Gerard Kelly MD MEd FRCS(Ed) FRCS(ORL-HNS) ENT & skull base surgeon Leeds General Infirmary

1. facial nerve trauma The Leeds Teaching Hospitals NHS Trust • Gerard Kelly MD MEd FRCS(Ed) FRCS(ORL-HNS) • ENT & skull base surgeon • Leeds General Infirmary • 7th November 2018

2. aims and objectives

3. aims make us better at the management of facial nerve paralysis give us the best chance to pass the intercollegiate exam

4. aims and objectives

5. aims the aims reflect the long-term outcomes – it is a general direction the objectives are the short term targets of the learner

6. objectives s m a r t

7. objectives s m a r t

8. objectives list the causes of facial nerve paralysis list the steps in Wallerian degeneration label the parts of a peripheral nerve section describe the landmarks of facial nerve donor graft harvesting list the types of facial nerve dynamic repair operations, and their pros and cons grade a facial nerve paralysis using the House Brackmann system in a patient formulate a management plan for a patient presenting with a facial nerve paralysis in set situations score maximum points in the intercollegiate exam in a clinical scenario on the facial nerve

9. the facial nerve muscles of facial expression gives us the ability to blink, smile, talk, sing, eat and play musical instruments paralysis gives morbidity most often related to the inability to close the eye and this can result in keratitis and corneal ulceration speech can be impaired and the failure of the sphincter mechanism of the mouth results in loss of food and especially fluid while eating and drinking perhaps the most dramatic impact of facial paralysis, however, is the psychological effect on the patient

10. facial paralysis Morbidity of facial paralysis Difficulty eating Difficulty speaking Corneal ulceration Psychologically devastating Nicolas de Leyde, Tête à paralysiefaciale, Musée de l’Œuvre Notre-Dame

11. the facial nerve Facial paralysis was significantly associated with increased depression scores and worse QOL scores. Consistent with prior literature, female sex is also significantly associated with increased depression scores. Furthermore, there is no significant association between facial paralysis etiology and screening positive for depression. However, patients with more severe facial paralysis (HB grade ≥3) were more likely to screen positive for depression. Clinicians initially evaluating patients seeking treatment for facial paralysis should consider the psychological impact of facial paralysis to better direct patients to the appropriate psychiatric services if required. Association Among Facial Paralysis, Depression, and Quality of Life in Facial Plastic Surgery Patients Nelliset al. JAMA Facial Plast Surg. 2017;19(3):190-196. doi:10.1001/jamafacial.2016.1462

12. the facial nerve anatomy classification of facial function peripheral nerve degeneration classification of nerve injury causes of facial paralysis temporal bone fractures facial nerve repair special investigations exam questions

13. the facial nerve - anatomy

15. the facial nerve - anatomy Situated in the lower third of the pons, the facial motor nucleus contains approximately 7000 neurones

16. the facial nerve - structure

17. the facial nerve - anatomy Situated in the lower third of the pons, the facial motor nucleus contains approximately 7000 neurones Fibres from the facial nucleus must loop around the adbucens nucleus (forming the facial colliculus) before emerging from the brain stem The nerve has a motor and a sensory root (the nervus intermedius) The two roots emerge from the caudal border of the pons, lateral to the recess between the inferior olive and inferior cerebellar peduncle, at the cerebellopontine angle The motor root lies medial, and the vestibulocochlear nerve lies lateral, to the nervus intermedius The two roots of the facial nerve and the vestibulocochlear nerve pass anterolaterally to the internal acoustic meatus. At the lateral end of the meatus the nerve enters the facial canal (Fallopian canal), lying above the vestibule; it then turns at the geniculum to produce the genicular ganglion (giving the greater superficial petrosal nerve) and travels posteriorly through a bony canal on the medial wall of the middle ear Here the facial nerve is unique. No other nerve in the body has such a long course (28-30 mm) in a bony canal

18. the facial nerve - anatomy in the middle ear the facial canal lies behind the processuscochleariformis and tensor tympani tendon the nerve travels horizontally above the oval window and the stapes The facial nerve then turns downwards forming the second genu, the start of the mastoid segment of the nerve (giving nerve to stapedius and then corda tympani) It then runs vertically down the anterior wall of the mastoid process to emerge from the stylomastoid foramen Near the foramen three branches arise. First, the posterior auricular branch, which ascends in front of the mastoid process, giving auricular and occipital branches to supply auricular muscles and the occipital belly of occipitofrontalis respectively. Second, the digastric branch which supplies the posterior belly of the digastric muscle and third, the stylohyoid branch which supplies the stylohyoid muscle.

