Head and Neck ImagingFacial nerve palsy
paralysis of the facial muscles supplied by the facial nerve (seventh cranial nerve). In the central type, the
lesion is located above the pontine nuclei (producing contralateral facial paralysis excluding the forehead muscles). In the peripheral type, the
lesion is between the pontine nuclei and the end branches of the facial nerve (producing ipsilateral facial paralysis of all facial muscles).
In a patient with peripheral facial nerve paralysis, the facial nerve must be imaged over its entire course, from the level of the pontine nuclei to the branches in the parotid gland. The lesions causing peripheral facial nerve paralysis are diverse; they can be classified according to the anatomical region where they occur (Table 1).
Facial nerve palsy, Table 1. Overview of causes of facial nerve paralysis (adapted from Joel D. Schwartz and H. Ric Harnsberger: Imaging of the temporal bone, 3 Edit., 1998, Thieme Verlag, p. 368 and 370).
| Brain stem lesions | tumour | glioma, metastasis, lymphoma |
| inflammation | multiple sclerosis, abscess, cerebritis |
| vascular lesion | vascular malformation, ischaemia |
| Cisternal/intracanalicular lesions | tumour | acoustic schwannoma, meningioma, epidermoid cyst |
| inflammation | granulomatous disease, bacterial infection, facial neuritis |
| vascular lesion | neurovascular injury (may cause hemifacial spasm) |
| Intratemporal lesions | congenital | primary cholesteatoma |
| traumatic | fracture (Fig. 1), postsurgery |
| tumour | facial nerve schwannoma, metastasis (Fig. 2), haemangioma, sarcoma (Fig. 3), ..... |
| inflammation | secondary cholesteatoma (Fig. 4), Bells palsy |
| Extracranial lesions | malignant tumour in parotid gland, malignant otitis externa | |
RH
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Coronal CT image of left temporal bone in a patient with cholesteatoma and facial nerve palsy. As well as causing a large defect in the roof of the middle ear (arrowhead), the cholesteatoma eroded the tympanic segment of the facial canal (arrow).
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Facial nerve palsy, Fig.1 | | Facial nerve palsy, Fig.2 | | Facial nerve palsy, Fig.3 |
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Facial nerve palsy, Fig.4 | |