Diagnostics and management of sleep-related respiratory disturbances in children with skeletal dysplasia caused by FGFR3 mutations (achondroplasia and hypochondroplasia)

To evaluate the frequency of clinical indicators for sleep-related respiratory disturbances (SRD) and the polysomnographical manifestations of these disorders in children with skeletal dysplasia caused by FGFR3 mutations. From January 1990 to January 2009, 24 patients (22 achondroplasia, 2 hypochondroplasia; 13 boys, 11 girls; age 8 days to 15 years, median age 3.0 years) were examined, including a semi-structured interview, a clinical examination, and a polysomnographic sleep recording (65 polysomnographic sleep recordings (PSG) in 24 patients). We performed PSG in a subgroup of five patients before and after adenoidectomy (AT) and/or tonsilectomy (TE). Daytime symptoms suggestive of SRD (daytime somnolence, attention and concentration problems, behavioural problems, and pallor) were found in 4/24 patients (16.7%). Sleep-related symptoms (snoring, mouth breathing, cyanosis, observed apneas, excessive sweating, enuresis, problems of initiating and maintaining sleep) were present in 18/24 patients (75%). Prior to the first PSG, 11/24 patients (45.8%) had undergone AT, 1/24 (4.2%) TE, 2/24 (8.3%) adenotonsilectomy (ATE), 3/24 (12.5%) liquor drainage, and 6/24 (25%) a craniocervical decompression operation. Clinical examination prior to PSG revealed hypertrophied tonsils in 11/24 patients (45.8%), disturbed nasal breathing in 8/24 patients (33.3), and enlarged cervical lymph nodes as a sign of chronic tonsillitis in 5/24 patients (20.8%). PSG findings were abnormal in 19/24 patients (79.2%) with a nadir of oxygen saturation (pulse oximetry) below 90% and/or a nadir of transcutaneous partial pressure of oxygen below 45 mmHg. Pathologic PSG findings were found in 10/24 patients (41.7%): obstructive sleep apnea syndrome (OSAS) was diagnosed in 8/24 patients (33.3%), central sleep apnea syndrome in 1/24 patients (4.2%), and hypoventilation in 1/24 patients (4.2%). As a consequence, the following therapeutic interventions were performed: AT in 1/24 patients (4.2%), TE in 2/24 (8.3%), ATE in 2/24 (8.3%), and nasal continuous positive airway pressure (continuous positive airway pressure) and bilevel positive airway pressure therapy (bilevel positive airway pressure), respectively, in 3/24 patients(12.5%). SRD, especially OSAS, represent a complication of clinical and prognostic relevance in children with achondroplasia. We therefore think that not only those children with a history suggestive of SRD, but all achondroplastic children should be evaluated by PSG. At least in a part of these patients, the pathophysiological mechanisms of OSAS are connected with the etiology of achondroplasia. Achondroplastic children with OSAS, who do not benefit from AT and/or TE, should be treated with NCPAP therapy.