Immune-mediated conditions affecting the brain, eye and ear (BEE syndromes)

The neurocognitive and neuropsychiatric manifestations of Susac syndrome: a brief review of the literature and future directions

Encephalopathy is part of the clinical triad of Susac syndrome, but a detailed understanding of the neurocognitive and neuropsychiatric profile of this condition is lacking. Existing literature indicates that cognitive deficits range in severity from subtle to profound. Executive function and short-term recall are affected frequently. Psychiatric manifestations may be absent or may include anxiety, mood disorders or psychosis. If psychiatric phenomena develop during the disease course, it can be hard to disentangle whether symptoms directly relate to the pathology of Susac syndrome or are secondary to treatment-related side effects. In this article, we review what is known about the cognitive and psychiatric morbidity of Susac syndrome and identify areas where knowledge is deficient. Importantly, we also provide a framework for future research, arguing that better phenotyping, understanding of pathophysiology, evaluation of treatments on cognitive and psychiatric outcomes, and longitudinal data capture are vital to improving patient outcomes.

Susac's Syndrome: A Tale of Disability Due to Late Recognition

Susac's syndrome is a rare inflammatory microangiopathy characterized by the triad of retinopathy, encephalopathy, and hearing loss. The syndrome causes recurrent microinfarcts in these organs, which in turn manifests with repeated attacks of visual field loss, hearing loss and tinnitus, and various brain syndromes. These often lead to the significant accumulation of disability over time, particularly if there is a delay or failure in diagnosis. The brain lesions associated with this condition may resemble those of multiple sclerosis, especially to those who are unfamiliar with the disease and its distinctive clinical and radiological features. Such misdiagnosis may have grave clinical consequences. Here, we present the case of a 41-year-old Danish man who presented with the classical triad of Susac's syndrome but was misdiagnosed with multiple sclerosis. It took three years from disease onset before the eventual diagnosis was recognized, and by this time, he had accrued a lot of neurological deficits. With this case report, we aim to draw awareness to this rare but unforgiving entity which if missed can lead to the accumulation of disabilities. We also aim to emphasize the features that help distinguish it from multiple sclerosis, the condition with which it is most often confused.

Central Nervous System Involvement in Systemic Autoimmune Rheumatic Diseases-Diagnosis and Treatment

Central nervous system (CNS) involvement in autoimmune rheumatic diseases represents a significant challenge for clinicians across all specialties. While most reviews on the subject focus on neurological manifestations within a specific rheumatic disease, few descriptions shift from neurological clinical syndromes to achieve rheumatological diagnoses. This narrative review aims to synthesize current knowledge on the diagnosis and management of CNS manifestations occurring in the most prevalent rheumatic conditions in adults. We searched the MEDLINE database using the terms "central nervous system", "rheumatic diseases", "systemic lupus erythematosus", "rheumatoid arthritis", "Sjögren syndrome", and "vasculitis". The search strategy included review articles from 2019 to 2024, published in English, Spanish, or Portuguese. We explored the pathophysiological mechanisms linking autoimmunity to CNS pathology, emphasizing the role of syndromic reasoning, autoantibody profiles, and imaging modalities as tools for diagnosis and determination of inflammatory activity. The review also discusses differential diagnoses through a stepwise approach to neurological syndromes, summarized in diagnostic flowcharts, and presents updated treatment options. Although our approach is primarily semiology-based, the complexity of the subject invites future endeavors involving new technologies, such as functional MRI, MR spectroscopy, and nuclear medicine.

Audiovestibular Dysfunction in Systemic Lupus Erythematosus Patients: A Systematic Review

Audiovestibular dysfunction in patients with systemic lupus erythematosus has been underestimated for decades. Systemic lupus erythematosus can affect both the auditory and vestibular systems simultaneously. Several potential pathophysiological mechanisms behind systemic lupus erythematosus-related audiovestibular dysfunction have been proposed, including antibody-mediated immune responses, cell-mediated cytotoxicity, immune complex deposition in microvessels, central involvement in the audiovestibular pathway, and ototoxicity from medications used in systemic lupus erythematosus treatment. Currently available tests to evaluate audiovestibular function in systemic lupus erythematosus patients are neither specific nor sensitive. Nevertheless, there is no consensus regarding the efficacy of treatments for audiovestibular dysfunction in such patients. In this systematic review, we electronically searched the PubMed, Embase, ClinicalKey, Web of Science, and ScienceDirect platforms to find eligible articles. The first inspection date was on 29 December 2023 and the final update search date was on 11 June 2024. Further, we rated the quality of the included articles with Newcastle-Ottawa Scale. Based upon the aforementioned systematic review process, we have summarized the currently available evidence on the characteristics, pathophysiology, examination, and treatment of audiovestibular dysfunction related to systemic lupus erythematosus. Furthermore, we have proposed a specific steroid treatment protocol to manage audiovestibular dysfunction related to systemic lupus erythematosus. Audiovestibular dysfunction related to systemic lupus erythematosus may be responsive to adequate treatments, potentially allowing for reversibility if the disease is recognized and managed in a timely manner. Therefore, to provide clinically relevant evidence to clinicians, we have organized this literature review article to summarize the available evidence on the characteristics, pathophysiology, examination, and treatment of audiovestibular dysfunction in patients with systemic lupus erythematosus. Finally, based on our modified steroid treatment protocol, we would like to provide a new treatment strategy to clinicians to manage systemic lupus erythematosus-related audiovestibular dysfunction.

