Enhancement along the normal facial nerve in the facial canal: MR imaging and anatomic correlation

The clinical availability of facial nerve enhancement in temporal bone MRI for the patients of idiopathic acute peripheral facial palsy

PURPOSE

This study is to evaluate the duration of facial nerve enhancement in gadolinium-enhanced temporal bone MRI after the onset of acute facial palsy.

METHODS

Gd-enhanced MRI imagines were examined in 13 patients with idiopathic acute facial palsy within 14 days after the onset. The degree of facial nerve function was measured according to the House-Brackmann (H-B) grading system at their first visit at outpatient clinic. The follow-up MRI was taken about 16.5 months (7-24 months) after onset of disease. The degree of facial nerve enhancement was measured with signal intensity (SI) which was quantitatively analyzed using the region-of-interest (ROI) measurements for each segment of the facial nerve. SI was statistically analyzed by comparing SI values of contralateral site and ipsilateral site using the paired t test with SPSS program.

RESULTS

The gadolinium enhancement was statistically increased at labyrinthine segment and geniculate ganglion area of facial nerve at initial temporal bone MRI. The gadolinium enhancement was statistically decreased at all the segments of facial nerve except tympanic segment (p < 0.05) at follow-up MRI.

CONCLUSIONS

The facial nerve enhancement in Gd-enhanced MRI images prolonged more than 21 months of the onset. The newly developed pathologic lesions of acute facial palsy especially occur at the site of labyrinthine and geniculate ganglion.

Variability of the Cervical Branch Depending on the Facial Nerve Branching Pattern and Anthropometric Type of the Head

(1) Background: Considering that the specialty literature supplies only general data about the variability of the cervical branch of the facial nerve, this study aimed to determine this branch's variation and individual peculiarities depending on the nerve branching pattern and anthropometric type of the head. (2) Methods: The study was conducted on 75 hemifaces of adult formalized cadavers. Ahead of anatomical dissection, each head was measured to establish the anthropometric type, according to Franco and colleagues. The branching patterns were then distributed according to the Davis classification. (3) Results: The number of cervical branches (CB) of the facial nerve varied from one to five branches, with the following rate: 1 CB (61.3%), 2 CB (28%), 3 CB (6.7%), 4 CB (2.7%), and 5 CB (1.3%). Seven branching patterns of the facial nerve were revealed: Type I in 18.7%, Type II in 14.7%, Type III in 20%, Type IV in 14.6%, Type V in 5.3%, Type VI in 18.7%, and Type NI in 8% (bizarre types). According to the branching pattern, the mean numbers of the cervical branches were as follows: Type I-1.6 ± 1.02; Type II-1.4 ± 0.50; Type III-1.4 ± 0.50; Type IV-1.4 ± 0.67; Type V-2.0 ± 1.41; Type VI-1.8 ± 1.12; and Type-NI-1.8 ± 0.75; p = 0.599. According to the anthropometric type of the head, the mean number of CB in the mesocephalic type (MCT) was 1.5 ± 0.82, in the dolichocephalic type (DCT), 1.7 ± 0.87, and in the brachycephalic type, (BCT) 1.8 ± 1.04; p = 0.668. (4) Conclusions: The cervical branch of the facial nerve varies depending on the facial nerve branching pattern and the anthropometric type of the head. The highest degree of variation was characteristic of BCT and Type V and the lowest, of MCT and Types II, III, and IV.

Extra-axial cranial nerve enhancement: a pattern-based approach

Cranial nerve enhancement is a common and challenging MRI finding that requires a meticulous and systematic evaluation to identify the correct diagnosis. Literature mainly describes the various pathologies with the associated clinic-radiological characteristics, while the radiologist often needs a reverse approach that starts from the radiological findings to reach the diagnosis. Therefore, our aim is to provide a new and practical pattern-based approach to cranial nerve enhancement, which starts from the radiological findings and follows pattern-driven pipelines to navigate through multiple differential diagnoses, guiding the radiologist to reach the proper diagnosis. Firstly, we reviewed the literature and identified four patterns to categorize the main pathologies presenting with cranial nerve enhancement: unilateral linear pattern, bilateral linear pattern, unilateral thickened pattern, and bilateral thickened pattern. For each pattern, we describe the underlying pathogenic origin, and the main radiological features are displayed through high-quality MRI images and illustrative panels. A suggested MRI protocol for studying cranial nerve enhancement is also provided. In conclusion, our approach for cranial nerve enhancement aims to be an easy tool immediately applicable to clinical practice for converting challenging findings into specific pathological patterns.

The radiologic (CT/MRI)-pathological correlations of the salivary duct carcinoma (SDC) with hyaline degeneration and peripheral nerve invasion

OBJECTIVES

Salivary duct carcinoma is an aggressive tumour commonly showing local invasion and/or nerve palsy. However, their CT/MRI findings, especially, regarding T2WI, and the diffusion-weighted-image (DWI), were not well known. In this study, we correlated the CT/MRI appearance and the pathological findings containing the nerve invasion cases such as a facial nerve.

METHODS

We reviewed 14 cases of SDC (parotid = 11, submandibular = 2, minor salivary gland = 1) pathologically proven peripheral nerve involvement. Their CT findings of all patient including dynamic contrast-enhancement study､MRI (n = 9) and DWI (n = 6) were also analyzed with histopathological correlation.

RESULTS

On contrast-enhanced CT, the solid component was moderately enhanced. On MRI, T2WI central low signal core (n = 6) with peripheral high intensity rim (n = 5) was frequently observed except heterogeneous low and high (n = 1), diffuse low (n = 1), and high (n = 1) signal cases. The hyaline degenerative area located in the tumour core was poorly enhanced. Eleven tumours had an ill-defined margin, reflecting invasive tumour growth. On DWI, they showed high signal [the central low and peripherally high (n = 4), and diffuse (n = 1), heterogeneously high signal (n = 1)]. The mean ADC value was 1.148 ~ 0.961 x 10-3 mm²/s. With pathological correlation, the central low signal area on T2WI reflected hyaline degeneration. The sites of gross nerve involvement were revealed as tubular or branching structures on CE-CT (n = 3), and MRI (n = 1).

