3D-FLAIR MRI in facial nerve paralysis with and without audio-vestibular disorder

The Pathogenesis of Cytomegalovirus and Other Viruses Associated with Hearing Loss: Recent Updates

Virus infection is one of the most common etiologies of hearing loss. Hearing loss associated with viral infection can be unilateral or bilateral, mild or severe, sudden or progressive, and permanent or recoverable. Many viruses cause hearing loss in adults and children; however, the pathogenesis of hearing loss caused by viral infection is not fully understood. This review describes cytomegalovirus, the most common virus causing hearing loss, and other reported hearing loss-related viruses. We hope to provide a detailed description of pathogenic characteristics and research progress on pathology, hearing phenotypes, possible associated mechanisms, treatment, and prevention measures. This review aims to provide diagnostic and treatment assistance to clinical workers.

Features of Audio-Vestibular Deficit and 3D-FLAIR Temporal Bone MRI in Patients with Herpes Zoster Oticus

Herpes zoster oticus (HZO) is characterized by otalgia and erythematous vesicles in the auricle or external auditory canal. Ramsay Hunt syndrome (RHS) can be diagnosed when facial nerve palsy is accompanied by these symptoms of HZO, and in this case, audio-vestibular symptoms such as hearing loss or dizziness often develop. Recently, 3D-fluid-attenuated inversion recovery sequence (3D-FLAIR) magnetic resonance imaging (MRI) has been introduced in order to evaluate the inner ear structure pathology. The purpose of this study was to investigate the audio-vestibular characteristics in correlation with temporal bone MRI findings in HZO patients. From September 2018 to June 2022, 18 patients with HZO participated in the study. Thirteen patients (77%) showed high-signal intensity in the inner ear structures in 4 h post-contrast 3D-FLAIR images. In a bithermal caloric test, the lateral semicircular canal showed high signal intensity in 4 h post-contrast 3D-FLAIR images in 75% of patients with abnormal canal paresis. While the cochlea showed high signal intensity in 4 h post-contrast 3D-FLAIR images in 75% of patients with hearing loss, the vestibulo-cochlear nerve showed enhancement in post-contrast T1-weighted images in only 33% of patients with hearing loss. The present study demonstrates that audio-vestibular deficits are well-correlated with increased signal intensity of the inner ear endorgans in 4 h post contrast 3D-FLAIR MRI.

MRI With Gadolinium as a Measure of Blood-Labyrinth Barrier Integrity in Patients With Inner Ear Symptoms: A Scoping Review

Objective: Capillaries within the inner ear form a semi-permeable barrier called the blood-labyrinth barrier that is less permeable than capillary barriers elsewhere within the human body. Dysfunction of the blood-labyrinth barrier has been proposed as a mechanism for several audio-vestibular disorders. There has been interest in using magnetic resonance imaging (MRI) with intravenous gadolinium-based contrast agents (GBCA) as a marker for the integrity of the blood labyrinth barrier in research and clinical settings. This scoping review evaluates the evidence for using intravenous gadolinium-enhanced MRI to assess the permeability of the blood-labyrinth barrier in healthy and diseased ears.

Methods: A systematic search was conducted of three databases: PubMed, EMBASE, CINAHL PLUS. Studies were included that used GBCA to study the inner ear and permeability of the blood-labyrinth barrier. Data was collected on MRI protocols used and inner ear enhancement patterns of healthy and diseased ears in both human and animal studies.

Results: The search yielded 14 studies in animals and 53 studies in humans. In healthy animal and human inner ears, contrast-enhanced MRI demonstrated gradual increase in inner ear signal intensity over time that was limited to the perilymph. Signal intensity peaked at 100 min in rodents and 4 h in humans. Compared to controls, patients with idiopathic sudden sensorineural hearing loss and otosclerosis had increased signal intensity both before and shortly after GBCA injection. In patients with Ménière's disease and vestibular schwannoma, studies reported increased signal at 4 h, compared to controls. Quality assessment of included studies determined that all the studies lacked sample size justification and many lacked adequate control groups or blinded assessors of MRI.

