Management of bells palsy

management of bells palsy and facial reanimation surgeries-plastic surgery point of view

1. MANAGEMENT OF BELLS PALSY

2. Bell’s palsy Bell’s palsy is an acute, unilateral paresis or paralysis of the face in a pattern consistent with peripheral nerve dysfunction, without detectable causes. It is the most common cause of acute onset unilateral peripheral facial weakness. It acounts for 60-70% of all cases of unilateral peripheral facial palsy.

3. Bell’s palsy Affects with equal frequency on the right and left sides of the face. Either sex is affected equally . M ay occur at any age, the median age is 40 years .(10 years -70 years) Patients who have had one episode of Bell's palsy have an 8 percent risk of recurrence. M ean interval to first recurrence is reported at 9.8 years after the first episode.

4. Bell’s palsy The cause is unclear. Viral infection, vascular ischemia, autoimmune inflammatory disorders, and heredity have been proposed as the underlying cause. A viral cause has gained popularity since the isolation of the herpes simplex virus-1 genome from facial nerve endoneurial fluid in people with Bell’s palsy.10

5. Bell’s palsy sudden onset and symptom typically peak within a few days. weakness or complete paralysis of muscles on one side of the face. Additional symptoms: Pain in or behind the ear. Numbness or tingling in the affected side of the face usually without any objective deficit on neurological examination . Hyperacusis . Disturbed taste on the ipsilateral anterior part of the tongue

6. Bell’s palsy Bell's phenomenon - on attempted closure, the eye rolls upward . Tear production decreases; however, the eye may appear to tear excessively because of loss of lid control, which allows tears to spill freely from the eye . Food and saliva can pool in the affected side of the mouth and may spill out from the corner

7. Diagnosis D etermine whether facial weakness is central or peripheral. Bell's palsy is differentiated from other causes of facial palsy such as diabetes mellitus, human immunodeficiency virus (HIV) infection, Lyme disease, Ramsay Hunt syndrome (peripheral facial palsy with zoster oticus ), sarcoidosis , Sjogren's syndrome, parotidnerve tumors , leprosy, polyarteritis nodosa , Amyloidosis. Facial palsy secondary to other causes progresses over days to months.

8. Diagnostic Workup Diagnosis of Bell's palsy in a patient with unilateral peripheral facial weakness of unknown cause is purely clinical . However, electrodiagnostic testing done within 14 days of onset may provide prognostic information

9. Trigeminal blink reflex M easure intracranial pathway S tudy various postparalysis sequelae such as synkinesis and hemifacial spasms . P rolongation of this response correlates with greater loss of facial motor function Nerve excitability test M inimum electrical stimulus required to produce visible muscle contraction. Difference greater than 3.5 mA between affected and unaffected sides is considered to be significant in terms of poorer outcome. Gadolinium MRI: reveals enhancement internal acoustic meatal segment on the affected side; however, this is a nonspecific finding. should be the investigation to look for other possible causes

10. Clinicians may offer oral antiviral therapy in addition to oral steroids within 72 hours of symptom onset for patients with Bell's palsy . Either acyclovir 400 mg can be given five times per day for seven days or valacyclovir 1 g can be given three times per day for seven days

11. Management NONSURGICAL MANEUVERS TO PROTECT THE EYE Lid taping, particularly while sleeping Soft contact lenses Modification of eyeglasses to provide a lateral shield Eye patches Temporary tarsorrhaphy Physical Therapy In Bell's palsy various physical therapies, such as exercise, biofeedback, laser, electrotherapy , massage and thermotherapy are used to hasten recovery . However , the evidence for the efficacy any of these therapies, is lacking

12. Prognosis About 71% of patients with Bell's palsy have motor function recovery completely within 6 months. Poor prognostic factors : old age, hypertension, diabetes mellitus, impairment of taste and complete facial weakness. About one-third of patients may have incomplete recovery and residual effect.

