Obstructive sleep apnea following pharyngeal flap surgery

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It has been suggested that this article or section be merged with Sleep apnea. (Discuss)

Obstructive sleep apnea (OSA) is a serious complication that seems to be most frequently associated with pharyngeal flap surgery, compared to other procedures for treatment of velopharyngeal inadequacy (VPI) [1]. In OSA, recurrent interruptions of respiration during sleep are associated with temporary airway obstruction. Following pharyngeal flap surgery, depending on size and position, the flap itself may have an “obturator” or obstructive effect within the pharynx during sleep, blocking ports of airflow and hindering effective respiration [2] [3]. There have been documented instances of severe airway obstruction, and reports of post-operative OSA continue to increase as healthcare professionals (i.e. physicians, speech language pathologists) become more educated about this possible dangerous condition [4]. Subsequently, in clinical practice, concerns of OSA have matched or exceeded interest in speech outcomes following pharyngeal flap surgery.

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[edit] Rate of co-occurrence

Early work by Ysunza et al. [5] analyzed pre- and post-surgery signs of OSA in individuals (5 to 18 years old) who underwent pharyngeal flap surgery. Patients were examined for symptoms related to OSA and were evaluated with polysomnography and videonasoendoscopy five months to one year after surgery. Fifteen of eighteen symptomatic patients were actually diagnosed with OSA based on criteria of 5+ apnea episodes per hour of sleep with a mean decrease of oxygen saturation >10% during episodes. The authors reported no clear correlation between severity of OSA and flap width (despite finding a high complication (OSA) rate in these patients). However, they made the important observations that 13 of 15 patients diagnosed with OSA had “sizeable” tonsils, and that tonsils may be a prime contributor to OSA if they are displaced under the airway ports of the flap structure. Despite a statistically high rate, the small number of patients examined in this study and diagnosed with OSA limited drawing definitive conclusions. But, pharyngeal flap patients should be carefully monitored post-operatively for symptoms of OSA and, if possible, have tonsillar tissue assessed pre-operatively via videonasopharyngoscopy to limit possible obstruction caused by pharyngeal flap-tonsil overlap.

Liao et al. (2002) [6] also examined patients pre- and at least six months post-operatively to prospectively investigate incidence and severity of OSA after pharyngeal flap surgery. The authors also sought to determine effects of age or flap width. All patients with repaired nonsyndromic cleft palate +/- lip who underwent a superior pharyngeal flap procedure by one designated surgeon over a three-year period were assessed. For analysis, the 38 patients were divided into groups according to age at the time of surgery (18 years or older (n=10) and patients below the age of 18 (n=28)). Patients underwent assessment of VPI and clinical signs of OSA (snoring, choking during sleep, fragmented sleep, etc.) before and six months after surgery. Additionally, during post-operative evaluation, each patient completed a sleep study. OSA was diagnosed if a patient evidenced absent nasal or oral airflow, despite persistent respiratory movements, for longer than 10 seconds.

Results showed that all 38 patients were without symptoms of OSA prior to pharyngeal flap placement. However, all except two patients were symptomatic six months after surgery. Also, more severe OSA was correlated with more clinical symptoms. This study revealed a high incidence of OSA following pharyngeal flap, but only when stratified according to severity, were differences between age groups found (the younger age group showed a higher percentage of moderate-to-severe OSA). Investigation of flap width revealed no relation between width and incidence or severity in either age group. Overall, results suggested that age does not affect incidence but does correlate to severity of OSA following pharyngeal flap surgery. As the authors explained, greater size and maturity of the respiratory-palatal-pharyngeal system likely limits predisposition of adults to moderate-to-severe upper airway obstruction compared to children who have not completed craniofacial skeleton growth and respiratory development.

[edit] Comparison to other procedures

In 2004, Liao et al [3]. compared pharyngeal flap patients to patients who underwent Furlow palatoplasty. Forty-eight patients participated in all evaluations, 20 who received Furlow palatoplasty and 28 who underwent pharyngeal flap surgery. All 48 patients had a thorough VPI evaluation before surgery and were assessed for OSA symptoms (snoring, dyspnea, fragmented sleep, witnessed apnea) before and six months or more after surgery. Additionally, each patient had a polysomnographic sleep study at least six months following surgery [6]. All patients were free of OSA symptoms prior to surgery, and 34 patients evidenced post-operative symptoms. Thus, the overall incidence of post-operative OSA was 62%. Comparing groups of subjects based on surgical technique, OSA symptoms were observed to a greater degree (95%) in pharyngeal flap patients compared to Furlow palatoplasty patients (35%). Additionally, patients who received a pharyngeal flap showed a higher incidence of moderate-to-severe OSA. These authors concluded that pharyngeal flap seemed to have a more severe impact on airway patency during sleep compared to Furlow palatoplasty.

A year after the previous study, research by Abyholm et al. [7] compared pharyngeal flap surgery to sphincter palatoplasty in an investigation of post-operative OSA. In this randomized trial, ninety-seven patients who met study criteria were assigned to have either a pharyngeal flap or a sphincter palatoplasty procedure. All patients were assessed in terms of perceptual speech and resonance, hearing, and general surgical complications, and a subset of 43 patients underwent pre- and post-operative sleep studies. Within the context of this project, OSA was defined as absence of oral and nasal airflow with continued respiratory effort for five seconds or more. Results showed no statistically significant differences pre- and post-surgery between groups, but rather revealed that OSA may follow either pharyngeal flap procedures or sphincter palatoplasty

[edit] Robin Sequence

A study by Abramson, Marrinan, and Milliken in 1997 aimed to evaluate the outcomes of pharyngeal flap surgery in patients with Robin Sequence (RS), a population with characteristically crowded airways [4]. Records of all patients with RS from 1980 to 1995 (n=151) who had cleft repair completed between 8 and 14 months of age were retrospectively reviewed [8]. Only 7 patients had also undergone pharyngeal flap placement, and six of seven pharyngeal flap patients had polysomnographic findings indicative of OSA. Therefore, this study’s main conclusion (based on 86% incidence in patients studied) was that OSA seems highly likely in children with RS.

