Direct muscle neurotization for facial paralysis reanimation and recovery

Facial Reanimation in Facial Paralysis, Direct Muscle Neurotization

Plastic Surgery- facial paralysis: Considerations

Paralysis of the face is uncommon and is estimated to occur one in four thousand persons. It is noted by various practitioners ranging from "neurologists and neurosurgeons, trauma surgeons, ENT surgeons, head and neck surgeons, plastic surgeons, internists, and psychiatrists." (1) the face being the most important part of the human existence, paralysis causes physical and psychological problems. For example the inability to animate one side of the face causes trauma and restricts normal communication. (1) People adopt various methods to disguise their paralysis and often avoid disclosure and sometimes express anger. The case of facial paralysis and the response by the patient vary with age. In children often tend to be withdrawn and have personality problems. In the case of children who have "a congenital Bell's phenomenon or closure of the eye with upward gaze, the paralysis is often incomplete, involving only the muscles to the upper lip or central face." (1)

The primary objective of face surgery is to restore spontaneous symmetrical animation. The use of the "spinal accessory, the hypoglossal, or the mandible nerve" can bring back animation to facial muscles. (1) the analysis of facial paralysis in animals throws some light on the actual causes of paralysis other than Bell's palsy. The paralysis could be as a result of 'brain stem inflammation' or through 'intracranial injury, with or without 'petrosal bone fracture'. Other causes noted could be due to compression of the 'neoplasia' or 'otitis'. It is also observed that in dealing with animal paralysis of similar nature, trauma in dogs and cats was successfully repaired by direct 'coaptation'; tabulation and grafting with the help of non-nerve elements. (38)

All etiologies of facial paralysis, congenital, post traumatic, secondary to tumor excision

In identifying the etiology of facial palsy secondary to retro cochlear pathology or mass lesions of the middle ear for example, the 'Audiometric testing', including 'acoustic reflexes' and 'tympanometry', may be useful, while the Radiography and CT and MRI scans are essential in the probe for 'traumatic facial nerve palsy' to evaluate patients with possible parotid, skull base, temporal bone, intracranial, or extra temporal tumors. (3) Electrodiagnostic tests of nerve function can include exitablity tests, "electroneuronography -- ENog, and electromyography -- EMG." (3) the test is done by 'percutaneous stimulation' of the 'facial nerve'. The 'Maximum Stimulation Test - MST' and the electroneurography -- ENog and the EMG are used to measure the volitional muscle response'. (3) the modern measure also includes photography and visual documentation. (3)

Etiology in some diseases like 'craniosynostosis' would be noted having undeveloped 'mesoderm' usually occurring in the embryo in the fourth week of pregnancy. The law of Virchow states that the premature closure of one or more sutures results in limiting the expansion of the skull which limits the expansion in the perpendicular. The brain while expanding pushes the skull outward in the same perpendicular to the closed structure. This will be marked by the occurrence of 'papilledema' 'pseudoproptosis' as also 'optic atrophy.' (39) This results in the orbital socket being smaller and the eyes getting 'protoposed'. The intercranial pressure is bound to be high. The symptoms in such cases will be optic atrophy, head ache and papilledema. Or in the case of 'Crouzon's disease' where occurs a marked hooked nose and a frontal lobe which makes the disease also called the parrot head disease. Surgery in both these types of situations become mandatory as the result of the cranial pressure could result in death. (39)

Regarding the facial surgery discussions always centre on perfecting features and cosmetic changes. The debate must rather be on the goals of the surgery and the overall benefits that can accrue to the patient in terms of anatomical benefits. (7) in cases of adults and children different considerations of etiologies exist. For planned intervention and rehabilitation etiology is important. It is crucial that the etiology of the patient and associated problems be determined including the severity of the paralysis. In some cases etiology is apparent as in the case of a 'temporal bone fracture' or in 'partoid' cancer. Where it is obscure further tests may be necessary. In the absence of proper verification it may result in the deterioration of the patient's condition. (5)

