[Persistent facial paralysis: contribution of imaging to identification of perineural infiltrating tumor].

To describe imaging features suggestive of retrograde perineural spread in progressive facial palsy without known tumoral origin. Two reports of perineural infiltration by salivary malignant tumors were diagnosed on abnormal enhancement of the facial nerve associated with an abnormal nerve enlargement (1/2). These unsuspected tumors were located in parotid gland (1/2) and the sub-maxillary gland (1/2). ENT tumors (especially adenoid cystic carcinomas) should be carefully searched in case of perineural spread, as these tumors may be misdiagnosed due to their size, location and signal. Therefore, imaging studies of facial palsy should include temporal bone, skull base, parotid gland, submaxillary gland and sub cutaneous areas of the face. A sub-maxillary gland tumor should be searched in case of facial palsy associated with glossodynia.