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Paralysis of the seventh nerve
PARALYSIS OF T H E S E V E N T H NERVE By N. R. DUTT, M.B., B.S., M.Sc.
Royal Victoria Hospital, Montreal, Canada E m b r y o l o g y . - - T h e seventh cranial (facial) nerve appears during the fifth and sixth weeks of intrauterine life. Motor and sensory nuclei are arranged in definite masses within the basal and alar plates of the myelencephalon respectively. Motor fibres, after emerging from the hindbrain, run to the hyoid arch. Because o f this primary relationship they innervate the muscles of facial expression and all other muscular derivations of the second arch. Sensory fibres grow from the geniculate ganglion, which develops from a more rostral portion of an originally common facial-acoustic ganglion. Central fibres enter the alar lamina and peripheral ones form the chorda tympani and greater superficial petrosal nerves. A n a t o m y . - - T h e facial nerve consists of motor and sensory divisions. The motor nucleus in the pons contains multipolar cells in ventral and dorsal groups. Ventral neurones supply the lower facial muscles, the lower half of the orbicularis oris, levator labii superioris, and chin. Dorsal ones supply the upper facial muscles, frontalis, zygomatics, and upper half of the orbicularis oris. After emerging from the brain at the inferior border of the pons medial to the auditory nerve, the facial nerve enters the internal auditory meatus with its sensory root. It then passes through the facial canal in the temporal bone and lies on the inner wall of the tympanum. In this part of the course it gives off a small branch to the stapedius muscle, a twig to join the auricular branch of the vagus nerve and the chorda tympani separates from it. The seventh nerve emerges from the skull through the stylomastoid foramen, and passes forward through the parotid gland to the facial units. The stylohyoid and posterior digastric muscles as well as the muscles of the pinna and the posterior belly of the occipitofrontalis receive small rami after its exit from the stylomastoid foramen but before its entrance into the parotid gland. Finally, after sending out minute twigs to join the greater auricular, auriculotemporal and glossopharyngeal nerves, it divides into two sets--temporofacial and cervicofacial--which, with their respective branches, supply all the muscles from frontalis to platysma. The sensory root, called the nerve of Wrisberg, is actually a separate nerve. It is composed of fibres from the geniculate ganglion, many efferent salivary fibres, vasodilator fibres to the pial vessels, fibres carrying proprioceptive impulses from facial muscles and the chorda tympani, supplying the anterior two-thirds o f the tongue. FACIAL NERVE LESIONS IEtiology.--Traumatic injuries such as stabs, lacerations, and gunshot wounds can interrupt the facial nerve beyond the stylomastoid foramen because of its superficial position. Fractures of the base of the skull, compression by tumours, especially at the pontocerebellar angle, aneurysms, abscesses, hmmorrhagic effusions, meningitic hyperplasias, tabetic or gummatous lesions, and so on, are the pathological phenomena responsible for intracranial injury to this 278
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nerve. Outside the skull, similar morbid processes such as expanding or invasive lesions in adjacent tissue may harm the nerve. Surgical procedures dealing with such lesions, birth injuries, and mastoid operations may injure the facial nerve. Many toxic or infective processes affect the nerve usually in the region of the facial canal. These include simple catarrh, sepsis, cholesteatoma, tubercle, epithelioma, osteitis, and necrosis. Others, more general, include erysipelas, herpes zoster, mumps, so-called uveoparotitic disease, scarlatina, diphtheria, influenza, cerebrospinal meningitis, rabies, tetanus, malaria, and leprosy. Sometimes facial palsy forms part of a cranial polyneuritis or of multiple peripheral neuritis. Cold wind blowing on the cheek is also said to be a factor affecting this nerve. S y m p t o m a t o l o g y . - - h is of importance to distinguish extracranial from intracranial lesions and to determine accurately the site of the disturbance of the nerve. I. Intraeranial--frequently diplegic. I. Cortical Lesion. (a) Total paralysis of the lower part of the face on the opposite side. (b) Partial paralysis of the upper part of the face on the opposite side. The upper part of the face is supplied from both sides of the cortex of the brain so that if one cortex is injured the upper half of the face still gets a supply from the other cortex, the paralysis being partial. (c) Taste and salivary fibres normal. (d) Corneal reflex retained. (e) Stapedius not paralysed. ( f ) No reaction of degeneration. 2. Lesion of Internal Capsule.--Symptoms as above but movements of expression retained.
II. ExtraeranialBalmost always monoplegic. I. Lesion at Entrance of Nerve into Internal Auditory Meatus, e.g., in fractured skull. (a) Paralysis of all the motor functions of the nerve. Taste fibres unaffected. (b) Stapedius paralysed. This produces hyperacusis (unusually loud voice). (c) Corneal reflex lost. (d) Movements of expression lost. (e) Pronounced reaction of degeneration. 2. Lesion in Bone Distal to the Nerve to the Stapedius.--Same symptoms but no hyperacusis. Taste is absent from the anterior two-thirds of the tongue. 3. Lesion at the Stylomastoid Foramen.--The same symptoms as in 2 except that taste fibres are unaffected.