Conclusions: The included studies provided convincing evidence that gadolinium crosses the blood-labyrinth barrier in healthy ears and more rapidly in some diseased ears. The timing of increased signal differs by disease. There was a lack of evidence that these findings indicate general permeability of the blood-labyrinth barrier. Future studies with consistent and rigorous methods are needed to investigate the relationship between gadolinium uptake and assessments of inner ear function and to better determine whether signal enhancement indicates permeability for molecules other than gadolinium.

Mastoid effusion on temporal bone MRI in patients with Bell's palsy and Ramsay Hunt syndrome

This study aimed to investigate the incidence of mastoid effusion on temporal bone magnetic resonance imaging (MRI) in patients with Bell’s palsy (BP) and Ramsay Hunt syndrome (RHS), and evaluate the usefulness of mastoid effusion in early differential diagnosis between BP and RHS. The incidence of mastoid effusion on 3.0 T—temporal bone MRI, which was conducted within 10 days after the onset of acute facial nerve palsy, was compared between 131 patients with BP and 33 patients with RHS. Findings of mastoid cavity on temporal bone MRI were classified into three groups as normal mastoid, mastoid effusion, and sclerotic change, and the incidence of ipsilesional mastoid effusion was significantly higher in RHS than BP (P < 0.001). Tympanic membrane was normal in 7 of 14 RHS patients with mastoid effusion, and injected without middle ear effusion in 7 patients. This study highlights significantly higher incidence of ipsilesional mastoid effusion in RHS than BP, and suggests that the presence of mastoid effusion may provide additional information for differential diagnosis between RHS and BP.

Imaging of facial neuritis using T2-weighted gradient-echo fast imaging employing steady-state acquisition after gadolinium injection

BACKGROUND

MRI is the modality of choice for the imaging of facial neuritis. Previously, gadolinium-enhanced T1-weighted imaging of the petrous bone, then FLAIR sequences were thought to be most informative for acute facial neuritis imaging. The aim of this study is to evaluate the value of contrast-enhanced T2-weighted sequence for the diagnosis of acute facial neuritis and compare it to contrast-enhanced T1-weighted and FLAIR sequences.

METHODS

We included 50 patients with an acute unilateral idiopathic peripheral facial neuritis. An MRI (3 T) with three sequences was performed (T1-weighted, T2-weighted and FLAIR), all acquired after intravenous contrast-media injection.

RESULTS

The contrast-enhanced T2-weighted sequence appeared to be the most accurate one for the diagnosis of acute facial neuritis (Se 94%, Sp 100%, accuracy 98.2%, p < 0.001), with a pathological facial nerve strongly (grade 2-3) enhancing and a homogenous enhancement along the course of the entire facial nerve. Contrast-enhanced T1-weighted (Se 80%, Sp 100%, accuracy 94.1%) and FLAIR sequences (92%, Sp 88%, accuracy 90%, p < 0.001) showed lower accuracy. On T1-weighted sequence, a strong enhancement (blurred margins) of the canalicular segment was observed in 80% of the cases when it was never observed in normal nerves.

CONCLUSION

A strong (= iso to hyperintense to the petrous fat signal) and diffuse (all segments) enhancement of the facial nerve on T2-weighted steady-state free precession sequence is a sensitive and specific sign for the diagnosis of acute idiopathic facial neuritis, and appears superior to T1WI and FLAIR sequences.

Direction-fixed and Direction-changing Positional Nystagmus in Ramsay Hunt Syndrome

OBJECTIVES

To investigate the incidence of positional nystagmus (PN) using a head-roll test in patients with Ramsay Hunt syndrome with vertigo (RHS_V) and discuss possible mechanisms.

STUDY DESIGN

Retrospective study.

SETTING

Tertiary referral academic medical center.

PATIENTS

Twenty-eight patients with RHS_V were enrolled.

