[Secondary obstructive sleep apnea syndrome in a patient with tracheal stenosis and bilateral recurrent paresis. Successful treatment with nasal continuous positive airway pressure therapy].

HISTORY AND ADMISSION
FINDINGS: A 67-year-old woman complained of marked daytime sleepiness, as well as loud snoring and apnoeas during sleep. She was known to have had 3 thyroidectomies for goitre 41, 23 and 12 years ago, with known tracheal stenosis and recurrent nerve palsy for 11 years. Physical examination revealed marked stridor, hoarse voice and slightly enlarged and palpable recurrent right thyroid. INVESTIGATIONS: Polysomnography demonstrated a clearly elevated obstructive sleep apnoea activity (apnoea index: 34/h, apnoea-hypopnea index: 40/h, desaturation index: 31/h, minimal saturation: 63%). Selective tracheal imaging showed subglottic tracheal stenosis with an inspiratory luminal diameter of 4 mm and an expiratory luminal diameter of 8 mm. Lung function analysis revealed marked flattening of the flow-volume curve as sign of a functionally effective tracheal stenosis. These findings indicated a secondary obstructive sleep apnoea (OSA) due to tracheal stenosis and bilateral recurrent nerve palsy. The patient declined further studies, such as bronchoscopy. TREATMENT AND COURSE: As the patient did not want any surgical treatment, nasal continuous positive airway pressure therapy (CPAP) was instituted as a trial. No apnoea occurred at a pressure of 12 mm H2O and this was well tolerated. She has now continued CPAP at home for 12 months and her vigilance was markedly improved.
CONCLUSIONS: Tracheal stenosis or recurrent nerve palsy is a rare cause of OSA which can be effectively treated by nasal CPAP.