Diagnostic and therapeutic approach to adult central nervous system vasculitis

The clinical manifestations of central nervous system (CNS) vasculitis are highly variable. In the absence of a positive CNS biopsy, CNS vasculitis is particularly suspected when markers of both vascular disease and inflammation are present. To facilitate the clinical and therapeutic approach to this rare condition, CNS vasculitis can be classified according to the size of the involved vessels. Vascular imaging is used to identify medium vessel disease. Small vessel disease can only be diagnosed with a CNS biopsy. Medium vessel vasculitis usually presents with focal neurological signs, while small vessel vasculitis more often leads to cognitive deficits, altered level of consciousness and seizures. Markers of CNS inflammation include cerebrospinal fluid pleocytosis or elevated protein levels, and vessel wall, parenchymal or leptomeningeal enhancement. The broad range of differential diagnoses of CNS vasculitis can be narrowed based on the disease subtype. Common mimickers of medium vessel vasculitis include intracranial atherosclerosis and reversible cerebral vasoconstriction syndrome. The diagnostic workup aims to answer two questions: is the neurological presentation secondary to a vasculitic process, and if so, is the vasculitis primary (i.e., primary angiitis of the CNS) or secondary (e.g., to a systemic vasculitis, connective tissue disorder, infection, malignancy or drug use)? In primary angiitis of the CNS, glucocorticoids and cyclophosphamide are most often used for induction therapy, but rituximab may be an alternative. Based on the available evidence, all patients should receive maintenance immunosuppression. A multidisciplinary approach is necessary to ensure an accurate and timely diagnosis and to improve outcomes for patients with this potentially devastating condition.

Diagnosis, differential diagnosis and misdiagnosis of Susac syndrome

Background and purpose

Susac syndrome (SuS) is an inflammatory condition of the brain, eye and ear. Diagnosis can be challenging, and misdiagnosis is common.

Methods

This is a retrospective review of the medical records of 32 adult patients from an Australasian cohort of SuS patients.

Results

An alternative diagnosis prior to SuS was made in 30 patients (94%) with seven patients receiving two or more diagnoses. The median time to diagnosis of SuS was 3 months (range 0.5–100 months). The commonest misdiagnoses were migraine in 10 patients (31%), cerebral vasculitis in six (19%), multiple sclerosis in five (16%) and stroke in five (16%). Twenty‐two patients were treated for alternative diagnoses, 10 of whom had further clinical manifestations prior to SuS diagnosis. At presentation seven patients (22%) met criteria for definite SuS, 19 (59%) for probable SuS and six (19%) for possible SuS. Six patients (19%) presented with brain–eye–ear involvement, 14 with brain–ear (44%), six with brain–eye (19%) and six (19%) with only brain involvement. In patients with the complete triad of symptoms the median delay to diagnosis was 3 months (range 1–9 months) compared to 5.25 months (range 0.5–100 months) for patients with encephalopathy and ocular symptoms at presentation.

Conclusions

Susac syndrome patients are frequently misdiagnosed at initial presentation, despite many having symptoms or radiological features that are red flags for the diagnosis. Delayed diagnosis can lead to patient morbidity. The varied ways in which SuS can present, and clinician failure to consider or recognize SuS, appear to be the main factors leading to misdiagnosis.

Vogt-Koyanagi-Harada Syndrome - A Neurologist's Perspective

Vogt-Koyanagi-Harada (VKH) syndrome is an immune-mediated granulomatous disease which affects melanin-rich organs like eyes, skin, nervous system, and ears. Neurological and auditory manifestations usually precede the involvement of other sites. Patients may manifest with “complete” or “incomplete” syndrome. We report two patients who presented with acute headache and impaired vision. Fundus examination revealed optic disc hyperemia and exudative retinal detachment which provided a clue for the diagnosis at the bedside. Fundus fluorescein angiogram (FFA) revealed abnormal dye leakage, whereas B scan showed choroid thickening. Cerebrospinal fluid (CSF) pleocytosis contrasted with unremarkable brain magnetic resonance imaging and lack of meningeal signs. Melanophagocytosis was evidenced by melanin-laden macrophages in CSF and skin biopsy. This finding is specific for VKH syndrome and helps to clinch the diagnosis even when the complete syndrome is not present cross-sectionally. VKH syndrome should be suspected in patients with aseptic meningitis if tests for common infectious and immune-mediated diseases are negative.

