MRI findings of optic pathway involvement in Miller Fisher syndrome in 3 pediatric patients and a review of the literature

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.

Inflammatory Sixth Nerve Palsy Post-COVID-19 Vaccination: Magnetic Resonance Imaging Findings

Sixth nerve palsy is the most common post-vaccination oculomotor palsy. It is generally transient with most patients making a complete recovery. We report the case of a 46-year-old healthy male patient who presented with a painless sixth nerve palsy after the second dose of the Pfizer BioNTech COVID-19 vaccine, which recovered over the course of the next month. We confirmed the lesion localisation by demonstrating enhancement of the root exit zone and the cisternal portion of the sixth nerve on sequential magnetic resonance imaging during the symptomatic period. Here, a temporal relationship between vaccine application and diplopia onset suggests an aetiologic relationship. Moreover, the lack of pre-existing medical conditions suggests a post-vaccination inflammatory process.

Miller Fisher Syndrome Triggered by Infections: A Review of the Literature and a Case Report

AIM

We reported a case of Miller Fisher syndrome following a breakthrough varicella zoster virus infection in an otherwise healthy 6-year-old male. The objective of this review was to summarize the infectious etiologic agents known to trigger Miller Fisher syndrome.

METHODS

Review of the literature on infections associated with Miller Fisher syndrome.

RESULTS

We identified 762 studies after duplicates were removed. Titles, abstracts, and full texts were screened. Finally, 37 studies were included in qualitative synthesis after citations and reference list were checked. The age range of cases reported was 0-78 years, and male sex was predominant in studies where these parameters were reported. The most common causative agent was Campylobacter jejuni followed by Haemophilus influenzae.

CONCLUSIONS

Our review highlights the importance of recognizing the infections triggering Miller Fisher syndrome. We also present a unique case of Miller Fisher syndrome associated with breakthrough varicella zoster virus infection. Preventive policies may consider population immunization for certain causative agents.

High-resolution MR imaging of cranial neuropathy in patients with anti-GQ1b antibody syndrome

OBJECTIVE

The value of conventional MRI in patients anti-GQ1b antibody syndrome is subject to debate. Our purpose was to evaluate the diagnostic accuracy of high-resolution MRI for detecting cranial nerve abnormalities in patients with anti-GQ1b antibody syndrome.

MATERIALS AND METHODS

This retrospective cohort study enrolled 15 anti-GQ1b-positive patients diagnosed with MFS and related disorders and 17 age-matched controls, all of whom underwent high-resolution MR imaging including pre-contrast and contrast-enhanced (CE) 3D FLAIR and 3D CE T1-weighted turbo field echo (T1-TFE) between 2010 and 2016. The diagnostic performance of high-resolution MRI was assessed using the area under the curve (AUC) of the receiver operating characteristics curve. Inter- and intraobserver agreements were calculated using kappa statistics and intraclass correlation coefficients (ICC), respectively.

RESULTS

Ophthalmoplegia, ataxia, and hypo/areflexia were present in 100%, 60%, and 67%, respectively. Other neurologic findings included ptosis (40%), mydriasis (13%), and facial (27%) and bulbar (13%) palsy. Fourteen of sixteen (88%) MR examinations in 15 patients demonstrated at least one cranial nerve abnormality corresponding to the clinical findings. The involved cranial nerves on MRI were the IIIrd cranial nerve in 14 patients, VIth in nine, VIIth in four, Vth in one, and VIIIth in one. AUC values for detecting cranial neuropathy on high-resolution MRI were 0.938 (95% CI: 0.795-0.992) on a per patient basis. Inter- and intraobserver agreements were 0.842 and 0.945, respectively.

CONCLUSION

High-resolution 3D FLAIR and CE 3D T1-TFE MRI has high reliability and accuracy for demonstrating cranial neuropathy in patients with anti-GQ1b antibody syndrome.

Miller Fisher Syndrome Triggered by Infections: A Review of the Literature and a Case Report

AIM

We reported a case of Miller Fisher syndrome following a breakthrough varicella zoster virus infection in an otherwise healthy 6-year-old male. The objective of this review was to summarize the infectious etiologic agents known to trigger Miller Fisher syndrome.

METHODS

Review of the literature on infections associated with Miller Fisher syndrome.

RESULTS

We identified 762 studies after duplicates were removed. Titles, abstracts, and full texts were screened. Finally, 37 studies were included in qualitative synthesis after citations and reference list were checked. The age range of cases reported was 0-78 years, and male sex was predominant in studies where these parameters were reported. The most common causative agent was Campylobacter jejuni followed by Haemophilus influenzae.

CONCLUSIONS

Our review highlights the importance of recognizing the infections triggering Miller Fisher syndrome. We also present a unique case of Miller Fisher syndrome associated with breakthrough varicella zoster virus infection. Preventive policies may consider population immunization for certain causative agents.

