The diagnostic dilemma of neuro-imaging in acute isolated sixth nerve palsy:

High resolution 3D magnetic resonance imaging of Gruber's ligament: a pilot study

INTRODUCTION

Gruber's ligament (GL), a surgical landmark, extends from the lateral upper clivus to the petrous apex (PA), forming the superior boundary of Dorello's canal (DC). It overlies the interdural segment of the abducens nerve (CN VI). High-resolution 3D skull base MRI (SB-MRI) demonstrates anatomic details visible to the surgeon, but not well seen on traditional cross-sectional imaging. The aim of this study was to demonstrate visualization of the GL and its relationship to CN VI utilizing contrast enhanced high-resolution SB-MRI.

METHODS

Two neuroradiologists retrospectively reviewed in consensus the SB-MRIs of 27 skull base sides, among 14 patients. GL detection rate, confidence of detection, and GL length were recorded. When GL was successfully identified, the position of the interdural segment of CN VI within DC was recorded.

RESULTS

GL was readily identified in 16 skull base sides (59%), identified with some difficulty in 2 skull base sides (7%), and failed to be identified in 9 skull base sides (33%). The mean GL length was 7.1 mm (4.5-9.3 mm). Among the 18 cases where GL was successfully identified, CN VI was readily identified in all cases (100%), coursing the lateral third of DC in 72% of sides, and middle third in the remaining 28% of sides.

CONCLUSION

GL can be identified in approximately two-thirds of cases utilizing 3D high resolution SB-MRI. CN VI passes most commonly along the lateral third of DC. This is the first report demonstrating visualization of GL and its relation to CN VI, on imaging.

Isolated Sixth Nerve Palsy as a First Presentation of Nasopharyngeal Carcinoma: A Case Series

Purpose

To describe isolated sixth nerve palsy as an uncommon presentation of nasopharyngeal carcinoma (NPC).

Patients and Methods

We analyzed the demographics, clinical presentation, neuroimaging findings, and pathological examination results of the nasopharyngeal masses of patients diagnosed with isolated sixth nerve palsy due to NPC.

Results

Isolated sixth nerve palsy as the first presenting sign of NPC was diagnosed in five patients. Two patients were aged <50 years and three were aged >50 years, and one of these three older patients had vascular risk factors. Most of the patients in our case study had an uncommon presentation of isolated sixth nerve palsy with diplopia, followed by typical NPC signs such as a neck lump (two patients), nasal obstruction (two patients), tinnitus (two patients), hearing loss (one patient), and epistaxis (one patient). Pathological examination revealed non-keratinizing NPC in all cases. Neuroimaging showed that the sites of tumor invasion were the clivus, Dorello's canal, and cavernous sinus, which explained the sixth nerve palsy. One patient whose NPC had progressed to the orbital apex later developed other cranial nerve palsies. Three patients underwent concurrent chemoradiotherapy (CCRT), and one patient underwent CCRT with adjuvant chemotherapy. The last patient was unfortunately lost to follow-up. The symptoms of four patients who underwent treatment improved.

Conclusion

Isolated sixth nerve palsy can be the first presentation of NPC, especially in patients aged <50 years old without microvascular risk factors or even in patients aged >50 years old with microvascular risk factors. This case study emphasizes that a thorough clinical history and careful physical and neuroimaging examinations might be necessary to rule out life-threatening conditions in patients with isolated sixth nerve palsy.

Analysis of Early Neuroimaging Results in Patients with Acute Isolated Ocular Motor Nerve Palsy

Purpose: To evaluate the efficacy of early neuroimaging in patients with acute isolated 3rd, 4th, and 6th nerve palsy.Methods: Neuroimaging tests were performed in patients >50 years old with acute isolated 3rd, 4th, and 6th nerve palsy. The frequencies and types of abnormal findings were evaluated. All patients were divided into ischemic and non-ischemic groups and differences in clinical characteristics between groups were analyzed.Results: Of the 55 patients, nine (16.4%) had abnormal findings on brain imaging. Among 26 patients with 6th nerve palsy, four (15.4%) were found to have a cause including brain tumor, cerebrovascular compression, carotid cavernous fistula. Superior oblique muscle atrophy was found in two of 19 patients (10.5%) with 4th nerve palsy. Three of 10 patients (30%) with 3rd nerve palsy had abnormal findings and there were cases of pituitary apoplexy, posterior communicating, and cerebrovascular compression.Conclusions: In patients with acute isolated oculomotor paralysis, early neuroimaging tests play an important role in differential diagnosis and evaluation of causes that may lead to mortality.

