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FOCAL PERIPHERAL NERVOUS SYSTEM LESIONS

 

FACIAL NERVE

Trauma
Facial nerve damage in the neonate is usually traumatic. Trauma usually occurs just after the facial nerve exits from the facial canal through the stylomastoid orifice. Intracanalicular trauma is less frequent. Petrous bone fractures may be present with traumatic facial nerve injury. Petrous bone fractures are often associated with hemotympanum. Petrous fractures are better detected by CT than by MRI.

Congenital Anomalies
Anomalies of the facial nerve canal may occur with or without associated inner ear anomalies. Computed tomography of the petrous bone may show anomalies of the inner ear (Figure 259.1) or just a narrow canal.

A B

Figure 259.1. [A] Left facial palsy. [B] CT of the petrous bone demonstrates evidence of left inner-ear malformation.


Tumors

Tumors in the parotid glands may produce facial nerve palsy. The most common tumors in this area are lymphangiomas and hemangiomas (Figure 259.2).

A
B

Figure 259.2. [A] Right facial nerve lesion. [B] Hemangioma of the parotid gland.

SYMPATHETIC FIBERS

Tumors
Neuroblastoma of the cervical sympathetic chain may produce Horner syndrome. Vanillylmandelic acids and homovanillic acid may be elevated in the urine.

 

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McHugh, 1963 Shapiro, 1996 Shapiro, 1996 Hepner, 1951 Shapiro, 1996 Ogita, 1988 Click on figure for animated labels.  Pause pointer on different areas of the figure for labels. Figure must be centered. abnormal internal ear normal internal ear