WRITE A NOTE ON ASSESSMENT AND MANAGEMENT OF LMN FACIAL PALSY AFTER MASTOID EXPLORATION ?
INTRODUCTION
1 The facial nerve (cranial nerve VII) carries motor, secretory, and afferent fibers from the anterior two thirds of the tongue.
2 It originates in the facial nucleus, which is located at the caudal pontine area.
3 Corticobulbar fibers from the precentral gyrus (frontal lobe) project to the facial nucleus, with most crossing to the contralateral side. As a result, crossed and uncrossed fibers are found in the nucleus.
4 Moreover, the facial nucleus can be divided into two parts -
(1) the upper part, which receives corticobulbar projections bilaterally and later courses to the upper parts of the face, including the forehead, and
(2) the lower part, the predominantly crossed projections of which supply innervation to lower facial muscles (stylohyoid; posterior belly of digastric, buccinator, and platysma
5 Innervations
A ) The temporal trunk innervates the following muscles -
Frontalis
Orbicularis oculi
Corrugator supercilii
Pyramidalis
B ) The zygomatic division innervates the following muscles:
Zygomaticus major
Zygomaticus minor
Elevator ala nasi
Levator labii superioris
Caninus
Depressor septi
Compressor nasi
Dilatator naris muscles
The buccal division gives off fibers to innervate the buccinator and superior part of the orbicularis oris muscle.
C ) Mandibular division innervations are found in the following muscles
Risorius
Quadratus labii inferioris
Triangularis
Mentalis
Lower parts of the orbicularis oris
D ) The cervical division provides platysma innervation. A “facial danger zone” is known to follow an imaginary line drawn from the lateral canthus to the lateral corner of the mouth and from the zygomatic arch down to the angle of the mandible.
IMPORTANT POINTS
1 The plastic surgeon should keep in mind that the more distal the injury to the facial nerve, the better the chances for spontaneous recovery.
2 Generally, good reconstructive results for facial nerve repair were reportedly yielded by Terzis et al even when a comparatively small number of axons were regenerated.
3 Terzis found a higher nerve-to-muscle fiber ratio than in other skeletal muscles (1:8, compared with 1:50 in other skeletal muscles - VV IMP
ASSESSMENT
1 Thru History taking
2 Thru HOUSE BRACKMANN facial grading system
A ) For monitoring changes - SUNNY BROOK FACIAL NERVE GRADING SYSTEM
3 By use of EMG - In this Sticky electrodes are placed on your face over various muscles, usually the brows, temples, cheek, chin and neck.
A ) This is a painless procedure, and takes just a few minutes.
B ) In this energy measurement of facial muscles are done when you are still and when you try to move them
C ) for example, when you try to raise your brow, close your eyes, smile and whistle.
1 In order for a muscle to move, the muscle fibres must contract.
2 A muscle can only contract if the nerve to that muscle is intact and working.
3 facial nerve can be likened to the flex of a kettle. If the flex from the plug to your electric kettle is damaged, then your kettle will not work properly because the electricity cannot travel through it in the normal way.
4 perform a Schirmer test of tearing to assess lacrimal gland function.
5 Imaging
Computed tomography (CT) scanning and magnetic resonance imaging (MRI) are useful in the diagnosis of injury to intratemporal and/or intracranial affections of the facial nerve, as they may reveal temporal fracture patterns (vertical, transversal, mixed) and edema formation. Under certain circumstances, the facial nerve can be viewed, and swelling or disruption may be seen.
EFFECTS OF FACIAL NERVE PARALYSIS
A ) Functional effects -
1 Difficulty eating and drinking as lack of lip seal makes it difficult to keep fluids and food in the oral cavity
2 Reduced clarity of speech as the “labial consonents” (ie. b, p, m, v, f) all require lip seal
3 Dryness of the affected eye
B ) Somatic effects -
1 The facial nerve supplies the lachrymal glands of the eye, the saliva glands, and to the muscle of the stirrup bone in the middle ear (the stapes).
2 It also transmits taste from the anterior 2/3 of the tongue
3 Lack of tear production in the affected eye, causing a dry eye, with risk of corneal ulceration.
A ) In Facial Nerve palsy there are 2 problems which contribute towards making the eye dry -
-
The greater petrosal nerve, derived from the facial nerve, supplies the parasympathetic autonomic component of the lacrimal gland. - controlling production of moisture/tearing in eyes.