All medical problems, and the time of onset of the paralysis is important along with the condition of the internal 'audiary canal'. MRI scan is helpful in diagnosis. A front cranial nerve examination and procedures like the 'hypoglossal facial anamostosis' need be conducted in cases where severe injuries in the cranial area are noted." (Park (5) p. 140) While assessing the anatomy of the patient, the forehead must be analyzed for cosmetic reasons. The degrees of the 'ptosis' of the brow along with eye examination are warranted. Regarding the eye it is important to observe for Bells disease, and the closure rate of the eye. Corneal anesthesia and dry eye are called Bad by Gulbor. Nasal functions and 'valve collapse' with or without 'septal' deformities must be noted. The depth of the 'septal' muscles and location are important. Similar examination of the mouth with particular notice to the mouth, upper and lower lips, dysfunction, dentures, drooling, biting etc. ought to be observed and recorded. (5)

Other tests that form the part of etiology are electrophysiological tests that help measure muscle dysfunction, and the maximal simulation test that determines the amount of facial nerve degeneration. Electromyography is used to find the 'depolarization' potentials of fibers and motor units. The patient may also be subjected to the nerve excitability test. Through this test we can obtain the current in amps that is necessary to obtain minimum 'facial movement'. (5) a difference to 3.5 amp between affected to the normal side will indicate a poor chance of recovery. To test the muscles an electrode stimulated record of muscle function is obtained by the 'electroneurography'. CT scans of the temporal bone helps in surgical planning. (5)

In short the necessary test for etiology may be summed up as "The history of the patient, Topognostic tests- Including hearing, stapes and schimers's tests, electrical tests - MST, EENG, and EMG tests, Radiographic study of chest, CAT Scan, magnetic resonance scan, and many laboratory tests needed for a surgical evaluation of the individual including lumbar puncture, WBC count, Mono spot tests, test for 'sarcodisis' and so on." (May, Schaitkin (6) p. 183) Bell's palsy is the most noted etiology, but there must be a diagnosis of exclusion all infections and congenital and developmental influences, and other causes must be ruled out. In a differential diagnosis for bell's palsy the diagnosis of exclusion works for 40% cases, the "chronic 'otitis media' may occur due to nerve compression from granulation tissue, or 'herpes 'zoster' 'oticus' which causes hearing problems with vertigo, and 'lyme disease' that forms after inoculation, and tumors - like temporal bone leukemia, fractures, and 'Melkwerson -Rosenthal Syndrome.'" (Kahan (10) p. 30)

In pediatric cases a surgical scoring system to asses the severity of the RRP disease is needed to track the course of the disease in the infant. (9) a case study of the etiology of a 3-day-old male child with left facial paralysis had the following history: The maternal history prior to delivery was normal, and the delivery was a 'vaginal delivery' without the use of forceps. There was mild facial asymmetry and no record of family inheritance of the disease. The physical examination did not show any abnormalities related to systemic, crano-facial or ophthalmologic, neuralgic defects. The etiology posed the problem of determining if it is traumatic, or congenital. Congenital facial paralysis can occur at the use of forceps caused by 'ecchymosis' or by indentation of the bony canal. In the case of paralysis with traumatic causes, the recovery can be better predicted. CT scan and other tests showed that this was a case of congenital unilateral facial paralysis of traumatic etiology. After three months full recovery of the patient was spontaneous and therefore no further intervention was necessary. (8)

The fact that natural recovery is possible without surgical intervention in case of infants with trauma, or facial paralysis owing to gynecological complications the case has to be studied in depth over time. In childhood the 'Acute lower motor neurone facial paralysis' is commonly observed and it is resolved in course of time naturally. (11) Some times conditions at the facial canal and mastoid cavity are the hot spots where the facial nerve which after leaving the pns at the 'pontomedullary junction' enters inside the skull through 'the internal auditory meatus' and the hot spots and problem areas may occur in these locations, along with the branches at the petrous temporal bone. (11)

