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Just Face It, We Could All Use a (Pictorial) Review: Anatomy, Variants, and Pathology of the Facial Nerve
Abstract and Figures
Imaging plays a central role in the work-up of patients who present with suspected facial nerve pathology. Imaging evaluation, however, can be quite challenging due to the complex anatomy and function of the facial nerve, as well as the diversity of pathology that affects this nerve. The purpose of this article is to provide a pictorial review of the normal anatomy, function, and imaging appearance of the facial nerve, as well as review the numerous pathologic processes that affect the facial nerve, with emphasis on key differentiating imaging features.
Learning Objective: To understand the normal anatomy and imaging appearance of the facial nerve and to recognize facial nerve pathology when encountered on both CT and MR imaging.
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Many studies have considered the temporal patterns of reproduction of Engraulis ringens, but little attention has been given to the spatial patterns of reproduction (spawning areas), which have shown great variability in both location (geographical position) and extent (the area covered by positive stations), without a satisfactory explanation. Along the Chilean coast, the daily egg production method (DEPM) has been used for several years to estimate spawning biomass in the northern Chile E. ringens population, with 24 surveys being carried out from 1992 to 2020. The most fluctuating parameters estimated in the DEPM have been the location and extent of the spawning area and the average female weight. In the last few years the eggs were distributed near the coast, whereas in the first few years they showed a more oceanic distribution. The average female weight has fallen from 30 g in the 1990s to 11 g in the last few years. In the present study, we analysed the relationship of the location and extent of spawning areas with female size and abundancy in E. ringens from northern Chile. According to the results, periods of high abundancy of eggs are positively correlated with larger females that spawn in more oceanic zones and to the south, expanding the spatial egg distribution and increasing the egg density. By contrast, in years with low abundance of eggs, the spawning was located north and towards the coast, with a smaller spawning area and smaller female size.
Multiple sclerosis is an inflammatory demyelinating disease of the central nervous system with a variety of presentations and unclear pathogenesis. Multiple sclerosis has been associated with the term autoimmunity as a surrogate for pathogenesis. Multiple sclerosis is an organ-specific disease with immune-mediated myelin destruction. Understanding the complex etiology of multiple sclerosis and the importance of axon integrity is critical for clinicians who treat the disease. This review discusses the immune and autoimmune aspects of multiple sclerosis based on the current published data and novel evidence of strategies that promote remyelination and protect axons.
Neurovascular compression syndromes are usually caused by arteries that directly contact the cisternal portion of a cranial nerve. Not all cases of neurovascular contact are clinically symptomatic. The transition zone between the central and peripheral myelin is the most vulnerable region for symptomatic neurovascular compression syndromes. Trigeminal neuralgia (cranial nerve V) has an incidence of 4-20/100,000, a transition zone of 4 mm, with symptomatic neurovascular compression typically proximal. Hemifacial spasm (cranial nerve VII) has an incidence of 1/100,000, a transition zone of 2.5 mm, with symptomatic neurovascular compression typically proximal. Vestibular paroxysmia (cranial nerve VIII) has an unknown incidence, a transition zone of 11 mm, with symptomatic neurovascular compression typically at the internal auditory canal. Glossopharyngeal neuralgia (cranial nerve IX) has an incidence of 0.5/100,000, a transition zone of 1.5 mm, with symptomatic neurovascular compression typically proximal. The transition zone overlaps the root entry zone close to the brain stem in cranial nerves V, VII, and IX, yet it is more distal and does not overlap the root entry zone in cranial nerve VIII. Although symptomatic neurovascular compression syndromes may also occur if the neurovascular contact is outside the transition zone, symptomatic neurovascular compression syndromes are more common if the neurovascular contact occurs at the transition zone or central myelin section, in particular when associated with nerve displacement and atrophy.
During the last decades, only a few cases on the association between peripheral demyelinating diseases and multiple sclerosis (MS) have been reported. We describe the case of a young man who was initially diagnosed with Bell's palsy, and only after performing a brain MRI was the diagnosis of MS made. We review the literature and discuss some pitfalls which may lead to missing the diagnosis of MS.
Background:
Traumatic perforation of the tympanic membrane (TPTM) is often encountered in primary care or in the emergency department (ED). Several therapeutic interventions have been described, but conservative follow-up until spontaneous complete recovery is the most common choice.
Objective:
Our goal was to analyze the trauma mechanism, perforation characteristics, and outcome of patients with TPTM.
Methods:
The study included patients examined in the ED of a tertiary, university-affiliated medical center because of TPTM between 2012 and 2016. Their medical records were retrospectively reviewed for demographics, trauma mechanism, clinical characteristics, and outcome. A phone survey was performed to obtain the missing information of all the patients who did not continue their follow-up in our outpatient clinic.
Results:
We reviewed the histories of 80 patients with a mean age of 26.7 ± 14.6 years (20 children; 25%). TPTM was caused by blunt trauma in 45 patients (56%) and penetrating trauma in 35 patients (44%). Thirty-five patients (44%) completed their follow-up in the hospital outpatient clinic, with a mean duration of 6.2 weeks. Twenty-five patients (38%) completed their follow-up in a community-based otolaryngology clinic, 6 patients (9%) chose not to complete their follow-up, and 14 patients were lost to follow-up. Of the 60 patients who completed follow-up, 56 patients recovered spontaneously, 3 patients underwent successful tympanoplasty, and 1 patient was referred to surgery but was lost to follow-up. All children healed spontaneously.