-
The zygomatic branch of the Facial Nerve supplies Orbicularis Oculi, and the resulting paralysis causes inability(or reduced ability) to close the eye or blink, so the tears (or indeed artificial lubrication in the form of drops, gel or ointment) are not spread across the cornea properly.
4 Hyperacusis = sensitivity to sudden loud noisesAltered taste sensation
MANAGEMENT
A ) MEDICAL MANAGEMENT
- 1 treated with corticoteroids (prednisone), given within 72 hours of onset and this can be accompanied by antiviral medication.
2 Botulinum Toxin Therapy
Management of synkinesis and hyperkinesis can include botulinum toxin injection.
This technique yields good results in the control of these sequelae of reinnervation procedures but must be repeated approximately every 3 months.
Usually, 5-10 units are injected initially to control eyebrow spasm, and an additional 10-20 units are injected into the zygomaticus muscle and then repeated with an adapted dose as needed.
B ) CONSERVATIVE / NON SURGICAL
A ) COUNSELLING/ PATIENT EDUCATION
1 - it includes telling the patient causes , prognosis based upon the severity of injury
2 - Reassure the patient
3 - Goal setting
4 - Advicing to take on time medications
B ) DIFFERENT THERAPIES
1 Neuromuscular Retraining (NMR) - To establish coordinated movement pattern
2 Electromyography (EMG) biofeedback - Avoids development of synkinesis
3 Trophic Electrical Stimulation (TES) - Galvanic to reduce muscle atrophy until regeneration occurs
A ) pulsed Swd , ultrasound in neuropraxia
B ) Laser therapy and biofeedback in axontmesis and neurotomesis
4 Proprioceptive Neuro Muscular Facilitation
5 Home exercise programme - It includes the following-
1 Massage to keep the muscles mobile and healthy.
2 Stretches to lengthen muscles which have become short or tight.
3 Exercises to help relearn and develop balanced facial movements.
4 Relaxation of your facial nerve and muscles.
5 Exercises to reduce involuntary, unwanted movements.
6 MIME therapy - which consists of massage, relaxation, inhibition of synkinesis, and co-ordination and emotional expression exercises, has been proposed only at a late stage of paresis, with no reports on its potential role when applied at an early stage 2
7 COMBINED THERAPY - ALL
8 POSTURAL CORRECTING TECHNIQUES - RELAXATION THERAPY
9 KABAT REHABILITATION
principle is similar with PNF stretching
Ice stimulation is provided prior to this for promoting contraction of muscle
C ) SURGICAL
1 Facial reanimation surgeries which involve nerve graft or anastomosis -
A ) Direct Coaptation ( VII - VII transfer) -
This technique requires 2 operations.
Primarily, a sural nerve graft is coapted to the contralateral buccal branch, then tunneled through the upper lip and usually left in the subcutaneous tissue. This is performed to allow axonal regeneration in the sural nerve.
B ) Interposition nerve grafts
2 Facial reanimation surgeries which involve muscle transposition -
A ) use of Temporalis and masseter muscle
3 Static surgeries, ie. plastic surgery to improve symmetry at rest but no improvement in movemenT -
A ) use of static sling - temporalis sling ( gore tex sling )
B ) Crossover facial reinnervation
RECOVERY
1 ( Early ) 4 weeks to 12 weeks ( Late )
2 Nerve regenerates 1 mm per day
3 According to SUNDERLAND CLASSIFICATION ( VV IMP )
GRADE 2 AND 3 - more than 12 weeks
GRADE 3 - Management of choice is Neuromuscular reeducation through biofeedback
4 clinically According to House-Brackmann
A ) grade 1 injury refers to neurapraxia, which is the most likely stage for spontaneous recovery.
B ) Axonotmesis is the term for longer compression of the nerve, clinically a House-Brackmann level 2-3 injury, with temporary axonoplasmal flow interruption and subsequent Wallerian anterograde degeneration.
B 1 ) Degeneration in axonotmesis is most often incomplete, with more or fewer axons surviving. Thus, partial facial weakness often results.
C ) Neurotmesis is a state of permanent loss of axons further characterized by (partial) demyelinization leading to moderate to severe facial musculature dysfunction.
C 1 ) Regenerative impulses may end in facial synkinetic movements, mass movements, or contracture.
D ) Finally, clinical findings in House-Brackmann stage 5 and 6 injuries (partial or complete transection of the facial nerve) are either the retaining of minimal facial musculature movements or complete loss of function (grade 6).
5 POOR RECOVERY FOR PT WITH HYPERTENSION , DIABETES AND OBESE