Sixth Cranial Nerve Palsy and Vertigo Caused by Vertebrobasilar Insufficiency

A 38-year-old woman presented with a week’s history of binocular horizontal double vision and acute vertigo with gaze-induced nystagmus. We considered a diagnosis of one of the six syndromes of the sixth cranial nerve and evaluated several causes. She had history of severe anemia, vitamin B12 deficiency, and hypertension. Magnetic resonance imaging with angiography showed stenosis of the right vertebral artery and hyperintensity on both basal ganglia. As we describe here, we should consider vertebrobasilar insufficiency as a cause for sixth cranial nerve palsy if a patient has high risk for microvascular ischemia, even in the absence of acute brain hemorrhage or infarction.

Guidelines for radiographic imaging of cranial neuropathies

Disruption of the complex pathways of the 12 cranial nerves can occur at any site along their course, and many, varied pathologic processes may initially manifest as dysfunction and neuropathy. Radiographic imaging (computed topography or magnetic resonance imaging) is frequently used to evaluate cranial neuropathies; however, indications for imaging and imaging method of choice vary considerably between the cranial nerves. The purpose of this review is to provide an analysis of the diagnostic yield and the most clinically appropriate means to evaluate cranial neuropathies using radiographic imaging. Using the PubMed MEDLINE NCBI database, a total of 49,079 articles' results were retrieved on September 20, 2014. Scholarly articles that discuss the etiology, incidence, and use of imaging in the context of evaluation and diagnostic yield of the 12 cranial nerves were evaluated for the purposes of this review. We combined primary research, guidelines, and best practice recommendations to create a practical framework for the radiographic evaluation of cranial neuropathies.

Clinical features of visual disturbances secondary to isolated sphenoid sinus inflammatory diseases

Background

Visual disturbances associated with isolated sphenoid sinus inflammatory diseases (ISSIDs) are easily misdiagnosed due to the nonspecific symptoms and undetectable anatomical location. The main objective of this retrospective case series is to investigate the clinical features of visual disturbances secondary to ISSIDs.

Methods

Clinical data of 23 patients with unilateral or bilateral visual disturbances secondary to ISSIDs from 2004 to 2014 with new symptoms were collected. Collected data including symptoms, signs, neuroimaging and pathologic diagnosis were analyzed.

Results

There were 14 males and 9 females, and their ages ranged from 31 to 83 years. Fifteen patients suffered blurred vision and 11 patients suffered binocular double vision, including 3 patients who had unilateral visual changes and diplopia simultaneously. Headache was observed in 18 patients, and orbit pain/ocular pain in 8 patients. Other presenting symptoms included ptosis (4 patients) and proptosis (1 patient). Only 5 patients had nasal complaints. The corrected visual acuities were between NLP to 20/20. Patients with diplopia included 5 with unilateral oculomotor nerve palsy and 6 with unilateral abducens nerve palsy. All patients performed orbital/sinus/brain radiologic examination and found responsible lesions in sphenoid sinus. All patients underwent endoscopic sinus surgery, and 9 patients were found to suffer sphenoid mucocele, 9 with fungal sinusitis, and 5 with sphenoid sinusitis. Visual disturbances improved in 6 patients, and all the patients with diplopia had a postoperative recovery.

Conclusion

Visual disturbances resulting from ISSIDs are relatively uncommon, but it is crucial that the patient with new vision loss or diplopia and persistent headache or orbit pain be evaluated for the possibility of ISSIDs especially before corticosteroid administration.

Case Report: Adenocarcinoma of the Lacrimal Gland Presenting as an Abduction Deficit

SIGNIFICANCE

It is imperative to follow the clinical guidelines for abduction deficits to ensure prompt diagnosis of potentially serious etiologies and monitor only those in which a microvascular etiology is most likely. This case reports highlights a rare diagnosis of a malignant tumor of the lacrimal gland presenting as an abduction deficit.

PURPOSE

Tumors of the lacrimal gland can cause abduction deficits, which may mimic an abducens nerve palsy. Abducens nerve palsies are often encountered by optometrists. This case report highlights the appropriate workup of an abduction deficit and reviews the literature of adenocarcinoma not otherwise specified.

CASE REPORT

A 67-year-old white man was transferred to the optometry clinic with a presumed ischemic abducens palsy. He was found to have an isolated left abduction deficit without vascular risk factors that prompted neuroimaging revealing a mass of the lacrimal gland. After an en bloc resection, a diagnosis of adenocarcinoma not otherwise specified was made. The patient underwent aggressive surgical exenteration followed by radiation.

