Sleep disorders in succinic semialdehyde dehydrogenase deficiency: a family report

Succinic semialdehyde dehydrogenase deficiency (SSADH) is a rare neurometabolic disorder involving the degradation of gamma-aminobutyric acid. Clinically, SSADH deficiency causes progressive or static encephalopathy with late infantile to early childhood onset. It is known that sleep disorders are a common clinical finding in these patients. However, very few studies have investigated sleep disorders with polysomnographies.

To analyze sleep disorders breathing, sleep architecture and paroxysmal EEG activity through polysomnographic recordings of two siblings suffering from SSADH deficiency

Each patient underwent laboratory diurnal and overnight video-polysomnographic recordings in a room specially dedicated to mothers and their children.

The background EEG activity during quiet wakefulness consisted in abnormal, diffuse, low-voltage, disorganized slow theta waves. In both patients there was a general disorganisation of the sleep architecture with an increase of light sleep and a decrease of REM sleep. In patient 1, during sleep, there were 36 hypopneas, 13 central apneas and one obstructive apnea with a variable duration of 7-30s. The apnea/hypopnea index (AHI) was 7/h and oxygen saturation dropped to 80% during the respiratory events. In patient 2, the respiratory events consisted in 8 central apneas and 23 hypopneas of 6-20s; no obstructive apneas or hypopneas were observed. The oxygen saturation dropped to 90% during the apneas and the AHI was 5/h.

Sleep-disordered breathing (SDB) is a common finding in patients with SSADH deficiency and polysomnography recording is a useful tool for its diagnosis.