|Year : 2021 | Volume
| Issue : 2 | Page : 52-56
Delayed facial nerve paralysis following tympanomastoid surgery
Santosh Kumar Swain
Department of Otorhinolaryngology, IMS and SUM Hospital, Siksha “O” Anusandhan University, Bhubaneswar, Odisha, India
|Date of Submission||11-May-2021|
|Date of Acceptance||28-Aug-2021|
|Date of Web Publication||09-Dec-2021|
Dr. Santosh Kumar Swain
Department of Otorhinolaryngology, IMS and SUM Hospital, Siksha “O” Anusandhan University, K8, Kalinga Nagar, Bhubaneswar - 751 003, Odisha
Source of Support: None, Conflict of Interest: None
Facial nerve paralysis is the most severe form of cranial neuropathy that causes facial deformity. Late-onset or delayed facial nerve palsy is uncommon following tympanomastoid surgery, although it can occur up to 2 weeks following the procedure. Although pinpointing the specific reason for delayed facial nerve paralysis following tympanomastoid surgery is complex, several variables such as facial nerve injury and/or viral reactivation can play a role. Late facial nerve paralysis after tympanomastoid surgery is caused by exposure of the facial nerve and fallopian canal dehiscence. Late facial nerve paralysis may be produced by viral reactivation and damage to the chorda tympani nerve. This study aims to look at the prevalence, etiology, clinical signs, diagnosis, and current treatment options for delayed facial nerve paralysis following tympanomastoid surgery. The exact cause of delayed facial nerve paralysis after tympanomastoid surgery has significant consequences for therapy and prognosis. The use of steroid and antiviral drugs is helpful for the treatment of the delayed facial nerve paralysis due to viral reactivation. The overall prognosis of the delayed facial nerve paralysis following tympanomastoid operation is good. This article discusses the prevalence, etiopathogenesis, clinical features, diagnosis, and present treatment of late/delayed facial nerve palsy following the tympanomastoid operation.
Keywords: Delayed facial nerve paralysis, fallopian canal, tympanomastoid surgery, viral reactivation
|How to cite this article:|
Swain SK. Delayed facial nerve paralysis following tympanomastoid surgery. Ann Indian Acad Otorhinolaryngol Head Neck Surg 2021;5:52-6
|How to cite this URL:|
Swain SK. Delayed facial nerve paralysis following tympanomastoid surgery. Ann Indian Acad Otorhinolaryngol Head Neck Surg [serial online] 2021 [cited 2022 Jan 18];5:52-6. Available from: https://www.aiaohns.in/text.asp?2021/5/2/52/332060
| Introduction|| |
The most visible cranial neuropathic disease is facial nerve paralysis. It results in obvious facial deformity and impacts the emotional aspect of a person, leading to social isolation and decreased self-esteem. Tympanomastoid surgery is a routine surgical procedure performed commonly by otolaryngologists or otologists. In clinical practice, late facial nerve paralysis following tympanomastoid surgery is unusual. The connection between tympanomastoid operation and the development of facial nerve paralysis suggests that the surgery is to blame, casting doubt on the surgeon's technique. Facial nerve paralysis after tympanomastoid surgery is one of the greatest fears among otolaryngologist. It can occur after 3 days to 2 weeks after the surgery. Many etiological factors postulated in the pathogenesis of the late-onset facial nerve paralysis. Although technological advancements such as the operating microscope, motorized surgical drill, and preoperative imaging of the temporal bone, the risk is still there for facial nerve paralysis. Iatrogenic trauma, medical history of the patient, patient examination, and imaging are all factors that affect the diagnosis, treatment, and prognosis of delayed facial nerve paralysis after tympanomastoid surgery. The prediction of the late facial nerve paralysis following tympanomastoid surgery appears to be good. The delayed facial nerve paralysis after tympanomastoid surgery is infrequently reported in the medical literature. This review article aims to discuss the details of epidemiology, etiopathology, clinical presentations, diagnosis, treatment, and prognosis of delayed facial nerve paralysis following tympanomastoid surgery.
| Methods of Literature Search|| |
Multiple systematic methods were used to find current research publications on delayed facial nerve paralysis after tympanomastoid surgery. We started by searching the Scopus, PubMed, Medline, and Google Scholar databases online. This search strategy recognized the abstracts of published publications, while other papers were discovered manually from the citations.