In the case of the diseases that originate from malformities of the skull, 'Craniofacial techniques' are handy where the issue is an 'orbitofrontal fractures' and for 'post-traumatic sequelae', especially 'malar' and 'ethmoidal fractures'. "Craniofacial malformations' are very diverse and optimal timing for surgery is different from case to case." (39) the surgery is multidiscipline, spanning neurosurgery and plastic surgery. The amount of bone and soft tissue involvement in the deformities will determine the result of the surgery. Modern methods that involve the use of 'microplate' systems and computer aided imaging have gone a long way in aiding the surgery of the facial paralysis and anomalies. (39) the suggested etiology of the 'proptopsis' thus is a study of the history, physical records. The work-up for proptosis should begin with a complete history and physical, complete 'ophthalmic examination', 'orbital examination' with a record of palpitation, and proper imaging. Patients who show 'proptosis' "should have baseline thyroid function tests like TSH, free T3, free T4 and anti-thyroid antibodies are mandatory. Initial imaging should be in the form of a CT scan, followed by MRI if indicated." (Omer, Ozak, Ozgencl, Oouz, Faruk, Kamuran (38) p. 336)

Direct nerve to muscle neurotization of EYE SPHINCTER (orbicularis ori muscle, 12 LIPS DEPRESSOR, SMILE RESOTRATION and TONGUE specifically.

Disregarding the cause, whether by surgery or trauma, facial paralysis causes emotional disturbance in patients of any age group. It is the most outwardly identifiable trauma or surgery, exacts a dramatic physical and emotional toll from patients. The surgery for restoring the facial nerve must have created a difference in restoring tone, symmetry and simple voluntary motion. (14) the most important challenge in plastic surgery is reconstructing the eye and tongue movement which is a challenge to the surgical abilities and the nature of the process. The muscles used for facial surgery include "extensordigitorum brevis', Gracilis, 'Lassimus dorsi', 'Pectoralis major,' 'Rectus abdominis' and' Serratus anterior'." (Papel (17) p. 679) Surgeons speaking of the muscle nerve selection have the opinion that "muscle transfer should receive impulses from the uninjured facial nerve if a natural smiling response is to be provided." (Stone (16) p. 363)

The serious problem for the patient often is the inability to smile or move the lips. For the eye closure "free functional muscle transplantation offers a good solution for regaining near-normal eye protection without the need for implants." (Frey, Giovanoli, Tzou, Kropf, Friedl (12) p. 865) in an experiment wherein 42 of the patients with the issue of facial paralysis were being treated with the "Temporalis muscle transposition' to the eyes, in thirty four cases, free 'gracilis muscle transplant' with 'double cross-face nerve grafting' was resorted to." (Frey, Giovanoli, Tzou, Kropf, Friedl (12) p. 865) Further a study pertaining to "the preopertaion and post surgery details revealed that the 'gracilis muscle transplant' that was 'reinnervated by a 'zygomatic branch of the 'contralateral' through the nerve graft, changed the eyelid close count from 10.21 +/- 2.72 mm to 1.68 +/- 1.35 mm, compared with 13.70" (Frey, Giovanoli, Tzou, Kropf, Friedl (12) p. 865)

The techniques vary and there are variations that are caused by the mobility of donors in the case of 'hypoglossal-facial nerve repair'. (14) Today modern methods use 'innervated microvascular free muscle transfer'. (14) Challenges in surgery are reconstructing the lips to enable the patient to smile. In an analysis to chart out the dynamics of the smile, a 'dimensional analysis of smiles' was undertaken with volunteers having ten points marked on the 'nasolabial creases' and lips. (18) "The migration distance (in millimeters) and the direction (in degrees) between each point were measured in frontal and both lateral views, and thus 3-dimensional vectors (x, y, z scalars) were obtained." (Kang, Bae, Hwang, Nam (18) p. 379) and the resultant quantitative analysis is hoped to provide surgeons with data while doing the surgery. (18) "In younger patients, with congenital or with traumatic paralysis, the dynamic procedures provide a more natural and functional cosmetic appearance" (Park (13) p. 145)

The techniques in dealing with the tongue are called the direct approximation method. The tongue flaps and skin flaps may provide 'residual activity'. To obtain more graft for serious cases of tongue surgery is to consider the 'cutaneous flaps' at the 'cervical area', and chest or forehead. (20) 'The pectoralis major musculocutaneous flap' is a boon for the use in 'ortotal glossectomy'. (20) in the case of this type of surgery 'musculoaponeurotic system-platysma face lifts' resulted in one hundred percent recovery. (15) in a case where there was an 'resection of tongue cancer' five patients who underwent surgery using the 'reinnervated rectus abdominis myocutaneous free flap' which was used to coat 'tenth intercostal nerve' to the 'hypoglossal nerve'. (19) "Postoperative electromyographic assessment in two patients showed good functional recovery of the grafted muscle." (Yamamoto, Sugihara, Furuta, Fukuda (19) p. 993)