13. R esidual effects post-paralytic hemifacial spasm co-contracting muscles synkinesis sweating while eating or during physical exertion 2 most common abnormal regeneration patterns are : ‘ crocodile tears’ - lacrimation of the ipsilateral eye during chewing ‘ jaw-winking’ - closure of the ipsilateral eyelid when the jaw opens

14. SURGICAL MANAGEMENT OF ACUTE FACIAL PARALYSIS (<3 WEEKS) S urgical decompression within three weeks of onset has been recommended for patients who have persistent loss of function. Transmastoid approach Middle fossa approach Translabyrinthine approach The most common complication of surgery is postoperative hearing loss, which affects 3 to 15 percent of patients.

15. SURGICAL MANAGEMENT OF ACUTE FACIAL PARALYSIS (<3 WEEKS) National Guideline Clearinghouse & the American Academy of Neurology does not currently recommend surgical decompression for Bell's palsy.

16. AIMS OF RECONSTRUCTION to restore symmetry and coordinated dynamic animation with normal appearance at repose. symmetry during voluntary and involuntary expression , competent ocular and oral sphincters. preservation of existing facial function. minimal loss of function in other donor motor nerves should be the goal.

17. SURGICAL TREATMENT OF INTERMEDIATE DURATION FACIAL PARALYSIS ( 3 WEEKS to 2 YEAR )

18. NERVE TRANSFER Potential indications for nerve transfers include: The distal stump is present . Proximal , ipsilateral facial nerve stump is unavailable for grafting . Facial muscles are capable of useful function after reinnervation .

19. NERVE TRANSFER 1. Nerve transfer a . Hypoglossal-facial b . Spinal accessory-facial c . Masseteric -facial 2. Cross face nerve grafting using sural nerve

20. Hypoglossal-facial Nerve transfer The most commonly used procedure is the hypoglossal-facial transfer. The classic XII-VII transfer: transection of the entire hypoglossal nerve distal to the ansa cervicalis and coaptation to the main trunk of the facial nerve .

21. Classic XII-VII transfer Divide the facial nerve close to the stylomastoid foramen . The facial nerve can be further mobilised by dissecting it freeing it from the parotid distal to its bifurcation . Reflect the distal trunk of the facial nerve inferiorly. Sharply divide the hypoglossal nerve quite far anteriorly along its course to secure an adequate length of nerve to transfer. Reflect it superiorly up to the distal facial nerve stump. Coapt the hypoglossal and facial nerves.

22. Split XII-VII transfer A pproximately 30-40% of the hypoglossal nerve is divided longitudinally for several centimeters. As it provides fewer axons, it is best connected only to the lower division of the facial nerve.

23. XII-VII jump graft E nd-to-side neurorrhaphy between hypoglossal nerve and a donor cable nerve graft (e.g. great auricular nerve) which serves as a jump graft to the main trunk of the facial nerve.

24. Mobilization of mastoid segment of facial nerve T he facial nerve can be mobilized in its mastoid segment from the 2nd genu distally and rotated inferiorly to allow direct coaptation to the hypoglossal nerve. This typically requires removal of the mastoid tip.

25. Hypoglossal-facial Nerve transfer The major concerns with the XII-VII transfer is the potential of hemitongue paralysis leading to dysphagia and dysarthria. Contraindications : M ultiple cranialneuropathies . D evelopmental facial paralysis. P rolonged facial palsy of greater that two year duration. Improved facial tone and symmetry - 90 % of patients. often combined this procedure with static slings in order to obtain immediate results until the reinnervation is completed.

26. Make a preauricular incision and elevate a skin flap over the parotid . Make a transverse incision in the parotid capsule approximately 1cm below the zygomatic arch and 3cms anterior to the tragus . Bluntly dissect through the parotid tissue up to the surface of the masseter muscle to avoid transecting branches of the facial nerve . Split the masseter to gain access to the deep surface of the muscle . Use a nerve stimulator to locate the nerve; the nerve is generally located approximately 1.5cms deep to the superficial muscular aponeurotic system ( SMAS). Follow the nerve anteriorly until it ramifies . There is usually a branch-free segment measuring 1cm that can be cleanly transected distally and reflected laterally into the wound, ready for coaptation to the stump of the facial nerve . Masseteric -facial N Transfer

27. MASSETERIC – FACIAL NERVE TRANSFER It is increasingly being used for facial reanimation . Good option due to its minimal donor morbidity .