MAIN OUTCOME MEASURE

Eye movements were recorded at positions of head roll to the right or left, and PN was classified as direction-fixed or direction-changing. Vestibular function tests including caloric test were performed.

RESULTS

Direction-fixed nystagmus beating away from the affected side was the most common type of PN (61%), followed by direction-changing geotropic type (18%), direction-fixed nystagmus beating toward the affected side (14%), and direction-changing apogeotropic type (7%). The duration of nystagmus was longer than 60 seconds in all patients exhibiting direction-changing PN. Postcontrast T1-weighted internal auditory canal (IAC) magnetic resonance imaging showed enhancement of not only the facial and vestibulocochlear nerves, but also the inner ear structures or dura along the IAC, suggesting inflammatory changes within the labyrinthine membrane or IAC dura.

CONCLUSION

Although direction-fixed PN was more commonly observed (75%), direction-changing PN was also observed in some RHS_V patients (25%). The mechanism of direction-changing PN may be, at least in part, explained by the alteration of specific gravity of the lateral semicircular canal cupula or endolymph due to inflammation in the inner ear membrane.

Atypical clinical manifestations of herpes zoster oticus: diagnostic usefulness of magnetic resonance imaging

Typical symptoms of Ramsay Hunt syndrome (RHS) consist of painful vesicular eruptions in the external ear, unilateral facial palsy, and/or vestibulocochlear deficit. When RHS patients show atypical clinical manifestations, correct diagnosis can be delayed, and ideal treatment timing for antiviral therapy may be missed. The aim of this study is to describe RHS patients with atypical clinical manifestations and evaluate the usefulness of magnetic resonance imaging (MRI) for early differential diagnosis. We retrospectively reviewed the clinical data and investigated the findings of internal auditory canal (IAC) MRI of seven patients diagnosed with RHS presenting "atypical" clinical manifestations between January 2013 and December 2016. "Typical" symptoms of RHS consist of herpetic vesicular eruption and facial palsy with or without vestibulocochlear deficit. Regardless of symptomatic presentations, IAC MRI demonstrated post-contrast enhancement of cranial nerve (CN) VII, CN VIII, and IAC dura in patients with atypical clinical manifestations. In cases with multiple lower CN palsy, enhancement along the involved nerve was observed on IAC MRI. When RHS was complicated by acute parotiditis, diffuse enhancement of the parotid gland was demonstrated. The present study shows that in IAC MRI of RHS patients with atypical clinical manifestations, post-contrast enhancement was not confined to the facial nerve but also observed in CN VIII and IAC dura regardless of the symptoms, which may facilitate early diagnosis of RHS.

Characteristics of hearing loss in patients with herpes zoster oticus

Patients with herpes zoster oticus (HZO) may commonly show symptoms associated with 7th and 8th cranial nerve (CN VII and CN VIII) dysfunction. The aim of this study is to investigate the characteristics of hearing loss in patients with HZO and discuss possible mechanisms.Ninety-five HZO patients who showed at least one of the symptoms of CN VII and CN VIII dysfunction between January 2007 and October 2014 were included in this study. Hearing loss was defined when the mean thresholds of pure tone audiometry (PTA) in speech frequency (0.5 kHz + 1 kHz + 2 kHz/3) or isolated high frequency (4 kHz + 8 kHz/2) were greater than 10 dB in the affected ear compared with the healthy ear, and a total of 72 patients were classified as the hearing loss group.The difference of mean PTA thresholds between affected and healthy ears was significantly greater in the high frequency range than in low range (20.0 ± 11.5 dB vs. 12.9 ± 15.7 dB, P = 0.0026) in patients with hearing loss (n = 72). The difference between affected and healthy ear was significantly greater in patients with vertigo (n = 34) than those without vertigo (n = 38) in both the high (P = 0.033) and low (P = 0.024) frequency ranges. In contrast, the differences between affected and healthy ears were not significantly different between patients with facial palsy (n = 50) and those without facial palsy (n = 22) in both the high (P = 0.921) and low (P = 0.382) frequency ranges.In patients with HZO, hearing loss is more severe in the high frequency range than in the low frequency range. Hearing impairment is more severe in patients with vertigo than in those without vertigo in both the high and low frequency ranges, even though the degree of hearing impairment is not significantly different between patients with and without facial palsy. These findings indicate that the mechanisms of viral spread from CN VII to CN VIII may differ between vestibular and audiologic deficits.

