Johnson. THE TWITCHING SCAR

Transcription

1 THE TWITCHING SCAR By JOHN MARQUIS CONVERSE, M.D., F.A.C.S. and RICHARD J. COBURN, M.D., D.M.D. From the Institute of Reconstructive Plastic Surgery, New York University Medical Center, 550 First Avenue, New York, N.Y. " PRAY Dr Johnson, why do you make such strange gestures? From a bad habit (he replied). Do you, my dear, take care to guard against bad habits : " Boswell's Life of Johnson. A frequent occurrence following laceration of the cheek is a twitching which appears spontaneously and more frequently under emotional stress. The plastic surgeon will often, upon examination, note with satisfaction that the scar is inconspicuous, but that the mere fact that the patient is undergoing an examination produces an emotional situation sufficient to trigger the twitch. The interest of one of us (J. M. C.) was aroused some years ago by the case of a celebrated South American actress who developed facial twitching following a rhytidoplasty (face-lift) consisting of spasmodic elevation of the upper lip under emotional stress. Another case was that of a I6-year-old boy who manifested localised twitching after a small laceration over the zygoma which had been successfully repaired and the scar of which was inconspicuous. The word "tic ", from the French meaning a twitch, refers to the repeated involuntary contraction of associated muscle groups. The term is non-specific, connoting such disassociated conditions as the habitual, emotionally precipitated winks and blinks of children to the painful grimacing of a tic douloureux. Tics of facial origin exclusive of puerile habits are secondary to an extracranial injury of the facial nerve or less frequently to an idiopathic dysfunction of the central nervous system, the hemifacial spasm. The mechanism of tics of facial origin, the main concern of the plastic surgeon, has been documented in the laboratory ; hemifacial spasm has yet to be defined. Synkinesis is a related tic-like phenomenon in which voluntary motion triggers a synchronous involuntary contraction of associated muscle groups. The frequency of major facial injuries from vehicular and industrial accidents is responsible for the rising incidence of post-traumatic facial tics. They follow both traction cutting and crushing injuries and increase with the magnitude of nerve disruption. The two most frequently observed sites of post-traumatic facial tics have been the upper lip and cheek after full-thickness laceration of the cheek through the buccal branches of the facial nerve, and the eyelids following deep penetrating laceration through the temporofacial branches. The tick-like movements become apparent after the first evidence of muscle reinnervation, usually two to three months following injury. Some muscles remain paralysed, others offer a poor response to faradic stimulation. The twitch may be elicited by stroking the eyelids or cheek; stroking the eyelids often increases the spasm. Excitement or fear increases the muscular contraction. The risorius muscle is frequently involved in spasm; this may be noted even when no muscular response can be obtained by faradic stimulation through the skin. The twitch may be rhythmical and continuous or there may be intervals of quiescence between the spasms. Despite various rather convincing aetiological theories and the ability to reproduce the phenomenon in experimental animals, treatment remains unrewarding. The facial tic may be readily traded for a facial palsy, yet this is an unsatisfactory exchange by all criteria. With this necessarily pessimistic introduction, this report will 272