A search strategy using Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines was developed [Figure 1]. Randomized controlled studies, observational studies, comparative studies, case series, and case reports were evaluated for eligibility. This paper focuses only on the delayed facial nerve paralysis following tympanomastoid surgery. The search articles with immediate traumatic causes or any other causes other than delayed facial nerve paralysis following tympanomastoid surgery with their management are excluded. Review articles with no primary research data were also excluded.
This paper examines the epidemiology, etiopathogenesis, clinical manifestations, diagnosis, treatment, and prognosis of delayed facial nerve paralysis following tympanomastoid surgical procedure. This analysis provides a foundation for future prospective trials in late facial nerve palsy after tympanomastoid surgery. It will also serve as a catalyst for additional study into delayed facial nerve paralysis following tympanomastoid operation, allowing early detection and treatment.
| Epidemiology|| |
Incidence of iatrogenic facial nerve palsy following tympanomastoid operation has been documented to be between 0.6% and 3.7%. In the case of revision tympanomastoid surgery, the frequency of facial nerve paralysis is high as 4% to 10%. Delayed facial nerve paralysis has been documented as a complication of different tympanomastoid and neurotologic surgeries. The incidence of the delayed facial nerve paralysis following tympanomastoid surgery depends on the specific type of surgical procedure. Still, it is has been associated with surgery affecting because of manipulation of the facial nerve. The incidence of the delayed facial nerve paralysis following tympanomastoid surgery was documented as 1.4%. In otologic surgery like stapedectomy, there is less chance of manipulating the facial nerve and the incidence of delayed facial nerve paralysis is <1%. After cochlear implant surgery, 1.7% of people get delayed facial nerve paralysis. The acoustic neuroma is operated by different approaches including transmastoid route. The chance of delayed facial palsy following surgery for acoustic neuroma varies between 2.2% and 30%.
| Etiopathology|| |
The cause of delayed onset facial nerve palsy following tympanomastoid surgery is uncertain. Facial nerve injury, neural devascularization, and viral reactivation have all been associated with delayed facial nerve palsy after tympanomastoid surgery. A consequence of tympanomastoid surgery is facial nerve palsy. Following tympanomastoid operation, facial nerve paralysis can occur immediately or take several days. Ipsilateral facial nerve paralysis is often immediate and found after surgery and is usually caused by direct trauma to the facial nerve at the time of the surgery. Near facial nerve, paralysis may also occur due to the local anesthesia effect and regress thoroughly after few hours of the surgery. Several reasons have been linked to the pathophysiology of delayed facial nerve paralysis after tympanomastoid surgery, including surgical trauma-induced neural edema, local anesthetic medication, and virus reactivation. During tympanomastoid surgery, the facial nerve is the most susceptible component in the middle ear. Accidental injury to the facial nerve during tympanomastoid surgery might result in facial nerve paralysis if the surgeon ignores the facial nerve's location. This injury usually occurs when the bony defects of the fallopian canal often expected to be present. One study found that approximately 57% of the people have dehiscence of the fallopian canal at the oval window niche.
The degree of facial nerve manipulation during tympanomastoid surgery is directly proportional to delayed facial nerve paralysis. This shows that facial nerve injuries, whether direct or indirect, might generate inflammation and edema inside the fallopian canal, resulting in face nerve palsy. By 24–48 h after manipulative stress to the facial nerve, inflammation and edema had reached their climax. The development of facial nerve paralysis, on the other hand, might take up to 11 days after tympanomastoid surgery. Some other factors must be associated with explaining the significant delay between the surgical procedure and the onset of the facial nerve dysfunction. Reactivation of the latent virus following tympanomastoid surgery is not uncommon for causing delayed facial nerve paralysis. Cushing was the first to observe the latent herpes simplex virus (HSV) reactivating during a trigeminal nerve surgery in 1905. After surgical intervention on the trigeminal nerve, herpes labialis lesions and other mucocutaneous or cutaneous lesions are often found along with the distribution of the nerve. The degree of neural manipulation during surgical procedures/tympanomastoid