CONCLUSIONS

(1) We frequently observed a central low signal area on T2WI/DWI in SDC. With histopathological correlation, it corresponded to the central hyaline degeneration with the peripheral viable tumour. 2) The gross nerve involvement might be detected as a strongly enhancement structure.

Enhancement patterns of the normal facial nerve on three-dimensional T1W fast spin echo MRI

Objectives:

With increasing neuroimaging applications of contemporary three-dimensional T₁W fast spin echo (3D T1W FSE) sequences, it was aimed to reappraise the normal patterns of skull base facial nerve gadolinium enhancement.

Methods:

Pre- and post-gadolinium 3D T1W fast spin echo imaging studies (n = 64) were retrospectively analysed in patients without suspected facial nerve pathology. Two independent observers scored the signal at each of six skull base facial nerve segments. Wilcoxon signed-rank test was used to compare changes in signal between pre- and post-gadolinium sequences at each location, and how this differed between proprietary sequences or between the pairs of facial nerves.

Results:

There was significant enhancement at the fundal canalicular (16%), geniculate ganglion (96%), tympanic (45%) and mastoid (38%) facial nerve segments (p < 0.05). Two different proprietary sequences demonstrated similar patterns of enhancement and there was symmetry between the two sides.

Conclusions:

There is a differing pattern of normal facial nerve enhancement on contemporary 3D T1W FSE sequences compared to previous studies of 2D T1W SE imaging and fundal canalicular enhancement may be physiological.

Advances in knowledge:

This is the first study to evaluate patterns of normal facial nerve enhancement using contemporary 3D T1W FSE MRI sequences.

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.

Predictive Value of VIBE using Subtraction to Evaluate Idiopathic Facial Palsy after Starting Therapy

Purpose To determine the predictive value of 3-dimensional spoiled gradient-echo volumetric interpolated breath-hold examination (VIBE) using subtraction to evaluate the short-term effect of therapy for facial palsy.

Materials and Methods We included 97 patients with idiopathic facial palsy (52 male, 45 female; aged 50.7 ± 19.4 years) who underwent MR imaging with a contrast agent after starting therapy. The mean interval between onset and therapy was 1.55 ± 1.69 days, between therapy and MR imaging was 3.19 ± 2.78 days, and between MR imaging and assessment of the therapeutic effect was 3.50 ± 0.71 days. The degree of therapeutic effect was determined using a 4-grade scale based on the House–Brackmann scale for grading facial nerve function. Two radiologists reviewed VIBE with pre- and postcontrast subtraction using the 4-point scale. We evaluated the diagnostic performance and compared the degree of therapeutic effect and enhancement of facial nerves that were divided into 5 segments bilaterally.

Results We identified 98 facial palsy initially and significant enhancement in 55 facial nerves after the start of therapy and residual palsy in 87. Sensitivity for all facial palsy was 62.0 %, specificity was 90.9 %, positive predictive value was 98.2 %, negative predictive value was 23.3 %, and accuracy was 65.3 %. Eleven patients recovered completely, 1 showed significant enhancement, and the remaining 10 did not show significant enhancement of the facial nerve.

Conclusion VIBE has a potential to predict the prognostic outcome and assess facial palsy after the start of therapy.

Key points: 

Citation Format

Imaging the facial nerve: A contemporary review of anatomy and pathology

PURPOSE

The facial nerve is the seventh paired cranial nerve which anatomically can be divided into six distinct segments. There are a wide range of pathologies that may occur along each segment of the nerve. The aim of this pictorial review is to untangle the complex appearances of the facial nerve, both in its normal anatomical course and when affected by pathology.

METHOD

This review takes an evidence-based segmental approach to the evaluation of the facial nerve in terms of its anatomy and clinical features of common pathologies affecting specific segments of the nerve. The typical multimodal radiological findings of common facial nerve pathologies are included in the review using imaging from select pathologically confirmed cases.

RESULTS

A wide range of pathologies ranging from congenital abnormalities to inflammatory, infective and neoplastic processes can affect the facial nerve. As select segments of the nerve are better evaluated on certain imaging modalities a clear understanding of the anatomy and clinical features associated with specific facial nerve pathologies enables the radiologist to tailor the imaging test to best answer the clinical question.

CONCLUSIONS

This review provides a segmental clinical-radiological approach to imaging the facial nerve. In addition, recent developments in facial nerve imaging that may come into mainstream use in the near future are touched upon.

Normal Anatomy of Cranial Nerves III–XII on Magnetic Resonance Imaging

복잡한 해부학적 구조와 기능 때문에 뇌신경 질환의 신경영상검사는 항상 어려운 과제이다. 최근 자기공명영상(이하 MRI) 기법의 발달로 많은 경우에서 뇌신경 질환의 원인이 규명되고 있으며, 신경영상의학 의사들은 다학제 팀의 핵심적 팀원으로서 다양한 뇌신경 질환의 원활한 진단을 위하여 MRI에서 관찰되는 뇌신경의 세밀한 해부학적 구조를 잘 알아야 한다. 이 종설에서는 말초성 뇌신경 III–XII에 대해 뇌간으로부터 두개 밖까지 해부학적으로 비슷한 구조를 가지는 구역별로 분류하여 각 구역에서 보이는 뇌신경의 정상 해부학 및 MRI 소견을 설명하고자 한다. 또한 각 구역에서 가장 적합한 MRI 기법에 관하여도 기술하고자 한다.