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T r e a t m e n t . - - T h e surgical procedures for the alleviation of the symptoms of seventh nerve paralysis are of two types : those which attempt to reinnervate the facial muscles and those which attempt to conceal or minimise the deformity by mechanical measures. The former group comprises (I) decompression of the nerve, (2) direct end-to-end anastomosis, (3) nerve grafting, (4) facial nerve anastomosis with contiguous motor nerves. The latter group comprises (i) fascial suspension, (2) reanimation with or without tendon or fascia, (3) meloplasty. Sometimes temporary mechanical supports are used during the period of waiting to determine whether or not there will be return of function or to reduce stretching of the paralysed muscles. In addition to clinical signs and symptoms the following tests are of value in establishing the level and the cause of the lesion : (I) X-ray of the skull and temporal bone; (2) faradic stimulation for nerve; (3) galvanic stimulation for muscles; (4) audiometric test ; (5) vestibular test ; (6) taste and lacrimation tests ; (7) stapedius muscle test. Within six months some evidence of regeneration should be present if it is going to appear. After nerve anastomosis, the percentage of recovery is greater if continuity is re-established within a year after section. If galvanic current does not produce muscular contraction, the muscles are taken to be fibrotic and nerve suture is useless. Facial Decompression.--A curved retro-auricular incision is made down to and through the periosteum, the latter is elevated, and the cortex of the entire mastoid process is exposed. The digastric groove is located as a guide to the stylomastoid foramen and sufficient mastoid cortex and cellular content are removed to expose the horizontal semicircular canal. A line from this canal to the foramen marks the course of the nerve. Starting at the foramen and working upwards to the lesion, the bone is removed piece by piece so as to ensure the decompression. Other tissues compressing the nerve are also taken out. The sheath of the nerve is slit open freely above and below the lesion. The open canal is then covered with a piece of fresh muscle or silver foil. The wound is dosed, with or without drainage, as the occasion demands. When the injury is between the stylomastoid foramen and the anterior border of the parotid gland, the nerve, after being exposed at the foramen, should be followed distally until the lesion is located. Anastomosis.--If an interruption in continuity has occurred sharply, cleanly, and without laceration or crushing, the ends may be approximated by placing fine sutures in the sheath. Suture is not required in the bony canal if the ends are in approximation. In such a case the point of approximation is covered with a piece of muscle or silver foil. I f laceration or crushing has occurred, the injured part should be excised, and if the loss is slight the ends may still be approximated by freeing the nerve in its bed from the horizontal canal to the stylomastoid foramen. Graft.--When there has been so much destruction of the facial nerve in lesions peripheral to the stylomastoid foramen or in the bony canal that the ends cannot be approximated, a nerve graft may be used to bridge the gap. Usually the lateral or anterior femoral cutaneous nerve provides the autograft. In the bony canal the graft is laid into place without suture and is covered with fresh
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muscle tissue or blood clot. Distal to the canal it is necessary to suture the ends of the graft to the transected ends of the facial nerve. Facial Hypoglossal Anastomosis.--With the patient in a semi-supine position, with the shoulder elevated on a sandbag and the head turned to the opposite side, an incision is carried forwards from the mastoid process, parallel to and approximately one fingersbreadth below the angle of the jaw. The mastoid process is exposed with a periosteal elevator and the sternomastoid and digastric muscles are identified. The facial nerve is exposed at the stylomastoid foramen and approximately 2 cm. dissected free. It is transected at the stylomastoid foramen. The digastric muscle is exposed as far as the hyoid bone, and the hypoglossal nerve is easily found beneath the lower end of the upper belly of the digastric. Approximately 3 to 4 cm. of the hypoglossal nerve and descendens hypoglossi branch are freed and transected. The central end of the descendens hypoglossi is then sutured to the distal end of the twelfth cranial nerve (with No. 4o stainlesssteel wire). The needle is inserted through the centre of the cut end of the fasciculi and brought out through the epineurium approximately 8 ram. back. Now the central end of the twelfth nerve is carried underneath the digastric muscle and sutured to the peripheral end of the seventh nerve in the same manner. Approximately a gap of i mm. should separate the ends of the sutured nerves in each location. The site of the nerve suture is covered with gelatin sponge. The wound is irrigated with antibiotic solution if necessary, and closed in layers. Facial Accessory Anastomosis.