A challenging diagnosis of narcolepsy type 2 in a patient with Duane syndrome

Duane syndrome is a form of congenital strabismus with horizontal eye movement limitation. This may present a diagnostic challenge when assessing for rapid eye movements during stage REM utilizing PSG or MSLT. We present a case of a child with Duane syndrome who presented with excessive daytime sleepiness and underwent evaluation for hypersomnia. His eye movement limitation provided a challenge in identifying stage REM. In patients with eye movement limitations or prosthetic eyes, it is necessary to look for other features of stage REM such as low chin EMG tone and EEG pattern.