Polysomnography as an indicator for cervicomedullary decompression to treat foramen magnum stenosis in achondroplasia

Objective Management of cervicomedullary compression due to foramen magnum stenosis in achondroplasia remains controversial, especially for patients with no symptoms or mild symptoms. We examined the effectiveness of polysomnography (PSG) as an indicator for cervicomedullary decompression treatment. Methods We retrospectively reviewed nine achondroplasia cases (mean age 1 year and 9 months) treated from 2008 to 2015. All patients were examined by PSG, magnetic resonance imaging (MRI), and otolaryngeal fibroscopy. We analyzed demographic data, clinical presentation, degree and type of respiratory impairment, severity of foramen magnum stenosis and concomitant cervicomedullary compression, treatment (conservative or surgical), and clinical outcome. Results Eight of nine patients presented with no severe symptoms in the daytime. However, MRI revealed four severe, four moderate, and one mild case of cervicomedullary compression, and PSG demonstrated severe sleep apnea in four cases and moderate sleep apnea in five cases. All sleep apnea cases were obstructive or obstructive-dominant. Fibroscopy revealed no upper airway stenosis in six cases and mild stenosis in three cases. Four patients who had severe sleep-related respiratory disturbance on PSG and severe or moderate cervicomedullary compression were treated by cervicomedullary decompression. Three of these patients demonstrated improved sleep respiration soon after surgery, while one required temporary tracheostomy due to bilateral vocal cord paralysis caused by compression during intratracheal intubation. Conclusion Polysomnography can be a useful indicator for cervicomedullary decompression surgery, especially in cases of seemingly asymptomatic achondroplasia with severe foramen magnum stenosis.