Assessing Prevalence and Characteristics of Oro-bulbar Involvement in Children and Adults with SMA Type 2 and 3 Using a Multimodal Approach

Abstract

Bulbar and jaw muscles are impaired in patients with Spinal Muscular Atrophy (SMA) but the assessment of their severity and progression are limited by the lack of age-appropriate and disease-specific measures. We investigated mastication and swallowing in children and adults with SMA, sitters and walkers. In a 2-year multicentre cross-sectional prospective study, lip and tongue strength (Iowa Oral Performance Instrument), chewing and swallowing (Test of Masticating and Swallowing Solids), active mouth opening (aMMO) were compared to age-appropriate normative data. The perceived burden of oro-bulbar involvement (SMA-Health Index) was recorded. 78 patients were included, 45 children (median age 7.4 years),22 adults (median age 26.8 years) on nusinersen and 11 untreated (median age 32.7 years). Forty-three percent children had reduced mouth opening, 50% had prolonged total time to eat. These issues were more prominent in sitters than in walkers (p = 0.019, p = 0.014). Sixty-six percent needed increased swallows for bolus clearance. Nusinersen treated adults had median aMMO, tongue strength and total time at TOMASS values within normal range (z score: −1.40, −1.22, −1.32, respectively) whereas untreated adults had reduced aMMO (z score: −2.68) and tongue strength (z score: −2.20). Only a minority of children (2/17) and treated adults (5/21) reported burden in swallowing or mastication compared to all untreated adults (5/5). After 16 months, mastication and swallowing were stable in treated children and adults, whether sitters or walkers. The reported multimodal approach to assess oro-bulbar functions demonstrate that swallowing and mastication are impaired in SMA despite patients’ perception. These results suggest a trend towards stabilization of oro-bulbar function in patients on long-term treatment with nusinersen.

Assessing the Swallowing Function in Children with Spinal Muscular Atrophy: An Easily Accessible and Objective Multidimensional Approach

“…The max pressure index thus likely reflects the known severity in the different SMA subgroups. It is also in line with Trucco et al (2023)'s recent publication indicating that tongue strength was below normative data in 47% of patients in a children cohort of SMA type 2-3 patients [16].…”

“…These two questions would be best described by the intensity rather than by the frequency of these complaints. Other studies on swallowing in SMA patients used objective mouth opening measure and did not focus on frequency [16]. Thus, we should consider removing these two questions from the SFAQ in the future.…”

“…More recently, the Iowa Oral Performance Instrument (IOPI) was validated as a noninvasive investigation tool in patients affected by oropharyngeal muscular dystrophy and is currently being used in patients with myotonic dystrophy (TREAT-CDM at the University of Virginia, USA; and GUP19002, grant given to vs from Telethon and the Italian Muscular Dystrophy Association) [15]. Trucco et al (2023)'s study on patients with SMA type 2 and 3 shows that the assessment of tongue and lip strength via IOPI could well complement the other tests in both adults and children [16]. However, SF is still poorly investigated, with only scarce literature on this topic.…”

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

“…Further data on bulbar function in adult patients with SMA under gene-based therapies are scarce. Data available for nusinersen also support an overall positive effect on bulbar symptoms in adult patients with SMA, yet not as clearly and robustly [ 29 – 32 ]. A direct comparison of both therapies is challenging due to the significant differences in the clinical features of the two patient groups.…”

“…Both measuring tools are patient-reported outcome measures and are thus limited in their objectivity and could be biased by patients' expectations of a new therapy. Furthermore, a recent study assessing oro-bulbar involvement in adults and children with SMA using objective measures such as lip and tongue strength and mouth opening revealed that patients´ perception of bulbar function often differs from objectifiable deficits, some of which are not subjectively perceived by patients [ 32 ]. This limits the interpretability of patient-reported outcome measures in this field.…”