2 THE TWITCHING SCAR 273 classify the varieties of facial tics, and focus on the pathophysiology and clinical behaviour of secondary tics related to facial trauma. Classification.--The Table gives an aetiological classification of facial tics or spasms. The primary tic, also referred to as a hemifacial spasm (" tic non douloureux ") and extensively reviewed in the neurosurgical literature, may occur spontaneously at any age, usually beginning in one muscle group, especially the orbicularis oculi muscle, and spreads to adjacent areas innervated by the facial nerve (Diamant et al., I967). r. 2. TABLE Primary (hemifacial spasm) Secondary Traumatic Toxic Habitual Idiopathic Secondary tics, exclusive of the habitual spasms of childhood, arise from an injury to the facial nerve which results in damage or division of axons. The destructive effects of oedema of the facial nerve compressed within the Fallopian canal is another cause of the not infrequent twitch following a Bell's palsy. Idiopathic tics may be habitual tics persisting from childhood, resulting from unsubstantiated trauma or toxicity, or may be secondary to an as yet undetermined insult. Pathophysiology.--The pathophysiology of the secondary tic has been investigated with the aid of experimental animals. A central and peripheral focus were initially invoked but overwhelming laboratory evidence favours an extracerebral local insult. The classic experimental evidence was reported by Howe, Tower and Duel in r937 from their work in the Rhesus monkey. The facial nerve was either completely or partially divided, frozen, or injected with alcohol. Regeneration and tic development were carefully monitored and correlated with anatomical dissection and microscopical assessment. Function returned in an average of 44 days followed within 5 z to 79 days by adventitious contractures. Howe, Tower and Duel (I937) showed that actual branching of axons took place at the site of injury and concluded that single regenerated axons had, by branching, come to supply widely separated muscles thus establishing an irrevocable functional union between muscles which do not normally contract simultaneously. In one experiment conducted by these authors, an animal which had developed a facial tic following section of the main trunk of the facial nerve and subsequent regeneration was given light ether anaesthesia. Three large branches of the facial nerve were exposed on each side and their distribution was determined by unipolar stimulation. Stimulation of the temporal branch resulted in wrinkling of the brow, closure of the eye and elevation of the upper eyelid. After the nerve had been cut, stimulation of the distal segment caused wrinkling of the brow and closure of the eye ; excitation of the central stump (or proximal) caused closure of the eye and elevation of the upper lip. The presence of branched axons offered the only anatomical basis for the phenomenon, according to the authors. Since nerve fibres conduct equally well in both directions, excitation set up at any point in an axon will be propagated through its entire extent. Thus, impulses initiated in motor fibres in the proximaj stump of nerve AB would be conducted centrally but at the point at which axon branching takes place impulses would also pass distally into the branch CD to elicit muscular contraction in the lip. Similar experiments were conducted

3 274 BRITISH JOURNAL OF PLASTIC SURGERY on the normal side of the face. Stimulation of the cervical, zygomatic and temporal branches of the facial nerve yielded discreet movements of the lower, middle and upper portions of the face but never a mass contraction as on the side of the operation. As the facial paralysis regressed, the tics spread to involve additional and widely separated muscle groups, thus establishing an irrevocable functional union between muscles which do not normally contract simultaneously. The severity of the tic was proportional to the degree of injury. Once established, the twitch failed to diminish over the three-year observation and follow-up. Whether the actual anatomical lesion is due to the fact that single regenerated axons had, by branching, come to supply widely separated muscles, or a misdirection of regeneration is unknown. Howe and his associates favoured branching axons feeling that misdirected axons would eventually be voluntarily suppressed but this did not occur in the monkey. The tics which occur following Bell's palsy share similar mechanical derangements with those described in post-traumatic tics. The defect tends to be more global, a finding compatible with a more extensive regenerative process. The magnitude of nerve injury also correlates with the incidence and spread of the tic disorder (Boyle, 1966). The Seddon (1943) classification of peripheral nerve trauma can be related to secondary tic pathophysiology. A neuropraxia, the least insult, is confined to the myelin sheath, degeneration does not occur and consequently spasms do not develop. Axonotmesis designates those injuries in which axonal degeneration occurs, the sheath is undamaged, the guidepost for repair is intact ; nerve regeneration is more orderly ; tics are less frequent and more localised. The injury referred to as neurotmesis connotates complete transsection of the nerve also with classic Wallerian degeneration. Regeneration requires sprouting of axon stumps which may divide into a number of shoots as originally demonstrated by Ramon y Cajal (1928). Schwann cell regeneration may be equally disorganised, setting the stage for maximum tic formation. Rosenberg and Alford (1966) reached similar conclusions from dog experiments in which they occluded the auriculopalpebral branch of the facial nerve for varying intervals with variable pressure. If the nerve was compressed and then decompressed when excitability was normal or first noted to fail, the animal exhibited full recovery without evidence of synkinesis. Those relieved three weeks following loss of function also recovered, but two of eight had synkinesis, confirming that tics are found in direct proportion to nerve damage. Recovery from synkinesis suggests, however, that some explanation other than misdirection of branching of nerve fibres must be sought. The explanation suggested by Bickford and Lambert (I952), of" cross-firing " or the excitation of fibres by impulses travelling over adjacent fibres, may have merit. Clinical Manifestations.--The secondary tics, particularly those associated with trauma, generally involve small localised muscle groups in the area of injury. Trauma over the zygomatic and frontal areas results in tics of the brow and upper cheek musculature. The spasm is rarely incapacitating, but frequently appears as an unexpected complication in an otherwise well-healed inconspicuous scar. Age, sex, and race are not related to secondary tic development. The only positive variable is the magnitude of nerve injury ; the more the damage, the greater is the incidence and severity of facial tics. A syndrome related to facial twitching is the "crocodile tear" syndrome. The mechanism parallels post-traumatic tics in that misdirected regenerating axons which normally reach the submaxillary gland through the corda tympani nerve are misdirected to the lacrimal gland through the greater petrosal nerve. Subsequently, food or gustatory stimulation triggers paroxysmal lactimation or crocodile tears (Jacklin, 1956).

