Incidence of marginal mandibular nerve palsy in neck dissection

N Amin, H Dixon, N Gibbins, S Lew-GorBrighton and Sussex University Hospitals

United Kingdom

Marginal Mandibular Nerve

Our Project

• Limited data

• Informed consent important part of pre-assessment

• Communication errors heart of many complaints

Our Project

• Rate of MMN palsy (temporary/permanent) vs. Type of ND

Method• Retrospective 2 year review• 88 neck dissections (ND) reviewed• 4 excluded• 84 total

– Pre- and post-operative MMN function including whether the MMN was sacrificed intra-operatively.

– Time until palsy resolution– Type of neck dissection– The grade of the operating surgeon

• Statistical analysis

AAO-HNS classification of neck dissections• Radical neck dissection (RND) – removal of ipsilateral

cervical lymph nodes in levels 1-5 as well as the sternocleidomastoid muscle (SCM), internal jugular vein (IJV) and the spinal accessory nerve (SAN).

• Modified radical neck dissection (MRND) – removal of ipsilateral cervical lymph nodes in levels 1-5 with preservation of one or more of the SCM, IJV and SAN.

• Selective neck dissection (SND) – there is preservation of one or more groups of lymph nodes as well as the SCM, IJV and SAN.

• Extended neck dissection (END) – involves a RND with removal of another group of lymph nodes or another non-lymphatic structure.

Results

• 75 patients• 84 neck dissections

• Mean age 66.1 (32 – 89 years)• M 4.55:1 F

Results

• 20 RND • 20 MRND• 28 SND• 16 END

• 8 patients had pre-operative radiotherapy

Results

• 10/84 (11.9%) – MMN palsy

• 8/84 (9.5%) – permanent • 2/84 (2.4%) – temporary

Results

• 57 neck dissections involved level I

• Total palsy rate was 10/57 (18.5%)

• 14.0% (8/57) – permanent• 3.5% (2/57) – temporary

• p-value = 0.046

Results

•In RND there was a higher risk of a permanent MMN palsy (20%) compared to MRND (10%), SND (3.6%) or END (6.2%)

•10% risk of a temporary MMN palsy in patients undergoing MRND

•Statistically insignificant

10%

3.6%

20%6.2%

Results

•Parotid gland – 2•Oral cavity – 5•Larynx – 1

Discussion

• Informed consent is a vital part of pre-operative assessment.

• Incidence of MMN palsy post level I ND is not widely quoted.

• Important patients are aware of potential morbidity and potential treatment options.

Conclusion

• If level I dissection is performed, a permanent MMN palsy rate of 14% or 1 in 7 may be quoted to the patient.

• Adequate resection of disease in level I and the parotid region may require sacrifice of the MMN.

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