--After the facial nerve has been exposed at the stylomastoid foramen, using the same incision, the sternomastoid muscle is retracted posteriorly. The posterior part of the digastric muscle is elevated. The spinal accessory nerve lies on, or just in front of, the transverse process of the atlas, covered by a layer of deep fascia. The nerve is isolated up to its entrance into the sternomastoid muscle. The same procedure of crossanastomosing the descendens hypoglossi to the distal stump of the spinal accessory is carried out, and the proximal stump is sutured to the distal segment of the facial nerve. The spinal accessory divides and goes into trapezius and if only one division is used no trapezius paralysis results. Fascial Sling.--After an incision has been made above the hair line in the temporal region a Blair needle is passed downwards and medially to emerge at the midline of the lower lip, where a small incision is made. One end of the fascial strip taken from the fascia lata of the thigh is then inserted into the needle and withdrawn through the original incision in the temporal region. The needle is reinserted to pass through the subcutaneous tissue about a quarter of an inch below the initially inserted strip of fascia lata. The end of the fascia protruding from the lip incision is picked up and drawn through this second pathway, the loop in the midline, including a good bite of the orbicularis muscle. With the same procedures, the midline of the upper lip and the angle of the mouth of the paralysed side are drawn up and backwards to the desired position. A piece o f fascia should be inserted from the midline of the upper lip, around the angle, to the midline of the lower lip and securely sutured to the orbicularis muscle at all these points. The upper ends of the fascia strips are tightened as required and sutured to the temporal fascia. To correct the drooping of the lower eyelid, a fascial loop is passed through
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the lower lid and is fastened medially to the inner canthus, and laterally to the temporalis fascia. Reanimation.--The temporalis and the masseter muscle, supplied by the fifth nerve, are used in this operation. The masseter muscle is exposed by making an incision along the lower border of the mandible and elevating the overlying skin. The anterior half of the muscle is separated from below, retaining the nerve and blood supply, and is sutured to the orbicularis oris at the corner of the mouth. Alternatively, a skin incision is made to expose the temporalis fascia. The temporalis muscle is detached from the temporal fossa, after its fascia has been cut through. Three pedicles are made, one for the angle of the mouth, and two smaller ones--one for each of the eyelids. The largest pedicle is carried through a tunnel beneath the skin to the angle of the mouth and implanted into the orbicularis oris. In the same way the other two pedicles are passed through the individual tunnels in the upper and lower eyelids and are united at the inner canthus by making an incision through the skin to permit the suturing. Meloplasty.--In some cases of facial paralysis redundancy of the skin of the face is removed by meloplasty. In this operation the incision begins at the temple within the hair line and is carried down to the attachment of the helix, around which it is curved to the posterior surface of the tragus, thence down and around the lobule and upwards behind the ear, to end sharply downwards and backwards within tl,_e hair line. To avoid injury to the filaments of the facial nerve, the incision and undermining must be superficial. The skin of the face is undermined extensively. Complete hmmostasis is essential. With the skin flap adjusted to the desired tension, the excess skin is excised. Skin closure is done with interrupted sutures. A layer of sutures in the deep dermis is worth while to remove tension from the skin edges. A pressure dressing is applied. DISCUSSION
For brevity, only the treatment of well-established cases of facial paralysis is discussed here, and although some difference of opinion with regard to methods and results of treatment exists in the literature, only those procedures accepted by most workers are outlined. Surgical treatment of facial paralysis depends largely upon mtiology. The time when surgical treatment should be undertaken varies with circumstances. In general it is indicated when paralysis has persisted for not less than from six to nine months. The degree of palsy, presence of lagophthalmos or ectropion, lack of improvement in electrical response, and the sensitiveness on the part of the patient to his or her disability influence the decision. In relatively recent cases end-to-end anastomosis, nerve grafting, facial nerve anastomosis with a contiguous motor nerve or decompression of the nerve may be of value. But in some cases, especially in those of long-standing, a palliative operation is preferred, using muscle or fascial sling, or a combination of both. As a rule one or other type of nerve anastomosis should be preferred if galvanic reaction persists, and some kind of plastic reconstruction if it is lost. For nerve anastomosis, the hypoglossal, spinal accessory and glossopharyngeal have been used. On occasion a double anastomosis has been performed (facial hypoglosso-accessory).