Specific indications for the technique (direct muscle neurotization in facial reanimation)

The first of the 'facial nerve neurotization' was being attempted about a century back. The Hypoglossal was used extensively and the first recorded surgery was in 1903 conducted by the British neurologist Harris and the surgeon Low. The insertion of the damaged 'fascicles' of the spinal nerve C5 into the healthy C6 and C7 for reb's palsy. Similar neurotization of the brachial plexus with accessory nerve, still current in practice was first attempted in 1923 according to Tuttle. (21) Later on the technique of using muscles - in the 'Muscle-to-muscle neurotization' was attempted in 1970 Tried on dogs, and later on humans, the attempt established that muscle grafts did result in appreciable recovery. The method of grafting the donor and the patient muscle with axions that sprouted being used for the graft was proved to be highly successful. It also created marked symmetry between both the sides (22)

The principle of 'Myoneurotization' was proposed by Lexter and Eden. Further, Owens later stressed on implanting the 'masseter muscle' in the face to obtain a complete neurotization. Cross face graft using the facial nerves was proposed by Scaramella. (6) the facial paralysis that caused muscles to be paralyzed can only be brought to normal by the 'reinnervation of the muscle' with 'Cross-Face Nerve-Transplantation' -- CFNT. (24) for the eyes, more specifically the 'Orbicularis-oculi function' a transplant is placed in a bilateral placement. (24) Specific to 'marginal mandibular paralysis', the muscle nerve technique is advocated and tried on patients the formula being "neurotization' to induce 'reinnervation' of a 'denervated' angle of the mouth in patients." (Kermer, Millesi, Paternostro, Nuhr (25) p. 302)

Another suggested method is the 'End-to-side -- ETS nerve repair' where a stump of the injured nerve is coated to an uninjured portion of the donor nerve helps in recreating the degenerated nerve and also helps regenerate motor functions. (26) This technique is used in management and reanimation of the face, and prevention of 'neuroma'. The success of the method of treatment largely depend s upon the axonal motor injury and sensory nerves. The method is clinically being experimented, and can be used in similar indications. (26) Different regional nerves have also been used in facial surgery. Using cadavers, the possible use of the 'mylohyoid' in reanimation was studied to identify donors of the facial surgery process. (27)

Using a curvilinear cervicofacial skin incision, it was observed that all the chosen donors had a link to the 'mylohyoid. This gives the clue that this nerve can be explored to be made useful as a donor for multiple uses in facial surgery. (27) in going into details of the study with cadavers, we can note the technical findings which offer vistas to study the effects in actual surgeries. For example in the cadever experiment all the specimens had a nerve to the mylohyoid. The length, which was 5.5, was the same. The diameter of 1 mm. was same for all specimens, and the "nerve to the mylohyoid reached the facial nerve stem and the temporofacial and cervicofacial trunks without tension.." (Tubbs, Loukas, Shoja, Acakpo-Satchivi, Wellons, Blount, Oakes (27) p. 677) There was no injury to the tissues or surrounding systems. "Based on the results of this cadaveric study, the use of the nerve to the mylohyoid may be considered for facial nerve reanimation procedures." (Tubbs, Loukas, Shoja, Acakpo-Satchivi, Wellons, Blount, Oakes (27) p. 677)