Better continuity of the facial nerve demonstrated in the temporal bone on three-dimensional T1-weighted imaging with volume isotropic turbo spin echo acquisition than that with fast field echo at 3.0 tesla MRI

INTRODUCTION

Three-dimensional (3D) T1-weighted imaging (T1WI) is used for evaluation of the facial nerve. The signal intensity of normal and pathological facial nerves has been well evaluated at both 1.5T and 3.0T MRI after gadolinium (Gd)-enhancement with various pulse sequences. However, the continuity of the facial nerve has not been evaluated on 3D-T1WI. This study aims to compare the continuity of the normal facial nerve in the temporal bone demonstrated on T1-weighted volume isotropic turbo spin echo acquisition (T1-VISTA), which is a spin-echo sequence, to that on T1-weighted fast field echo (T1-FFE), which is a gradient-echo sequence, at 3.0T MRI.

METHODS

Forty-four normal facial nerves in 22 healthy volunteers were imaged with both sequences using 3.0T MRI without Gd-enhancement. The facial nerves were evaluated visually by two neuroradiologists in four anatomical segments with a 3-point grading system of continuity. The continuity was assessed by summing the grades of the four segments as a total score. The grades at each segment and the total scores were compared statistically between the T1-VISTA and T1-FFE.

RESULTS

The grades in all segments and the total score were significantly higher with T1-VISTA than those with T1-FFE.

CONCLUSIONS

T1-VISTA was superior to demonstrate the facial nerve as a continuous anatomical structure in the temporal bone at 3.0T MRI.

Guillain-Barré syndrome with associated unilateral ptosis without ophthalmoplegia - a rare presentation: a case report and review of the literature

BACKGROUND

Guillain-Barré syndrome is an acute inflammatory polyradiculoneuropathy. Nearly half of patients with Guillain-Barré syndrome have cranial nerve involvement. However, isolated bilateral ptosis without ophthalmoplegia is a rare manifestation, and isolated unilateral ptosis without ophthalmoplegia in Guillain-Barré syndrome has not previously been reported in the literature. Furthermore, only few cases of Guillain-Barré syndrome with cranial nerve enhancement visualized by gadolinium-enhanced magnetic resonance imaging have previously been reported. We describe the first reported case of unilateral ptosis without ophthalmoplegia in Guillain-Barré syndrome and associated multiple cranial nerve enhancement seen by gadolinium-enhanced magnetic resonance imaging.

CASE PRESENTATION

Our patient was a 55-year-old Sinhalese man who was admitted to a tertiary care hospital in Sri Lanka with acute-onset progressive weakness in the lower limbs followed by the upper limbs. He had bilateral symmetrical flaccid quadriparesis with absent reflexes and flexor plantar response. Left-sided isolated partial ptosis without associated ophthalmoplegia was noted with normal pupils. The patient's neurological examination was otherwise normal. A nerve conduction study showed a severe demyelinating type of polyneuropathy. No decremental response to repetitive nerve stimulation was observed, and the result of a single-muscle-fiber electromyogram was negative. A diagnosis of Guillain-Barré syndrome was made, and the patient was treated with intravenous immunoglobulin. His condition gradually deteriorated over the next few days, and he became quadriplegic despite the completion of immunoglobulin therapy. Later he developed multiple cranial nerve palsies, including bi-lateral lower motor neuron type facial nerve palsy, and he required mechanical ventilation. By this time, he had complete left-sided ptosis with a normal right eye. He never developed ophthalmoplegia or ataxia. Magnetic resonance imaging of the brain showed contrast enhancement in the intracranial part of multiple cranial nerve roots and basal leptomeninges. He gradually improved with plasmaparesis, and ptosis was the first to improve.

CONCLUSIONS

Even though Guillain-Barré syndrome was recognized a century ago, there are still many unanswered questions about it and its florid presentation. Large-scale studies are needed for better understanding of its pathophysiology and prototypes and to find answers for still-unanswered questions. The clinician must have a high index of suspicion and be familiar with mimics and prototypes to diagnose Guillain-Barré syndrome accurately without delay.

Is there a relationship between mastoid pneumatisation and facial canal dimensions?

OBJECTIVE

To evaluate mastoid pneumatisation and facial canal dimensions.

METHOD

In this retrospective study, 169 multidetector computed tomography scans of temporal bone were reviewed. Facial canal dimensions were evaluated at the labyrinthine, tympanic and mastoid segments using axial and coronal multidetector computed tomography scans of temporal bone. Mastoid pneumatisation and facial canal dehiscence were evaluated. Facial canal dehiscence was measured if it was found to be present.

RESULTS

This study showed that facial canal dimensions decreased in pneumatised mastoids. Facial canal dimensions in females were smaller than in males. Facial canal dehiscence was detected in 5.9 per cent and 6.5 per cent of the patients on the right and left sides, respectively. No correlations were found between facial canal dehiscence and mastoid pneumatisation. The length of dehiscence was 1.92 ± 0.44 mm (range, 0.86-2.51 mm) on the left side. In older subjects, left facial canal dehiscence was detected more, and the length of the dehiscence increased.

CONCLUSION

This study concluded that during surgery, facial canal dehiscence should be kept in mind in order to avoid complications.

Imaging of Nontraumatic Temporal Bone Emergencies

This section aims to cover the non-traumatic pathologies affecting the temporal bone including external auditory canal, middle ear and inner ear which usually need emergent clinical attention. Many of the conditions in this section are secondary to infections in different clinical settings with resultant complications which may leave temporary or permanent sequelae if not suspected, timely diagnosed or treated.

A Review of Salivary Gland Malignancies: Common Histologic Types, Anatomic Considerations, and Imaging Strategies

Major and minor salivary gland malignancies come in various shapes and sizes. They can present as palpable masses or can be detected incidentally when imaging patients for other indications. A complete evaluation of salivary gland malignancies requires knowledge of the anatomy and various routes of spread of neoplasias. Computed tomography (CT) and MR imaging are complementary tools in this respect and offer useful information to the proceduralist. Advanced imaging (diffusion-weighted imaging and PET-CT) and other modalities (eg, ultrasound) help with characterization, although biopsy or excision is often needed for definitive tissue diagnosis.

