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Facial Reanimation:

Anatomy:

• 3 segments: intracranial, infratemporal and extratemporal
• Ipsilateral supranuclear lesions give contralateral facial paralysis but maintain frontalis function (from intracranial portion)
• Infratemporal region contains the narrowest portion of the fallopian canal (called meatal foramen)- temporal fractures can cause facial paralysis
• Extratremporal region begins with the nerve exits the stylomastoid foramen
• Facial nerve trunk is 1cm deep just inferior and medial to the tragal pointer
• 5 branches of the facial nerve: temporal, zygomatic, buccal, mandibular, cervical branches
• Lies deep to the SMAS and arborizes within the parotid cland
• Superior and inferior divisions
• Superior division (temporal, zygomatic, and buccal)
• Inferior division (marginal mandibular and cervical)
• Temporal branch: Pitanguy’s line –> 0.5cm below the tragus to 1.5cm above the lateral brow
• Lies within temporopareital fascia
• Does not arborize (more likely for permanent injury)
• Marginal mandibular nerve: 
• Lies superficial to the facial artery and vein (water UNDER the bridge)
• Nerve is located above the inferior border of the mandible in 81% of people
• All muscles receive innervation from facial nerve from their deep surface EXCEPT MLB
• Mentalis, levator anguli oris, buccinator
• Exam:
• Frontalis: raise eyebrows
• Orbicularis: close eyelids
• Zygomatic branch: smile
• Orbicularis: purse lips

Etiology of facial paralysis: trauma, infections, temporal bone fractures, Bell’s palsy, parotid tumors, other malignant etiology

• Trauma: second most common cause (usually by transverse temporal bone fractures)
• Penetrating wounds (lacerations medial to the orbital canthus do not require repair because of nerve arborization)
• repair before 72h if possible (neurotransmitters are still there so can stimulate nerve for identification, after 72 hours they become depleted)
• wait at least 6mo since it can take that long to recover function from primary nerorrhaphy congenital malformation
• Bell’s Palsy: most common cause of facial paralysis. Associated with pregnancy. Diagnosis of exclusion
• Watchful waiting for treatment- all patients recover function within 6 months of paralysis
• 70% of patients have complete recovery
• Steroids can be used within 24 hours of diagnosis
• imaging in form of CT/MRI may be obtained after 3 weeks if no sign of improvement
• Most often results in ectropion and inability to close eyelid
• Tumors: think neoplasm if… unilateral facial weakness slowly increasing for more than 3 months
• Types: cholesteatoma, primary, parotid, acoustic neuroma, metastases
• Viral: Varicella, herpes, EBV
• Ramsay Hunt Syndrome: varicella-zoster virus infection with facial paralysis, ear pain, rash in external auditory canal
• Treat with steroids
• Infection: Lyme disease, HIV
• Can cause bilateral facial palsy
• Treat Lyme with doxycycline
• Pediatric:
• Mobius Syndrome: u/l or b/l loss of eye abduction (LR6 or CN VI)
• u/l or b/l facial paralysis
• Can be accompanied with other cranial nerve palsies
• Need free NM muscle transfer
• Hemifacial Microsomia (only in select few of patients)
• CULLP: congenital unilateral lower lip palsy
• Normal resting tone but have marginal mandibular dysfunction, has other major congenital anomalies in 3/4 of children
• In a pediatric patient with unilateral facial weakness, obtain CT scan to evaluate temporal bone
• Facial dyskinesias: can include hemifacial spasm, blepharospasm, facial myokymia
• Physical exam can show an S shaped deformity
• Testing: 
• Nerve excitability test: subjective, measures stimulus to produce twitch–> difference in each side is abnormal > 3.0 milliamps
• ENOG: apply current to stylomastoid foramen and record maximal muscle action potentials –> most accurate and reproducible test to determine prognosis–> facial nerve decompression indicated when >75% degeneration within 2 weeks of onset
• EMG: measures muscle activity –> positive 2-3 weeks after paralysis –> useful for later prognosis *fibrillations pathgnomonic of denervation
• Grading
• House-brackmann Facial nerve grading system
• 
• Treatment
• Goal: restore symmetry of the face at rest and in dynamic expression for cultural social intaraction
• Time from injury
• ><12 months: nerve repair, ipsilateral nerve graft, cross facial nerve graft (after 18-24 months motor end plates die and muscles atrophy)
• 12-24 months: nerve repair, grafting, or transfer (hypoglossal, masseter) or jump graft
• >24 months: static reconstruction, cross facial nerve grafting and free muscle transfer
• Reinnervation: (primary nerve repair, or interpositional nerve graft). Remember that axons grow 1mm/day
• Cross facial nerve grafting: indicated when proximal ipsilateral facial nerve stump is unavailable for grafting, when distal stump is present, and when facial muscles are capable of useful function
• Uses contralateral facial nerve
• Sural nerve grafts
• One stage or two stage (repairing both, or repairing distal end to graft in second stage 9-12 months later after a Tinel’s sign)
• Outcome depends largely on axonal density
• Babysitter: denervation >6 months may use babysitter with hypoglossal or masseter to preserve motor end plates while facial nerve growing through graft (faster to functional reanimation)
• Dynamic Reconstruction: when facial muscles will not provide useful function after reinnervation. Used in conjunction with crossfacial nerve graft or ipsilateral nerve to masseter. 
• Advantages to microvascular transfer vs regional muscle transfers: increased ability for spontaneous expression (facial nerve vs trigeminal nerve)
• Regional muscles: temporalis, masseter
• Free functional muscle transfer: Gracillis, pec minor, serratus, latissimus
• 2 stage: cross facial nerve transfer followed by free muscular transfer
• 1 stage: ipsilateral nerve to masseter
• Gracillis used for microvascular free transfer due to reliable vascular pedicle, one direction of pull, no overlying tendon, single nerve (does not reach contralateral side)
• vector should be in line with pull of zygomaticus major
• Static: 
• Brow 
• Brow lift (direct may be best to address asymmetry): remember coronal, direct, suerciliary, endoscopic
• Weaken contralateral side with botulinum toxin
• Eye 
• Gold weight in upper lid (superficial to levator aponeurosis and tarsal plate with the inferior portion of the plate 2-3mm from lash line, between the medial and central thirds of the lid)
• Gold weights used to bring eyelid 2-4 mm of lower lid to cover cornea
• Supportive measures (taping and eyedrops)
• Lower eyelid: and undergo canthopexy for paralytic ectropion or FTSG for cicatricial ectropion
• MidFace: suture suspension (SOOF lift)
• Nose: 
• Nasalis and levator labii superioris responsible for dilating the nasal apertures (buccal branch of facial nerve)
• Can treat stenosis with slings, rhinoplasty, suture suspension
• Lips
• fascial strips for static suspension sling of soft tissues (lower lip may require second tension vector downward ie depressor labii inferioris to evert lip). anchor fascia to orbicularis oris, ok to cross median, and attach to zygomatic bone or temporalis aponeurosis. may need surgical revision to tighten later
• botox to platysma