surgery is strongly related to the rate of postoperative HSV reactivation. Physical manipulation of the facial nerve or ganglion, which is generally dormant, might be one explanation for viral reactivation. Another plausible cause is impaired immune system function, which is a more significant stressor following tympanomastoid surgery. One study reported that magnetic resonance imaging (MRI) findings in delayed facial nerve paralysis patients following stapedectomy are similar to Bell's palsy. This gives evidence that viral infection could be the cause of delayed facial nerve paralysis. The revival of facial nerve paralysis might be linked to thermal damage. When nearing the entrance of the facial recess, thermal or vibration injury to the facial nerve can be a triggering factor for delayed facial nerve paralysis although it usually results in immediate postoperative facial nerve paralysis. In addition, patients with abnormal temporal bone such as hypoplasia of the aditus, mastoid antrum, and facial recess put the patient at risk of the delayed facial nerve paralysis following tympanomastoid surgery. The uncommon anatomic abnormalities of the temporal bone are frequently accompanied by a fallopian canal abnormality, lowering or even eliminating the Trautman's triangle and putting the patient at risk for delayed facial nerve paralysis. Slight injuries to the chorda tympani nerve, for example, stretching or retrograde facial nerve edema, may be responsible for late facial nerve paralysis after stapedectomy surgery. To avoid late facial nerve paralysis, otorhinolaryngologists should avoid amputation or overstretching of the chorda tympanic nerve during surgery if at all feasible. The chorda tympani nerve can be lacerated, transected, or crushed during a traumatic injury, resulting in intraneural hemorrhage or edema. The prognosis and treatment options differ depending on the cause of the damage. However, the traumatic injury of the chorda tympanic nerve leading to delayed facial nerve paralysis is controversial. There is a close relationship between diabetic angiopathy and neuropathy with facial nerve paralysis. Neurogenic factors play an important role for regulation of the microcirculation. In the case of diabetic neuropathy, there is damage to the facial nerve because of disturbances in hemodynamic with increased arteriovenous shunting and abnormal responses to the tissue injuries. Abnormal neurogenic regulations of the microvascular hemodynamics can result in microangiopathy which affects the facial nerve by the pathogenesis of ischemia. So, identification of the exact cause is usually a challenge for management and outcome of the delayed facial nerve paralysis after tympanomastoid surgery.
| Clinical Manifestations|| |
Facial nerve's function is crucial in a person's physical, psychological, and emotional composition. All of these components can be affected by facial nerve paralysis, resulting in social and vocational limitations. The condition of facial nerve paralysis causes significant alterations in facial function and appearance. The onset of the delayed facial nerve paralysis following tympanomastoid surgery is bimodal with two peaks: Early and late-onset. The early formation of the facial nerve paralysis occurs around 3–5 days following tympanomastoid surgery due to neural edema, particularly in the meatal foramen. It was thought that heat production and/or inflammation by drilling the temporal bone at the time mastoid surgery might indirectly result in intratubal facial nerve edema. The facial nerve and/or chorda tympani nerves responsible for late-onset delayed facial nerve palsy after tympanomastoid operation may reactivate the herpes virus after tympanomastoid surgery. Delayed facial nerve paralysis is most common on the same side of the operated ear. The delayed facial nerve paralysis is although reversible often results in dissatisfaction for the patient and also a surgeon. Patients who have their facial nerves paralyzed following ear surgery experience a considerable deal of psychological distress. Determination of onset of the delayed facial nerve paralysis, severity, duration, and recovery must be assessed for the patient. House-Brackmann (HB) grading system is often employed for assessment of the facial nerve. One study showed delayed facial nerve paralysis after mastoid surgery for acoustic neuroma; patient developed Ramsay Hunt syndrome, where patients developed clinical features like rashes in the pinna and external auditory canal along with aural pain and vertigo with serological confirmation of the varicella-zoster infection. Patients who experience delayed facial nerve paralysis after tympanomastoid surgery frequently experience psychosocial issues such as social disengagement, anxiety, negative body image, and low mood.