Facial Palsy Following Embolization of a Juvenile Nasopharyngeal Angiofibroma

Objectives:

To describe a case of the rare complication of facial palsy following preoperative embolization of a juvenile nasopharyngeal angiofibroma (JNA). To illustrate the vascular supply to the facial nerve and as a result, highlight the etiology of the facial nerve palsy.

Methods:

The angiography and magnetic resonance (MR) imaging of a case of facial palsy following preoperative embolization of a JNA is reviewed.

Results:

A 13-year-old male developed left-sided facial palsy following preoperative embolization of a left-sided JNA. Evaluation of MR imaging studies and retrospective review of the angiographic data suggested errant embolization of particles into the petrosquamosal branch of the middle meningeal artery (MMA), a branch of the internal maxillary artery (IMA), through collateral vasculature. The petrosquamosal branch of the MMA is the predominant blood supply to the facial nerve in the facial canal. The facial palsy resolved since complete infarction of the nerve was likely prevented by collateral blood supply from the stylomastoid artery.

Conclusions:

Facial palsy is a potential complication of embolization of the IMA, a branch of the external carotid artery (ECA). This is secondary to ischemia of the facial nerve due to embolization of its vascular supply. Clinicians should be aware of this potential complication and counsel patients accordingly prior to embolization for JNA.

Comparison of normal facial nerve enhancement at 3T MRI using gadobutrol and gadopentetate dimeglumine

Background and purpose The facial nerve is unique among cranial nerves in demonstrating normal enhancement of particular segments. The effect of varying T1 relaxivities of gadolinium-based contrast agents on facial nerve enhancement is unclear. In this study, we assess differences in normal facial nerve enhancement with two different gadolinium-based contrast agents, gadobutrol and gadopentetate dimeglumine. In addition, we evaluate differences in facial nerve enhancement with spin-echo (SE) T1 versus 3D inversion recovery prepared fast spoiled gradient-echo (FSPGR) post-contrast sequences. Methods A total of 140 facial nerves in 70 individuals were evaluated (70 with gadobutrol and 70 with gadopentetate dimeglumine) by two blinded reviewers. Differences in enhancement of facial nerve segments between the two agents were analyzed. Differences in enhancement between SE T1 and FSPGR imaging were also evaluated. Results There was no significant difference in facial nerve enhancement between gadobutrol and gadopentetate dimeglumine. Enhancement was commonly observed in the geniculate, tympanic and mastoid segments (98%-100%) with either contrast agent; enhancement was less common in the labyrinthine segments (9%-14%) and lateral canalicular segment (2%-5%). There was a smaller enhancing proportion of labyrinthine and tympanic segments with FSPGR as compared to SE T1 images with gadobutrol. Conclusion There is no significant difference in overall enhancement of the facial nerve between gadobutrol and gadopentetate dimeglumine. Mild enhancement of the lateral canalicular portion of the facial nerve may be a normal finding. With FSPGR sequence, there is lesser perceived enhancement of the labyrinthine and tympanic segments of the facial nerve with gadobutrol.

Importance of Contrast-Enhanced Fluid-Attenuated Inversion Recovery Magnetic Resonance Imaging in Various Intracranial Pathologic Conditions

Intracranial lesions may show contrast enhancement through various mechanisms that are closely associated with the disease process. The preferred magnetic resonance sequence in contrast imaging is T1-weighted imaging (T1WI) at most institutions. However, lesion enhancement is occasionally inconspicuous on T1WI. Although fluid-attenuated inversion recovery (FLAIR) sequences are commonly considered as T2-weighted imaging with dark cerebrospinal fluid, they also show mild T1-weighted contrast, which is responsible for the contrast enhancement. For several years, FLAIR imaging has been successfully incorporated as a routine sequence at our institution for contrast-enhanced (CE) brain imaging in detecting various intracranial diseases. In this pictorial essay, we describe and illustrate the diagnostic importance of CE-FLAIR imaging in various intracranial pathologic conditions.

Temporal bone MRI with 3D-FIESTA in the evaluation of facial and audiovestibular dysfunction

PURPOSE

To evaluate the clinical usefulness of magnetic resonance imaging (MRI) of the temporal bone using three-dimensional fast imaging employing steady-state acquisition (3D-FIESTA) sequences in patients with facial and audiovestibular dysfunction.

METHODS

We retrospectively reviewed the MR images of 1263 patients who presented with hearing loss (n=429), peripheral facial palsy (n=96), tinnitus (n=341) or vertigo (n=397). There were 605 men and 658 women, with a mean age of 46.97±16.95 (SD) years (range: 2-83 years). Positive MRI findings that were responsible for clinical manifestations in individual patients were categorized according to the anatomic sites and etiologies of the lesions.

RESULTS

Positive MRI findings possibly responsible for clinical manifestations were found in 232/1263 (18.37%) patients, including 86/429 (20.05%) patients with hearing loss, 21/96 (21.88%) patients with facial palsy, 62/341 (18.18%) patients with tinnitus, and 63/397 (15.87%) patients with vertigo.

CONCLUSION

Although the use of MRI of the temporal bone using 3D-FIESTA shows positive findings in only 18.37% of patients, it provides important information in those with facial and audiovestibular dysfunction. However, for patients with normal MRI of the temporal bone, other etiological factors should be investigated in order to clarify or elucidate the cause of clinical manifestations.

Treatment of Bell's Palsy Using Monochromatic Infrared Energy: A Report of 2 Cases

OBJECTIVE

The purpose of the study is to describe the use of monochromatic infrared energy (MIRE) therapy in the management of 2 patients with Bell's palsy.