Brain magnetic resonance imaging lesion load at diagnosis, severity at onset and outcomes in Susac syndrome: A prospective cohort study

BACKGROUND

Susac syndrome (SuS) is a rare occlusive microvessel disease of the brain, retina and inner ear. We aimed to determine whether brain lesion load at the acute phase predicts poor outcomes in SuS.

METHODS

A prospective national cohort study was conducted from December 2012 to December 2019 in 20 centres in France. Patients included at the principal investigator's center with available brain magnetic resonance imaging (MRI) at diagnosis were analyzed. MRI was reviewed by an experienced neuroradiologist blinded to clinical status. The size, topography and number of hyperintense lesions on diffusion-weighted imaging (DWI-HL) were analyzed at diagnosis and during follow-up. Outcomes involved descriptive characteristics of patients at onset and last follow-up.

RESULTS

Twenty-three patients (38.1 [18.8-56.5] years, 16 females) were prospectively studied. The triad (i.e., brain, eye and ear involvement) was complete at onset in 17 patients. Brain MRI was performed 1.1 (0.1-3.4) months after the first symptom. All patients had DWI-HL at the acute phase. Patients were separated into two groups according to the number of DWI-HL on first MRI: a first group of patients (n=15) displaying low brain lesion load (<50 DWI-HL per patient) and a second group of patients (n=8) displaying high brain lesion load (≥100 DWI-HL). The median follow-up was 57.9 (9.7-98) months. Clinical features, treatment, relapse rate, time to disappearance of DWI-HL, disabilities and professional outcome did not differ according to brain lesion load.

CONCLUSION

Brain lesion load assessed by DWI at the acute phase is not associated with risks of disability in SuS.

Leptomeningeal enhancement on post-contrast FLAIR images for early diagnosis of Susac syndrome

BACKGROUND

Leptomeningeal enhancement (LME) is a key feature of Susac syndrome (SuS) but is only occasionally depicted on post-contrast T1-weighted images (T1-WI).

OBJECTIVE

As post-contrast fluid-attenuated inversion recovery (FLAIR) may be more sensitive, our aim was to assess LME in SuS on this sequence.

METHODS

From 2010 to 2020, 20 patients with definite SuS diagnosis were retrospectively enrolled in this multicentre study. Two radiologists independently assessed the number of LME on post-contrast FLAIR and T1-WI acquisitions performed before any treatment. A chi-square test was used to compare both sequences and the interrater agreement was calculated.

RESULTS

Thirty-five magnetic resonance imagings (MRIs) were performed before treatment, including 19 post-contrast FLAIR images in 17 patients and 25 post-contrast T1-WI in 19 patients. In terms of patients, LME was observed on all post-contrast FLAIR, contrary to post-contrast T1-WI (17/17 (100%) vs. 15/19 (79%), p < 0.05). In terms of sequences, LME was observed on all post-contrast FLAIR, contrary to post-contrast T1-WI (19/19 (100%) vs. 16/25 (64%), p < 0.005). LME was disseminated at both supratentorial (19/19) and infratentorial (18/19) levels on post-contrast FLAIR, contrary to post-contrast T1-WI (3/25 and 9/25, respectively). Interrater agreement was excellent for post-contrast FLAIR (κ = 0.95) but only moderate for post-contrast T1-WI (κ = 0.61).

CONCLUSION

LME was always observed and easily visible on post-contrast FLAIR images prior to SuS treatment. In association with other MRI features, it is highly indicative of SuS.

Another 'BEE'? - Brain-Eye-Ear (BEE) Disease Secondary to HbSC Disease Masquerading as Multiple Sclerosis

Recurrent episodes of neurological dysfunction and white matter lesions in a young adult raise suspicion for multiple sclerosis (MS). However, occlusive retinopathy, hearing loss and absence of CSF oligoclonal bands are atypical for MS and should make the clinician consider an alternative diagnosis. We describe a man with hearing loss, visual signs and symptoms, and an accumulating burden of brain lesions, who was treated for a clinical diagnosis of MS for nearly two decades. Genetic testing revealed a unifying diagnosis.