28. Cross-facial nerve grafting (CFNG) CFNG may also be useful with a partial facial palsy to enhance residual function . The CFNG harnesses neuronal activity from the uninjured facial nerve activity to the contralateral side to power a free muscle transfer

29. Cross-facial nerve grafting (CFNG) CFNG may be done as a one- or two-stage procedure – One-stage CFNG : Both ends are repaired at the same operation. Two-stage CFNG

30. Cross-facial nerve grafting (CFNG) F irst stage on the unaffected side through a preauricular incision with a submandibular extension . The zygomaticobuccal nerve branches medial to the parotid gland are meticulously identified. Facial nerve mapping : identifies which nerve fibers stimulate the orbicularis oris and oculi muscles , lip retractors. When stimulated, the facial nerve branches that produce a smile and no other movement are selected.

31. CFNG All of the branches that create a smile are identified. Only branches that have smile function should be used. There should be no orbicularis oris function present in any of these branches. then approximately one half of them are divided and coapted to the nerve graft. Usually one or two branches are used. The nerve graft is passed across the face, and the end is banked in the upper buccal sulcus just past the midline.

32. CFNG The sural nerve is the usual donor nerve . The proximal ends of the donor facial nerve branches are sutured to the distal end of the nerve graft . Technical Modifications : Splitting : split longitudinally and half is used splitting provides a better end-to-end match Nerve Graft Length : In the past 25-cm nerve was used for the nerve graft and passed subcutaneously across the face to the opposite pretragal area ..The current practice is to use a short nerve graft, approximately 10 cm in length, and to bank the free end in the upper buccal sulcus. This should provide an innervated graft that is better. the waiting period between the first and second stages is reduced with use of a short cross-facial nerve graft from 12 months to around 6 months. Patients who have had short nerve grafts achieve stronger muscle contraction than was previously obtained with traditional long cross-facial nerve grafts

33. 1 st stage of 2-stage CFNG

34. 2nd stage CFNG This is often performed 6-12 months following the 1st stage . The distal end of the sural nerve graft then coapted to corresponding branches supplying specific muscle groups on the paralysed side.

35. The Principle of Babystters Although the concept of CFNG is ingenious, it necessitates a prolonged denervation period of the affected facial muscles while regeneration and elongation of the contralateral axons take place . This could lead to irreversible muscle atrophy, unless the CFNG procedure is undertaken soon after the facial nerve injury (within the first 6 months).

36. The Principle of Babystters For later cases {over 6 months to 2years ), Terzis in 1984 introduced the "babysitter" procedure. This is a two-stage procedure : the first stage involves use of 40% of the ipsilateral hypoglossal nerve, which provides powerful motor fibers to the affected facial nerve, reaching target connectivity quickly, and therefore preserving the facial muscle bulk. At the same time, several CFNGs are placed which are connected to seleaed branches of the unaffected facial nerve.

37. The Principle of Babysitters The second stage, usually 9 to 12 months later, involves secondary microcoaptations between the CFNGs and selected distal branches of the affected facial nerve. Variations of the "babysitter procedure" have been reported , including techniques such as end-to-side grafting and concomitant CFNG and hypoglossal facial grafting using a single sural nerve graft.

38. SURGICAL TREATMENT OF CHRONIC FACIAL PARALYSIS (>2 YR)

39. SURGICAL TREATMENT OF CHRONIC FACIAL PARALYSIS (>2 YR) STATIC CORRECTION OF ASYMMETRY : Static procedures aim to correct asymmetry at rest. DYNAMIC REANIMATION Dynamic reanimation attempts to restore symmetry both at rest and while smiling. Three elements are required for the formation of a smile: neural input, a functional muscle innervated by the nerve, and proper muscle arrangement

40. Brow : Direct Brow lift B est able to correct large discrepancies. incision be placed just along the main line of hair follicles. An ellipse of skin and frontalis muscle is excised and the paralyzed frontalis muscle repaired. Slight overcorrection is particularly beneficial if the person's normal side of the forehead is quite active during facial expression.

