Abstract
Bell’s palsy is an idiopathic and acute, peripheral nerve palsy resulting in inability to control facial muscles on the affected side because of the involvement of the facial nerve. This study describes a case of Bell’s palsy that developed after dental anaesthesia. A 34-year-old pregnant woman at 35 weeks of amenorrhea, with no history of systemic disease, was referred by her dentist for treatment of a mandibular left molar in pulpitis. An inferior alveolar nerve block was made prior to the access cavity preparation. 2 h later, the patient felt the onset of a complete paralysis of the left-sided facial muscles. The medical history, the physical examination and the complementary exams led neurologists to the diagnosis of Bell’s palsy. The treatment and results of the 1-year follow-up are presented and discussed. Bell’s palsy is a rare complication of maxillofacial surgery or dental procedures, the mechanisms of which remain uncertain.
Bell’s palsy is an idiopathic and acute, peripheral nerve palsy resulting in inability to control facial muscles on the affected side because of the involvement of the facial nerve, which supplies motor response for the muscles of facial expression . The annual incidence of Bell’s palsy is about 20–30 per 100,000 people . It has been described in patients of all ages, with a peak incidence around the age of 40 years . Association between this disease and pregnancy was first described by C harles B ell but its increased incidence during pregnancy is still controversial in the literature . As the origin of Bell’s palsy is still unclear, aetiologies such as viral infection, vascular ischaemia, autoimmune inflammatory disorders and familial susceptibility have been proposed as underlying causes in the general population , of these, the reactivation of herpes simplex virus (HSV) has become the most likely hypothesis. Thanks to the development of molecular biology and animal models, several reports of herpes virus infection have been recorded . In pregnant women, the most frequent physiologic and pathologic processes could be viral infection, hypertension and immunosuppression . The authors present a case of complete unilateral Bell’s palsy.
Case report
A 34-year-old pregnant woman at 35 weeks of amenorrhea was referred by her dentist for a severe pain in her mandibular left second molar in October 2008. She had no history of systemic disease but reported recurrent labial herpetic vesicles. Her medication was Phloroglucinol/Trimethylphloroglucinol and Macrogol 4000. The patient complained of the recent onset of spontaneous pain, increased by the decubitus position. The history, and clinical and radiological examinations revealed the loss of a prosthetic crown on this tooth (#37), and its replacement by a temporary metal crown. The X-ray examination showed no periradicular change ( Fig. 1 ). No panoramic radiograph was available. The diagnosis was irreversible pulpitis in the mandibular left second molar. An inferior alveolar nerve block (IANB), a technique of choice in case of irreversible pulpits, was made with an injection of 1.8 ml of chlorydrate of mepivacaine without epinephrine (Scandicaïne ® , Septodont, Saint-Maur-des-fossés, France). A disposable needle, 25G, 0.50 × 35 mm, mounted on a dental syringe was used. The injection of the anaesthetic solution was uneventful. A pulpotomy was carried out as emergency treatment. Analgesic treatment with acetaminophen was prescribed, and a second appointment was made to terminate the endodontic treatment. 2 h later, the patient felt the onset of a fast and complete paralysis of all of the left-sided facial muscles. She went to the general emergency unit of Brest hospital and was referred immediately to the neurology department.
Her medical history excluded recent arthralgia, ear pain, fever, influenza or exposure to ticks and the enquiry into family history yielded no history of a similar disorder. Physical examination revealed the disappearance of the left facial and forehead creases, the left naso-labial fold, the asymmetry of the mouth left corner and drooping of the lower left eyelid ( Fig. 2 ). The patient was unable to close her left eyelid, and her eye rolled upward when she attempted to close it. She appeared unable to smile properly ( Fig. 2 c,f) and reported a feeling of a discomfort on eating. Her mouth, pharynx and ears showed no signs of disease. No herpetic vesicles were found. To evaluate eventual neurological lesions, brain magnetic resonance imaging and computed tomography scans were acquired, and were found to be normal. After ruling out Lyme disease, Guillain-Barré syndrome, otitis media, Ramsay Hunt syndrome, sarcoidosis and tumour, the neurologists diagnosed a complete Bell’s palsy (grade VI using the House–Brackman grading system).
To eliminate any risk to the foetus, the obstetrician, neurologist, consulting physician and patient decided not to prescribe corticosteroids or antiviral drugs.
No ophthalmic intervention was undertaken because of the neurological aetiology of the patient’s palsy. To prevent ophthalmic damage, an eye lubricant was prescribed for the first months of patient’s palsy.
A clinical follow-up was organized and 1 week after the onset of the paralysis, the first electromyography was performed to evaluate the nervous lesion. The patient gave birth in November 2008, 5 weeks after the first appointment. The facial nerve palsy did not change immediately after giving birth.
3 months after the onset, a progressive and partial recovery was observed with recovery of the left naso-labial fold and symmetry of the mouth corners. The slight dissymmetry between the eyes remained, probably resulting from a drooping of the lower left eyelid, which indicates incomplete recovery. The patient was able to close both her eyes correctly.
4 months after the onset of the disease, evidence of good re-innervation in all the areas of the left facial nerve by electromyography justified the continuation of the clinical and electrical follow-up. The patient was examined in June 2009, 8 months after the onset. There was still very slight dissymmetry between the eyes, but the patient showed good recovery to grade II of the House–Brackman grading system ( Fig. 3 ). She was examined 1 year after the onset and presented a subtotal recovery with persistent slight muscular stiffness (grade I/grade II) ( Fig. 4 ). 1-year follow-up was carried out in October 2009. The patient is still under follow-up.
