Idiopathic Facial Nerve Paralysis
I thought we'd continue our theme from last week about peripheral neuropathies and talk about a neuropathy that we all (I think) see fairly regularly: Idiopathic facial nerve paralysis.
What is it?
Idiopathic facial nerve paralysis (IFNP) happens for, ahem, unknown reasons. There is some type of synaptic block that, as of now, has an unknown cause. The facial nerve is a motor nerve that starts in the medulla (brainstem), courses through the skull and bulla on it's way to the face. Other causes of facial nerve paralysis such as hypothyroidism, neoplasia, otitis media, polyps, and rarely neuritis. Remember: you must localize the lesion to the peripheral CN 7 to include IFNP on your list of differential diagnoses!
What does it look like?
The facial nerve innervates the muscles of facial expression in dogs and cats as well as providing innervation to the lacrimal eye glands. Clinical signs are typically unilateral and, result in an inability to move the eyelids (inability to blink), inability to move the lips (dogs may accidentally chew on their lips), lack of ear movement (especially noticeable in cats), and a dry, red eye with possible ocular ulceration.
Clinical Course
Signs are typically acute in nature with rapid progression to full clinical manifestation. Spontaneous resolution occurs in 3-6 weeks. Yay!
Management
Supportive care, such as eye lubricant, and ensuring lip injury is minimized by limiting chewing toys/bones, is the mainstay treatment. Antibiotics, steroids, NSAIDs and other medications do not improve the recovery time!
It's short and sweet this week. Please let me know if you have a specific topic of interest! Have a great week, and keep those consults coming.
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