Facial Nerve Paralysis as a Complication of Acute Otitis Media

Background:Facial nerve paralysis is not a very frequent association with acute otitis media (AOM). The pathophysiology and treatment of this condition still under debate. Aim of the Work:to review the treatment strategies and extent of recovery in patients with facial nerve paralysis after AOM. Patients and Methods:The study was a retrospective study. Authors reviewed a total of 4710 cases of AOM seen during the period form 2010 to 2020. Fourty cases developed facial nerve paralysis. All were reviewed for epidemiological data and clinical assessment. Facial palsy was graded by House-Brackmann scale. All patients were treated with antibiotics combined with oral or intravenous corticosteroids. Myringotomy with or without application of a ventilation and mastoidectomy without decompression of the facial nerve were performed in selected cases. Result:Normal facial function was resumed to normal in all patients. The paralysis was mainly of acute onset (90.0%) and otorrhea reported among 12.5%.  The initial paralysis grade was mainly grade IV (41.3%) followed by grade III (26.3%). The topography was mainly infrageniculate (86.3%). A collected material for bacteriology was reported for 40.0%, and 53.1% of them had negative culture. The most common detected organism was staphylococcus aureus (18.8%). Myringotomy was done for 7.5%, aspiration for 10.0% and Mastoidectomy for 10.0%. The overall outcome was good among 90.0% and bad among 10.0%. The duration for complete cure in cases with good outcome not exceeded 3 months. Only lower initial grade on House-Brackmann scale and infrageniculate topography were associated with favorable outcome. Conclusion: The management of facial nerve paralysis due to acute otitis media could be conservative by antibiotics with corticosteroids.


INTRODUCTION
Acute otitis media [AOM] is more common in pediatric age, with an estimated incidence around 0.004% [1] .
American Academy of Pediatrics [AAP] recommended the diagnosis of AOM in children with moderate to severe tympanic membrane bulge, or in new onset otorrhea which is not due to acute otitis externa [2] .
In adults, AOM is not common; however adults have up to 10 time's greater chance of developing peripheral facial paralysis [PFP] as a complication than pediatrics [3] .
AOM complications are traditionally categorized as intracranial or intratemporal. Among intratemporal complications, mastoiditis and facial nerve paralysis are the commonest. The pathophysiology of facial nerve paralysis with AOM is not yet fully understood. There are several hypotheses to explain the condition. Nerve compression by edema and exposure to bacterial toxic metabolites are the most accepted theories [4] .
Today, antibiotics are associated with marked reduction of the peripheral facial paralysis (PFP) associated with AOM [5,6] .
Antibiotics make a significant reduction of facial paralysis in many series [7][8][9] As far as conservative treatment is indicated, the use of intravenous antibiotics, with or without corticosteroids and myringotomy are generally accepted in patients with intact tympanic membrane. Surgery is a debatable option of treatment [10] .

THE AIM OF THE WORK
Here we aimed to represent cases of peripheral facial paralysis associated with acute otitis media, and to also study the epidemiological, and prognostic aspects. We analyzed files of 4710 cases of acute otitis media, seen at our department during the period from 2010 to 2020.

MATERIALS AND METHODS
A total of 80 patients (1.69%) had peripheral facial paralysis associated with (as a complication of) AOM. All patients were clinically evaluated to confirm the diagnosis of AOM. Then, they were categorized according to the House-Brackmann scale [11] at the treatment onset and at the end of treatment.
Hilger stimulator or electroneurography were the electric tests [12] used to assess prognosis of facial nerve paralysis. The topography of paralysis was evaluated by the study of tearing, stapes reflex and image assessment (if patient refereed to surgery).
The clinical treatment was achieved by a broad spectrum antibiotics to assure the coverage for the most common bacterial pathogen responsible for acute otitis media, associated with steroids.
In addition, eye drops and intendments were prescribed to protect the eye. Surgical treatment options included myringotomy and/or Mastoidectomy to decompress the facial nerve, with intact nerve sheath during the acute phase of OM.

Statistical analysis:
For qualitative variables, relative frequency and percentages were calculated. But, for quantitative variables, mean and standard deviations were presented. To examine association between outcome and studied variables, Chi square or student "t" tests were used for qualitative and quantitative data, respectively. P < 0.05 was set as significant to interpret data. All statistic calculations were performed by statistical package for social science package, version 16 (SPSS Inc., USA).

