B7.024 Bell's Palsy

Question 1

corticobulbar tract

Answer 1

supplies all UMN innervation to the cranial nerves

Question 2

upper face innervation

Answer 2

bilateral

both hemispheres

Question 3

lower face innervation

Answer 3

contralateral hemisphere

Question 4

central facial weakness

Answer 4

only lower facial weakness

UMN type lesion (bc upper face still receives innervation from ipsilateral brain)

Question 5

peripheral facial weakness

Answer 5

entire hemisphere is weak (upper and lower face)

LMN type lesion

Question 6

where would a peripheral facial weakness lesion localize

Answer 6

between brainstem and muscles

Question 7

2 classes of peripheral facial weakness lesions

Answer 7

intra-axial = inside brainstem
extra-axial = outside brainstem

Question 8

hallmark of a brainstem lesion

Answer 8

“alternating hemiplegia”
if nuclei within the brainstem are damaged, the corticospinal system which also runs through the brainstem would be damaged as well
would see body weakness on the opposite side of facial weakness

Question 9

pattern of deficits for brainstem lesions

Answer 9

ipsilateral CN

contralateral long tracts (weakness, numbness)

Question 10

how to rule out intra-axial lesions

Answer 10

no long tract symptoms / signs

Question 11

where does the facial nerve exit the brainstem

Answer 11

pons

Question 12

4 nuclei of the facial nerve

Answer 12

facial motor nucleus
gustatory nucleus
main sensory nucleus
superior salivatory nucleus

Question 13

functions of the facial nerve

Answer 13

facial muscle movement
taste on anterior 2/3 of tongue
ear region sensation
parasympathetic salivation / lacrimation

Question 14

facial motor nucleus innervation

Answer 14

face muscles
stapedius
digastric

Question 15

gustatory nucleus innervation

Answer 15

taste on anterior 2/3 of tongue

Question 16

main sensory nucleus innervation

Answer 16

ear region sensation

Question 17

superior salivatory nucleus innervation

Answer 17

lacrimal, submandibular, sublingual glands

Question 18

patterns of facial nerve deficits

Answer 18

facial weakness
hyperacusis
decreased taste
dry eyes

Question 19

why is it important to understand the basic course of the facial nerve

Answer 19

branch points help to localize the site of the lesions

Question 20

geniculate ganglion

Answer 20

contains nerve cell bodies of all sensory nerve branches of the facial nerve

Question 21

important of a lesion located after the stylomastoid foramen

Answer 21

increases likelihood of a malignant parotid tumor

higher up lesions are usually benign

Question 22

list the relevant branch points of facial nerve proximally to distally

Answer 22

geniculate ganglion

• greater petrosal nerve to pterygopalatine ganglion (lacrimal gland)
• nerve to stapedius (hearing)
• chorda tympani (taste, salivatory glands)
• *stylomastoid foramen**
• facial motor branches

Question 23

how is taste sensation tested

Answer 23

table salt and table sugar

Question 24

what might you see on an MRI in bell’s palsy

Answer 24

increased signal intensity in the internal auditory canal

nerve / blood barrier broken down

Question 25

what is Bell's palsy

Answer 25

idiopathic | peripheral CN 7 palsy

Question 26

Bell's palsy pathology

Answer 26

``` based on autopsy specimens and clinical observations at surgery (doesn't kill people) intraneural inflammation (+/- segmental demyelination) swelling and compression within the Fallopian canal and the perineurium (+/- axon loss) ```

Question 27

suspected relationship between HSV1 and Bell's palsy

Answer 27

can be isolated from nasopharynx of people with Bell's HSV antibody titer rises virus isolated from epineurium of biopsy specimen PCR positive for HSV in endoneurial fluid of Bell's patients saliva positive for HSV by PCR in 11/38 Bell's patients and 0/10 normal controls

Question 28

components of natural history of Bell's palsy

Answer 28

``` proportion complete recovery time to recovery complications -aberrant re-innervation -hemi-facial spasm ```

Question 29

outcomes by which degree of recovery from Bell's palsy is measured

Answer 29

``` primary motor function -symmetry at rest -forehead -eye closure -mouth secondary defects -synkinesis -gustatory tears -facial spasm ```

Question 30

synkinesis

Answer 30

aberrant reinnervation due to Wallerian degeneration in some axons leading to nerve regeneration if connective tissue is damaged, nerve can regenerate to the wrong place

Question 31

examples of synkinesis

Answer 31

people wink when they try to smile | tear up when smiling

Question 32

house and brackmann grading scale

Answer 32

1 = normal 6 = total paralysis lower number is better in recovery from Bell's

Question 33

what % of patients recover well from Bell's

Answer 33

85% have grades of 1-2 on house and brackmann scale | 15% do poorly (grades 3-6)

Question 34

time to recover form Bell's

Answer 34

``` initiation of recovery -within 3 weeks (85%) -after 8 weeks (10%) medial time to final recovery -45 to 60 days ```

Question 35

poor prognostic factors in Bell's

Answer 35

``` older age non ear region pain complete palsy gradual onset vertigo diabetes HTN ```

Question 36

why is vertigo indicative of poor prognosis

Answer 36

CN 8 (vertigo) is next to CN 7 (Bell's) and thus damage to CN 8 may signify more severe inflammation

Question 37

components of treatment of Bell's

Answer 37

prevention of exposure keratitis medications facial nerve decompression

Question 38

why is a patient with bell's at increased risk of exposure keratitis

Answer 38

decreased eye closure | decreased lacrimal gland function

Question 39

what reduces the risk of bell's (aka why isn't it very common to begin with)

Answer 39

preservation of corneal sensation | basically, people can feel their eye getting irritated and take action against it

Question 40

preventive interventions for exposure keratitis

Answer 40

eye lubrication | eye patching

Question 41

mainstay of therapy for Bell's

Answer 41

steroids - reduce inflammation - reduce compression within temporal bone

Question 42

other treatments for Bell's

Answer 42

acyclovir -treat underlying infection surgery -relieve compression by fallopian canal and perineurium

Question 43

steroid regimens for Bell's

Answer 43

prednisolone 60 mg daily x 5, taper by 10 (total 10 days) OR prednisolone 25 mg BID x 10 days

Question 44

how well do steroids work in bells

Answer 44

highly likely to be effective in increasing the likelihood of good facial functional recovery by about 12 %

Question 45

antiviral recommendation in Bell's

Answer 45

may be offered to patients with new onset Bells should be counseled that a benefit from antivirals has not been established and if there is a benefit it is likely that it is at best modest

Question 46

other therapies for Bell's that lack evidence for support

Answer 46

facial nerve re-education Kabat physical rehab cutaneous electrical stimulation acupuncture