Susac Syndrome: Clinical characteristics, diagnostic findings and treatment in 19 cases

Case report: Susac syndrome-two ends of the spectrum, single center case reports and review of the literature

Susac syndrome is a rare and enigmatic complex neurological disorder primarily affecting small blood vessels in the brain, retina, and inner ear. Diagnosing Susac syndrome may be extremely challenging not only due to its rarity, but also due to the variability of its clinical presentation. This paper describes two vastly different cases-one with mild symptoms and good response to therapy, the other with severe, complicated course, relapses and long-term sequelae despite multiple therapeutic interventions. Building upon the available guidelines, we highlight the utility of black blood MRI in this disease and provide a comprehensive review of available clinical experience in clinical presentation, diagnosis and therapy of this disease. Despite its rarity, the awareness of Susac syndrome may be of uttermost importance since it ultimately is a treatable condition. If diagnosed in a timely manner, early intervention can substantially improve the outcomes of our patients.

A young soldier with Susac syndrome: a case report

Background

Susac syndrome is a rare disease with multisystem manifestations. While the exact pathogenesis is not known, it has been proposed to be an autoimmune endotheliopathy affecting the microvasculature of the brain, retina, and inner ear. The disease is characterized by a triad of encephalopathy, vision loss, and hearing loss. However, patients may not have the triad at initial presentation and present with only a single finding.

Case presentation

A 25-year-old male resident of Panu Akil presented to Combined Military Hospital Lahore with complaints of dizziness and vertigo associated with severe migraine like headaches. He experienced sudden painless loss of vision in his right eye and was admitted to the medical intensive care unit. On examination, he had right-beating nystagmus and diplopia along with scintillating scotoma. After his admission, contrast-enhanced magnetic resonance imaging (MRI) was done which showed numerous enhancing bilateral white matter internal capsule micro-infarcts indicating typical “string of pearls” sign and a snowball lesion on the corpus callosum. His fundus fluorescein angiography (FFA) did not exhibit any branched retinal artery occlusions (BRAO). Fundoscopy showed the presence of drusen spots. His pure tone audiometry was unremarkable. Based on the highly characteristic findings present on the MRI, a diagnosis of Susac syndrome was made. He was started on injection methylprednisolone 1 gm IV in 500 ml normal saline over 1 h once a day for 5 days and then once a week for 8 weeks. He was also started on tablet mycophenolate mofetil 500 mg once daily for 7 days. Patient showed marked clinical improvement afterwards.

Conclusions

Susac syndrome is a rare multisystem illness with an often insidious presentation. Patients can be misdiagnosed due to the nonspecific nature of the early complaints present in the disease. High index of suspicion is required for timely diagnosis and adequate management. Although no specific guidelines exist, management consists mainly of immunosuppressants.

Susac Syndrome: Description of a Single-Centre Case Series

This study describes the clinical characteristics, diagnostic results, treatment regimens, and clinical course of a cohort of patients with Susac syndrome (SS). It is a retrospective observational study of all patients with the diagnosis of SS evaluated at the Hospital Clinic (Barcelona, Spain) between March 2006 and November 2020. Nine patients were diagnosed with SS. The median time from the onset of the symptoms to diagnosis was five months (IQR 9.0), and the median follow-up time was 44 months (IQR 63.5). There was no clear predominance of sex, and mean age of symptoms onset was 36 years (range 19–59). Six patients (67%) presented with incomplete classical clinical triad, but this eventually developed in six patients during the disease course. Encephalopathy, focal neurological signs, visual disturbances, and hearing loss were the most frequent manifestations. Brain magnetic resonance imaging showed callosal lesions in all patients. Most were in remission within two years. Only four patients met the proposed criteria for definite SS. When SS is suspected, a detailed diagnostic workup should be performed and repeated over time to identify the clinical manifestations that will lead to a definite diagnosis.

Susac Syndrome Following COVID-19 Vaccination: A Case Report

Due to the COVID-19 pandemic, numerous vaccines have been developed for the disease. However, with large-scale vaccination has come the gradual emergence of immunological phenomena caused by these new vaccines. Herein, we report a 48-year-old female with a sudden onset of inferior visual field defects in the left eye following her first dose of the ChAdOx1 vaccine. Dilated fundus examination combined with optical coherence tomography and fluorescein angiography confirmed the diagnosis of branch retinal artery occlusion. Within 4 weeks following vaccination, symptoms associated with hearing impairment developed, and magnetic resonance imaging revealed leptomeningeal enhancement. The diagnosis of Susac syndrome (SS) was confirmed. The development of SS may be caused by endotheliopathy resulting from the molecular mimicry of the ChAdOx1 vaccine. Clinicians should be aware of the symptoms of SS, which may develop after COVID-19 vaccination. Further experimental surveillance and case–control studies are required to confirm this relationship.

