Objective measurement of oral function in adults with spinal muscular atrophy

Abstract

Background Impairment of bulbar function in adult individuals with spinal muscular atrophy (SMA) usually is not assessed by established motor scores. Measurements of oral function including quantitative muscle and endurance tests are able to detect subtle changes. The aim of this study was to systematically evaluate the measurement of maximum bite force and endurance, maximum tongue pressure and endurance, as well as maximum mouth opening in adult individuals with SMA types 2 and 3. Methods Data from oral function tests in 43 individuals were analyzed. Differences in oral function between individuals with different SMA types and numbers of SMN2 copies were tested. Spearman´s rho correlations among oral function measures themselves as well as with established clinical outcome scales were analyzed. Results The absolute maximum measures of oral function (maximum bite force, maximum tongue pressure, maximum mouth opening) were able to discriminate between individuals with different SMA types, individuals with a different number of SMN2 copies and with different walking abilities. The pairwise correlations of the absolute maximum measures of oral function were fair to moderate in size; the same was true for their correlations with the established motor scores. All correlations assessing endurance measures of oral function were weaker and statistically insignificant. Conclusions Among the oral function tests maximum tongue pressure and maximum mouth opening are particulary promising as clinical and sensitive outcome measures for clinical trials. Oral function tests may supplement existing motor scores, in particular concerning specific questions about bulbar function or in severely affected non-ambulatory individuals where mild (treatment-related) changes would otherwise remain undetected. Trial registration DRKS, DRKS00015842. Registered 30 July 2019, https://drks.de/search/de/trial/DRKS00015842

Risdiplam improves subjective swallowing quality in non-ambulatory adult patients with 5q-spinal muscular atrophy despite advanced motor impairment

“…Therefore, this score does not cover the entire bulbar spectrum. Components such as the mandibular range of motion, masticatory and tongue forces, and head posture, identified as relevant bulbar function components in previous studies [ 15 , 39 – 41 ], are only indirectly assessed. As a complement, the b-ALSFRS-R assesses speech, salivation, and swallowing using one item each.…”

Assessing the Assisted Six-Minute Cycling Test as a Measure of Endurance in Non-Ambulatory Patients with Spinal Muscular Atrophy (SMA)

“…Muscular endurance is important to measure in the SMA population as reduced endurance is a common yet under-assessed symptom that interferes with daily living [18]. Endurance can be defined as the prolonged maintenance of a constant or self-regulated power, velocity, or force level [19][20][21][22]. Endurance can be further broken down into muscular endurance, which is a muscle's ability to continuously perform successive exertions or repetitions against a submaximal load, and aerobic endurance, which is the ability of the heart and lungs to fuel the body with oxygen [23][24][25].…”