Plasticity of the Extracranial Facial Nerve

Abstract

Although the expansion properties of peripheral nerves have been a matter of considerable study in recent years, investigations of the plasticity of cranial nerves, including the facial nerve, have been lacking. Clinicians, however, have long recognized the tenacity of facial nerve function in patients with slow-growing benign tumors that enormously distort the nerve. An experimental study was designed to assess whether tissue expansion techniques can be applied to the extracranial portion of the facial nerves of cats. In eight cats the frontozygomatic branch of the facial nerve was expanded by stages in seven sessions over a period of 40 days. The length of the nerve increased an average of 95% without significantly impairing nerve function. Pressure changes in the expander averaged 75 mm Hg during each stage of expansion. Electroneurography was performed after each injection of the expander. Statistical analysis of these data did not show consistent evidence of demyelination or denervation, and all but one cat exhibited a normal blink reflex and had normal electromyographic findings at the end of the experiment. Histologic examination of the expanded nerves, however, did show inflammatory changes, intraneural edema, and occasional demyelination.

Potential Nerve Damage following Contact with a Piezoelectric Device

“…Some findings suggest that the human nerve could tolerate significant stretching without demonstrating impaired function; this characteristic was not considered in the previous research. 16 The histologic examinations showed no significantly worse results with the OT7 (bone saw) after 5 and 10 seconds. For this reason, the changes found after 10 and 20 seconds seem to be related to the mechanical application of the device, but not to activation of the ultrasonic vibration.…”

A 42-Year-Old Man With Facial Nerve Weakness and Multiple Recurrent Pleomorphic Adenoma

“…Pathologic evaluation of each case revealed benign mixed tumor (pleomorphic adenoma) with no evidence of malignancy. In these examples of benign disease, facial nerve paresis is thought to be due to nerve compression rather than invasion of the nerve by tumor (13). As alluded to in previous case reports (8,10), extension of tumor into the stylomastoid foramen may be more likely to occur in patients who have had previous parotid surgery because fibrous scar tissue formation in the parotid wound bed could impede asymptomatic spread into the neck or face and favor extension into the nonviolated stylomastiod foramen and temporal bone.…”

Effects of antineoplastic agents on the peripheral nerves under a surgical tissue expansion procedure: An experimental study

“…17 Limitations on the extent of the expansion are imposed by alterations in the intraneuronal blood flow and axonal ischemia. Deterioration of the nerve function resulting from compression injuries is mainly a function of the ischemia, but not of the local deformation of the nerve fibers.…”

“…14 Although expansion properties, plasticity, and histological and biorheological features of expanded nerves have been a matter of investigation, there have been no experimental or clinical study of effects of pharmacological agents on the expanded peripheral nerves since the expanded peripheral nerves are ischemic during procedure. [15][16][17][18] The present experimental study was designed to investigate the effects of some antineoplastic agents on the peripheral nerves under a surgical tissue expansion procedure.…”