CLINICAL FEATURES

Two patients presented to a chiropractic clinic with Bell's palsy that was diagnosed by a medical physician. Both patients were treated using MIRE. The acute patient was a 32-year-old male. He presented with left facial palsy 1 day before the consultation. He was unable to puff the left cheek and close the left eyelid. He had difficulty raising the left eyebrow. The chronic case was a 46-year-old lady. Prior to the first consultation, she was treated with corticosteroid and electro-acupuncture for one and a half years, with incomplete recovery. When first seen, the left corner of mouth drooped and she had difficulty raising her left eyebrow.

INTERVENTION AND OUTCOME

Monochromatic infrared energy therapy, emitting 890 nm infrared light, was placed on the post-auricular area, pre-auricular area, the temple and mandibular area of the affected side. Each treatment lasted 30 minutes. Photographs were taken every week to document changes. The acute case received 19 treatments in 6 weeks. He reported an improvement of 95%. The chronic case received a total of 45 treatments in 9 months. She rated an improvement of 50%. At the conclusion of treatment, she was able to close her left eyelid and puff her left cheek but still could not raise her left eyebrow.

CONCLUSION

These 2 patients seemed to respond to a different degree to the MIRE therapy. As 71% of patients with Bell's palsy recover uneventfully without any treatment, the present study describes the course of care but cannot confirm the effectiveness of MIRE therapy in the management of Bell's palsy.

Facial neuropathy with imaging enhancement of the facial nerve: a case report

A young women developed unilateral facial neuropathy 2 weeks after a motor vehicle collision involving fractures of the skull and mandible. MRI showed contrast enhancement of the facial nerve. We review the literature describing facial neuropathy after trauma and facial nerve enhancement patterns with different causes of facial neuropathy.

Redefining normal facial nerve enhancement: healthy subject comparison of typical enhancement patterns--unenhanced and contrast-enhanced spin-echo versus 3D inversion recovery-prepared fast spoiled gradient-echo imaging

OBJECTIVE

Normal facial nerve enhancement patterns derived from spin-echo (SE) sequences have not been systematically compared on contrast-enhanced 3D inversion recovery-prepared fast spoiled gradient-echo (IR-FSPGR) sequences, now in widespread use. We hypothesize that features unique to IR-FSPGR may engender differences in the appearance of the normal facial nerve, which may confound analysis of pathologic enhancement. We compared unenhanced and contrast-enhanced SE and IR-FSPGR sequences in a cohort of patients without facial nerve pathology.

MATERIALS AND METHODS

Twenty-three patients without facial nerve pathology were examined. Unenhanced and contrast-enhanced signal intensity (SI) of seven facial nerve segments was assessed on SE and IR-FSPGR by two neuroradiologists. SI was assigned a value of 0-3 (0, absent; 1, faint; 2, equivalent to brain; 3, equivalent to enhancing dural sinus). Statistically significant differences were assessed for each segment.

RESULTS

Significantly higher unenhanced and contrast-enhanced SI was present in most facial nerve segments on IR-FSPGR compared with SE, including cisternal, canalicular, labyrinthine, and geniculate segments (p ≤ 0.01). Enhancement patterns were generally similar; however, significant enhancement of the labyrinthine segment was detected only on SE (p = 0.011). For unenhanced images, mean kappa statistic was 0.32, and for the contrast-enhanced images, mean kappa statistic was 0.04, implying fair and slight agreement between readers, respectively.

CONCLUSION

Significantly greater SI is observed in most facial nerve segments on both unenhanced and contrast-enhanced IR-FSPGR among healthy subjects and may be misinterpreted as pathologic when evaluated in the context of existing enhancement paradigms. Examiners should remain cognizant of normal deviations from expected enhancement patterns in IR-FSPGR imaging to avoid misdiagnosis and other interpretive pitfalls.

A comparative study of locoregionally advanced nasopharyngeal carcinoma treated with intensity modulated irradiation and platinum-based chemotherapy

PURPOSE

To investigate the prognosis of three subgroups of locoregionally advanced nasopharyngeal carcinoma treated with intensity-modulated radiotherapy and platinum-based chemotherapy.

PATIENTS AND METHODS

Hundred and eighty-one consecutive patients with locoregionally advanced untreated nasopharyngeal carcinoma were retrospectively divided into three subgroups: locally advanced group (T3-4N0-1M0), regionally advanced group (T1-2N2-3M0) and the mixed group (T3-4N2-3M0). They were all treated with definitive intensity-modulated radiotherapy and platinum-based chemotherapy. Their prognosis were investigated and compared. Multivariate analysis was applied to identify the independent risk factors of study endpoints.

RESULTS

The 3-year locoregional control rates for locally advanced group, regionally advanced group, and the mixed group were 91.5%, 90.6% and 84.3% respectively, no significant difference was observed (P=0.656, P=0.429). The 3-year distant metastasis-free survival rates were 89.6%, 75.7% and 76.3%, respectively. The distant metastasis-free survival rate of the locally advanced group was significantly higher than the other two subgroups (P=0.028, P=0.028). The 3-year progression-free survival rates were 85.5%, 67.9% and 67.1% respectively with significance also favoring the locally advanced group (P=0.043, P=0.023). Nodal stage and the performance status were the independent risk factors of distant metastasis in the observed period.

CONCLUSIONS

In the context of intensity-modulated radiotherapy and platinum-based chemotherapy, the locally advanced group had a better prognosis compared with the regionally advanced group and the mixed group. Treatment stratification may be based on nodal stage.

Infranuclear facial palsy: importance of imaging the geniculate fossa

OBJECTIVE

To highlight the importance of imaging the geniculate fossa in patients with solitary infranuclear facial palsy.

STUDY DESIGN

Prospective.

SETTING

Tertiary referral center.