41. Coronal brow lift with static suspension performed through a coronal incision leaves an inconspicuous scar. amount of lifting that can be achieved is much less. with or without a fascial graft to suspend the brow from the temporalis fascia or medially on the frontal bone

42. If there is marked wrinkling of the forehead on the normalside , a normal-side frontal nerve resection with or without a frontalis muscle resection will help to correct forehead asymmetry . Because a simple resection of the frontal branches often results in reinnervation , the surgeon should consider resecting the entire lateral margin of the frontalis to obtain a permanent paralysis .

43. MANAGEMENT OF UPPER EYE LID

44. LAGOPHTHALMOS These are all directed at overcoming the unopposed action of the levator palpebrae superioris . Gold weight Temporalis transplantation Spring Tarsorrhaphy

45. Gold weight lid loading with gold prostheses is the most popular technique technical ease and reversibility. patient's eyelid configuration is important . If the amount of exposed eyelid skin above the lashes is more than 5 mm when the eye is open. 24-carat gold is used. Prostheses are available in weights ranging from 0.8 to 1.8 g. Adequate improvement in eye closure can be obtained with a weight of 0.8 to 1.2 g,

46. Gold weight The appropriate weight is selected by taping trial prostheses to the upper eyelid over the tarsal plate with the patient awake . The lightest weight that will bring the upper eyelid within 2 to 4 mm of the lower lid and cover the cornea should be used.

47. Complications include extrusion, excessive capsule formation causing a visible lump, and irritation of the eye by the weight

48. Gold weight T here is a high extrusion rate ( approxima-tely 10%) after 5 years.

49. P alpebral spring D escribed by Morel- Fatio WIRE LOOP WITH 2 ARMS

50. palpebral spring The advantage of this procedure is that it is not dependent on gravity . However, problems with malpositioning of the spring, spring breakage or weakening, pseudoptosis due to excessive spring force, and skin erosion have prevented the widespread use of this procedure. It is certainly a more involved procedure than insertion of the gold weight, and results may be dependent on the surgeon's skill level.

51. Temporalis M uscle transplantation Gillies

52. Temporalis transplantation ADVANTAGES : uses autogenous tissue addressing both upper eyelid lagophthalmos and lower eyelid ectropion . an excellent static support . eye closure on command . good lubrication of the eye through distribution of the tear film.

53. Temporalis transplantation DISADVANTAGES : disadvantages of this transfer are that with muscle contraction, the lid aperture changes from an oval to a slit shape. there may be skin wrinkling over the lateral canthal region. an obvious muscle bulge over the lateral orbital margin . Movements of the eyelids during chewing may also be a disturbing feature for the patient.

54. lateral tarsorrhaphy

55. lateral tarsorrhaphy M ain indication : lateral tarsorrhaphy is for the patient with an anesthetic cornea . severe corneal exposure . failure of aesthetically more acceptable techniques .

56. McLaughlin lateral tarsorrhaphy For mild degrees of orbicularis oculi palsy and lagophthalmos . A triangle of the anterior lamella (skin, muscle and eyelashes) is removed from the lateral 1/4 of the lower lid (from the grey line muco -cutaneous junction down). A similar triangle is removed from the posterior lamella (conjunctiva and tarsus) of the upper lid (from the grey line up). The lower lid is thus drawn under the upper, effectively tightening and elevating it. The lashes are preserved on the upper lid for camouflage of lateral lid adhesion

57. McLaughlin lateral tarsorrhaphy The palpebral fissure’s horizontal length is reduced by this procedure and the lateral visual field may be reduced . The elevation of the lateral canthus is minimal .