RESULTS
Patients who developed facial nerve paralysis were mainly males (58.8%). Their age ranged between 2 and 62 years, the mean age was 17.5 years.
Facial paralysis associated with acute otitis media was predominantly of acute or sudden onset (90.0%).
Otorrhea (external discharge) was reported in 12.5% of patients.
The topography was mainly infrageniculate (86.3%). A collected material for bacteriology was reported for 40.0%, and 53.1% of them had negative culture.
Antibiotics with corticosteroids were used for all patients. Myringotomy was done for 7.5%, aspiration for 10.0% and Mastoidectomy for 10.0%.
The overall outcome on the basis of electrophysiological studies was good among 90.0% and bad among 10.0%. The duration for complete cure in cases with good outcome not exceeded 3 months, the mean duration was 1.53±0.55 months. The final grade was I among 90.0%, II among 5% and III among 5% (Table 1).
Among studied variables, only lower initial grade on House-Brackmann scale and infrageniculate topography were associated with favorable outcome (Table 2).

DISCUSSION
Of 4710 cases of acute otitis media, 80 patients (1.69%) developed facial nerve paralysis. Makeham et al. [7] investigated the infective causes of facial nerve paralysis and reported that, about 1% of cases are developed as a complication of acute otitis media. They reported that, about 70.0% of patients were under the age of 12, the commonest affected age by AOM. However, our patient's mean age is above that age and this could be attributed to the retrospective nature of the study with heterogeneity of cases, as we included all patients who had developed AOM during the study period.
The incidence reported in the current study is much higher than the western literature (about 0.02%) [16,17] . This could be attributed to antibiotic abuse and over the counter drugs, a common problems in our country.
The cause of facial nerve paralysis in AOM is not well understood, but possible mechanisms include direct neurotoxic effects exerted by metabolites, inflammation, and nerve ischemia due to pressure by edema [18] .
In the current work, the majority of patients (86.3%) had infrageniculate facial nerve lesion in relation to topography, as this is the site in direct contact with the AOM associated infection [10] .
Results of bacteriological analysis in the current study is in line with previous studies in literature. For example, Ngo et al. [13] , Mittal et al. [14] , and Thorne et al. [15] reported that, the most common cause of AOM includes infection by Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. However, otitis media with complications, the commonest organisms involve S. pneumoniae, Streptococcus pyogenes, P. aeruginosa, and Staphylococcus species. Thorne et al. [15] added that, as an interesting finding, no growth has been detected in up to 36% of examined material.
The possible cause for negative culture in the current work is the fact that, the patient was under antibiotic therapy.
All patients in the current study were recovered with good prognosis in 90.0% after the fist course of treatment. This is in line with previous studies, reported that, In AOM, greater than 95% of patients had complete recovery [10,17,19] .
Regarding antibiotic treatment, Posa et al. [20] recommended the use of intravenous third-generation cephalosporin, as it had a good meningeal penetration and target the majority of causative organisms. Carmel et al. [21] reported that, the commonest causative organisms are Streptococcus pneumoniae, Staphylococcus aureus, and Streptococcus pyogenes.
Redaelli de Zinis et al. [17] reported that, there is a consensus about the use of antibiotics in treatment of facial paralysis due to AOM with the use of oral or intravenous corticosteroids. However, the consensus on the use of corticosteroids as a routine association with antibiotics is absent, irrespective of its continued use. This could be attributed to the low number of cases of facial paralysis associated with AOM. Popovtzer et al. [16] , as in the current work, reported that, myringotomy, with or without insertion of a ventilation tube is also indicated in cases with intact tympanic membrane. They added, the surgical intervention in the form of mastoidectomy associated with decompression of the facial nerve is indicated in specific cases with a worsening symptoms of AOM or facial nerve paralysis irrespective of clinical antibiotic and steroid treatment. Patient should keep three weeks of grade VI paralysis after treatment or had a bad prognosis on electrophysiological tests to be indicated for mastoidectomy.
For patient's undergone mastoidectomy, we noticed areas of dehiscence and edema of the tympanic portion of the facial nerve. This is in line with Tschiassny's theory described by Redaelli de Zinis et al. [17] .

CONCLUSION
Based on the results of the current work, we could conclude that, the development of facial nerve paralysis after or in association with AOM is relatively rare. The treatment by antibiotics with corticosteroids is a suitable treatment option with good results.