19. the facial nerve - anatomy the main trunk of the facial nerve emerges from the stylomastoid foramen to run forwards in the parotid gland, crossing the styloid process, retromandibular vein and external carotid artery within the substance of the parotid gland the nerve divides into its terminal branches (temporal, zygomatic, buccal, mandibular and cervical) The temporal branch crosses the zygomatic arch supplying intrinsic muscles on the lateral surface of the auricle and the anterior and superior auricular muscles. The more anterior branches supply the frontal belly of occipitofrontalis, orbicularis oculi and corrugator. The zygomatic branches cross the zygomatic bone to the lateral canthus, supplying orbicularis oculi. The buccal branch passes horizontally to a distribution below the orbit and around the mouth. This branch supplies procerus, the zygomaticus muscles, levator labii superioris, levatorangulioris, levator labii superioris alaeque nasi, buccinator and orbicularis oris. The mandibular branch runs forwards below the angle of the mandible, turning again above the mandible to supply the risorius and muscles of the lower lip and chin. The cervical branch runs anteroinferiorly to the front of the neck, under platysma, which it supplies (Gray’s Anatomy 1989)

20. Dehiscent Facial Nerve incidence of dehiscence 55% Baxter (535 bones) Deitzel (211 bones)

21. 91% Tympanic segment 9% Mastoid segment Facial Nerve Dehiscence – common sites

22. 83 % adjacent to oval window Facial Nerve Dehiscence - Tympanic segment 0.5 - 3.1 mm greatest diameter

23. Facial Nerve Dehiscence - Tympanic segment1 in 4 cases nerve protruded beyond canal

24. Facial Nerve Dehiscence - Mastoid segment 79% open into facial recess

25. The facial Nerve anomalies in course 0.3%

26. Facial palsy assessment House Brackmann grades I - VI (1985)

27. House, W. H. & Brackmann, D. E. 1985, "Facial nerve grading system", Otolaryngology- Head and Neck Surgery, vol. 93, no. 2, pp. 146-147. • the facial nerve – classification Association Among Facial Paralysis, Depression, and Quality of Life in Facial Plastic Surgery Patients Nelliset al. JAMA Facial Plast Surg. 2017;19(3):190-196. doi:10.1001/jamafacial.2016.1462

28. the facial nerve - degeneration When a peripheral nerve is divided (neurotmesis) Wallerian degeneration takes place distal to the site of injury and the proximal nerve undergoes degeneration at least to the nearest node of Ranvier, although greater degeneration can happen with more significant injury The proximal end of the severed nerve swells and there is proliferation of schwann cells and fibroblasts The distal segment of the nerve loses its connection with the cell body and cannot maintain its structural and functional integrity Initially, the axon swells and myelin disintegrates into droplets, being phagocytised by schwann cells and macrophages Wallerian degeneration is characterised initially by a granular disintegration of axoplasmic microtubules and neurofilaments, due to proteolysis. The collagen content of the distal segment is increased at the basement membrane of schwann cells. With collagen deposition in, and shrinkage of, the endoneurial tubes, their size becomes considerably reduced

29. the facial nerve - degeneration Axons that do establish peripheral connections will mature and enlarge, perhaps as a result of trophic substances from these targets. Thus the number of axons distal to a nerve repair may not vary proportionally with functional success of that repair, and indeed may indicate the opposite situation, with multiple branching due to scar tissue. Neurones are destined to be either myelinated or unmyelinated. If originally myelinated, axons will develop myelin, and similarly unmyelinated fibres will remain as such, even when regenerating into a graft which was originally myelinated Rates of growth vary after repair of neurotmeses. In the rat, a nerve will regenerate at approximately 3 mm per day (Forman, Wood, & Desilva 1979). In the human, repair occurs at approximately 1 - 2 mm per day (Seddon 1972)