58. LOWER EYELID ECTROPION Ordinarily, the eyelid margin rests at the level of the limbus of the eye. Ectropion with lid eversion and more than 2 to 3 mm of scleral show is usually associated with symptoms of dryness and aesthetic concerns . This situation requires support of the entire length of the eyelid.

59. LOWER EYELID ECTROPION Options available are : Tendon sling Lateral canthoplasty Horizontal lid shortening Temporalis transplantation Cartilage graft

60. Tendon Sling A chieved with a static sling passed 1.5 to 2 mm inferior to the gray line of the eyelid and fixed both medially and laterally. This procedure provides good support to the lower lid. It does not deform the eyelid, it is not apparent to an observer. Tendon provides longer lasting support with less stretching than the fascia lata . If the sling is placed too loosely, it may be tightened at the lateral orbital margin.

61. Tendon Sling Proper placement is crucial; too low of a position will exacerbate the ectropion . In the elderly patient with particularly lax tissues, too superficial or high placement may result in an entropion .

62. Tendon Sling In patients with a relatively proptotic eye : patients with a negative vector - the lower eyelid sling will correct ectropion , but it may not decrease scleral show . In patients with a positive vector, in which the globe is posterior to the lid margin and the lid margin is posterior to the cheek prominence, the sling will be effective.

63. Lateral C anthoplasty Milder eyelid problems consisting of lower lid laxity and minimal scleral show. The canthal ligament must be reapproximated to the position of Whitnall tubercle, which is situated not only above the horizontal midpupillary line but also 2 to 3 mm posterior to the lateral orbital margin . V arious techniques of canthoplasty , such as the tarsal strip, dermal pennant, and inferior retinacular lateral Canthoplasty.

64. Lateral canthoplasty These methods are useful in the aesthetic or posttraumatic situation but stretch over the long term in a patient with facial paralysis.

65. Horizontal lid shortening This procedure tends to distort and expose the caruncle and does not provide a lasting correction.

66. Cartilage grafts prop up the tarsal plate. The cartilage, usually conchal , augmentation of the middle lamella and suturing of the cartilage to the inferior orbital margin. The cartilage tends to rotate outward rather than sit in a vertical position , thus producing a visible bulge and poor eyelid support

67. Upper lip and cheek P aralysis of the oral musculature, including drooling of saliva and speech difficulties. lead to difficulties with chewing food, cheek biting, and pocketing of food in the buccal sulcus due to paralysis of the buccinators. T he main emphasis of surgery is usually centered on reconstruction of a smile.

68. NASAL VALVE RECONSTRUCTION

69. Nasal Airway Paralysis of : nasalis and levator alaeque nasi combined with drooping and medial deviation of the paralyzed cheek . This results in a visual asymmetry and significant breathing problems particularly when sleeping, congenital facial paralysis, congenital airway obstruction.

70. Nasal Airway reconstruction S ling of tendon from the lateral aspect of the alar base up to the orbital margin. Use of spreader graft. C orrection of the lower face and lips with either a static or dynamic procedure will usually reposition the nasal base and correct the nasal obstruction

71. MANAGEMENT OF UPPER LIP AND CHEEK

72. Smile Analysis It is recognized that the unopposed smile on the normal side in unilateral facial paralysis will be an exaggerated expression of the same movement after reconstruction of the paralyzed side.

73. Smile Analysis The preoperative plan : The two arrows on the left cheek illustrate the direction of movement of the left commissure and upper lip when smiling. The location of the cross-facial nerve graft is outlined in the upper lip . On the right side of the face is the intended location of the transferred muscle.

74. Upper lip and cheek If the concern is primarily for asymmetry at rest, then a static procedure with slings can be quite beneficial. For the patient who is willing to apply conscious effort and desires static correction as well as the ability to achieve a smile, dynamic correction is required .

75. Static reconstruction Autologous : made of fascia such as tensor fascia lata or a tendon, preferably the plantaris , If this tendon is not available , the extensor tendon of the second or third toe can be used. immune compatible . incorporated into the surrounding tissues and closely maintains its pre-surgical length.

