INTRODUCTION
Although cleft lip and/or palate is the most commonly encountered craniofacial malformation, its surgical treatment and clinical management still differs vastly among treatment centres worldwide [
1]. In general, the success of surgical treatment is determined by several criteria, such as fistula incidence, hearing problems, maxillary growth, and speech development. To date, the optimal timing of palate closure remains a topic of discussion. Early palatal closure likely promotes better speech development. In contrast, early closure of the hard palate is likely detrimental for mid-facial growth, as the iatrogenic scar tissue interferes with maxillary outgrowth.
Schweckendiek [
2] was one of the first clinicians to perform two-stage palatoplasty in the 1950s (Marburg project). In this two-stage repair, the soft palate cleft is closed at an early age, leaving the hard palate unrepaired. The hard palate is subsequently closed at a second stage later in life, and in the Marburg project, even after the age of 12 years [
3]. It was hypothesised that primary soft palate closure would benefit speech development, and that late hard palate closure would allow for normal maxillary outgrowth. Twenty-five years later, subjects treated according to Schweckendieck's protocol showed excellent maxillary and facial growth, often within the normal growth ranges [
4]. However, their long-term speech results were poor [
4].
In the following years, both unfavourable and satisfactory speech outcomes have been reported after delayed hard palate closure [
4567]. One-stage and two-stage protocols are still used in daily practice, as hard evidence favouring one technique over the other is lacking. Comparing clinical outcomes after one-stage or two-stage closure is difficult due to the paucity of studies reporting long-term outcomes, small patient groups, the lack of prospective studies, and heterogeneity in study design leading to contradictory outcomes. So far, most studies have solely focused on the timing of hard palate repair when evaluating speech outcomes or facial growth. Other factors should, however, also be considered, including the incidence of fistulas, dental occlusion, surgical skill, and the technique used in soft palate closure. Furthermore, few studies have evaluated speech outcomes after two-stage palatoplasty in adults with complete unilateral cleft lip and palate (UCLP).
The present centre used a two-stage palatoplasty protocol for over 30 years. The aim of this study was to investigate factors affecting long-term speech outcomes after two-stage palate repair in patients with a non-syndromal complete UCLP treated at our hospital.
DISCUSSION
Previously published studies have reported contradictory speech results after two-stage palate closure [
571314]. In addition, only a few studies have investigated speech outcomes in adults [
714]. In the present study, 48 non-syndromal UCLP patients were included in a long-term speech assessment approximately 20 years after delayed hard palate closure was performed at a median age of 33 months. Intelligibility was regarded as our main outcome measure. Forty-one patients (84.4%) had normal intelligibility, with possible minimal speech aberrations, as indicated by an intelligibility score of 1 or 2. As expected, the intelligibility scores were significantly correlated with the amount of articulation errors (P<0.001). To achieve this result, 42% of the patients needed speech-enhancing surgery.
So far, few studies have reported good long-term speech results after delayed hard palate closure [
37]. Lohmander et al. [
7] found excellent long-term intelligibility results in UCLP subjects after delayed palate closure at the age of 8. In their cohort, 98%–100% of the patients were intelligible; no patients showed moderate or severely reduced intelligibility (3–4 on a 4-point scale). Furthermore, 94% of the UCLP patients treated according to the original Schweckendiek protocol (from the Marburg project) had ‘normal’ or ‘intelligible’ speech [
3]. These results should, however, be interpreted with caution, as Bardach et al. [
4] published less favourable results in adults treated by a similar protocol a few years later, showing high rates of velopharyngeal insufficiency (
Table 5). Similarly, Holland et al. [
14] reported more unfavourable speech results after two-stage closure than after one-stage closure. The currently available long-term studies, therefore, show contradictory outcomes regarding speech and intelligibility after delayed hard palate closure. Factors other than surgical timing are likely to influence speech outcomes and should be considered.
As resonance and articulation contribute to normal intelligibility, both parameters should be assessed when analysing intelligibility results [
15]. We found a significant correlation between the amount of articulation errors and the level of intelligibility (P<0.001). The cohort described by Lohmander et al. [
7] showed a lower incidence of articulation errors, which could be an explanation of their better outcomes. In our series, the presence of nasal fricatives, nasal emissions, and nasal consonants for pressure consonants seemed to be correlated with worse intelligibility outcomes (P=0.006, P=0.003, P=0.001, respectively). Remarkably, we also found a high incidence of dentalisation and lateralisation (27.6%) in the present series, mostly during the pronunciation of alveolar consonants. In cleft patients, the production of alveolar sounds is vulnerable due to the irregular alveolar structure and/or dental occlusion. In the present cohort, nearly 45% of patients had significant malocclusion with an initial Goslon Yardstick score of 4-5, which might therefore have negatively influenced articulation and intelligibility in our series. In addition, interdental articulation seems to be a common articulation error in the general Dutch and Flemish populations [
21]. A similar phenomenon might be present for the /s/ sound in the Dutch language [
21], and could explain our high incidence of /s/ distortions compared to previous reports (
Table 4) [
721].
