A case of ipsilateral chin-eyelid synkinesis after brain trauma without peripheral facial nerve lesion

Abstract

1. IntroductionThe involuntaryco-contractionofipsilateralmusclesofthefaceis a common consequence of facial nerve lesion. A chin-eyelidsynkinesis is a common consequence of facial nerve pathologiesgenerally due to a peripheral facial paresis, although otherpathological processes might be involved [1]. The most frequentlyobserved phenomenon is a contraction of perioral musclessynchronous with the rhythmic eyelid closures. It is generallyaccepted that a pathologic rearrangement of facial nerve fibersleads to an ectopic diffusion of the contraction signals [2,3]. To ourknowledge, there are no reports of patients showing chin-eyelidsynkinesis in absence of a facial nerve injury. Here we report theclinical case of a young male who developed an orbicularis oculimentalis muscle synkinesis after a brain trauma. Interestingly,neither clinical nor instrumental evidences of facial nerve lesionwere demonstrated. We therefore, hypothesize that the abnormalco-activation was due to central nervous plasticity.2. Clinical caseA 20 years old male had a traumatic brain injury during a caraccident inSeptember2011,determiningatwomonthsprolongedloss of consciousness. He was admitted to an intensive care unit,mechanically ventilated and underwent an endovascular proce-dure in order to treat a right cavernous sinus-carotid fistula. Aftersix months of rehabilitation, he was admitted to a long term carefacility, in a stable condition of minimally conscious state andbilateral hemiparesis, more severe to the left side. Eighteenmonths after the trauma, he was admitted to our neuro-rehabilitation unit, with three main purposes: titration ofintrathecal baclofen and treatment of postural deformities,evaluation/treatment of a post-hemorrhagic hydrocephalus topossibly ameliorate the level of consciousness. At the hospitali-zation, he showed a left chin and perioral contraction for everyspontaneous closure of the eyelids (video).Furthermore, when the left palmomental reflex was elicited,theipsilateraleyelidclosurewas consistentlyinduced.Thesmilingwas completely symmetric, and all the facial muscles of the leftside had a normal strength, including the orbicularis oculi. Thepatient had not a previous history of facial palsy and no signs offacialhemiatrophyweredetectedatthephysicalexamination.MRIscan showed sequelae of diffuse axonal injury, and contusivelesions in both frontal lobes and temporal poles (Fig. 2).3. Electrophysiologic evaluation3.1. ENG–EMG–Blink reflexENG–EMG data were collected using a data acquisition system(Micromed Myoquick Device, Mogliano Veneto, Italy). The signalswere