ELIGIBILITY CRITERIA

Patients with solitary infranuclear facial palsy sent for imaging.

INTERVENTION

Diagnostic.

MAIN OUTCOME MEASURE

Imaging specifics concerning high-resolution computed tomography (HRCT) and magnetic resonance imaging (MRI) are described in detail for evaluation of the intratemporal part of the facial nerve with special focus on the geniculate fossa.

RESULTS

Normal appearances of the geniculate fossa on HRCT and MRI and its normal anatomic variant, that is, dehiscence of the overlying bone are described. Imaging findings in a range of pathologies involving the geniculate fossa in a clinical setting of infranuclear facial nerve palsy is demonstrated. These include infections (tuberculosis), trauma, schwannoma, hemangioma, meningioma, and perineural spread of parotid malignancy.

CONCLUSION

The geniculate fossa is a small bony hiatus in the temporal bone and is situated at the junction of the labyrinthine and the tympanic segments of the intratemporal facial nerve canal. It houses important neural structures and is best visualized by a combination of HRCT and high-resolution MRI examination of the temporal bone. It is therefore imperative for imaging specialists to be familiar with the normal appearance of this structure on HRCT and MRI examinations of the temporal bone as subtle imaging findings involving the geniculate fossa can be indicators of a variety of abnormalities.

MR diagnosis of facial neuritis: diagnostic performance of contrast-enhanced 3D-FLAIR technique compared with contrast-enhanced 3D-T1-fast-field echo with fat suppression

BACKGROUND AND PURPOSE

Current MRI with the CE T1-weighted sequence plays a limited role in the evaluation of facial neuritis due to prominent normal facial nerve enhancement. Our purpose was to retrospectively investigate the usefulness of the CE 3D-FLAIR sequence compared with the CE 3D-T1-FFE sequence in facial neuritis patients.

MATERIALS AND METHODS

We assessed 36 consecutive patients who underwent temporal bone MR imaging at 3T for idiopathic facial palsy. Two readers independently reviewed CE 3D-T1-FFE and CE 3D-FLAIR images to determine the degree of enhancement in each of 5 segments of the facial nerve. We compared AUCs using the Z-test, compared diagnostic performance of 2 MR techniques with the McNemar test, and evaluated interobserver agreement. The Pearson χ(2) test was used for each segment of the facial nerve.

RESULTS

The AUC of CE 3D-FLAIR (reader 1, 0.754; reader 2, 0.746) was greater than that of CE 3D-T1-FFE (reader 1, 0.624; reader 2, 0.640; P < .001). The diagnostic sensitivities, specificities, and accuracies were 97.2%, 86.1%, and 91.7%, respectively, for CE 3D-FLAIR, and 100%, 56.9%, and 78.5%, respectively, for CE 3D-T1-FFE. The specificity and accuracy of CE 3D-FLAIR were greater than those of CE 3D-T1-FFE (specificity, P = .029; accuracy, P = .008). The interobserver agreements for CE 3D-FLAIR (κ-value, 0.831) and CE 3D-T1-FFE (κ-value, 0.694) were excellent. Enhancement of the canalicular and anterior genu segments on CE 3D-FLAIR were significantly correlated with the occurrence of facial neuritis (P < .001 for canalicular; P = .032 and 0.020 for anterior genu by reader 1 and reader 2, respectively).

CONCLUSIONS

CE 3D-FLAIR can improve the specificity and overall accuracy of MR imaging in patients with idiopathic facial palsy.

Enhancement pattern of the normal facial nerve at 3.0 T temporal MRI

The purpose of this study was to evaluate the enhancement pattern of the normal facial nerve at 3.0 T temporal MRI. We reviewed the medical records of 20 patients and evaluated 40 clinically normal facial nerves demonstrated by 3.0 T temporal MRI. The grade of enhancement of the facial nerve was visually scaled from 0 to 3. The patients comprised 11 men and 9 women, and the mean age was 39.7 years. The reasons for the MRI were sudden hearing loss (11 patients), Méniàre's disease (6) and tinnitus (7). Temporal MR scans were obtained by fluid-attenuated inversion-recovery (FLAIR) and diffusion-weighted imaging of the brain; three-dimensional (3D) fast imaging employing steady-state acquisition (FIESTA) images of the temporal bone with a 0.77 mm thickness, and pre-contrast and contrast-enhanced 3D spoiled gradient record acquisition in the steady state (SPGR) of the temporal bone with a 1 mm thickness, were obtained with 3.0 T MR scanning. 40 nerves (100%) were visibly enhanced along at least one segment of the facial nerve. The enhanced segments included the geniculate ganglion (77.5%), tympanic segment (37.5%) and mastoid segment (100%). Even the facial nerve in the internal auditory canal (15%) and labyrinthine segments (5%) showed mild enhancement. The use of high-resolution, high signal-to-noise ratio (with 3 T MRI), thin-section contrast-enhanced 3D SPGR sequences showed enhancement of the normal facial nerve along the whole course of the nerve; however, only mild enhancement was observed in areas associated with acute neuritis, namely the canalicular and labyrinthine segment.

Imaging of inflammatory and infectious diseases in the temporal bone

Inflammatory and infectious diseases of the temporal bone are a major indication to perform high-resolution CT and MR imaging studies. Such studies allow one to evaluate the extent of the disease in the soft tissues and in the bony structures of the temporal bone. On these same imaging studies the possible extension of the infection to surrounding regions is visualized. In this article a segmental approach is used, focusing on four structures in the temporal bone: the external ear, the otomastoid and petrous apex, the inner ear, and the facial nerve. For each of the four sections imaging findings are described and illustrated, and if relevant a differential diagnostic approach is highlighted.

Trigeminal nerve palsy in nasopharyngeal carcinoma: correlation between clinical findings and magnetic resonance imaging

BACKGROUND

Our aim was to document the relationship between clinical and MRI evidence of trigeminal nerve involvement.