CONCLUSIONS

Using the guidelines for evaluation of an abduction deficit, this serious malignancy was diagnosed. An adenocarcinoma not otherwise specified of the lacrimal gland is rare, and there are limited data on its clinical course, prognosis, and treatment. Recurrence and metastases occur at high rates; therefore, prompt diagnosis and aggressive intervention are crucial.

Sixth Nerve Palsy from Cholesterol Granuloma of the Petrous Apex

Herein, we report a patient who had an isolated sixth nerve palsy due to a petrous apex cholesterol granuloma. The sixth nerve palsy appeared acutely and then spontaneously resolved over several months, initially suggesting a microvascular origin of the palsy. Subsequent recurrences of the palsy indicated a different pathophysiologic etiology and MRI revealed the lesion at the petrous apex. Surgical resection improved the compressive effect of the lesion at Dorello’s canal and clinical improvement was observed. A relapsing–remitting sixth nerve palsy is an unusual presentation of this rare lesion.

Efficacy of intraorbital electroacupuncture for diabetic abducens nerve palsy: study protocol for a prospective single-center randomized controlled trial

Abducens nerve palsy (ANP) is commonly seen in patients with diabetes mellitus. The validity of acupuncture as a traditional Chinese medicine method in peripheral nerve repair is well established. However, its efficacy in randomized controlled trials remains unclear. Herein, we designed a protocol for a prospective, single-center, randomized controlled trial to investigate the effect of intraorbital electroacupuncture on diabetic ANP. We plan to recruit 60 patients with diabetic ANP, and randomly divide them into treatment and control groups. Patients in both groups will continue their glucose-lowering therapy. A neural nutrition drug will be given to both groups for six weeks. The treatment group will also receive intraorbital electroacupuncture therapy. We will assess efficacy of treatment, eyeball movement, diplopia deviation and the levels of fasting blood-glucose and glycosylated hemoglobin before treatment at 2, 4, and 6 weeks after treatment. The efficacy and recurrence will be investigated during follow-up (1 month after intervention). This protocol was registered at Chinese Clinical Trial Registry on 16 January 2015 (ChiCTR-IPR-15005836). This study was approved by the Ethics Committee of First Affiliated Hospital of Harbin Medical University of China (approval number: 201452). All protocols will be in accordance with Declaration of Helsinki, formulated by the World Medical Association. Written informed consent will be provided by participants. We envisage that the results of this clinical trial will provide evidence for promoting clinical use of this new therapy for management of ANP.

The diagnostic yield of neuroimaging in sixth nerve palsy--Sankara Nethralaya Abducens Palsy Study (SNAPS): Report 1

Aims:

The aim was to assess the etiology of sixth nerve palsy and on the basis of our data, to formulate a diagnostic algorithm for the management in sixth nerve palsy.

Design:

Retrospective chart review.

Results:

Of the 104 neurologically isolated cases, 9 cases were attributable to trauma, and 95 (86.36%) cases were classified as nontraumatic, neurologically isolated cases. Of the 95 nontraumatic, isolated cases of sixth nerve palsy, 52 cases were associated with vasculopathic risk factors, namely diabetes and hypertension and were classified as vasculopathic sixth nerve palsy (54.7%), and those with a history of sixth nerve palsy from birth (6 cases) were classified as congenital sixth nerve palsy (6.3%). Of the rest, neuroimaging alone yielded a cause in 18 of the 37 cases (48.64%). Of the other 19 cases where neuroimaging did not yield a cause, 6 cases were attributed to preceding history of infection (3 upper respiratory tract infection and 3 viral illnesses), 2 cases of sixth nerve palsy were found to be a false localizing sign in idiopathic intracranial hypertension and in 11 cases, the cause was undetermined. In these idiopathic cases of isolated sixth nerve palsy, neuroimaging yielded no positive findings.

Conclusions:

In the absence of risk factors, a suggestive history, or positive laboratory and clinical findings, neuroimaging can serve as a useful diagnostic tool in identifying the exact cause of sixth nerve palsy. Furthermore, we recommend an algorithm to assess the need for neuroimaging in sixth nerve palsy.

Focal and entrapment neuropathies

Of the many patterns of peripheral nerve disorders in diabetes mellitus (DM), isolated clinical involvement of single nerves, though less common than distal symmetric polyneuropathy and perhaps polyradiculoneuropathy, constitute an important collection of characteristic syndromes. These fall into four anatomical regions of the body: cranial, upper limb, truncal, and lower limb territories. Each of these groups of mononeuropathies has its own ensemble of epidemiologic patterns, clinical presentations, laboratory and radiologic findings, differential diagnosis, management principles and prognosis.

