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بسم الله الرحمن الرحيم

بسم الله الرحمن الرحيم. THE FACIAL NERVE. Topics. Gross applied anatomy Pathology of nerve injury and regeneration Principles of the electrophysiological tests Causes of facial nerve paralysis Principles of treatment of facial paralysis Bell’s palsy. Facial Nerve Fibers. Motor

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بسم الله الرحمن الرحيم

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  1. بسم الله الرحمن الرحيم

  2. THE FACIAL NERVE

  3. Topics • Gross applied anatomy • Pathology of nerve injury and regeneration • Principles of the electrophysiological tests • Causes of facial nerve paralysis • Principles of treatment of facial paralysis • Bell’s palsy

  4. Facial Nerve Fibers • Motor • to the stapedius and facial muscles • Secreto-motor (parasympathetic) • to the lacrimal gland and the submandibular and sublingual salivary glands • Taste • from the anterior two thirds of the tongue and palate • Sensory • from the external auditory meatus

  5. Anatomical Divisions • Intracranial • Cranial (intratemporal) • Extracranial (extratemporal)

  6. The Intracranial Part • Include the nuclei and the Cerebello Pontine angle semgents

  7. Facial nerve nuclei

  8. Lower motor lesions affect all the ipsilateral facial muscles • Upper motor lesions spare the upper facial muscles and affect the contralateral lower face

  9. Upper motor Lower motor

  10. The CP angle segment

  11. The Intra-temporal (Cranial)

  12. The extracranial part

  13. The extracranial part

  14. Facial Nerve Fibers • Motor • to stapedius, and facial muscles • Secreto-motor • to the submandibular, sublingual, and lacrimal glands • Taste • from the anterior two thirds of tongue and palate • Sensory • from the external auditory meatus

  15. The secreto-motor and the taste fibres

  16. The secreto-motor and the taste fibres

  17. Variations and Anomalies

  18. Facial Nerve Paralysis

  19. Clinical Manifestations • Paralysis of facial muscles • Asymmetry of the face • Inability to close the eye • Accumulation of food in the cheek

  20. Clinical Manifestations • Paralysis of facial muscles • Asymmetry of the face • Inability to close the eye • Accumulation of food in the cheek • Phonophobia • Dryness of the eyes • Loss of taste

  21. Pathophysiology of Nerve Injury

  22. Neuropraxia (Conduction block) Neurotmeses (Degeneration)

  23. Regeneration • In neuropraxia: restoration of full function if the cause is treated • In neurotmeses : No recovery unless the distal and the proximal parts approximated • Recovery is delayed and usually is incomplete

  24. Principles of management of facial nerve paralysis • Care of the eye • Treatment of the cause if applicable • Treatment of the nerve varies according to the degree of the paralysis

  25. Partial facial paralysis • Being partial means that some of the nerve fibres are in continuity and recovery is expected by conservative treatment (e.g. removal of pressure, steroid etc)

  26. Complete facial paralysis • Complete paralysis may be a result of neuropraxia or/and degeneration • If it is due to neuropraxia, recovery is expected by conservative treatment • If it is due to degeneration, surgical treatment is required • To differentiate between degeneration and neuropraxia electrophysiological tests are required

  27. Electrophysiological Tests • It detect degeneration of the nerve fibres • Useful only 48-72 hours following the onset of the paralysis

  28. Electrophysiological Tests • Nerve Excitability Test (NET) • Electroneurography (ENoG)

  29. Nerve excitability test (NET) • The current’s thresholds required to elicit just-visible muscle contraction on the normal side of the face are compared with those values required over corresponding sites on the side of the paralysis

  30. Electroneurography (ENoG) • The amplitude of action potentials in the muscles induced by the maximum current is compared with the normal side ; and used to calculate the percentage of intact axons.

  31. Interpretation of the tests • Not useful in the first 48 – 72 hours • After 48-72 hours (the time required for degeneration to take place) • Normal results means that there is no degeneration (Neuropraxia) • Abnormal results means degeneration

  32. Topognostic Tests • Indicated in some cases to locate the site of the injury

  33. Topognostic Tests • Schirmer's test • Test the lacrimation function

  34. Topognostic tests • Schirmer's test • Stapedial reflex • Taste sensation

  35. Topognostic tests • Schirmer's test • Stapedial reflex • Taste sensation

  36. Causes of facial paralysis • Intracranial causes • Cranial (intratemporal) causes • Extracranial causes

  37. Causes of facial paralysis • Congenital: Birth trauma • Traumatic: Head and neck injuries & surgery • Inflammatory: O.M, Necrotizing O.E., Herpes • Neoplastic: Meningioma, malignancy ear or parotid • Neurological: Guillain-Barre syndrome, multiple sclerosis • Idiopathic: Bell’s palsy

  38. Congenital Facial Palsy • 80-90% are associated with birth trauma • 10 -20 % are associated with developmental lesions

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