METHODS

The MRI and medical records of 924 consecutive patients with newly diagnosed nasopharyngeal carcinoma (NPC) were reviewed retrospectively.

RESULTS

A total of 92 divisions of palsied trigeminal nerves were found clinically in 46 patients (5.0%). The involved trigeminal nerve was ophthalmic nerve (V1; n = 21), the maxillary division (V2; n = 41), and the mandibular division (V3; n = 30). Of the 316 patients with MRI-demonstrated trigeminal nerve involvements, the symptoms were lacking in 270 patients (85.4%). Of the 92 clinical palsied trigeminal nerve divisions, 91 nerves (98.9%) showed MRI evidence of 1 or more trigeminal nerve involvements. Of the 91 palsied trigeminal nerve with MRI evidence, 85 divisions (93.4%) were found with intracranial or orbital segment involvement, 6 (6.6%) divisions were found only basicranial evidence, and 83 (91.2%) divisions were found with cavernous sinus invasion.

CONCLUSION

The incidence of MRI-evidenced trigeminal nerve involvement is high and often asymptomatic in NPC. Almost all patients with clinical trigeminal nerve palsies had MRI evidence of trigeminal nerve involvement in intracranial or orbital segment, especially in cavernous sinus.

Correlation between enhanced MRI and surgical findings in herpes zoster oticus

CONCLUSION

This study demonstrates good correlation between enhanced MRI and surgical findings.

OBJECTIVES

This study investigated the reliability of enhanced magnetic resonance imaging (MRI) to make a surgical decision on the strategy for facial nerve decompression in herpes zoster oticus, by determining the degree of correlation between contrast enhancement in MRI and the pathologic change in the facial nerve.

SUBJECTS AND METHODS

This retrospective study of 13 patients, who underwent facial nerve decompression with herpes zoster oticus, was designed to compare gadolinium-enhanced segment of facial nerve on MRI and the pathologically changed segment confirmed by surgical exploration, grouping them by the timing of operation after onset of facial paralysis.

RESULTS

Commonly enhanced segments on MRI were the labyrinthine, intracanalicular, and geniculate ganglion, found in 84%, 69%, and 69% of all patients, respectively. The most common pathologic segment was the labyrinthine segment (92%), followed by the geniculate ganglion (84%).

Prognostic impact of magnetic resonance imaging-detected cranial nerve involvement in nasopharyngeal carcinoma

BACKGROUND

: The purpose of this study was to evaluate the prognostic value of magnetic resonance imaging (MRI)-detected cranial nerve (CN) involvement in nasopharyngeal carcinoma (NPC).

METHODS

: Retrospective analysis was made of the magnetic resonance images and medical records of 924 consecutive patients with newly diagnosed NPC.

RESULTS

: Of 924 patients, 82 (8.9%) initially presented with CN palsy. CN involvement was seen on MRI in 333 (36%) patients. In T3-4 disease, MRI-evidenced CN involvement was associated with poor 3-year overall survival (OS) (35.7% vs 89.2%, P = .001) and distant metastasis-free survival (DMFS) (77.1% vs 87.8%, P = .002) rates. The survival curves of OS and DMFS for T3 disease with MRI-detected CN involvement approximated those of T4 disease (P = .322 and P = .809, respectively). In patients with MRI-detected CN involvement, no significant differences were observed in 3-year OS (78.3% vs 72.9%, P = .120), local relapse-free survival (LRFS) (89.7% vs 84.1%, P = .154), or DMFS (79.6% vs 74.8%, P = .466) rates between those with and without intracranial or orbital CN involvement. Furthermore, in patients with clinical and/or MRI-detected CN involvement, there were no significant differences in the 3-year OS (74.2% vs 80.1%, P = .067), LRFS (86.7% vs 87.9%, P = .899), or DMFS (74.6% vs 84.6%, P = .094) rates between symptomatic and asymptomatic patients.

CONCLUSIONS

: The incidence of MRI-detected CN involvement was higher than CN palsy. MRI-detected CN involvement has a negative impact on the prognosis independent of lesion localization and symptoms. Cancer 2009. (c) 2009 American Cancer Society.

Clinical significance of quantitative analysis of facial nerve enhancement on MRI in Bell's palsy

CONCLUSIONS

Quantitative analysis of the facial nerve on the lesion side as well as the normal side, which allowed for more accurate measurement of facial nerve enhancement in patients with facial palsy, showed statistically significant correlation with the initial severity of facial nerve inflammation, although little prognostic significance was shown.

OBJECTIVES

This study investigated the clinical significance of quantitative measurement of facial nerve enhancement in patients with Bell's palsy by analyzing the enhancement pattern and correlating MRI findings with initial severity of facial palsy and clinical outcome.

SUBJECTS AND METHODS

Facial nerve enhancement was measured quantitatively by using the region of interest on pre- and postcontrast T1-weighted images in 44 patients diagnosed with Bell's palsy. The signal intensity increase on the lesion side was first compared with that of the contralateral side and then correlated with the initial degree of facial palsy and prognosis.

RESULTS

The lesion side showed significantly higher signal intensity increase compared with the normal side in all of the segments except for the mastoid segment. Signal intensity increase at the internal auditory canal and labyrinthine segments showed correlation with the initial degree of facial palsy but no significant difference was found between different prognostic groups.

Correlation between MRI and operative findings in Bell's palsy and Ramsay Hunt syndrome

PURPOSE

To investigate the correlation between gadolinium enhanced magnetic resonance image (MRI) results and surgical findings of facial nerves in Bell's palsy and Ramsay Hunt syndrome.

MATERIALS AND METHODS

From 1995 to 2004, MRI was performed on 13 patients with Bell's palsy or Ramsay Hunt syndrome, who were offered with surgical decompression of the facial nerve through the middle cranial fossa approach. Gadolinium enhanced MRI was performed on all patients and the enhancement of the facial nerve was evaluated by radiology specialists. Operative findings including the degree of the facial nerve segment swelling were examined. Furthermore, the time interval from the onset of palsy to surgery was evaluated.