Acute Abducens Nerve Paralysis in the Pediatric Emergency Department: Analysis of 14 Patients

OBJECTIVES

Sixth cranial nerve (SCN) palsy is an uncommon but important neurological problem in patients admitted to pediatric emergency department. The underlying etiology of SCN palsy has a wide range from viral infections to intracranial tumors; therefore, a careful and systematic approach is necessary while examining these patients.

METHODS

Fourteen patients who presented with acute SCN paralysis to pediatric emergency department during the last 10 years were examined.

RESULTS

The age at the time of admission ranged between 14 months and 16 years (median, 9.5 years). Of the 14 patients, 5 were girls and 9 were boys. A total of 3 of the 14 patients had bilateral cranial nerve VI paralysis, and 9 patients had additional abnormal findings on neurological examination. Neuroimaging studies included cranial tomography (n = 3) and brain magnetic resonance imaging in all patients. The underlying etiology was malignancy (n = 3); glioma, medulloblastoma, acute lymphoblastic leukemia, and dural sinus thrombosis (n = 2); as well as Guillain-Barre syndrome (n = 2), multiple sclerosis (n = 1), pseudotumor cerebri (n = 1), and meningitis (n = 1). The remaining 4 patients had miscellaneous benign etiologies.

CONCLUSIONS

Other lesions of primary brain tumors causing increased intracranial pressure constitute 50% of the underlying etiology, followed by Guillain-Barre syndrome (14.2%). However, these patients had neurological symptoms signs, in addition to diplopia or SCN paralysis. Patients admitted to pediatric emergency department with acute SCN paralysis should be examined in detail to disclose the underlying etiology especially if they present with additional clinical signs or symptoms.

Microvascular Non-Arteritic Ocular Motor Nerve Palsies-What We Know and How Should We Treat?

Patients with isolated unilateral pupil-sparing third or isolated fourth or sixth nerve palsies over 50 years are often diagnosed with "microvascular extraocular palsies". This condition and its management provoke divergent opinions. We review the literature and describe the incidence, pathology, clinical presentation, yield of imaging, and management. A retrospective diagnosis of exclusion has little practical use. We suggest a pragmatic approach to diagnosis, investigation, and management from initial presentation.

Hypertropia in unilateral isolated abducens palsy

PURPOSE

To evaluate the incidence and features of hypertropia in abducens nerve palsy.

METHODS

The records of consecutive patients with unilateral, isolated, previously unoperated abducens nerve palsy were reviewed for binocular alignment on cover testing, Krimsky measurement, or Hess screen testing. Patients with associated cranial nerve palsy (including bilateral abducens palsies), orbital disease, myasthenia gravis, Horner syndrome, hemiplegia, cerebellar signs, arteritis, or previous strabismus surgery were excluded. Control subjects underwent complete examination to confirm normality.

RESULTS

A total of 79 patients were included (40 males; mean age 49.2 years). Hypertropia in lateral or central gazes was present in 15 of 79 cases (19%) on alternate cover or Krimsky testing, in 32 of 56 cases (57%) on Hess screen testing, and absent in all 30 normal controls. Of cases with hypertropia, the mean of the greatest hypertropia in lateral or central gaze on was 5.0(Δ) ± 2.3(Δ) (standard deviation; range, 1(Δ)-8(Δ)) routine clinical examination, and 5.8(Δ) ± 4.2(Δ) (range, 2(Δ)-24(Δ)) on Hess screen testing. Of 39 cases with partial abducens palsy evaluated by Hess screen testing, the ipsilesional eye was hypertropic in 24 (61%) and hypotropic in 15 cases (39%).

CONCLUSIONS

Small-angle hypertropia is common in isolated, unilateral abducens and does not imply existence of multiple cranial neuropathies or skew deviation.

Headache medicine meets neuro-ophthalmology: exam techniques and challenging cases

The neuro-ophthalmology examination is critical to anyone who sees patients with the common symptom of headache. By examining the visual acuity, pupils, visual fields, motility, and fundus, clues to both secondary causes of headache and primary headaches exist. In this review, we discuss how to do the neuro-ophthalmology examination and we review cases of primary and secondary headache where key features of the examination assisted in making the correct diagnosis.

Isolated third, fourth, and sixth cranial nerve palsies from presumed microvascular versus other causes: a prospective study

PURPOSE

To estimate the proportion of patients presenting with isolated third, fourth, or sixth cranial nerve palsy of presumed microvascular origin versus other causes.

