The synovial cyst is a rare cause of cervical medullar compression. We report on one case of a 74-year-old man hospitalized for electric discharge in the limbs at neck extension. The MRI and CT-scan revealed a posterior extradural cystic lesion at the level of C5-C6. The surgical excision of the lesion resulted in completed recovery. The histological examination confirmed the diagnosis of a synovial cyst. Through this case and the review of the 9 reported cases in the literature, we discuss the etiopathogenesis, diagnosis and treatment of the lower cervical synovial cyst.