High-frequency ultrasound as an adjunct to neural electrophysiology: Evaluation and prognosis of Bell's palsy

Bell's palsy is a form of temporary facial nerve paralysis that occurs primarily in young adults. Previously, various methods were used to assess outcomes in facial nerve disease. The aim of the present study was to characterize the main branches of the normal and abnormal facial nerve using high-frequency ultrasonography (HFUS). A total of 104 healthy volunteers, 40 patients with acute onset of Bell's palsy and 30 patients who underwent 3-month routine therapy for Bell's palsy disease were included in the study. The healthy volunteers and patients were selected for HFUS examination and VII nerve conduction. The results showed significant differences in nerve diameter, echogenicity, delitescence and amplitude in different groups. Statistically significant correlations were identified for severity grading in one of the experimental groups during HFUS examinations. In conclusion, HFUS as a complementary technique paired with neural electrophysiology may establish the normal values of facial nerve. Additionally, HFUS was beneficial in the process of evaluation and prognosis of Bell's palsy disease.

The Technical and Clinical Features of 3D-FLAIR in Neuroimaging

In clinical MR neuroimaging, 3D fluid-attenuated inversion recovery (3D-FLAIR) with a variable-flip-angle turbo spin echo sequence is becoming popular. There are more than 100 reports regarding 3D-FLAIR in the PubMed database. In this article, the technical and clinical features of 3D-FLAIR for neuroimaging are reviewed and summarized. 3D-FLAIR allows thinner slices with multi-planar reformation capability, a higher flow sensitivity, high sensitivity to subtle T1 changes in fluid, images without cerebrospinal fluid (CSF) inflow artifacts, and a 3D dataset compatible with computer-aided analysis. In addition, 3D-FLAIR can be obtained within a clinically reasonable scan time. It is important for radiologists to be familiar with the features of 3D-FLAIR and to provide useful information for patients.

Vibration- and hyperventilation-induced nystagmus in patients with Ramsay Hunt syndrome with vertigo

OBJECTIVES

The aims of this study were to compare vibration-induced nystagmus (VIN) and hyperventilation-induced nystagmus (HVIN) findings in patients with Ramsay Hunt syndrome with vertigo (RHS-V), sudden sensorineural hearing loss with vertigo (SSNHL-V), and vestibular neuritis (VN) during the acute stage and to address the possible lesion sites of vestibular deficit in RHS-V.

STUDY DESIGN

Case series with chart review.

SETTING

Tertiary referral center.

METHODS

We conducted a retrospective case series study in 27 patients with SSNHL-V, 104 patients with VN, and 17 patients with RHS-V and evaluated the findings of VIN and HVIN tests.

RESULTS

An abnormal VIN was observed in 91% of the patients with VN, 89% of those with SSNHL-V, and 94% of those with RHS-V, and the prevalence of abnormal VIN was not significantly different (P = .436). An abnormal HVIN was observed in 51% of the patients with VN, 22% of those with SSNHL-V, and 59% of those with RHS-V. While the prevalence of an abnormal HVIN was significantly different between SSNHL-V and VN groups (P = .007) and between SSNHL-V and RHS-V groups (P = .014), that between VN and RHS-V groups did not show a significant difference (P = .547).

CONCLUSION

Since the results of HVIN in RHS-V patients were more similar to those in VN patients than those in SSNHL-V patients, a lesioned site may be more likely within the vestibular nerve than the inner ear as a cause for vestibular deficit in patients with RHS-V who show caloric canal paresis of 25% or greater.

