Incidence of marginal mandibular nerve palsy in neck dissection N Amin, H Dixon, N Gibbins, S Lew-Gor Brighton 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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