In another study the spinal chord was examined for creation of axons. However it was found that the chord was 'non-permissive to that of the axons' formed from the 'presynaptic motoneurons.' (Brunelli (28) p. 632) Experiments in this direction are being conducted on rats, using the chor's 'cephalad stump' using 'peripheral-nerve grafts' and other methods. The effort showed that "presynaptic motoneurons are also able to reconstruct the cytoskeleton of peripheral neurons, as well as motor end-plates." (Brunelli (28) p. 632) in the case of ocular nerves, it has been observed that "A 'denervated' half of the 'orbicularis oris' muscle is not 'reinnervated' spontaneously by axon sprouting from the intact 'contralateral' side." (Kermer, Millesi, Paternostro, Nuhr (25) p. 302) There appears to be a borderline between the facial nerves that appear to act as a huge barrier. Therefore a suggestion is made to use the 'muscle-nerve-muscle' method to 'reneurotize a denervated half' of the 'orbicularis oris muscle' in patients with the 'marginal mandibular paralysis'. This is a method that was attempted with four patients resulting in better function of the lower lip. (Kermer, Millesi, Paternostro, Nuhr (25) p. 302)

ElectroMyography before and after the direct neurotization technique to the muscles (eye sphincter, depressor, tongue, smile restoration) to show improvement in function

The evaluation of the effects of the 'neurotrophic factors' especially on the 'transected peripheral nerve' is underway. The most used method is 'muscular neurotization'. What is to be considered in depth is the NGF or 'nerve growth factor', "which is one of the primary neurotrophic factors, on the reinnervation of denervated muscles by neurotization." (Menderes, Mustafa, Vayvada, Ozer, Barutcu (35) p. 415) "The positive effects of NGF on the neurotization of denervated muscles seen in this study suggest that it may be useful for treating some difficult reconstructions caused by denervation." (Menderes, Mustafa, Vayvada, Ozer, Barutcu (35) p. 415) the importance in any facial paralysis case is the consideration of the eye. Earlier 'Neurotization of denervated muscles' was also done using 'coaptation of peripheral nerves' of the viens that drained the chosen muscles. "Sprague-Dawley experiment" on rats with the "lateral gastrocnemius branch" from the "tibial nerve" which was attached to the distal stump at the 'astrocnemius vein' confirmed the electropsychollogical relevance of nerve fibers in all animals. The fibers were formed in "lose proximity to the outside of the vessel, to enter the muscle" (Tada, Hirayama, Atsuta, Takemitsu (37) p. 397)

The eye is to be regarded in a separate light, with great importance to the trauma and the eyelids. "Patients with immediate onset of paralysis are likely to need surgery." (Haberman (29) p. 143) ENog is argued to be the primary method of determining the need for surgical intervention. According to Fisch, patients who were treated for facial nerve degeneration with transactions for tumors gave out a result of hundred percent degeneration o three days while all patients had full recovery. The management of traumatic paralysis is still a controversial subject. (29) the urgent priority consideration in management of the surgery ought to be a) 'Corneal Protection', with proper lubrication, steroids, and proper management of the edema of the 'facial nerve'. If the 'ipsilateral facial nerves' are being used, reinnervation of the muscles can be considered. (30)

Nerve grafting is necessary where nerve gaps are noticed. (30) the electrophysiological evaluation was done formerly by the MRC especially in 'brachial plexus' for 15 patients with "neurolysis and/or nerve transfer and/or neurotization were performed, within 3 weeks to 6 months after the injury was incurred, to ameliorate the resulting severe disabilities." (Tsai, Chuang, Yen, Huang, Lin, Cheng (36) p. 12) the scale used to measure was a modification of 'Dumitru's and Wilbourn's scale' and the results that were arrived at were as shown: "Normal to slight decrease of SNAP amplitude and CMAP amplitude, and occasional denervation; moderate: profound decrease of SNAP amplitude and CMAP amplitude, constant denervation, and normal to slight decrease in motor unit recruitment; severe: absent SNAP amplitude, absent CMAP amplitude, marked denervation, and profound decrease or no volitional motor unit recruitment. mild = 1; moderate = 2; severe = 3). The motor power of the target muscles was graded through MRC scores. The pre-surgical vs. post-surgical differences in the severity of the injury to each brachial plexus component, and differences in the grading of target muscle power, were calculated through the Wilcoxon signed-rank test. The pre-surgical degrees of the severity of injury, as measured by the electromyography (EMG) were 3.00 a± 0.00 (mean a± SD) in root, 2.84 a± 0.50 in trunk, 3.00 a± 0.00 in cord, and 2.85 a± 0.38 in terminal nerves." (Tsai, Chuang, Yen, Huang, Lin, Cheng (36) p. 12)