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So far as the palsy is concerned, the results are often encouraging, but hemiatrophy of the tongue entailing no gross inconvenience, loss of power in the sternomastoid and trapezius (if the eleventh nerve is chosen), and the occurrence of facial movements when the other nerve is in action constitute serious disadvantages. In the process of eating, swallowing, or moving the shoulder, according to the particular method employed, facial grimaces may cause embarrassment ; for example, a patient had to discontinue using her umbrella, since every time she held it up her face went into spasm. For this reason such unnatural operations are being abandoned in favour of resection of the nerve with end-to-end suture of a graft from another nerve. Ballance (I932), who advocated the procedure, thought it would also prevent the occurrence of spasmodic contractions in facial muscles. Plastic surgery can do much in the case of total paralysis with atrophic musculature. One of the most successful methods consists in applying a muscle pedicle, from the temporal or masseter to the orbicularis of the eye and mouth, whereby the unpleasantness of the condition is relieved, the eye can be closed, the corner of the mouth lifted, and the patient's state of mind correspondingly benefited. However, in evaluating a patient for some type of reanimation in seventh nerve paralysis, several points must be considered. It is necessary to determine whether the nerve injury is degenerative or non-degenerative, whatever may be the cause of the injury ; and to what extent the nerve is going to regenerate, if at all. A block in the transmission of the nerve impulses in this motor nerve may be of only a transient nature such as is seen in Bell's palsy. This may persist up to ten weeks, followed by rapid and complete return of movement. It is probably an ischa:mic block due to pressure oedema of the nerve as it passes through the bony canal. In this palsy there is no destruction of the nerve pathways. The nerve degeneration means an interruption of the axons and denervation of the muscle. Denervated muscle becomes flaccid and atrophic with progressive shrinkage of the muscle fibres, an increase in connective tissue, and finally obliteration of the terminal Schwann tubes of the degenerated nerves and motor end-plates. When this stage is reached good clinical recovery is impossible, since destruction of the nerve end-plates prevents reinnervation. Muscle atrophy in denervated muscle increases with overstretching, which is brought about by the pull of gravity and the normal muscles of the other side of the face. Stretching and thinning of the skin and obliteration of the normal facial contours are the usual accompanying factors. In arriving at the final decision regarding the nature and progress of the pathology in this motor nerve, the history of the nature of the injury should be thoroughly explored. Electromyography may also be useful in evaluating the nature of the pathology. Unfortunately, faradic and galvanic tests do not give an exact picture of the excitability of the muscle and nerve. Reaction of degeneration gives little guidance to regeneration of the nerve, since good functional recovery is possible with abnormal electrical reactions still present. Fairly good information can be obtained by serially taken strength-duration curves, using the Bauwen's constant current or a Ritchie Sheath stimulator. In the later stages electromyography and observation of the fibrillation of the muscle are good guides to the status of the muscle.
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Though the choice of the time of operation for reanimation is difficult, when it is reasonably certain that spontaneous recovery cannot be expected, operative treatment is indicated. Time should be allowed for regeneration because the operation itself can damage muscles and nerves still capable of regenerating. One must therefore support the face temporarily during the observation period to prevent overstretching of muscles and skin. Mechanical elevation of the corner of the mouth and associated areas, to counteract gravitational pull and that of the normal muscle from the opposite side, is of value. A hook from the corner of the mouth is used, but itself can be responsible for overstretching the orbicularis oris, elevators, and depressors. A more satisfactory method in adults is the intraoral splint attached to the upper teeth. In children the hook is used until the permanent teeth erupt to make it possible to fit a cap splint.
A
B FIG. i A, Facial paralysis following a radical m a s t o i d operation on the right side. B, R e g a i n e d right facial n e r v e f u n c t i o n a p p r o x i m a t e l y one year after I cm. n e r v e graft in facial canal f r o m t h e anterior femoral cutaneous nerve.
The reanimation procedure is in most cases associated with ridectomy to take up the slack skin, and lateral tarsorrhaphy when epiphora develops. In children the procedure is unsatisfactory since the transplanted fascia does not grow, and as time passes this results in a more disfigured face. Grundt (195 o) noted the tendency of the fascia to be attached to surrounding tissue along with degeneration of the muscle, resulting in a fixed smile. To eradicate this difficulty he prefers a graft of the palmaris longus with paratenon attached to a muscle flap from the temporalis and to the corner of the mouth. CONCLUSION Facial paralysis is one of the most pathetic deformities to which humans are subjected; and the complications both physical and psychological make the life of the patient miserable. However, in properly chosen cases with due respect to time and method, in co-operative patients, reconstructive surgery can do much
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~Fig. 2.--A, Exposure of perineural fibroblastoma involving right seventh and eighth cranial nerves. Removal required the intracranial sectioning of both nerves with resultant facial paralysis. B, C, Post-operative. B, face at rest ; C, tongue protruding. Facialhypoglossal anastomosis with supporting fascia lata stings. Recovery of facial nerve function illustrated after one year.
A
B
A
FIG. 2
C
B FIG. 3 A, Twin siblings with congenital right-sided facial paralysis. B, Reanimation with fascia lata slings to right temporal and masseter muscles and modified meloplasty.
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A
B FIG. 4 Facial paralysis following removal of perineural fibroblastoma of right eighth nerve. A, Dissection to show exposure in accessory facial anastomosis. B, Illustrating recovery of facial nerve function, with shoulder elevated, one year after spinal accessory-facial anastomosis.
Fig. 5-- A, Radiological evidence of a fracture of left parietal and temporal bone extending into the middle ear, with resultant facial paralysis. B, C, Supporting wire slings were inserted to support facial muscles pending spontaneous recovery of facial nerve as illustrated.
A
B
FI~. 5
C
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to alleviate physical disabilities and thereby enable the patient to endure his misfortune more easily. Although it is almost impossible to restore the original cosmetic appearance and functional ability in long-standing well-established cases, the improvement as illustrated by the photographs makes surgical treatment well worth while (Figs. I to 5). REFERENCES BALLANCE, C., and DUEL, A. B. (~932). Arch. Otolaryng., I5, I. GRUNDT, B. (I95O). Brit. ft. plast. Surg., 3, 5°.