[edit] Research limitations

Because a number of studies on the topic of pharyngeal flap surgery and OSA were completed retrospectively, there is a significant lack of well-designed research with deliberate controls over surgical procedures/technique and assessment of OSA. Retrospective studies do not allow designation of, and thus limit conclusions about, potentially important variables (i.e. flap width, age at the time of surgery, pre- and post-operative evaluations). Similarly, because previous studies were not designed as longitudinal projects, little can be concluded about the time course of OSA after pharyngeal flap surgery or long-term effects of this procedure [6][3].

Issues related to significant variability across studies further complicate and raise issues of interpreting and using data reported to date. For example, in the literature, there is no standard definition of OSA [8]. As a result, it is difficult to determine incidence of OSA following pharyngeal flap surgery, because it may be diagnosed with different criteria. Furthermore, adult guidelines for diagnosing disordered respiration during sleep can not be validly applied to children [6]. Airway anatomy and function vary with age and are influenced by growth and maturity of the craniofacial skeleton [9]. Applying adult criteria to studies of children, as seems to be common practice, can result in underdiagnosis of OSA [6].

Another limitation created by research procedures is inconsistent use of polysomnography. In most studies, polysomnographic evaluation has not been conducted pre-operatively to identify pre-existing OSA. Thus, patients could actually have OSA (without showing major clinical signs) before having pharyngeal flap surgery [3]. Furthermore, in some studies, polysomnography is only conducted post-operatively on those patients who fit a clinical profile for OSA. Again, patients with less symptomatic OSA following pharyngeal flap surgery may not be identified, confounding validity of reported results [5].

As explained, failing to assess size and location of tonsillar tissue (to know how it may or may not obstruct the airway in relation to pharyngeal flap structure) may limit the value of reported findings. Finally, as always, research characteristics such as sample size, attrition, reliability of judges, and blinding are always essential to note in individual studies. Evident lack of consideration for such qualities of good research may affect validity and interpretation of findings, as may be the case for some studies investigating OSA after pharyngeal flap surgery.

[edit] Conclusions

From the research that has been conducted to this point, it only seems reasonable to state that studies have revealed a link between pharyngeal flap surgery and OSA, especially in children. However, it goes without saying that further investigation in this area is required to uncover more details of this single evidenced conclusion. Until more can be revealed about specific characteristics or features of pharyngeal flap procedures leading to the dangerous condition of OSA, the ideal surgical technique for VPI will continue to be a source of controversy.

[edit] References

  1. ^ Sloan, G.M. (2000). Posterior pharyngeal flap and sphincter pharyngoplasty: The state of the art. Cleft Palate-Craniofacial Journal, 37(2), 112-122.
  2. ^ Pugh, M.B. et al. (2000). Apnea. Stedman’s Medical Dictionary (27th ed.) Retrieved June 18, 2006 from STAT!Ref Online Medical Library database.
  3. ^ a b c d Liao, Y., Noordhoff, M.S., Huang, C., Chen, P.K.T., Chen N., Yun, C. et al. (2004). Comparison of obstructive sleep apnea syndrome in children with cleft palate following Furlow palatoplasty or pharyngeal flap for velopharyngeal insufficiency. Cleft Palate-Craniofacial Journal, 41(2), 152-156.
  4. ^ a b Peterson-Falzone, S.J., Hardin-Jones, M.A., & Karnell, M.P. (2001). Cleft Palate Speech (3rd ed.). St. Louis: Mosby.
  5. ^ a b Ysunza, A., Garcia-Valesco, M., Garcia-Garcia, M., Haro, R., & Valencia, M. (1993). Obstructive sleep apnea secondary to surgery for velopharyngeal insufficiency. Cleft Palate-Craniofacial Journal, 30(4), 387-390.
  6. ^ a b c d e Liao, Y., Chuang, M., Chen, P.K.T., Chen, N., Yin, C., & Huang, C. (2002). Incidence and severity of obstructive sleep apnea following pharyngeal flap surgery in patients with cleft palate. Cleft Palate-Craniofacial Journal, 39(3), 312-316.
  7. ^ Abyholm, F., D’Antonio, L., Davidson, S.L., Kjoll, L., Saeed, M., Shaw, W. et al. (2005). Pharyngeal flap and sphincterplasty for velopharyngeal insufficiency have equal outcome at 1 year postoperatively: Results of a randomized trial. Cleft Palate-Craniofacial Journal, 42(5), 501-511.
  8. ^ a b Abramson, D.L., Marrinan, E.M., & Mulliken, J.B. (1997). Robin sequence: Obstructive sleep apnea following pharyngeal flap. Cleft Palate-Craniofacial Journal, 34(3), 256-260.
  9. ^ Lin, K.Y., Goldberg, D., Williams, C., Borowitz, K., Persing, J., & Edgerton, M. (1999). Long-term outcome analysis of two treatment methods for cleft palate: Combined levator retropositioning and pharyngeal flap versus double-opposing Z-plasty. Cleft Palate-Craniofacial Journal, 36(1), 73-78.
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