Hypoglossal to Facial Nerve Transfer

The hypoglossal to facial nerve transfer has been a popular choice for facial reanimation because it reestablishes neuronal impulses to the facial muscles and supplies a base line resting tone. However, simply regaining tone and some facial motion does not ensure a satisfactory outcome. With hypoglossal to facial transfer, it is very rare for a patient to regain any movement that could be considered spontaneous or emotive. In fact, it is rare for patients to achieve voluntary movement of discrete regions of the face; instead, they have mass motion of all ipsi-lateral facial muscles. Those few patients likely to regain control of individual regions of the face are highly motivated, undergo extensive training, and, most importantly, have the crossover performed early (within 2 years) after injury to the facial nerve.5'6 A review of several large series of patients with hypoglossal to facial nerve transfers shows that patients obtain "excellent" results only approximately 40 to 50% of the time.7-9 The major reasons for a less-than-excellent result with hypo-glossal to facial nerve transfers are synkinesis, facial movement on eating or talking, hypertonicity with excessive resting tone, and exaggerated movement with attempts at volitional movement. The hypertonicity and synkinesis can be so severe and the appearance of the face so grotesque (particularly with eating, where the face moves in concert with the motions of the tongue) that it becomes a deformity rivaling the original facial paralysis in terms of disability. In addition, when the entire hypoglossal nerve is sacrificed, there is a certain degree of morbidity due to the resultant hemitongue flaccidity, and eventual tongue atrophy, which may cause difficulty with speaking, eating, and swallowing. The actual incidence of significant postoperative morbidity varies from series to series, but it may be as high as 74% of patients.9 The hypoglossal facial nerve jump graft, in which a cable graft is sewn to a partially transected hypoglossal nerve and distal end of the facial nerve, described by May et al.10 would theoretically alleviate many of the shortcomings of the hypoglossal facial crossover by intentionally limiting the strength of the hypoglossal neuronal input and preserving most of the hypoglossal connections to the tongue. However, other surgeons are reporting difficulty obtaining significant facial movement with this technique (G.B. Hughes, personal communication, 1996).

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