DESIGN

Prospective, multicenter, observational case series.

PARTICIPANTS

A total of 109 patients aged 50 years or older with acute isolated ocular motor nerve palsy.

TESTING

Magnetic resonance imaging (MRI) of the brain.

MAIN OUTCOME MEASURES

Causes of acute isolated ocular motor nerve palsy (presumed microvascular or other) as determined with early MRI and clinical assessment.

RESULTS

Among 109 patients enrolled in the study, 22 had cranial nerve III palsy, 25 had cranial nerve IV palsy, and 62 had cranial nerve VI palsy. A cause other than presumed microvascular ischemia was identified in 18 patients (16.5%; 95% confidence interval, 10.7-24.6). The presence of 1 or more vasculopathic risk factors (diabetes, hypertension, hypercholesterolemia, coronary artery disease, myocardial infarction, stroke, and smoking) was significantly associated with a presumed microvascular cause (P = 0.003, Fisher exact test). Vasculopathic risk factors were also present in 61% of patients (11/18) with other causes. In the group of patients who had vasculopathic risk factors only, with no other significant medical condition, 10% of patients (8/80) were found to have other causes, including midbrain infarction, neoplasms, inflammation, pituitary apoplexy, and giant cell arteritis (GCA). By excluding patients with third cranial nerve palsies and those with GCA, the incidence of other causes for isolated fourth and sixth cranial nerve palsies was 4.7% (3/64).

CONCLUSIONS

In our series of patients with acute isolated ocular motor nerve palsies, a substantial proportion of patients had other causes, including neoplasm, GCA, and brain stem infarction. Brain MRI and laboratory workup have a role in the initial evaluation of older patients with isolated acute ocular motor nerve palsies regardless of whether vascular risk factors are present.

A prospective study on 132 cases of ocular palsy

OBJECTIVES

In this prospective study, we used one diagnostic protocol to establish an early diagnosis in patients with ocular palsies in absence of other neurological findings.

MATERIALS AND METHODS

The study was performed on a consecutive series of 132 patients who visited our Neurological Department for ptosis and/or diplopia in absence of other neurological signs, using the same diagnostic protocol.

RESULTS

An etiological diagnosis was made in 74% of cases during a mean time of 17 ± 23 months from symptom onset. Myasthenia gravis was the most common diagnosis (n = 60, 45.5%). Thirty-four cases (26%) remained undiagnosed in spite of a follow-up lasting 32 ± 33 months on average.

CONCLUSIONS

Identifying the cause of an isolated ocular palsy can be difficult, and an extended follow-up time does not aid in further establishment of the diagnosis.

Neuro-imaging: a review for the general ophthalmologist

The diagnosis of many neuro-ophthalmic conditions is facilitated with neuro-imaging. The two main modalities are Computed Tomography (CT) and Magnetic Resonance Imaging (MRI). Clinicians who refer patients for either of these techniques must not only know which of them to choose, but also where the imaging should be performed (e.g. brain, orbit), whether or not contrast is indicated, and if angiography should be supplemented. These complexities often result in imaging studies that are either unneeded or unhelpful. The goal of this manuscript is to provide a practical set of guidelines for the general ophthalmologist of how to choose the correct parameters for neuro-imaging studies.

Evaluation of orbital disorders and cranial nerve innervation of the extraocular muscles

A wide range of orbital disorders, including an orbital mass, infection, inflammation, systemic disease, or intracranial lesions, may be encountered with imaging. Evaluation of orbital disorders requires the combination of accurate and relevant clinical information with an understanding of anatomy and pathologic processes. An imaging approach to an orbital differential diagnosis includes assessment for alteration of a normal orbital structure, a lesion that does not belong in the orbit, or alteration of the orbit from bone or periorbital disorders. This approach, combined with key elements of clinical history, leads to a narrower differential diagnosis and improved patient care.

Role of imaging in the management of neuro-ophthalmic disorders

Advancements in physics, computers, and imaging science in the last century have seen neuro-imaging evolving from a plain X-ray to computed tomography, magnetic resonance imaging scans, noninvasive angiography, and special sequences such as fat suppression, fluid attenuation recovery and diffusion-weighted imaging. A prompt prescription of an appropriate imaging modality and the most suitable sequence can increase the diagnostic yield, and in many instances, it can be a sight-saving and even a life-saving decision. This article discusses basic principles of neuro-imaging, its common indications, and the appropriate application in an ophthalmology practice.