RESULTS

Swelling of facial nerve segments was found in patients with enhanced facial nerves from MRI. The swelling of the facial nerve in the labyrinthine segment in particular was identified in all patients with enhanced labyrinthine segments in MRI. The intraoperative swelling of geniculate ganglion of facial nerve was found in 78% of patients with enhanced facial segment in MRI (p=0.01). The intraoperative swelling of tympanic segment was observed from fourth to ninth weeks after the onset of palsy.

CONCLUSION

MRI enhancement of facial nerves in Bell's palsy and Ramsay Hunt syndrome is associated with the extent of intratemporal lesions of facial nerves, especially in the labyrinthine segment.

Imaging Nuances of Perineural Spread of Head and Neck Malignancies

Perineural spread is a common growth pattern of head and neck malignancies. Recognizing this pattern by imaging is important for two reasons: 1) it may be the only evidence of malignancy; and 2) its presence in conjunction with a mass converts management from surgical resection to radiation or chemotherapy. High field strength magnets and thin sections with high resolution and fat suppression now allow earlier diagnosis of this entity, but even with these imaging developments, familiarity with the relevant anatomy and the subtle alterations on MRI are necessary to identify this condition.

MAGNETIC RESONANCE IMAGING OF THE INTRATEMPORAL FACIAL NERVE IN IDIOPATHIC FACIAL PARALYSIS IN THE DOG

The most common cause of peripheral facial nerve paralysis in dogs, in the absence of otitis media, is thought to be idiopathic. Gadolinium-enhanced (Gd) magnetic resonance (MR) imaging has been used to study peripheral facial weakness in humans with a wide variety of disorders, including Bell's palsy, the clinical equivalent of idiopathic facial nerve paralysis in dogs. Gd-MR imaging may be useful to demonstrate abnormal enhancement of the intratemporal facial nerve. The aim of this study was to define the role of the Gd-MR imaging in dogs with idiopathic facial nerve paralysis, with regard to pattern of enhancement, and to search for prognostic information. Six dogs with peripheral facial nerve paralysis, followed between 2003 and 2005, were studied. Physical and neurologic examinations, as well as clinical tests, were performed, including routine hematology, serum biochemistry, thyroid screening, cerebrospinal fluid analysis, and MR imaging. The time interval between the onset of the clinical signs, the progress of the disease, and the final recovery was noted in each dog. The following four intratemporal segments of the facial nerve were analyzed: internal acoustic meatus, labyrinthine segment/geniculate ganglion, tympanic segment, and mastoid segment. Along its length, contrast enhancement was found in four dogs. In this group, contrast enhancement of the facial nerve was found in all segments of two dogs, in three segments of one dog, and in one segment of the other dog. In the four dogs with enhancement, one recovered completely in 8 weeks and three have not recovered completely. The two dogs without evidence of enhancement recovered completely in an average time of 4 weeks.

Role of magnetic resonance imaging in entrapment and compressive neuropathy—what, where, and how to see the peripheral nerves on the musculoskeletal magnetic resonance image: part 1. Overview and lower extremity

The diagnosis of nerve entrapment and compressive neuropathy has been traditionally based on the clinical and electrodiagnostic examinations. As a result of improvements in the magnetic resonance (MR) imaging modality, it plays not only a fundamental role in the detection of space-occupying lesions but also a compensatory role in clinically and electrodiagnostically inconclusive cases. Although ultrasound has undergone further development in the past decades and shows high resolution capabilities, it has inherent limitations due to its operator dependency. We review the general concepts that should be known to evaluate the entrapment and compressive neuropathy in MR imaging. We also review the course of normal peripheral nerves, as well as various clinical demonstrations and pathological features of compressed and entrapped nerves in the lower extremities on MR imaging, according to the nerves involved. The common sites of nerve entrapment of the lower extremity are as follows: sciatic nerve around the piriformis muscle; tibial nerve at the popliteal fossa and tarsal tunnel, common peroneal nerve around the fibular neck, and digital nerve near the metatarsal head. Although MR imaging can depict the peripheral nerves in the extremities effectively, radiologists should be familiar with nerve pathways, common sites of nerve compression, and common space-occupying lesions resulting in nerve compression in MR imaging.

MRI of cranial nerve enhancement

OBJECTIVE

In this pictorial essay, we review the MR appearance of cranial nerve enhancement in a variety of entities including neoplastic, infectious, and idiopathic diseases.

CONCLUSION

MRI with contrast enhancement is a valuable tool for detecting and characterizing disease of the cranial nerves. Abnormal cranial nerve enhancement on MRI may sometimes be the first or only indication of an underlying disease process.

Imaging of the upper cranial nerves I, III–VIII, and the cavernous sinuses

This article discusses the upper cranial nerves (I, III-VIII) and their anatomy as it pertains to intra-axial nuclei and tracts, cisternal portions, and extracranial portions. In addition, the most common pathologic processes affecting the upper cranial nerves are discussed and illustrated. Because the evaluation of small structures requires imaging techniques that provide high resolution and contrast, MR imaging is the examination of choice. CT still plays a limited but important role in the evaluation of intraosseous portions of some cranial nerves.

Imaging of the lower cranial nerves

This article discusses the normal anatomy and pathologic entities that involve the lower cranial nerves. Normal anatomy is described and correlated with line diagrams and MR images. Distinct pathologic processes that involve the individual nerves along their various components are discussed. The imaging characteristics of these lesions are provided. Knowledge of the nuclear origins, the normal course of the cranial nerves, their func-tional components, and the imaging characteristics of pathologic lesions involving the nerves are important in any evaluation of cranial neuropathy.