Discussion

Patients in our cohort were referred to the clinic because of concerns over dysphagia. They therefore represent a subset of inclusion body myositis patients encountered in clinical practice. Subtle features of dysphagia in inclusion body myositis may be present without spontaneous reporting: in a study by Cox et al.,^{Reference Cox, Verschuuren, Verbist, Niks, Wintzen and Badrising8} 37 of 57 patients had symptoms of dysphagia picked up by a questionnaire, but only 17 spontaneously reported dysphagia during clinical assessment.

The patients in our cohort were almost evenly split between the sexes: 13 male and 11 female. This is an interesting finding given that other studies have found that the majority of patients with inclusion body myositis are male.^{Reference Oh, Brumfield, Hoskin, Kasperbauer and Basford13,Reference Phillips, Zilko and Mastaglia15} The mean age at presentation is comparable with other studies.^{Reference Cox, Verschuuren, Verbist, Niks, Wintzen and Badrising8,Reference Oh, Brumfield, Hoskin, Kasperbauer and Basford13} One patient in our study died because of aspiration pneumonia, though our patients were only followed up over the four-year study duration.

Four patients (17 per cent) had dysphagia as their presenting symptom of inclusion body myositis; this is unusual since dysphagia is thought to usually present later in the disease.^{Reference Cox, Verschuuren, Verbist, Niks, Wintzen and Badrising8,Reference Oh, Brumfield, Hoskin, Kasperbauer and Basford13,Reference Badrising, Maat-Schieman, van Houwelingen, van Doorn, van Duinen and van Engelen16,Reference Lotz, Engel, Nishino, Stevens and Litchy17} One patient in our cohort was investigated for dysphagia for eight years before their diagnosis of inclusion body myositis, similar to a previous case report.^{Reference Shibata, Izumi, Hara, Ohshima, Nakamura and Suzuki18}

Twenty-three patients presenting to our clinic completed a Reflux Symptom Index questionnaire. The median score was 21. Normative data suggests that a Reflux Symptom Index score greater than 13 may be indicative of significant reflux. Twenty-two patients (96 per cent) had scores over 13, suggesting this could be a common component of the symptom burden. When reflux was identified, this was addressed with discussion, written advice and provision of reflux medication. However, the Reflux Symptom Index has not been correlated with reflux in an inclusion body myositis population. It is therefore possible that the high score reflects the underlying dysphagia associated with inclusion body myositis. Additional studies would be needed to evaluate the correlation of the Reflux Symptom Index in this population.

Results from the cohort's modified Sydney Swallow Questionnaires suggest particular difficulties with hard and dry food, food sticking, and repeated swallowing. These results resemble those found previously in the literature,^{Reference Mulcahy, Langdon and Mastaglia7,Reference Cox, Verschuuren, Verbist, Niks, Wintzen and Badrising8,Reference Oh, Brumfield, Hoskin, Kasperbauer and Basford13} suggesting these are common features of the dysphagia in inclusion body myositis. These questions could provide a good screening for dysphagia in these patients.

All patients underwent contrast swallow assessment (Figure 3 and Table 1). The most common features identified were impairment in tongue base retraction (96 per cent), pharyngeal constriction (82 per cent) and residual pharyngeal pooling (92 per cent). Cricopharyngeal dysfunction and hypertrophy were identified in 75 per cent of patients, a figure comparable with previous studies.^{Reference Oh, Brumfield, Hoskin, Kasperbauer and Basford13} Aspiration was identified in 30 per cent of patients at baseline. Median penetration-aspiration score was 2, similar to a previous study,^{Reference Murata, Kouda, Tajima and Kondo9} although the distribution of scores was uneven (Figure 2). However, it should be noted that we did not have a standardised protocol to ensure inter-rater reliability, nor any software to measure dynamics of upper oesophageal sphincter opening. Moreover, barium swallows have a lower frame per second rate and quality compared with videofluoroscopy. Therefore, we recommend that future studies use videofluoroscopy to better define swallowing abnormalities and that there is a validated protocol and analysis tool (e.g. the Modified Barium Swallow Impairment Profile). Given the reported difficulties with solids, incorporating both fluid and solid boluses within the video fluoroscopy protocol could be informative for this population.

Fig. 3.

Images of video fluoroscopy showing common features identified. (a) Sagittal view of cricopharyngeal hypertrophy evident at the height of swallow (maximal displacement of the hyoid), (b) sagittal view of silent aspiration of post-swallow pharyngeal residue, (c) coronal view of spontaneous, passive opening of the cricopharyngeus muscle to allow eventual bolus transit into the oesophagus and (d) sagittal view of cricopharyngeal hypertrophy and laryngeal penetration evidence at the height of swallow (maximal displacement of the hyoid).

All patients received support by our speech and language team. This support depended on several factors: the swallow mechanism, risks associated with oral intake, imaging results, patient goals and effect on life. The amount and timing of therapy was tailored to individual need.

Six of our patients (25 per cent) underwent surgical procedures, a lower proportion than in previous studies.^{Reference Oh, Brumfield, Hoskin, Kasperbauer and Basford13} Three of the four who underwent balloon dilatation received no lasting benefit and required further procedures. These findings are similar to those of Oh et al. (2008), who found that the majority of dilatations resulted in no benefit.^{Reference Oh, Brumfield, Hoskin, Kasperbauer and Basford13}

Only one patient received botulinum toxin injection to alleviate their dysphagia; symptoms improved for just one month before recurrence. By contrast, some studies have shown longer lasting benefits,^{Reference Schrey, Airas, Jokela and Pulkkinen10,Reference Liu, Tarnopolsky and Armstrong19} whereas others have suggested limited efficacy.^{Reference Oh, Brumfield, Hoskin, Kasperbauer and Basford13}

Cricopharyngeal myotomy was only offered to three patients in our cohort and was performed in two patients; it was effective at improving dysphagia in both without documented complications. Cricopharyngeal myotomy was reported to be an effective procedure in several previous studies when used appropriately, using either an endoscopic or transcervical approach.^{Reference Houser, Calabrese and Strome5,Reference Mohannak, Pattison, Hird and Needham6,Reference Oh, Brumfield, Hoskin, Kasperbauer and Basford13,Reference Langdon, Mulcahy, Shepherd, Low and Mastaglia20,Reference McMillan, Bowen, Bayan, Kasperbauer and Ekbom21}

There were several limitations to this study. There was a small sample size, but inclusion body myositis is a rare condition. The study was retrospective and there was limited follow up for a few patients who were most recently referred. However, despite these limitations, we recommend that all patients with inclusion body myositis and dysphagia undertake serial modified Sydney Swallow Questionnaires and videofluoroscopy in order to fully assess their dysphagia and to quantify the effect of the different interventions. Moreover, the high reporting of reflux symptoms suggested that actively screening and treating reflux at an early stage should be considered. Future research should include the use of validated swallowing scales such as the Modified Barium Swallow Impairment Profile^{Reference Martin-Harris, Brodsky, Michel, Castell, Schleicher and Sandidge22} to allow for standardised analysis of swallow features alongside the use of additional outcome measures such as the penetration aspiration scale^{Reference Steele and Grace-Martin23} and the Dynamic Imaging Grade of Swallowing Toxicity measure^{Reference Hutcheson, Barrow, Barringer, Knott, Lin and Weber24} to detail residue, penetration and aspiration.