Rhonchopathy : long-term clinical results after palatal surgery

Abstract

Up to one third of Swedish middle-aged men snore habitually, disturbing their surroundings. More than 5% suffer from medical rhonchopathy combining snoring with obstructive breathing and fragmented sleep. This may lead to excessive daytime sleepiness (EDS) interfering with activities of daily life and may cause involuntary sleep attacks and an increased risk of car accidents. Furthermore, medical rhonchopathy expressed as obstructive sleep apnea syndrome (OSAS) may cause hypertension, cardiovascular disease and early death. Treatment with palatal surgery has been reported to alleviate symptoms, including EDS. However, the long-term results have been questioned. Diagnosing OSAS with full-night polysomnography, considered "gold standard", is not sufficiently cost-effective. Oximetry is a widespread diagnostic method, but the criterion of a desaturation >4% in Sa02 for diagnosing OSAS has seldom been questioned.

The aim of this thesis was to investigate the long-term effects of palatal surgery with respect to driving performance, traffic accidents, survival and clinical symptoms. Furthermore, to see whether lowering the 4% desaturation cut-off level could improve the diagnostic accuracy of oximetry.

Methods: Thirteen male drivers, suffering from medical rhonchopathy and habitual sleepiness whilst driving, were retested in an advanced driving simulator in average 45 months after uvulopalatopharyngoplasty (UPPP). The results were compared to the preoperative test drive. Forty-nine male drivers, suffering from medical rhonchopathy, answered a questionnaire concerning traffic accidents during a 5-year period prior to palatal surgery, and again 5 years postoperatively. Their mileage adjusted accident risk-rate was compared to that of 123 controls. The survival of 400 consecutive, non-obese patients with rhonchopathy, operated with palatal surgery, was investigated 5-9 years postoperatively and compared to 744 nasal-operated controls as well as a sex- and age-matched general population. Causes of death were analysed. Sixty-one patients operated with UPPP and 60 with laser-uvulopalatoplasty (LUPP) were prospectively studied. Symptoms of rhonchopathy were investigated by means of a questionnaire preoperatively as well as 3 months- and 5-8 years postoperatively. At the long-term follow-up side-effects were studied as well. Seventy-two whole-night, digitized sleep recordings, including oximetry, were conducted simultaneously with full-night polysomnography in a sleep laboratory. Recordings were scored manually for periods of sleep by two independent investigators and then analysed automatically to calculate the oxygen desaturation index (ODI) using a 4, 3 and 2% cut-off level for desaturations. These ODIs were compared to apnea index (Al) and hypopnea index (AHI) calculated from polysomnography.

Results: Simulated driving performance at the long-term follow-up was significantly improved in patients as compared to the preoperative condition and no longer different from that of controls. Similarly, the risk rate for self-reported car accidents decreased and was comparable to that of normal controls. Eighty-two percent of the patients considered themselves as better drivers. No decreased survival was present amongst rhonchopathic patients when compared to any of the control groups. However, death due to cerebral- and cardiovascular disease was almost 3-fold higher for deceased patients diagnosed with obstructive sleep apnea syndrome (OSAS). UPPP was superior to LUPP in all measurable clinical effect. Patients operated with UPPP had worse clinical symptoms preoperatively and a higher body mass index (BMI), but still a better long-term outcome. The clinical effect of palatal surgery remained significant, even though a slight recurrence of symptoms, except for sleepiness while driving, was seen long-term. Persistent postoperative swallowing disturbances were reported by one third of all patients, but none of those few regretting surgery were bothered by this. By lowering the 4% cutoff level for desaturations the diagnostic accuracy of oximetry could be improved. Choosing the 3%-Ievel raised sensitivity with unchanged specificity while choosing the 2%-Ievel, the only level not significantly different form Al/AHl, gave a high sensitivity but lowered specificity somewhat.

Conclusion: The overall conclusion is that palatal surgery had a long-lasting positive effect on simulated driving performance and normalized the increased traffic accident risk in patients suffering from medical rhonchopathy. No decreased long-term survival could be found following surgery. UPPP showed a better long-term clinical outcome than LUPP. A slight recurrence of symptoms was seen long-term but the improvement was still significant. Surgery remains a recommendable treatment for rhonchopathy.