76. Static reconstruction Alloplastic materials : polytetrafluoroethylene , polypropylene mesh, and silicone rods that tend to form granulomata, Granulomata formation . have a high rate of extrusion . are easily stretchable .

77. Photo 1: Subdermal dissection to expose SMAS Photo 2: Skeletonization of zygomatic arch Photo 3: Orientation of Fascia lata

78. Photo 4: Insertion of Fascia lata Photo 5: Suspension with Fascia lata Photo 6: Pre and post operative photos

79. Static reconstruction S light overcorrection is more acceptable than an under correction because the patient is more symmetric when smiling .

80. Dynamic Reconstruction

81. Temporalis muscle transfer R etrograde temporalis muscle transplantation : Gillis It involves detaching the origin of the muscle from the temporal fossa and turning it over the zygomatic arch to extend to the oral commissure. Fascial graft is required to achieve the necessary length to reach the mouth.

82. Temporalis muscle transfer Advantage : excellent static positioning as well as voluntary activity . It is capable of producing an oblique lift to the mouth Diadvantage : significant hollowing in the temporal region . T he bulge of muscle present where it passes over the arch of the zygoma . N o control of the direction of movement.

83. Temporalis muscle transfer H ollowing in the temporal region that can be filled with an implant . Baker and Conley : recommend leaving the anterior portion of the temporalis behind to partially camouflage the temporal hollowing.

84. Temporalis muscle transfer McLaughlin : A ntegrade temporalis transplantation T he temporalis muscle is detached from the coronoid process of the mandible and brought forward . Fascial grafts are used to reach the angle of the mouth

85. M asseter muscle transplantation Baker and Conley : T ransplanting the entire muscle Rubin : separating the most anterior half of the muscle only and transposing it to the upper and lower lip. Rubin : transplanting the temporalis and masseter muscles together The temporalis provides motion to the upper lip and nasolabial fold; the masseter provides support to the corner of the mouth and lower lip.

86. Free muscle transplantation

87. Two Staged Free muscle transplantation Cross-facial nerve graft followed by the muscle transplantation. S uitable approach is to pare down a muscle to the desired size before transplantation. Muscle can be used are : Gracilis , P.Minor ,rectus abdominis ,LD, ECRB,SA,RF , Abductor haullicis . G racilis muscle is suitable for facial paralysis reconstruction because:

88. Free muscle transplantation : Two Staged The neurovascular pedicle is reliable and relatively easy to prepare . A segment of muscle can be cut to any desired size based on the neurovascular pedicle. This allows the surgeon to customize the muscle to the patient's facial requirements . There is no functional loss in the leg. Because the scar is in the medial aspect of the thigh, it is reasonably well hidden. The thigh is far enough removed from the face that a simultaneous preparation of the muscle and the face is easily accomplished

89. Free muscle transplantation : Two Staged The muscle is split longitudinally & the anterior portion of the muscle is used. The amount of muscle that is taken varies from 30% to 70% of the cross section of the muscle, depending on the muscle size and needs of the face. After facial measurements are taken, a piece of muscle with a little extra length is removed. It is usually inserted into the fibers of the paralyzed orbicularis oris above and below the commissure and along the upper lip . Preoperative smile analysis determines the points of insertion.

90. Free muscle transplantation : Two Staged The gracilis is positioned so that its hilum is close to the mouth and the motor nerve can be tunneled into the upper lip. The upper buccal sulcus incision is reopened, and the free end of the nerve graft is identified and coapted to the gracilis muscle motor nerve. vascular Anastomosis : facial vessels, superficial temporal vessels, transverse facial vein .

91. Free muscle transplantation : Two Staged Movement : 6 months or more have elapsed M aximal movement : gained by 18 months. At this stage, an assessment is made of the resting tension in the muscle and its excursion with smiling. T hird procedure to adjust the muscle : either tightening or loosening. T his can be combined with other touch-up procedures such as debulking or an adjustment of the insertion of origin.

