PERIPHERAL NERVOUS SYSTEM LESIONS
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.
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.
Figure 259.1.— [A] Left facial palsy. [B]
CT of the petrous bone demonstrates evidence of left inner-ear malformation.
in the parotid glands may produce facial nerve palsy. The most common
tumors in this area are lymphangiomas and hemangiomas (Figure 259.2).
Figure 259.2.— [A] Right facial nerve lesion.
[B] Hemangioma of the parotid gland.
of the cervical sympathetic chain may produce Horner syndrome. Vanillylmandelic
acids and homovanillic acid may be elevated in the urine.