Royal Victoria Hospital, Montreal, Canada E m b r y o l o g y . - - T h e seventh cranial (facial) nerve appears during the fifth and sixth weeks of intrauterine life. Motor and sensory nuclei are arranged in definite masses within the basal and alar plates of the myelencephalon respectively. Motor fibres, after emerging from the hindbrain, run to the hyoid arch. Because o f this primary relationship they innervate the muscles of facial expression and all other muscular derivations of the second arch. Sensory fibres grow from the geniculate ganglion, which develops from a more rostral portion of an originally common facial-acoustic ganglion. Central fibres enter the alar lamina and peripheral ones form the chorda tympani and greater superficial petrosal nerves. A n a t o m y . - - T h e facial nerve consists of motor and sensory divisions. The motor nucleus in the pons contains multipolar cells in ventral and dorsal groups. Ventral neurones supply the lower facial muscles, the lower half of the orbicularis oris, levator labii superioris, and chin. Dorsal ones supply the upper facial muscles, frontalis, zygomatics, and upper half of the orbicularis oris. After emerging from the brain at the inferior border of the pons medial to the auditory nerve, the facial nerve enters the internal auditory meatus with its sensory root. It then passes through the facial canal in the temporal bone and lies on the inner wall of the tympanum. In this part of the course it gives off a small branch to the stapedius muscle, a twig to join the auricular branch of the vagus nerve and the chorda tympani separates from it. The seventh nerve emerges from the skull through the stylomastoid foramen, and passes forward through the parotid gland to the facial units. The stylohyoid and posterior digastric muscles as well as the muscles of the pinna and the posterior belly of the occipitofrontalis receive small rami after its exit from the stylomastoid foramen but before its entrance into the parotid gland. Finally, after sending out minute twigs to join the greater auricular, auriculotemporal and glossopharyngeal nerves, it divides into two sets--temporofacial and cervicofacial--which, with their respective branches, supply all the muscles from frontalis to platysma. The sensory root, called the nerve of Wrisberg, is actually a separate nerve. It is composed of fibres from the geniculate ganglion, many efferent salivary fibres, vasodilator fibres to the pial vessels, fibres carrying proprioceptive impulses from facial muscles and the chorda tympani, supplying the anterior two-thirds o f the tongue. FACIAL NERVE LESIONS IEtiology.--Traumatic injuries such as stabs, lacerations, and gunshot wounds can interrupt the facial nerve beyond the stylomastoid foramen because of its superficial position. Fractures of the base of the skull, compression by tumours, especially at the pontocerebellar angle, aneurysms, abscesses, hmmorrhagic effusions, meningitic hyperplasias, tabetic or gummatous lesions, and so on, are the pathological phenomena responsible for intracranial injury to this 278
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nerve. Outside the skull, similar morbid processes such as expanding or invasive lesions in adjacent tissue may harm the nerve. Surgical procedures dealing with such lesions, birth injuries, and mastoid operations may injure the facial nerve. Many toxic or infective processes affect the nerve usually in the region of the facial canal. These include simple catarrh, sepsis, cholesteatoma, tubercle, epithelioma, osteitis, and necrosis. Others, more general, include erysipelas, herpes zoster, mumps, so-called uveoparotitic disease, scarlatina, diphtheria, influenza, cerebrospinal meningitis, rabies, tetanus, malaria, and leprosy. Sometimes facial palsy forms part of a cranial polyneuritis or of multiple peripheral neuritis. Cold wind blowing on the cheek is also said to be a factor affecting this nerve. S y m p t o m a t o l o g y . - - h is of importance to distinguish extracranial from intracranial lesions and to determine accurately the site of the disturbance of the nerve. I. Intraeranial--frequently diplegic. I. Cortical Lesion. (a) Total paralysis of the lower part of the face on the opposite side. (b) Partial paralysis of the upper part of the face on the opposite side. The upper part of the face is supplied from both sides of the cortex of the brain so that if one cortex is injured the upper half of the face still gets a supply from the other cortex, the paralysis being partial. (c) Taste and salivary fibres normal. (d) Corneal reflex retained. (e) Stapedius not paralysed. ( f ) No reaction of degeneration. 2. Lesion of Internal Capsule.--Symptoms as above but movements of expression retained.
II. ExtraeranialBalmost always monoplegic. I. Lesion at Entrance of Nerve into Internal Auditory Meatus, e.g., in fractured skull. (a) Paralysis of all the motor functions of the nerve. Taste fibres unaffected. (b) Stapedius paralysed. This produces hyperacusis (unusually loud voice). (c) Corneal reflex lost. (d) Movements of expression lost. (e) Pronounced reaction of degeneration. 2. Lesion in Bone Distal to the Nerve to the Stapedius.--Same symptoms but no hyperacusis. Taste is absent from the anterior two-thirds of the tongue. 3. Lesion at the Stylomastoid Foramen.--The same symptoms as in 2 except that taste fibres are unaffected.
