|Year : 2016 | Volume
| Issue : 3 | Page : 80-82
Facial nerve paralysis after dental procedure
Melda Misirlioglu, Mehmet Z Adisen, Alime Okkesim, Yagmur Y Akyil
Department of Oral and Maxillofacial Radiology, Faculty of Dentistry, Kirikkale University, Kirikkale, Turkey
|Date of Web Publication||21-Dec-2016|
Mehmet Z Adisen
Department of Oral and Maxillofacial Radiology, Faculty of Dentistry, Kirikkale University, Kirikkale
Source of Support: None, Conflict of Interest: None
Peripheral facial nerve palsy (FNP) is a common neuropathy of cranial nerves. However, it is a rare condition in dental treatment and may be associated with local anesthetic injections. Initial trauma to facial nerve cab is usually minor. In this instance, a complete and rapid recovery is expected and most cases resolve within 12 hours. If more extensive damage occurs, nerve palsy can be significant and long lasting. We report a 15-year-old female patient with FNP that developed within 8 hours after a dental procedure. The treatment was continued for 10 days with prednisone and acyclovir. At the end of the 4 th day, movement began to return to her face and the symptoms disappeared within 3 weeks period. In dental practice, it should be considered that iatrogenic factors may play a direct or indirect role in FNP, as presented in our case. Clarification of the etiology and treatment of FNP requires a multidisciplinary medical team. Therefore, dentists should be aware of clinical findings along with an essential treatment plan of FNP in dental office.
Keywords: Bell′s palsy, facial nerve palsy, herpes simplex virus, local anesthetic procedure complications
|How to cite this article:|
Misirlioglu M, Adisen MZ, Okkesim A, Akyil YY. Facial nerve paralysis after dental procedure. J Oral Maxillofac Radiol 2016;4:80-2
|How to cite this URL:|
Misirlioglu M, Adisen MZ, Okkesim A, Akyil YY. Facial nerve paralysis after dental procedure. J Oral Maxillofac Radiol [serial online] 2016 [cited 2019 Apr 25];4:80-2. Available from: http://www.joomr.org/text.asp?2016/4/3/80/196356
| Introduction|| |
Peripheral facial nerve palsy (FNP) is a common neuropathological disorder affecting the branches of the seventh cranial nerve, causing an inability to control facial muscles on the affected side.  The possible causes are various and include trauma, infection, pregnancy, diabetes, and neoplastic infiltration. Involvement of the facial nerve in varying degrees results in a facial weakness with a characteristic facial distortion. 
FNP is a very rare condition in dental treatment. In most cases, nerve palsy begins instantly after local anesthetic injection into the retromolar region and usually resolves within 12 hours. However, in rare cases, onset of symptoms may be delayed for several hours to days. Dental infection or paradental foci is also believed to be responsible for the insult. 
This paper describes the diagnosis and treatment of a rare case of FNP that developed after a dental procedure with a local anesthetic injection.
| Case Report|| |
A 15-year-old young girl was admitted to a private dental practitioner with the complaint of mild pain because of a decayed mandibular molar tooth in the right side. The dentist, therefore, applied a block regional mandibular anesthesia with a disposable regular dental needle using 2% lidocaine with 1:250.000 epinephrine for dental treatment. There was no sign of FNP at the end of the treatment, however, the onset of symptoms was gradual during the next 8 hours. Within the next 8 hours, she noticed a weakness in the muscles around the eye and mouth at the right side of her face. She developed a typical facial weakness and could not smile or blink or even close her eye with maximal effort [Figure 1].
|Figure 1: (a) Showing full face of patient. (b) Deviation of mouth to the left side and failure to close the right eye|
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She was due to see an immediate consultation referred to our Department. Further examination revealed a reduction of sensation to the lips and a loss of taste at the right side of the tongue. Panoramic radiographic examination revealed nothing uncommon [Figure 2]. Treatment with prednisone (prednisolone, 60 mg per day), and because of the possible effect of Herpes Simplex Type 1 (HSV-1) in the etiology, antiviral drugs acyclovir (Zovirax, 5 × 400 mg per day) were administered as a combination therapy. The treatment was continued for 10 days. At the end of the 4 th day, movement began to return to her face and the symptoms were disappeared within a 3 weeks period.
| Discussion|| |
The mechanism of facial weakness after dental procedure can be explained as follows; direct anesthesia to the facial nerve can force a rapid onset that occurs while the anesthetic agent is being injected, reflex vasospasms of the external carotid artery can lead the ischemia of facial nerve, and dental infections may secondarily effect the facial nerve. 
Delayed onset of weakness may be associated with viral infections, especially with HSV-1.  The virus may remain in the ganglion latently, and then can be reactivated by the dental procedure. Other viral infections such as herpes zoster (Ramsey Hunt Syndrome) affecting the geniculate ganglion can also been involved in the pathogenesis of FNP. The difference between Ramsey Hunt Syndrome and FNP is clinically small vesicle eruptions on the tragus and aural concha of the ear as well as lesions forming on the tympanic membrane, soft plate, and anterior two-thirds of the tongue in Ramsey Hunt Syndrome. 
Dental procedure could damage the nerve by three mechanisms; direct trauma to facial nerve by a needle, intraneural hematoma formation, and toxic damage due to local anesthetics. Needle may damage the small blood vessels around the epineurium that causes hemorrhage within the nerve caused by compression and fibrosis. This effect occurs quickly (within 20-30 min) that the damage has been more increased than expected. Therefore, increasing pressure on the nerve results with damage. 
The local anesthetics containing vasoconstrictor agents may also act indirectly to sympathetic vascular reflex causing an ischemic reaction leading to FNP. The mechanic effect of the needle itself can also stimulate the sympathetic plexus. 
Pogrel et al.  reported that the amount of the nerve damage is neither related to any type of local anesthetic agents nor to the number of injections given at one site. In addition, they stated, as an interesting example, that the patients had received multiple dental injections within 3 months before the nerve damage occurred. They suggested that the nerve position is an important factor related to nerve injury by a needle.
Local anesthetic drugs can also be neurotoxic and can damage the facial nerve itself. Some of local anesthetics present fewer risks than most local anesthetics. Procaine and tetracaine cause more damage than bupivacaine or lidocaine. 
The article published by Gray  reported patients with multiple peripheral facial nerve paralyses in dental origin. He also reported 10 cases with Bell's palsy related with dental and paradental infections. The real mechanism in those cases was not known, however, toxicity was considered to be the probable reason.
Miles  suggested that the signs related with trigeminal neuropathy were impairment of taste, vestibular insufficiency, hearing disturbance, facial palsy, or cerebellar lesion signs. These signs led them to suspect a viral origin. Further, recent studies have shown that patients treated with an antiviral drug in combination with prednisolone demonstrated statistically full recovery in a higher percentage than patients treated with prednisolone alone. 
| Conclusion|| |
In dental practice, it should be considered that iatrogenic factors may play a direct or indirect role in FNP. Onset of the treatment using prednisolone and antiviral drugs combined therapy was successful in our case. However, clarification of etiology and treatment of FNP may require a multidisciplinary medical team. Therefore, dentists should be aware of clinical findings and should have an essential treatment plan of FNP in dental office.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]