 
Complications

• Synkenesis: unintentional motion in one area of the face produced during intentional movement in another area of the face
• Aberrent regeneration
• Treatment: retraining, Botox
• Hyperkinesis: hyperactivity of contralateral normal side.  may be treated with botox or mirror feedback

 

• Miscellaneous

Buccal branch of facial nerve travels with parotid duct in cheek –> buccal branch elevates upper lip –>explore parotid duct by cannulating stenson duct intraorally –> duct injury can result in sialocele and edema 
 
Cheek Reconstruction

• Cheek defects: Zone 1: suborbital, Zone 2 preauricular, Zone 3 buccomandibular
•  Zone 1: primary closure Skin grafts (full thickness <5mm- not first line), local flap <4cm (rhomboid, VY, bilobed, forehead flap), cervicofacial flap (>4cm), tissue expansion, free flaps, temporalis flap
• Zone 2: primary closure, FTSG, local flaps, regional flaps (cervicofacial used for posterior and large anterior defects blood supply from facial artery), cervicopectoral(6-10cm) defects from IMA, submental flap, TE
• Zone 3: need to consider lining and soft tissue coverage. lining with hemitongue flap, buccal fat, masseter, FAMM, submental; tissue coverage, primary closure FTSG (not first option), local flaps, regional (submental, advancement), TE, free flaps (pec major flap for salvage)

 

• Cervicofacial advancement flap (temple defects)- Good for zone 1/zone 2
• subcutaneous elevation is good for large defects

Submental island 

• Submental artery (facial artery): (Zone 2/3)
• runs between horizontal ramus of mandible and submandibular gland, courses down and ends close to mandibular symphysis. vein goes through lower pole of parotid and drains into IJ
• Can take platysma only (must be careful to preserve cutaneous perforators), or can take combination of anterior digastric, mylohyoid, bilateral anterior digastric, and cutaneous paddle all the way up to the contralateral earlobe (may take contralateral submandibular gland)
• anterior incision posterior to mandibular basilar edge, posterior incision straight line connecting one mandibular angle to another 
• Rhomboid (Limberg) 
• Nasolabial  (good for ala because of pincushion effect)
• usually 1-2 stage flap
• elevate as random pattern or perforator. Island flap may have less donor site contour problems than pedicled. 
• Mustarde
• for superior cheek, inferior eyelid
• like a tenzel but extend incision to preauricular skin
• Medial cheek rotation

Lip
Anatomy

• Lip aesthetic units
• oral sphincter
• commissures
• philtrum
• vermillion

Reconstruction based on deficit

• A: upper lip B: lower lip
• Modiolus: attachment site lateral to commissure for multiple muscles
• Reconstruction of orbicularis important for sphinteric competence
• Sensory: V2 upper lip, V3 lower lip
• Blood supply: superior and inferior labial arteries
• Vermillion defects: V-Y, lip switch, total defects use axial myovermillion advancement flap, myomucosal advancement flap (<50%),  > 50% use tongue flap, total lose use buccal mucosal advancement
• Abbe flap: 1/3-2/3 lip defect, no commissure involvement (preferred in upper lip because it preserves anatomy) (lip switch flap divides in 3 weeks full thickness), can use in philtral column defects
• Estlander flap: 1/3-2/3  for commissure defects, alters modiolus, insensate 
• Karapandzic Flap: 1/3-2/3, central defect, can cause microstomia, preserve innervation of the orbic unlike the gillies flap
• Bernard Burrow: >2/3 (central for upper lip), must have adequate cheek tissue, oral sphincter incompetence, insensate; webster modification preserves innervation
• Total lip reconstruction with palmaris longus sling and RFFF (lateral antebrachial cutaneous nerve); can use functional gracilis and STSG to maintain movement of lip and superior aesthetic result

Sources:
ACAPS Inservice 2013-2020
CME: non melanoma facial skin cancers