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Case Reports
. 2020 Jun 1;39(2):83-89.
doi: 10.36185/2532-1900-010. eCollection 2020 Jun.

Maximum bite force in patients with spinal muscular atrophy during the first year of nusinersen therapy - A pilot study

Teresa Kruse  1   2 , Raoul Heller  2   3 , Brunhilde Wirth  2   3   4 , Julia Glöggler  5 , Claudia D Wurster  6 , Albert C Ludolph  6 , Bert Braumann  1   2
Affiliations
Case Reports

Maximum bite force in patients with spinal muscular atrophy during the first year of nusinersen therapy - A pilot study

Teresa Kruse et al. Acta Myol. .

Abstract

Objectives: Spinal muscular atrophy is a monogenic disease characterized by progressive spinal and bulbar muscle weakness and atrophy. It is caused by the degeneration of alpha-motoneurons. The recent approval of the antisense oligonucleotide nusinersen highlights the need for reliable clinical tools to evaluate motor function in patients with neuromuscular disorders. Measurement of the bulbar neuromuscular function (e.g., bite force) could be an extension to existing motor scales, sensitive to more nuanced changes, especially in symptomatic patients with severely reduced functional abilities.

Materials and methods: Maximum bite force measurement was used to quantify changes of the masticatory function in adult monozygotic female twins with SMA type II. Using piezoelectric transducers, 550 observations were recorded for each patient during the first year of nusinersen therapy.

Results: During the application of four loading doses of nusinersen, bite force levels steadily increased and reached a statistically significantly higher level compared to the initial state in both patients. Subsequent maintenance doses coincided with smaller or no statistically significant changes in maximum bite force.

Conclusions: This pilot study indicates that the measurement of maximum bite force may be a useful tool to detect changes of the bulbar function in SMA patients. As such, it may supplement existing scales to identify treatment-related changes in motor function.

Keywords: antisense oligonucleotide; masticatory force; motor neurons; spinal muscular atrophy.

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Figures

Figure 1.
Figure 1.
Changes in maximum bite force during the application of four loading doses of nusinersen (LD1/4, predicted values, in %). Pre entails seven measurement points before first application (=70 observations); each Post LD entails two measurement points within two weeks after application (=20 observations).
Figure 2.
Figure 2.
Changes in maximum bite force during the application of two maintenance doses of nusinersen (MD1/2, predicted values, in %). Pre entails seven measurement points before first application (=70 observations); Post MD1/2 entails two/four measurement points within two weeks after application (=20/40 observations).
Figure 3.
Figure 3.
Maximum bite force in patient 1 and patient 2 over the first year of nusinersen therapy. Each circle indicates the mean value of 10 observations of maximum bite force per measurement point. Solid lines indicate the LOESS curve over time. Dashed lines indicate the mean maximum bite force before the first application of nusinersen.
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