Pediatric Miller Fisher Syndrome; Characteristic Presentation and Comparison with Adult Miller Fisher Syndrome

Background: We aimed to investigate the characteristic presentation of Miller Fisher syndrome (MFS) in pediatrics and compare it with that in adults. Methods: We performed a retrospective review of medical records, laboratory findings, and disease course of pediatric MFS. The data were compared with those of adult MFS, and literature review was done. Unpaired and paired comparisons between groups were made using Wilcoxon rank-sum and signed-rank tests, respectively. Results: Median age for pediatric MFS was 9.8 ± 6.5 years. There were 5 (45.5%) male and 6 (54.5%) female patients. All patients had preceding infection. Two patients (22.2%) had tested positive for anti-GQ1b antibody. Ten patients (90.1%) were treated with intravenous immunoglobulin, and 2 (18.2%) also received intravenous methylprednisolone. Within one month, 8 (72.7%) patients showed recovery, and all 11 (100%) recovered fully within 3 months. Further, the pediatric group had higher frequency of unilateral involvement of ophthalmoplegia, ataxia, and autonomic symptoms but lower antiganglioside antibody positivity and manifestations of areflexia than the adult group. Conclusions: Neuro-ophthalmic manifestations and disease course of pediatric MFS were similar to those of adult MFS as stated in the literature. However, the presence of autonomic symptoms was higher and anti-GQ1b antibody positivity was lower in pediatric MFS than in adult MFS.

A Pilot Study on Serial Nerve Ultrasound in Miller Fisher Syndrome

Objective: Miller Fisher syndrome (MFS) is predominantly a clinical diagnosis, with classic triad of ophthalmoplegia, ataxia, and generalized reduced reflexes. Previous studies in chronic and acute immune-mediated neuropathies indicated that ultrasound, may help to detect changes that could correspond with disease activity. We studied the feasibility of serial nerve ultrasound in MFS, using a healthy controls. Methods: All MFS patients (n = 5) and healthy controls (n = 18), underwent a standardized sonographic protocol that evaluated nerve sizes of facial, large arm and leg nerves, and spinal nerve roots. All MFS patients underwent routine ancillary investigations, including electrodiagnostic testing and for presence of anti-GQ1b antibodies. In addition, four MFS patients had 2nd, and 3rd clinical and sonographic evaluation at 14 and 90 days from onset. Results: The width of the facial nerve was significantly larger in the MFS group than in the control group (MFS: 1.19 ± 0.31 mm vs. normal: 0.67 ± 0.13 mm, P = 0.01). The size of the cervical roots and the nerves in the limbs were similar between the two groups. Two patients' facial nerve size subsided with time, but the decrease in other nerves' sizes were not obvious. Conclusion: Our study showed that serial nerve ultrasound studies are feasible in MFS, and can capture changes in facial nerve size that could complement routine diagnostic tests. Further studies are warranted to determine and compare its test characteristics in MFS.

Imaging of Nontraumatic Orbital and Neuro-ophthalmological Emergencies

Emergency department (ED) visits for eye and vision-related concerns are common. In most cases, accurate diagnosis is made using clinical history and physical exam findings without the need for emergent imaging. When orbital imaging is performed in the ED, it is often in patients with orbital trauma where CT is used to assess for orbital fractures and associated injuries. However, CT or MR imaging can also be critical to appropriately diagnose and manage certain ED patients with nontraumatic eye and vision-related conditions. The purpose of this article is to review the imaging findings and differential diagnoses for nontraumatic orbital and neuro-ophthalmological emergencies from a practical, clinical perspective, based on a patient's typical presenting symptoms. The more commonly imaged clinical indications will be discussed including periorbital swelling, proptosis, eye pain, diplopia, and visual disturbances. In addition, rare but easily overlooked and clinically important diagnoses for the emergency radiologist to recognize will be highlighted.

Miller Fisher Syndrome Mimicking Tolosa-Hunt Syndrome

We herein report a patient with Miller Fisher syndrome mimicking Tolosa-Hunt syndrome. A 47-year-old man presented with right orbital pain and diplopia. On a neurological examination, he had right oculomotor nerve palsy and diminished deep tendon reflexes. Brain magnetic resonance imaging failed to show any parenchymal lesions; however, the bilateral oculomotor nerves were gadolinium-enhanced. The presence of a triad of orbital pain, ipsilateral oculomotor nerve palsy, and a rapid response to steroid therapy met the diagnostic criteria for Tolosa-Hunt syndrome. After discharge, antibodies against GQ1b and GT1a were reported to be positive only with phosphatidic acid. The present case was ultimately diagnosed as an incomplete phenotype of Miller Fisher syndrome.