Rare Disorders of the Vestibular Labyrinth: of Zebras, Chameleons and Wolves in Sheep's Clothing

The differential diagnosis of vertigo syndromes is a challenging issue, as many - and in particular - rare disorders of the vestibular labyrinth can hide behind the very common symptoms of "vertigo" and "dizziness". The following article presents an overview of those rare disorders of the balance organ that are of special interest for the otorhinolaryngologist dealing with vertigo disorders. For a better orientation, these disorders are categorized as acute (AVS), episodic (EVS) and chronic vestibular syndromes (CVS) according to their clinical presentation. The main focus lies on EVS sorted by their duration and the presence/absence of triggering factors (seconds, no triggers: vestibular paroxysmia, Tumarkin attacks; seconds, sound and pressure induced: "third window" syndromes; seconds to minutes, positional: rare variants and differential diagnoses of benign paroxysmal positional vertigo; hours to days, spontaneous: intralabyrinthine schwannomas, endolymphatic sac tumors, autoimmune disorders of the inner ear). Furthermore, rare causes of AVS (inferior vestibular neuritis, otolith organ specific dysfunction, vascular labyrinthine disorders, acute bilateral vestibulopathy) and CVS (chronic bilateral vestibulopathy) are covered. In each case, special emphasis is laid on the decisive diagnostic test for the identification of the rare disease and "red flags" for potentially dangerous disorders (e. g. labyrinthine infarction/hemorrhage). Thus, this chapter may serve as a clinical companion for the otorhinolaryngologist aiding in the efficient diagnosis and treatment of rare disorders of the vestibular labyrinth.

Headache in Susac's Syndrome

PURPOSE OF REVIEW

Provide an overview of the current diagnosis, pathophysiology, and treatment of Susac's syndrome (SuS), with special emphasis on summarizing what is currently known about headache as a symptom of disease activity.

RECENT FINDINGS

The most recent literature in SuS has focused on furthering the understanding of the underlying pathology and efficacy of treatments for SuS. The importance of early recognition to facilitate timely treatment and avoid long-term disability has been highlighted. Headache, the most common symptom experienced by patients with SuS, can occur up to 6 months in advance of other symptoms, and exacerbations of headache can herald increased disease activity. Susac's syndrome (SuS) is a rare disorder classically characterized by triad of encephalopathy, branch retinal artery occlusion (BRAO), and sensory neuronal hearing loss (SNHL). The full triad is uncommon at initial presentation, which can confound efforts to make timely diagnosis and treatment decisions. Headache is the most common symptom in SuS, is often an early feature, and can help separate SuS from other diagnoses in the differential. However, the features and management of the headache associated with SuS have not been systematically defined in the literature.

Central nervous system vasculitis: advances in diagnosis

PURPOSE OF REVIEW

The main purpose of this review is to present advances in diagnostics of central nervous system vasculitis (CNS-V).

RECENT FINDINGS

Progress in molecular technologies and neuroimaging have added formidably to our knowledge of CNS-V. Next-generation sequencing has the promise to enhance our ability to diagnose, interrogate, and track infectious diseases, making this test attractive and capable of avoiding brain biopsy in cases where CNS infections are suspected. Further the continuum of neuroimaging progress has advanced our ability to diagnose CNS-V. Our capability to visualize the vessel wall have added a great value in differentiating inflammatory from noninflammatory vasculopathies. New genetic variations are being exposed with exome and genome sequences which will aid future diagnosis.

SUMMARY

We have witnessed tremendous advances in CNS-V mainly by our ability to rule out mimics. Progress in molecular technologies, neuroimaging and genetic studies will continue to enhance the field further.

Susac Syndrome and Pregnancy

Susac syndrome (SuS) is a rare poorly characterised disorder that affects the brain, retina, and cochlea. Here, we present a case of a 31-year-old pregnant female with a new diagnosis of SuS that was successfully managed to 36 weeks of gestation with minimal disease burden to both the mother and newborn. She was treated initially using intravenous methylprednisolone followed by oral prednisone, and intravenous immunoglobulin (IVIg). We stress the importance of a multidisciplinary approach, involving both neurology and maternal-fetal medicine, and provide guidance in navigating the various options for immunosuppressive therapy during pregnancy.

Menière's disease

Menière's disease causes paroxysmal rotatory vertigo, due to endolymphatic hydrops, an accumulation of endolymph in the endolymphatic space of the labyrinth. Its major symptoms are attacks of rotatory vertigo lasting minutes to hours, with unilateral hearing loss, tinnitus and aural fullness. As the disease progresses, attacks happen less often, but hearing loss and tinnitus gradually become permanent. Neuro-otological complications may develop, such as benign paroxysmal positional vertigo, vestibular drop attacks and bilateral vestibulopathy. The diagnosis of Menière's disease is based on the typical clinical picture and typical findings on the audiogram. Furthermore, it is now possible to diagnose it by MR of the inner ear. Long-term management has several steps, including diet, diuretics, intratympanic injection of corticosteroid or gentamicin and surgery (endolymphatic sac surgery, grommet insertion, surgical labyrinthectomy).