Conclusion:
TPTM was more common in young males with main mechanisms of blunt trauma (an assault) or cleaning the ear canal. All children demonstrated complete spontaneous recovery.
Age influences incidence and prognosis of Guillain Barre Syndrome (GBS), common cause of ascending areflexic quadriparesis. Dedicated studies on elderly GBS are infrequent. This study aimed to describe clinical features and outcome at hospital-discharge in patients aged≥60years with GBS. Medical records of 70 elderly GBS over 15years were analysed. Mean symptom-duration was 5.78±4.5days and onset-to-peak 5.14±4.4days. Antecedent events preceded GBS by 8.07±9.9days and included: fever (n=19), respiratory infection (n=6), and gastroenteritis (n=5). Clinical features were weakness of facial (n=34), bulbar (n=13), extraocular (n=4) and respiratory (n=20) muscles and recurrence (n=4). Nine had Hughes disability score (HDS) of three or less. Sensory symptoms and signs included paresthesias (n=40), pain (n=24), and impaired kinaesthetic sensation (n=14). Laboratory abnormalities included albumino-cytological dissociation (n=50), hyponatremia (n=36) and elevated creatine kinase (n=18). Electrophysiological subtypes were: primary demyelinating (n=52), inexcitable (n=3), equivocal (n=2) and axonal (n=1). Fifty-seven patients treated with plasmapheresis (n=48) or intravenous immunoglobulin (n=9) had mean HDS of 3.53±0.7 at discharge. Twenty-one were ambulant (HDS≥3), one had persisting respiratory weakness and one died. Striking differences between the 'elderly' and 100 'adults' seen over 20months were shorter symptom-duration, higher frequency of facial palsy and hyponatremia, lower frequency of pain, lower mean MRC sum score and worse HDS at study-entry and discharge (p<0.05). Requirement for mechanical ventilation and cardiac autonomic dysfunction was higher among elderly (p:0.02). In conclusion, in this cohort of elderly GBS, there was a higher frequency severe GBS and demyelinating electrophysiology.
Background:
Facial nerve schwannomas are rare, benign, nerve-sheath tumors. They can occur in any segment of the facial nerve and often clinically and radiographically mimic the common vestibular schwannoma when extending into the cerebellopontine angle. The optimal treatment strategy for intracranial facial nerve schwannomas remains controversial.
Methods:
We review the literature and discuss the natural history, clinical features, diagnosis and current management of facial nerve schwannoma.
Results:
Complete tumor resection with facial nerve preservation can be achieved in fewer cases. In most cases, the affected segment of facial nerve must be removed if the goal is to achieve complete tumor section. Regardless of type of facial nerve repair, patients can expect no better than an eventual HB grade III palsy. Stereotactic radiosurgery has good results in tumor control and facial function outcome.
Conclusions:
Treatment for intracranial facial nerve schwannomas depends on clinical presentation, tumor size, preoperative facial, and hearing function. Conservative management is recommended for asymptomatic patients with small tumors. Stereotactic radiosurgery may be an option for smaller and symptomatic tumors with good facial function. If tumor is large or the patient has facial paralysis, surgical resection should be indicated. If preservation of the facial nerve is not possible, total resection with nerve grafting should be performed for those patients with facial paralysis, whereas subtotal resection is best for those patients with good facial function.
Objective:
To determine the specificity of the current clinical diagnostic criteria for neurofibromatosis type 2 (NF2) relative to the requirement for unilateral vestibular schwannoma (VS) and at least 2 other NF2-related tumors.
Methods:
We interrogated our Manchester NF2 database, which contained 205 individuals meeting NF2 criteria who initially presented with a unilateral VS. Of these, 83 (40.7%) went on to develop a contralateral VS. We concentrated our genetic analysis on a group of 70 who initially fulfilled NF2 criteria with a unilateral vestibular schwannoma and at least 2 additional nonintradermal schwannomas.
Results:
Overall, 5/70 (7%) individuals with unilateral VS and at least 2 other schwannomas had a pathogenic or likely pathogenic LZTR1 mutation. Twenty of the 70 subsequently developed bilateral disease. Of the remaining 50, 5 (10%) had a germline LZTR1 mutation, equivalent to the number (n = 5) with a germline NF2 mutation.
Conclusions:
The most common etiology for unilateral VS and 2 additional NF2-associated tumors in this cohort was mosaic NF2. Germline LZTR1 and germline NF2 mutations were equally common in our cohort. This indicates that LZTR1 must be considered when making a diagnosis of NF2 in the presence of unilateral VS in individuals without a germline NF2 mutation.
Objective:
Sarcoidosis is referred to as a great imitator because of its propensity to radiologically mimic a variety of pathologic entities. Symptomatic neurosarcoidosis is present in approximately 5% of patients with sarcoidosis, and it is found histopathologically in approximately 25% of asymptomatic patients.
Conclusion:
An understanding of the multifaceted imaging manifestations of head and neck sarcoidosis will aid early recognition of the diagnosis, with a goal for earlier initiation of therapy and prevention of irreversible sequelae of the disease.
