean Power Frequency (MPF AP and MPF ML), which represents the mean frequency of the power spectrum, and the Fractal Dimension (FD) and Approximate Entropy (ApEn), which quantify the level of geometrical and temporal complexity of COP trajectory, respectively. Dataset associated with each parameter showed normal distribution (Shapiro-Wilk test) and was analyzed by a three way ANOVA with repeated measures for the effects of therapy, feet positions and vision conditions. Paired t-test was computed for local differences across all the conditions. RESULTSThe ANOVA showed that stability-related parameters changed significantly for feet position and vision conditions, but no effect of the ERT was detected among all the parameters except for RMS ML (F1,5=7.671; P=0.039). Comparing the performance pre and post ERT for each single condition, significant increases in stability were observed for 2 parameters in the condition with feet at 20 cm apart and the open eyes (Fig 1.): the AREA of COP exhibited a reduction of 42% (t5=3.390; P=0.019) and the RMS ML reduced of 33% of (t5=2.561;P=0.049). DISCUSSION ERT produced significant increases of postural stability (reduction of the COP AREA and the variability along the ML direction) when the feet were 20 cm apart and eyes open. This condition was the easiest and less fatigable among the six ones. Moreover, the oscillations along ML direction are commonly more stable than along AP direction. Thus, it is possible that the effects of ERT depend on the level of the effort request by the task. Overall, specific postural condition may be sensitive to the therapy.REFERENCES[1] Sampaolo S et al. Orphanet Journal of Rare Disease 8: 159, 2013.

Effects of enzyme replacement therapy on standing posture in patients with Pompe disease

VALLE, Maria Stella Carmela;FIUMARA, Agata;Cioni M.
2015

Abstract

INTRODUCTIONPatients with Pompe disease (PD) have a total (infantile form) or partial (late-onset form) deficiency of the lysosomal enzyme acid alpha-glucosidase [1]. The deficient enzymatic activity causes a progressive and debilitating glycogen accumulation, leading to progressive muscular weakness and easy fatigability. Enzyme replacement therapy (ERT) is given to correct the enzyme defect.. The objective of this study was to check whether in these patients the standing stability improves following ERT.METHODSSix male adults with late-onset PD (36,3±19,8 yrs; 179±12,6 cm; 81,7±14,3 kg) took part in this study. The dosage of ERT was 20 mg/kg patient body weight and the treatment is given at regular intervals, intravenously, once in a fortnight. Each participant was asked to stand on a force platform for 50 s performing single trials of bipedal quiet stance with 3 feet configurations: 1) feet parallel with 20 cm mediolateral-interfoot distance (ML-IFD); 2) feet parallel with 10 cm ML-IFD; 3) feet 30°extra-rotated with the heels together. For each configuration the postural task was performed either with open-eyes (OE) or closed-eyes (CE).The patients were evaluated 2 days pre and 5 days post the ERT. Center of Pressure (COP) trajectories were obtained and 2 types of assessment tools were used: stability-related parameters including the total Sway Path (tSP), which accounts for the entire length of body sway, the Sway Path in antero-posterior (SP AP) and medio-lateral (SP ML) directions, the Root Mean Square (RMS AP and RMS ML), that gives a measure of postural sway variability, and the 95% confidence ellipse area (AREA); the parameters to evaluate the postural control structure included the Mean Power Frequency (MPF AP and MPF ML), which represents the mean frequency of the power spectrum, and the Fractal Dimension (FD) and Approximate Entropy (ApEn), which quantify the level of geometrical and temporal complexity of COP trajectory, respectively. Dataset associated with each parameter showed normal distribution (Shapiro-Wilk test) and was analyzed by a three way ANOVA with repeated measures for the effects of therapy, feet positions and vision conditions. Paired t-test was computed for local differences across all the conditions. RESULTSThe ANOVA showed that stability-related parameters changed significantly for feet position and vision conditions, but no effect of the ERT was detected among all the parameters except for RMS ML (F1,5=7.671; P=0.039). Comparing the performance pre and post ERT for each single condition, significant increases in stability were observed for 2 parameters in the condition with feet at 20 cm apart and the open eyes (Fig 1.): the AREA of COP exhibited a reduction of 42% (t5=3.390; P=0.019) and the RMS ML reduced of 33% of (t5=2.561;P=0.049). DISCUSSION ERT produced significant increases of postural stability (reduction of the COP AREA and the variability along the ML direction) when the feet were 20 cm apart and eyes open. This condition was the easiest and less fatigable among the six ones. Moreover, the oscillations along ML direction are commonly more stable than along AP direction. Thus, it is possible that the effects of ERT depend on the level of the effort request by the task. Overall, specific postural condition may be sensitive to the therapy.REFERENCES[1] Sampaolo S et al. Orphanet Journal of Rare Disease 8: 159, 2013.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/20.500.11769/109272
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