Visualization of endolymphatic hydrops in Ménière's disease after single-dose intravenous gadolinium-based contrast medium: timing of optimal enhancement

PURPOSE

Visualization of endolymphatic hydrops (EH) in patients with Ménière's disease (MD) is now possible by heavily T(2)-weighted 3-dimensional fluid-attenuated inversion recovery (hT(2)W-3D-FLAIR) obtained 4 hours after intravenous (IV) administration of single dose gadolinium-based contrast medium (GBCM). Although maximum enhancement has been reported 4 hours after contrast administration in healthy volunteers, the timing of optimal enhancement in patients with MD is not reported. We investigated if that optimal timing is earlier or later than 4 hours.

MATERIALS AND METHODS

We evaluated 10 consecutive patients with suspected MD whom we randomly divided into 2 groups. We obtained hT(2)W-3D-FLAIR before GBCM administration and 10 min, 3.5 hours, and 4 hours after GBCM administration in Group A and before and 10 min, 4 hours, and 4.5 hours after GBCM administration in Group B. We compared signal intensity ratio (SIR) values of the perilymph and pons between 3.5 and 4 hours in Group A and between 4 and 4.5 hours in Group B and evaluated grades of EH at 3.5 and 4 hours in Group A and at 4 and 4.5 hours in Group B.

RESULTS

SIR values did not differ significantly between 3.5 and 4 hours in Group A and between 4 and 4.5 hours in Group B. However, SIR values at 4 hours were significantly higher in Group A than Group B. Grades of EH agreed between 3.5 and 4 hours in Group A and between 4 and 4.5 hours in Group B.

CONCLUSION

The optimal timing of contrast enhancement in patients with suspected MD remains unclear, but evaluation of EH may be possible from 3.5 to 4.5 hours after contrast administration.

3D-FLAIR MRI findings in patients with low-tone sudden deafness

CONCLUSION

The findings suggest that alterations in the composition of inner ear fluid play important roles in the development of low-tone sudden deafness (LTSD). High-intensity signals on three-dimensional fluid attenuated inversion recovery (3D-FLAIR) may reflect an increased concentration of protein in the inner ear due to the increased permeability of blood vessels. Disordered blood flow in the inner ear is associated with an increased permeability of the blood-labyrinth barrier. Therefore, the disordered blood flow in the cochlea may be closely related to the pathophysiological mechanisms of LTSD.

OBJECTIVES

The 3D-FLAIR sequence has been used to detect alterations in the composition of inner ear fluid. The purpose of this study was to report imaging findings in cases of LTSD.

METHODS

3D-FLAIR magnetic resonance imaging was performed in five women with nonrecurrent-type LTSD.

RESULTS

Three of the five patients (60%) showed high-intensity signals in the cochlear basal turn on precontrast 3D-FLAIR. Postcontrast enhancement was not prominent in any patient. In patient 1, the cochlea of the unaffected side showed high-intensity signals. No patients had such signals in the vestibulae or the semicircular canals.

Recent progress in facial paralysis: advances and obstacles

PURPOSE OF REVIEW

Facial paralysis is a devastating and debilitating condition for which a range of management options exists; all of them continue to have limitations. We review the recent scientific literature and highlight key developments and opportunities for further exploration with the goal that this may help direct clinical practice and research endeavor.

RECENT FINDINGS

We reviewed recent findings in the evaluation of facial paralysis, pharmacological management, nerve injury prevention and treatment. This includes review of novel techniques using photography and videography. Review of surgical and adjunctive techniques identifies several refinements of existing techniques, some novel techniques, and the value of adjunctive materials and therapies.

SUMMARY

Management of facial paralysis remains an area of active investigation and innovation. The challenge to researchers and care providers will be to continue to explore and refine management strategies while maintaining rigorous and standardized means of evaluation and follow-up, such that outcomes may be determined and reported accurately and in a way that they can be transferred to other clinical practices. Further study of the role of growth factors and stem cells in facial nerve regeneration is critical, and is the most likely means of surmounting the remaining barriers to successful outcomes in alleviating the ravages of this devastating malady.