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T r e a t m e n t . - - T h e surgical procedures for the alleviation of the symptoms of seventh nerve paralysis are of two types : those which attempt to reinnervate the facial muscles and those which attempt to conceal or minimise the deformity by mechanical measures. The former group comprises (I) decompression of the nerve, (2) direct end-to-end anastomosis, (3) nerve grafting, (4) facial nerve anastomosis with contiguous motor nerves. The latter group comprises (i) fascial suspension, (2) reanimation with or without tendon or fascia, (3) meloplasty. Sometimes temporary mechanical supports are used during the period of waiting to determine whether or not there will be return of function or to reduce stretching of the paralysed muscles. In addition to clinical signs and symptoms the following tests are of value in establishing the level and the cause of the lesion : (I) X-ray of the skull and temporal bone; (2) faradic stimulation for nerve; (3) galvanic stimulation for muscles; (4) audiometric test ; (5) vestibular test ; (6) taste and lacrimation tests ; (7) stapedius muscle test. Within six months some evidence of regeneration should be present if it is going to appear. After nerve anastomosis, the percentage of recovery is greater if continuity is re-established within a year after section. If galvanic current does not produce muscular contraction, the muscles are taken to be fibrotic and nerve suture is useless. Facial Decompression.--A curved retro-auricular incision is made down to and through the periosteum, the latter is elevated, and the cortex of the entire mastoid process is exposed. The digastric groove is located as a guide to the stylomastoid foramen and sufficient mastoid cortex and cellular content are removed to expose the horizontal semicircular canal. A line from this canal to the foramen marks the course of the nerve. Starting at the foramen and working upwards to the lesion, the bone is removed piece by piece so as to ensure the decompression. Other tissues compressing the nerve are also taken out. The sheath of the nerve is slit open freely above and below the lesion. The open canal is then covered with a piece of fresh muscle or silver foil. The wound is dosed, with or without drainage, as the occasion demands. When the injury is between the stylomastoid foramen and the anterior border of the parotid gland, the nerve, after being exposed at the foramen, should be followed distally until the lesion is located. Anastomosis.--If an interruption in continuity has occurred sharply, cleanly, and without laceration or crushing, the ends may be approximated by placing fine sutures in the sheath. Suture is not required in the bony canal if the ends are in approximation. In such a case the point of approximation is covered with a piece of muscle or silver foil. I f laceration or crushing has occurred, the injured part should be excised, and if the loss is slight the ends may still be approximated by freeing the nerve in its bed from the horizontal canal to the stylomastoid foramen. Graft.--When there has been so much destruction of the facial nerve in lesions peripheral to the stylomastoid foramen or in the bony canal that the ends cannot be approximated, a nerve graft may be used to bridge the gap. Usually the lateral or anterior femoral cutaneous nerve provides the autograft. In the bony canal the graft is laid into place without suture and is covered with fresh
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muscle tissue or blood clot. Distal to the canal it is necessary to suture the ends of the graft to the transected ends of the facial nerve. Facial Hypoglossal Anastomosis.--With the patient in a semi-supine position, with the shoulder elevated on a sandbag and the head turned to the opposite side, an incision is carried forwards from the mastoid process, parallel to and approximately one fingersbreadth below the angle of the jaw. The mastoid process is exposed with a periosteal elevator and the sternomastoid and digastric muscles are identified. The facial nerve is exposed at the stylomastoid foramen and approximately 2 cm. dissected free. It is transected at the stylomastoid foramen. The digastric muscle is exposed as far as the hyoid bone, and the hypoglossal nerve is easily found beneath the lower end of the upper belly of the digastric. Approximately 3 to 4 cm. of the hypoglossal nerve and descendens hypoglossi branch are freed and transected. The central end of the descendens hypoglossi is then sutured to the distal end of the twelfth cranial nerve (with No. 4o stainlesssteel wire). The needle is inserted through the centre of the cut end of the fasciculi and brought out through the epineurium approximately 8 ram. back. Now the central end of the twelfth nerve is carried underneath the digastric muscle and sutured to the peripheral end of the seventh nerve in the same manner. Approximately a gap of i mm. should separate the ends of the sutured nerves in each location. The site of the nerve suture is covered with gelatin sponge. The wound is irrigated with antibiotic solution if necessary, and closed in layers. Facial Accessory Anastomosis.