| Diagnosis|| |
Serological investigations are done for the varicella-zoster virus. Because of viral reactivation, we may observe elevated immunoglobulin M (IgM) and IgG titers, resulting in late-onset facial nerve palsy following tympanomastoid surgery The geniculate ganglion region of the ear's exudate sent for the polymerase chain reaction (PCR) method and valuable for detecting varicella-zoster infection. In one study, researchers employed the PCR methodology to identify HSV type 1 (HSV-1) in the saliva of patients with late facial nerve paralysis following tympanomastoid surgery, finding that four out of five patients had raised titer HSV-1. A high-resolution computed tomography (CT) scan often reveals the dehiscence of the fallopian canal. On the other hand, minor bone deformities may go undiagnosed due to the facial nerve's multiplanar and convoluted course. Obtaining an excellent picture of the fallopian canal necessitates the use of many planes of view. One study showed that CT scan coincided with surgical findings in approximately 75% of the patients with around 66% sensitivity and about 84% specificity. The facial nerve's complicated path necessitates a thorough radiological examination. The accuracy of MRI in identifying soft tissue lesions along the facial nerve, particularly in the neurological system, is higher. Gadolinium-enhanced MRI increases T1-weighted signal intensity. In the event of facial nerve paralysis caused by inflammation, increased capillary permeability to gadolinium is likely to cause a breakdown of the blood-peripheral nerve barrier. MRI often demonstrates abnormal enhancement of the facial nerve in delayed facial nerve palsy due to unknown causes. From the brainstem's nucleus to the extratemporal route, MRI may examine the facial nerve at all levels. The edema in the fallopian canal is easily demonstrated by contrast-enhanced MRI. However, the time interval between the MRI scan and the diagnosis varies with the time period from diagnosis to the time of surgery, these differences may affect the alterations in the lesions. CT scan is helpful to find out the injury of the fallopian canal or any bony compressive mass.
| Treatment|| |
Although many reports suggest that full recovery can occur without minimal medication, with the development of facial nerve paralysis, therapy possibilities include steroids and antivirals. The delayed facial nerve paralysis caused by viral reactivation can be treated with steroid and antiviral medications. Prednisone and acyclovir, given within 3 days after the beginning of facial nerve paralysis, were shown to be effective in treating delayed facial nerve paralysis induced by viral reactivation in one trial. It was a successful treatment choice that resulted in the complete normalcy of facial nerve function., The use of the combination of corticosteroids and antivirals is an established treatment option in idiopathic facial nerve paralysis. When patients are put on acyclovir and prednisone within 3 days after the onset of facial nerve dysfunction, they have a good result. Treatment of delayed facial nerve palsy after tympanomastoid surgery with acyclovir and prednisone is highly effective. However, the clinician should keep in mind regarding adverse effects of steroids. Steroids have several side effects including gastritis, increase blood glucose, osteoporosis, osteonecoris, hypertension, cataract, and myopathy. Alternatively, prophylactic antiviral treatment can be started for preventing the delayed facial nerve paralysis. There is no doubt regarding HSV-I is often present as the latent state in the geniculate ganglion of the facial nerve and the surgical stress can reactivate this virus and result in facial nerve palsy. Physical therapy, mainly neuromuscular retraining, is a valuable intervention for treating facial nerve paralysis. Fallopian canal decompression, particularly labyrinthine segment, is usually suggested to prevent delayed facial nerve paralysis in vestibular surgeries. Routine facial nerve monitoring during tympanomastoid surgery is highly effective and essential to avoid face nerve damage. Despite advancements in the operating microscope, microdrill, and preoperative imaging availability now minimize the chance of facial nerve paralysis following tympanomastoid operation.
| Prognosis|| |
Routine facial nerve monitoring during tympanomastoid surgery is highly effective and essential to avoid face nerve damage. Most people with delayed facial nerve palsy only have a partial impairment, and many recover completely. Although delayed facial nerve paralysis is usually reversible, it may result in dissatisfaction and worries among the patients and surgeons. In general, the patient's prognosis for delayed facial nerve paralysis is outstanding, with approximately 88% of cases returning to or exceeding the initial grading. HB grade is used to assess the facial nerve outcome for delayed facial nerve palsy following tympanomastoid surgery. One study showed 100% of patients with HB Grade-II recovered completely at 1 year follow-up, although only 57% of the patients with delayed facial nerve palsy in HB Grade-III palsy at 1 year follow-up. The data for cases those with delayed facial nerve palsy of HB Grade-I after surgery are more optimistic; 100% and 86% for delayed facial nerve palsy magnitudes of HB Grade-II and III respectively.
| Conclusion|| |
After tympanomastoid surgery, delayed paralysis of the facial nerve is an uncommon clinical occurrence. In otological practice and medical literature, this clinical occurrence is relatively unknown. As it had a favorable recovery rate, patients should be reassured, and corrective surgical procedures to restore facial nerve function should not be recommended. It is still unknown what causes delayed facial nerve paralysis following tympanomastoid surgery. After tympanomastoid surgery, viral reactivation and neural edema are still crucial factors in delayed onset facial nerve paralysis. More research is needed to confirm the mechanism of facial nerve damage. Because of the excellent recovery rate, the patient should be reassured and the patient should not undergo any surgical procedures for improving the facial nerve function.
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Conflicts of interest
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