Lecture Notes: Facial Palsy and Stroke

Speaker: Dr. Morton, Noted Anatomist

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Overview

• Facial Nerve Function
  • Innervates ipsilateral facial muscles.
  • Arises from the pons and exits through the stylomastoid foramen.
  • Divides into branches that control facial expression: frontalis, orbicularis oculi, nasalis, zygomaticus, and orbicularis oris muscles.
  • Does not innervate temporalis or masseter muscles, which are innervated by the trigeminal nerve.

Facial Palsy (Bell's Palsy)

• Definition: Paralysis of ipsilateral facial muscles due to facial nerve injury.
• Causes:
  • Injury at the facial motor nucleus or as the nerve exits the pons.
  • Pathology such as acoustic neuroma, inflammation, or compression (e.g., mumps, tumors).
• Symptoms: Complete paralysis on affected side, smooth forehead, inability to close eyes tightly, droopy nose, and corner of the mouth.
• Named After: Sir Charles Bell.

Anatomy and Pathophysiology

• Motor Homunculus: Somatotopic organization in the primary motor cortex; densely innervated muscles occupy more space.
• Upper Motor Neurons: Arise from the contralateral cerebral cortex.
  • Exception: Forehead receives input from both sides of the cerebral cortex (contralateral and ipsilateral).

Stroke

• Definition: Injury to upper motor neurons resulting in contralateral facial muscle paralysis with forehead sparing.
• Pathophysiology:
  • Supranuclear lesion prevents contralateral upper motor neuron stimulation.
  • Forehead sparing due to ipsilateral innervation.
• FAST Acronym: Facial drooping, Arm weakness, Speech difficulties, Time to call emergency services.
• Symptoms: Crooked smile, speech problems, arm immobility.

Clinical Practice

• Diagnosis: Differentiate between lower motor neuron lesions (Bell's Palsy) and upper motor neuron lesions (stroke).
  • Bell's Palsy: Same side paralysis.
  • Stroke: Opposite side lower face paralysis, forehead sparing.

Personal Note

• Gabriella Morton: Dr. Morton's mother experienced strokes and inspired his teaching approach.
  • Importance of medical professionals: family doctors, neurologists, physical and occupational therapists, speech therapists, and hospice nurses.

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Summary

• Bell’s Palsy: Lower motor neuron injury; complete paralysis on the same side.
• Stroke: Upper motor neuron injury; forehead sparing with contralateral lower face paralysis.
• Personal story highlights the impact of strokes and appreciation for healthcare providers.