4 THE TWITCHING SCAR 275 As nerve regeneration and function return, the tic becomes manifest. Laboratory studies suggest 5 to 79 days (Howe, Tower and Duel, 1937). The spasm characteristically increases as reinnervation progresses, involving wider units of facial musculature, until maximum regeneration is obtained. With functional return, tic progression is arrested ; regression however is unusual. Once established, the tic may become synchronous with purposeful movements of related facial structures. They are not infrequently associated with blinking or smiling. Fatigue, emotion, and nutrition have been implicated in increasing activity of established secondary tics. Treatment.--Correction of secondary traumatic tics is generally unsatisfactory. Complete relief can be offered only if the patient is willing to accept temporary or complete paralysis. Conservative methods which may minimise the trait include the use of tranquillisers, sedatives and antispasmodics. Emotion is a contributing factor, thus sedation may lessen the frequency and magnitude of the twitch. If the tic is localised to the lip or commissure of the mouth, a pipe or cigarette can be used to suppress activity. The more common ocular-related tics may be masked with appropriate spectacles. Current hair styles may be similarly fashioned to cover a forehead or zygomatic spasm. Fowler (1939) reported modest improvement from instructing the patient to relax the face and thereby gain further control over facial expression. Local anaesthetic blockade will provide temporary relief, but the spasm returns as the effect wanes. Alcohol injections following a trial test of local anaesthesia may produce a remission lasting several months ; however, the patient generally experiences a progressive return of symptoms. A more permanent cure can be rendered by selective partial or complete section of the involved nerve branch or branches. Partial interruption of conduction aims to weaken or abolish the tic, but preserve tone and function. This noble objective is rarely achieved. Local anaesthetics should be tried to map the neurological defect and to plot the surgical neurectomy. Once defined, partial interruption of the nerve fibre should be undertaken. The severed portion should be bound centrally as described by Miehlke (1961) to prevent regeneration of the severed axons. Finally, if the spasm becomes an overwhelming inconvenience to the patient, division of the nerve should be performed followed by reconstructive surgery to minimise the cosmetic defect. REFERENCES BICKFORD~ 1~. G. and LAMBERT, E. H. (1952). Personal communication to WILLIAMS, I-I. L., LAMBERT, E. H. and WOLTMAN, H. W. The problem of synkinesis and contracture in cases of hemifacial spasm and Bell's palsy. Annals of Otology, Rhinology and Laryngology~ 6I, BOYLE~ W. F. (1966). Facial-nerve paralysis. An experimental investigation of facial nerve regeneration in monkeys. Laryngoscope, 76, DIAMANT, H., ENEORS~ B. and WILBERG, A. (1967). Facial spasm with special reference to the chordal tympani function and operative treatment. Laryngoscope, 77, 35o-358. FOWLER, E. P. (1939). Abnormal movements following injury to the facial nerve. Journal of the American Medical Association, 113, loo3-1oo8. HOWE, H. A., TOWER, S. S. and DUEL, A. B. (1937). Facial tic in relation to injury of the facial nerve. An experimental study. Archives of Neurology and Psychiatry, 38, 119o JACKLIN, H. N. (1966). The gusto-lacrimal reflex (syndrome of crocodile tears). American Journal of Ophthalmology, 61, MIEHLKE, A. (1961). Die Chirurgie des Nervus facialis in sienem extratemporalen verlaufsab schnitt. Archly fiir klinische Chirurgie, 298,

5 276 BRITISH JOURNAL OF PLASTIC SURGERY RAMON Y CAJAL. (I928). " Degeneration and Regeneration of the Nervous System ". London : Oxford University Press. ROSENBERG, J. J. and ALFORD, B. R. (1966). Experimentally controlled facial nerve injuries, Archives of Otolaryngology, 84, SEDDON, H. J. (1943)- Three types of nerve injury, Brain, 66,