92. Free muscle transplantation : Two Staged With this procedure, patients usually gain around 50% as much movement on the paralyzed side as on the non paralyzed side.

93. 1 st Stage A “short” cross-facial nerve graft is seen lying on the cheek in the position that it will be in when inserted End of sural nerve

94. 2 nd Stage Gracilis muscle with nerve and vascular pedicle Inset into orbicularis oris Gracilis muscle sutured to deep temporal fascia

95. Single-stage muscle transfers I nnervation : contralateral facial nerve. Technique requires : muscle with a long nerve segment, such as the latissimus dorsi or rectus abdominis , gracilis . The nerve is tunneled across the lip and coapted to the facial nerve branches on the opposite side of the face. Advantages : only one operation only one site of coaptation for regenerating axons to cross. There does not appear to be any significant denervation atrophy of the muscle while it awaits reinnervation .

96. Single-stage muscle transfers Disadvantage : T he muscle may function with facial movement, it may not contract when the patient smiles . This is because the facial nerve branches that are used are close to the mouth and are usually found through a nasolabial incision on the unaffected side. This approach does not allow thorough facial nerve mapping to be performed; thus, the most appropriate nerve branches may not be recruited.

97. MANAGEMENT OF LOWER LIP

98. Lower Lip The lower lip deformity caused by marginal mandibular nerve palsy . The marginal mandibular nerve consists of one to three branches : supplies the depressor labii inferioris , depressor anguli oris , mentalis , and portions of the lower lip orbicularis oris . The muscle function that is missed most by the patient is that of the depressor labii inferioris . Paralysis of this muscle results in the inability to depress, lateralize, and evert the lower lip.

99. Lower Lip In the normal resting position : the deformity is not usually noticeable as the lips are closed and the depressors are relaxed . However, when the patient is talking, the paralyzed side stays in an elevated position, whereas the nonparalyzed side is able to move inferiorly and away from the teeth . The deformity is most accentuated when the patient attempts a full smile, showing his or her teeth

100. Muscle transplantation Edgerton : transplantation of the anterior belly of the digastric muscle. The insertion of the digastric muscle to the mandible on the paralyzed side is divided and attached to a fascia lata graft that is then secured to the mucocutaneous border of the involved lip. Conley : modified this technique by leaving the mandibular insertion intact but divided the tendon between anterior and posterior bellies, rotated the muscle, and reattached the tendon to the lateral aspect of the lower lip. d igastric transplantation tends to act more as a passive restraint on the lower lip rather than as an active depressor

101. Terzis : has further modified the digastric transplantation by combining it with a cross-facial nerve graft coapted to a marginal mandibular nerve branch on the unaffected side, thereby allowing the possibility of spontaneous activation with smiling.

102. S elective myectomy Achieves symmetry both at rest and with expression. S elective myectomy of the depressor labii inferioris of the nonparalyzed side. D epressor resection can be performed as an outpatient procedure under local anesthetic . Simple myotomy will not produce long-standing results, whereas results from myectomy have been permanent.

103. Selective myectomy I njection of either long-acting local anesthetic or botulinum toxin into the depressor labi inferioris . This injection allows the patient a chance to decide whether to proceed with the muscle resection based on the loss of function of the depressor. As a result of this operation, the shape of the smile is altered on the normal side, and the lower lip is now symmetric with the opposite side.

104. Selective myectomy Depressor labii inferioris : marked preoperatively by asking the patient to show the teeth and palpating over the lower lip . The muscle can be felt as a band passing from the lateral aspect of the lower lip inferiorly and laterally to the chin . I ncision : intraoral buccal sulcus incision.

105. The muscle is identified; it is partly hidden by the orbicularis oris , whose fibers must be elevated to reveal the more vertically and obliquely oriented fibers of the depressor labii inferioris , which measures approximately 1 cm in width Care must be taken to preserve the branches of the mental nerve during the dissection Once the muscle has been identified, the central portion of the muscle belly is resected

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