What causes facial paralysis itself is the subject matter of consideration with theories that state "The sequel of trauma to the facial nerve is well-known. Not only can gross facial asymmetry occur with paralysis, but the functional problem of corneal exposure, disturbances, with speech and eating can be present and be irritants." (Park (13) p. 180) the plastic surgeon does not have the tools to determine the integrity of the nerve and recurrence, for which it is better to rely on 'electrodiagnostic' tests, especially when the history of the paralysis is obscure. (13) "Voluntary and spontaneously generated facial motor responses can help to characterize the condition of motor units with high precision. The early EMG testing is therefore very important." (Lalwani (31) p. 899) in any ENoG test with the failure of the 'ENoG' in obtaining any compound muscle activity, the electromyography studies like confirmation of 'fibrillation potentials' 'prophysic potentials' will provide clues about the 'reinnervation' progress. (33) Anesthesia is blamed for some facial paralysis. "The most common cause of facial paralysis during stapes surgery is the local anesthetic used." (May, Schaitkin (6) p. 525) the drugs may spread to the 'stylomastoid foramen' and produce a complete or partial paralysis. When a facial exploration is to be done, general anesthesia is recommended. (6)

Evaluation and Conclusion

With the analysis of the evidence available and the etiology that is required to be studied in depth and various procedures that have been tested and implemented in facial plastic surgery for paralysis, we note that some considerations that are general to plastic surgery including cosmetic surgery and the technology of nerve and muscle grafts interlope. Plastic surgery is about making the muscles and nerves functional, while at the same time achieving the symmetry of the face and removing motor inhibitions. It extends to preoperative and post operative considerations of the ocular movements, care of the eye and mandible regions. The aim of the surgery is to achieve the goal of not only reactivating the paralyzed nerves and muscles but also obtain a better coordination of the involved organs in such a way that the patient has normal control of the voluntary muscles of both sides as far as possible and feasible. To this end the diagnosis, planning and execution of the surgery and the post operative care and rehabilitation techniques play a vital role in achieving success. Although the type of paralysis is rare in adults, we have noticed that in infants and children it is common. The consideration of surgery therefore stems from the basic understanding of the type of paralysis that has occurred.

Plastic surgery has brought in ample scope for rejuvenation and regaining the work of the inert muscles and nerves by grafting and even by the methods of creating axons. In this advanced state of technology at our disposal, surgery can bring about a near total recovery even in patients who have lost control of facial nerves on account of malignancy. Some other causes: It is to be noted that facial paralysis need not be on account of "Bell's Palsy." We now know that if the face paralysis was consistent over a year it may be due to causes other than Bells Palsy. It is pointed out that even anesthesia can result in facial paralysis. The approach to treatment varies with each patient and the surgical procedure to be adopted. There are static and dynamic methods available for the surgery, and each method is to be used analyzing the history and etiology of the patient. The general aim of plastic surgery, that is to create a proper 'facial symmetry', and voluntary facial movement with normal smile must also be a goal in the case of plastic surgery for the paralysis of the face too. Some of the modern successful methods that has been detailed include nerve grafts, and muscle transfer.

Etiology is the base for the surgical plan and the proper use of the information with the required differences for example between adults and children, different set of etiologies will exist. In physical observation the etiology for some patients is obvious as in the cases of fractures and some malignancy of the 'partoid' for example. In all other cases the etiology is built based on multiple tests and the imaging taken together. In the 'neurotization' techniques that evolved, the method of grafting the donor and the patient muscle with axions that sprouted being used for the graft was proved to be highly successful. Lexter and Eden's 'Myoneurotization' and the later 'reinnervation of the muscle' with 'Cross-Face Nerve-Transplantation' and the experiments for the future use of nerve to the 'mylohyoid' and the 'muscle-nerve-muscle' method are available to day for reconstruction and successful grafting. Therefore today there are many tested and documented methods for carrying out the plastic surgery to rework on the facial muscles and nerves, with the condition of the patient and the history and etiology determining the type and method of surgery and in determining the preoperative and post operative procedures.