Polysomnographic Abnormalities in Succinic Semialdehyde Dehydrogenase (SSADH) Deficiency

Objectives: Patients with SSADH deficiency, a disorder of chronically elevated endogenous GABA and GHB, were studied for Sleep symptoms and polysomnography. We hypothesized that patients would have excessive daytime somnolence and decreased REM sleep. Design: Polysomnography and MSLT were performed on patients enrolled for comprehensive clinical studies of SSADH deficiency. Setting: Sleep studies were obtained in the sleep laboratories at CNMC and NIH. Patients: Sleep recordings were obtained in 10 patients with confirmed SSADH deficiency. Interventions: Thirteen overnight polysomnograms were obtained in 10 patients (7 male, 3 female, ages 11-27 y). Eleven MSLT studies were completed in 8 patients. Measurements and Results: Polysomnograms showed prolongation of REM stage latency (mean 272 +/- 89 min) and decreased percent stage REM (mean 8.9%, range 0.3% to 13.8%). Decreased mean sleep latency was present in 6 of 11 MSLTs. Conclusions: SSADH deficiency is associated with prolonged latency to stage REM and decreased percent stage REM. This disorder represents a model of chronic GABA and GHB accumulation associated with suppression of REM sleep.