The presence of nasalance and velopharyngeal insufficiency affects speech and intelligibility, in addition to articulation. We also found a correlation between the presence of nasal fricatives or nasal emissions and poorer intelligibility scores (
Table 3). The incidence of perceptible nasal emissions was relatively high compared to previous long-term outcomes after early one-stage palate closure [
19]. Our high incidence is in line with the hypothesis that delayed hard palate repair leads to speech difficulty at a young age, with a higher risk of subsequent speech problems [
23]. In accordance, we observed a high pharyngoplasty rate (40%). High incidences of pharyngoplasty after two-staged palatoplasty have been described earlier (
Table 5) [
1418]. Interestingly, Lohmander et al. [
7] and Holland et al. [
14] both performed delayed hard palate closure around the age of 8 years, but found a great difference in the pharyngoplasty rate (11% vs. 63%). This again confirms that factors other than surgical timing are likely to have an influence on velum function, such as the degree of scarring, the skill of the individual surgeon, the technique used, and the cleft width.
One of those factors might also be the presence of fistulas needing additional surgical closure. In the present study, 25% of the patients had a history of clinically significant fistulas, which is higher than has been reported in previous studies (
Table 5) [
141819202122]. Similarly, Landheer et al. [
23] demonstrated a 24% fistula rate after two-stage repair, compared to a 14% rate after one-stage repair. In our series, patients with a history of fistulas had a significantly higher pharyngoplasty incidence (P=0.023). The previous literature seems to confirm a positive correlation between fistulas and the need for a pharyngoplasty [
4716171819202324]. This correlation might partially explain the difference in speech results and pharyngoplasty incidence (11% vs. 63%) between the results of Lohmander et al. [
7] and Holland et al. [
14], as fistula incidence differed greatly between the studies (3.6% vs. 58%, respectively) while the timing of palate closure was similar. Unintended fistula formation is caused by dehiscence of the surgical closure, which is inevitably followed by some healing of secondary intention, retraction, and scarring. As a result, the tissues remain under tension and the levator muscle is tethered more ventrally, even to the hard palate. Soft palate functioning is therefore negatively affected, which may in turn increase the need for speech-enhancing surgery. However, factors such as cleft width, extensive palatal dissection, and surgical technique increase both the risk of velopharyngeal insufficiency and of fistulas [
142325]. Fistula formation may therefore not be a direct cause of velopharyngeal insufficiency, but in this study the incidence of both factors seemed related. It is however clear that impairment of speech and/or maxillary growth is multifactorial, and not solely determined by the timing of cleft closure. Furthermore, surgical skill is hard to measure, but no doubt has an important influence on outcomes. Future treatment protocols should therefore not be determined mainly by the timing of surgery, but should also try to minimize scar tissue formation, especially around the soft palate, when taking speech into account.
Our study has some limitations. The completeness of data for this retrospective study depended upon the detail and accuracy of past medical records. As the time range of this study includes more than 20 years, some data could not be retrieved, resulting in missing values for some of the parameters. In addition, patients were invited for long-term follow-up and therefore participated voluntarily. It is possible that patients with a more prolonged treatment or a less favourable outcome be might more inclined to accept an invitation for the long-term evaluation of their treatment. This may lead to selection bias and, possibly, an underestimation of the speech outcomes. Nevertheless, we found no significant differences in the treatment history of the patients that presented for follow-up and those who did not (
Table 1).
In conclusion, this study describes long-term speech outcomes after two-stage palatoplasty, in which hard palate closure was performed at a mean age of approximately 3 years old. Intelligibility scores were moderate within this adult group. We observed a relatively high incidence of articulation errors and mild hypernasality within our population. In addition, 42% of the subjects needed speech-improving surgery and 25% had a history of clinically significant fistulas. Factors other than the timing of hard palate closure itself are likely to influence speech development. The high incidence of secondary surgical procedures, including fistula closures and surgery to address poor dental occlusion (as assessed by Goslon scores), might have contributed to the presently observed average speech outcomes.