--After the facial nerve has been exposed at the stylomastoid foramen, using the same incision, the sternomastoid muscle is retracted posteriorly. The posterior part of the digastric muscle is elevated. The spinal accessory nerve lies on, or just in front of, the transverse process of the atlas, covered by a layer of deep fascia. The nerve is isolated up to its entrance into the sternomastoid muscle. The same procedure of crossanastomosing the descendens hypoglossi to the distal stump of the spinal accessory is carried out, and the proximal stump is sutured to the distal segment of the facial nerve. The spinal accessory divides and goes into trapezius and if only one division is used no trapezius paralysis results. Fascial Sling.--After an incision has been made above the hair line in the temporal region a Blair needle is passed downwards and medially to emerge at the midline of the lower lip, where a small incision is made. One end of the fascial strip taken from the fascia lata of the thigh is then inserted into the needle and withdrawn through the original incision in the temporal region. The needle is reinserted to pass through the subcutaneous tissue about a quarter of an inch below the initially inserted strip of fascia lata. The end of the fascia protruding from the lip incision is picked up and drawn through this second pathway, the loop in the midline, including a good bite of the orbicularis muscle. With the same procedures, the midline of the upper lip and the angle of the mouth of the paralysed side are drawn up and backwards to the desired position. A piece o f fascia should be inserted from the midline of the upper lip, around the angle, to the midline of the lower lip and securely sutured to the orbicularis muscle at all these points. The upper ends of the fascia strips are tightened as required and sutured to the temporal fascia. To correct the drooping of the lower eyelid, a fascial loop is passed through
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the lower lid and is fastened medially to the inner canthus, and laterally to the temporalis fascia. Reanimation.--The temporalis and the masseter muscle, supplied by the fifth nerve, are used in this operation. The masseter muscle is exposed by making an incision along the lower border of the mandible and elevating the overlying skin. The anterior half of the muscle is separated from below, retaining the nerve and blood supply, and is sutured to the orbicularis oris at the corner of the mouth. Alternatively, a skin incision is made to expose the temporalis fascia. The temporalis muscle is detached from the temporal fossa, after its fascia has been cut through. Three pedicles are made, one for the angle of the mouth, and two smaller ones--one for each of the eyelids. The largest pedicle is carried through a tunnel beneath the skin to the angle of the mouth and implanted into the orbicularis oris. In the same way the other two pedicles are passed through the individual tunnels in the upper and lower eyelids and are united at the inner canthus by making an incision through the skin to permit the suturing. Meloplasty.--In some cases of facial paralysis redundancy of the skin of the face is removed by meloplasty. In this operation the incision begins at the temple within the hair line and is carried down to the attachment of the helix, around which it is curved to the posterior surface of the tragus, thence down and around the lobule and upwards behind the ear, to end sharply downwards and backwards within tl,_e hair line. To avoid injury to the filaments of the facial nerve, the incision and undermining must be superficial. The skin of the face is undermined extensively. Complete hmmostasis is essential. With the skin flap adjusted to the desired tension, the excess skin is excised. Skin closure is done with interrupted sutures. A layer of sutures in the deep dermis is worth while to remove tension from the skin edges. A pressure dressing is applied. DISCUSSION
For brevity, only the treatment of well-established cases of facial paralysis is discussed here, and although some difference of opinion with regard to methods and results of treatment exists in the literature, only those procedures accepted by most workers are outlined. Surgical treatment of facial paralysis depends largely upon mtiology. The time when surgical treatment should be undertaken varies with circumstances. In general it is indicated when paralysis has persisted for not less than from six to nine months. The degree of palsy, presence of lagophthalmos or ectropion, lack of improvement in electrical response, and the sensitiveness on the part of the patient to his or her disability influence the decision. In relatively recent cases end-to-end anastomosis, nerve grafting, facial nerve anastomosis with a contiguous motor nerve or decompression of the nerve may be of value. But in some cases, especially in those of long-standing, a palliative operation is preferred, using muscle or fascial sling, or a combination of both. As a rule one or other type of nerve anastomosis should be preferred if galvanic reaction persists, and some kind of plastic reconstruction if it is lost. For nerve anastomosis, the hypoglossal, spinal accessory and glossopharyngeal have been used. On occasion a double anastomosis has been performed (facial hypoglosso-accessory).