30. the facial nerve - degeneration Axons that do establish peripheral connections will mature and enlarge, perhaps as a result of trophic substances from these targets. Thus the number of axons distal to a nerve repair may not vary proportionally with functional success of that repair, and indeed may indicate the opposite situation, with multiple branching due to scar tissue. Neurones are destined to be either myelinated or unmyelinated. If originally myelinated, axons will develop myelin, and similarly unmyelinated fibres will remain as such, even when regenerating into a graft which was originally myelinated Rates of growth vary after repair of neurotmeses. In the human, repair occurs at approximately 1 - 2 mm per day (Seddon 1972)

31. a peripheral nerve

32. Classification of nerve injury Sneddon (1943) Neurapraxia Axonotmesis Neurotmesis

33. Classification of nerve injury Sunderland (1978) 1° physiological block 2° axon degenerates 3° endoneurium degenerates 4° perineurium degenerates 5° nerve transection

34. Sunderland (1978)

35. Causes of facial palsy CP angle Vestibular schwannoma Meningioma Facial schwannoma Cholesteatoma Glomus jugulare

36. Causes of facial palsy Skull base Osteopetrosis Malignant otitis externa Sarcoidosis TB

37. Causes of facial palsy Temporal bone Fracture Bell’s palsy Acute otitis media Chronic otitis media (with or without cholesteatoma) Schwannoma, meningioma, haemangioma, glomus

38. Causes of facial palsy Temporal bone trauma Blunt trauma to the temporal bone is much more frequent than penetrating injury Skull base fractures occur in 3–30% of head injury attendances to Emergency Departments 9–40% of these having temporal bone fractures. About 7.9% are bilateral Men in their late twenties and early thirties predominate (male : female 2.8–4 : 1) Temporal bone trauma without fracture has similar aetiologies. Road traffic accidents probably account for about 50%, other frequent causes being falls (16–40%), assaults (10-37%) and, in the US, gunshot wounds (3–30%) About 15% occur in children (males : females 2 : 1), the peak incidence being at approximately 5 years of age. Falls from a height predominate as the cause (40%) in children, with road traffic accidents accounting for only 34%

39. Causes of facial palsy Temporal bone trauma The most commonly used system classifies temporal bone fractures according to their orientation relative to the axis of the petrous ridge: longitudinal or transverse

40. Causes of facial palsy Temporal bone Fracture

41. Causes of facial palsy Temporal bone Fracture

42. Causes of facial palsy Temporal bone Fracture Longitudinal

43. Causes of facial palsy Temporal bone Fracture

44. Causes of facial palsy Temporal bone Fracture

45. Causes of facial palsy Temporal bone Fracture Transverse

46. Causes of facial palsy Temporal bone trauma Most series describe 80–90% of fractures as longitudinal and 10–20% as transverse Although a convenient system, it has not been proven to correlate well with clinical signs or outcome Fractures have been found to be randomly placed or comminuted, and they are often not adequately described by the traditional classification True longitudinal fractures are uncommon so alternative classifications attempt to include oblique and complex fracture orientations

47. Causes of facial palsy Temporal bone trauma An alternative system considering fractures as otic capsule violating or sparing is becoming more widely adopted This system emphasizes the structures involved rather than simply describe the fracture orientation Otic capsule fractures are associated with an increased incidence of serious sequelae Facial nerve paralysis, CSF leak and profound hearing loss were twice, four times and seven times, respectively, more likely in otic capsule violated cases. An attractive approach is simply to differentiate between petrous and non-petrous fractures. In one study CSF leak was only 1.1 times more common in transverse than in longitudinal fractures but was 9.8 times more common in petrous than in non-petrous fractures. Facial nerve injury is also more strongly correlated with fractures through the petrous temporal bone than with other fracture types. Sensorineural hearing loss did not correlate with the transverse fracture classification but was significantly more prevalent in petrous fractures

49. Causes of facial palsy Extracranial trauma parotid malignancy tonsil, oronasophanryngeal malignancy

50. Causes of facial palsy Others Melkersson-Rosenthal syndrome Sarcoid leukaemia Landry-Guillain-Barré syndrome Moebius’ syndrome