Respiratory disturbances during sleep in syringomyelia and syringobulbia

Objective: To determine the frequency and types of abnormalities of respira tory control during: sleep in syringomyelia and syringobulbia and to provid e a basis to predict patients at risk of sudden death. Methods: Thirty pati ents (15 male and 15 female; mean age 39.0 +/- 12.6 years) with communicati ng syringomyelia were divided into two groups: those with evidence of syrin gobulbia (17 patients) and those without compromise of the medulla or syrin gomyelia (13 patients). Patients were studied with pulmonary function studi es and polysomnography. Respiratory center sensitivity to CO2 (rebreathing technique) was measured in 9 patients. Results: Severely affected patients had mild-to-moderate restriction and individual patients had bilateral diap hragmatic or vocal cord palsy, abnormal respiratory rhythm, prolonged inspi ratory time, or an abnormal respiratory response to CO2. Very prolonged cen tral, obstructive, and mixed sleep apneas with low O-2 saturation values an d a fixed heart rate were recorded in most patients with syringobulbia. Fiv e patients developed severe respiratory complications and died during a fol low-up period of 10 years. Respiratory abnormalities failed to correlate wi th syrinx size. Conclusions: Severe abnormalities in respiratory rhythm gen eration during sleep occur in patients with syringobulbia. The respiratory disturbances are not due to muscle weakness and they are not correlated wit h the size of the cavity. The combination of dysphagia and dysphonia in pat ients with longstanding syringomyelia and syringobulbia predicted likelihoo d of respiratory disturbances during sleep.