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So far as the palsy is concerned, the results are often encouraging, but hemiatrophy of the tongue entailing no gross inconvenience, loss of power in the sternomastoid and trapezius (if the eleventh nerve is chosen), and the occurrence of facial movements when the other nerve is in action constitute serious disadvantages. In the process of eating, swallowing, or moving the shoulder, according to the particular method employed, facial grimaces may cause embarrassment ; for example, a patient had to discontinue using her umbrella, since every time she held it up her face went into spasm. For this reason such unnatural operations are being abandoned in favour of resection of the nerve with end-to-end suture of a graft from another nerve. Ballance (I932), who advocated the procedure, thought it would also prevent the occurrence of spasmodic contractions in facial muscles. Plastic surgery can do much in the case of total paralysis with atrophic musculature. One of the most successful methods consists in applying a muscle pedicle, from the temporal or masseter to the orbicularis of the eye and mouth, whereby the unpleasantness of the condition is relieved, the eye can be closed, the corner of the mouth lifted, and the patient's state of mind correspondingly benefited. However, in evaluating a patient for some type of reanimation in seventh nerve paralysis, several points must be considered. It is necessary to determine whether the nerve injury is degenerative or non-degenerative, whatever may be the cause of the injury ; and to what extent the nerve is going to regenerate, if at all. A block in the transmission of the nerve impulses in this motor nerve may be of only a transient nature such as is seen in Bell's palsy. This may persist up to ten weeks, followed by rapid and complete return of movement. It is probably an ischa:mic block due to pressure oedema of the nerve as it passes through the bony canal. In this palsy there is no destruction of the nerve pathways. The nerve degeneration means an interruption of the axons and denervation of the muscle. Denervated muscle becomes flaccid and atrophic with progressive shrinkage of the muscle fibres, an increase in connective tissue, and finally obliteration of the terminal Schwann tubes of the degenerated nerves and motor end-plates. When this stage is reached good clinical recovery is impossible, since destruction of the nerve end-plates prevents reinnervation. Muscle atrophy in denervated muscle increases with overstretching, which is brought about by the pull of gravity and the normal muscles of the other side of the face. Stretching and thinning of the skin and obliteration of the normal facial contours are the usual accompanying factors. In arriving at the final decision regarding the nature and progress of the pathology in this motor nerve, the history of the nature of the injury should be thoroughly explored. Electromyography may also be useful in evaluating the nature of the pathology. Unfortunately, faradic and galvanic tests do not give an exact picture of the excitability of the muscle and nerve. Reaction of degeneration gives little guidance to regeneration of the nerve, since good functional recovery is possible with abnormal electrical reactions still present. Fairly good information can be obtained by serially taken strength-duration curves, using the Bauwen's constant current or a Ritchie Sheath stimulator. In the later stages electromyography and observation of the fibrillation of the muscle are good guides to the status of the muscle.
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Though the choice of the time of operation for reanimation is difficult, when it is reasonably certain that spontaneous recovery cannot be expected, operative treatment is indicated. Time should be allowed for regeneration because the operation itself can damage muscles and nerves still capable of regenerating. One must therefore support the face temporarily during the observation period to prevent overstretching of muscles and skin. Mechanical elevation of the corner of the mouth and associated areas, to counteract gravitational pull and that of the normal muscle from the opposite side, is of value. A hook from the corner of the mouth is used, but itself can be responsible for overstretching the orbicularis oris, elevators, and depressors. A more satisfactory method in adults is the intraoral splint attached to the upper teeth. In children the hook is used until the permanent teeth erupt to make it possible to fit a cap splint.
A
B FIG. i A, Facial paralysis following a radical m a s t o i d operation on the right side. B, R e g a i n e d right facial n e r v e f u n c t i o n a p p r o x i m a t e l y one year after I cm. n e r v e graft in facial canal f r o m t h e anterior femoral cutaneous nerve.
The reanimation procedure is in most cases associated with ridectomy to take up the slack skin, and lateral tarsorrhaphy when epiphora develops. In children the procedure is unsatisfactory since the transplanted fascia does not grow, and as time passes this results in a more disfigured face. Grundt (195 o) noted the tendency of the fascia to be attached to surrounding tissue along with degeneration of the muscle, resulting in a fixed smile. To eradicate this difficulty he prefers a graft of the palmaris longus with paratenon attached to a muscle flap from the temporalis and to the corner of the mouth. CONCLUSION Facial paralysis is one of the most pathetic deformities to which humans are subjected; and the complications both physical and psychological make the life of the patient miserable. However, in properly chosen cases with due respect to time and method, in co-operative patients, reconstructive surgery can do much
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~Fig. 2.--A, Exposure of perineural fibroblastoma involving right seventh and eighth cranial nerves. Removal required the intracranial sectioning of both nerves with resultant facial paralysis. B, C, Post-operative. B, face at rest ; C, tongue protruding. Facialhypoglossal anastomosis with supporting fascia lata stings. Recovery of facial nerve function illustrated after one year.
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B
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B FIG. 3 A, Twin siblings with congenital right-sided facial paralysis. B, Reanimation with fascia lata slings to right temporal and masseter muscles and modified meloplasty.
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A
B FIG. 4 Facial paralysis following removal of perineural fibroblastoma of right eighth nerve. A, Dissection to show exposure in accessory facial anastomosis. B, Illustrating recovery of facial nerve function, with shoulder elevated, one year after spinal accessory-facial anastomosis.
Fig. 5-- A, Radiological evidence of a fracture of left parietal and temporal bone extending into the middle ear, with resultant facial paralysis. B, C, Supporting wire slings were inserted to support facial muscles pending spontaneous recovery of facial nerve as illustrated.
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FI~. 5
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to alleviate physical disabilities and thereby enable the patient to endure his misfortune more easily. Although it is almost impossible to restore the original cosmetic appearance and functional ability in long-standing well-established cases, the improvement as illustrated by the photographs makes surgical treatment well worth while (Figs. I to 5). REFERENCES BALLANCE, C., and DUEL, A. B. (~932). Arch. Otolaryng., I5, I. GRUNDT, B. (I95O). Brit. ft. plast. Surg., 3, 5°.