WIDEFIELD FLUORESCEIN ANGIOGRAPHY IN THE DIAGNOSIS OF SUSAC SYNDROME

PURPOSE

To present the clinical manifestations and results of key diagnostic investigations in patients with Susac syndrome, with special emphasis on the principal role of fluorescein angiography (FA) of the peripheral retina.

METHODS

A retrospective analysis of medical records (collected 2000-2019) of 20 patients (15 women and five men), aged 20 to 51 years (mean age: 31.6 years) with complete or incomplete Susac syndrome diagnosed by an ophthalmic examination and widefield fluorescein angiography (WF-FA) by Spectralis and Optos Tx200.

RESULTS

Fluorescein angiography abnormalities included vascular changes in the posterior pole in 64.7% and in the peripheral retina in 82.4%. Widefield FA abnormalities in the peripheral retina alone were seen in 35.3% and in the posterior pole, but without peripheral vascular involvement, in 17.6%. Secondary leakage from veins was noted in 58.8%.

CONCLUSION

Widefield FA of the peripheral retina has a key role in cases of suspected Susac syndrome as it confirms the diagnosis and assesses disease activity. In addition to the characteristic findings, late-phase FA revealed leakage from veins which is not a typical sign. Patients experiencing migraine headaches may benefit from increasing awareness of neurologists and otologists who more promptly referred patients with suspected Susac syndrome for ophthalmologic evaluation and WF-FA of the peripheral retina.

[Update on Susac syndrome]

Susac syndrome is a rare disease affecting mainly young women, characterized by a microangiopathy limited to the cerebral, retinal, and cochlear vessels. Although the pathophysiology of Susac syndrome is not yet fully elucidated, recent advances favour a primitive vasculitis affecting the cerebral, retinal and cochlear small vessels. Susac syndrome must be recognized in the presence of the pathognomonic clinical triad associating: 1/subacute encephalopathy with unusual headache and pseudopsychiatric features associated with diffuse white matter, grey matter nuclei and specifically corpus callosum lesions on brain MRI; 2/eye involvement that may be pauci-symptomatic, with occlusions of the branches of the central artery of the retina at fundoscopy and arterial wall hyperfluorescence on fluorescein angiography; and 3/cochleo-vestibular damage with hearing loss predominating at low frequencies on the audiogram. Relapses are frequent during an active period lasting approximately 2 years. Eventually, the disease resolves but isolated retinal arterial wall hyperfluorescence without new occlusions may recur, which should not lead to treatment intensification. First-line treatment consists of a combination of anti-aggregants and high dose corticosteroids. In refractory patients or in case of relapse, immunomodulatory molecules such as intravenous immunoglobulins or immunosuppressive drugs such as mycophenolate mofetil, cyclophosphamide or rituximab should be started. Unfortunately, sequelae-mostly hearing loss- remain frequent in these young patients.

Scoping review of cochlear implantation in Susac's syndrome

Objective

Scoping review of published literature to establish clinical characteristics and audiologic outcomes in patients diagnosed with Susac’s Syndrome(SS) who have undergone cochlear implantation (CI).

Data sources

All published studies of CI in SS and contribution of two of our own patients who have not been reported previously.

Methods

A comprehensive search of MEDLINE (via PubMed) was carried out in March 2020 using the following keywords and related entry terms: Susac’s Syndrome, Cochlear Implantation.

Results

Our search identified a total of five case reports of CI in SS. With the addition of our two patients reported here, we analyzed characteristics and outcomes in seven patients. Mean age at implantation was 30 years old (range 19–46), with six women and one man implanted. Mean time from onset of hearing loss to implantation was 17 months (range three months to four years). Best reported postoperative speech understanding was reported via different metrics, with six of seven patients achieving open set speech scores of 90% or better, and one subject performing at 68%. Vestibular symptoms were present preoperatively in four of seven patients (57%), with vestibular testing reported in two patients, and showing vestibulopathy in one patient. No complications were reported following cochlear implantation.

Conclusion

Cochlear implantation is a viable option for hearing rehabilitation in patients with SS, with levels of attainment of open set speech comparable to other populations of CI candidates.

Neuro-ophthalmic manifestations of Susac syndrome

PURPOSE OF REVIEW

This review discusses general features and organ-specific presentations of Susac syndrome as well as diagnosis and treatment.

RECENT FINDINGS

Latest literature regarding demographics, new diagnostic modalities such as optical coherence tomography and treatment options for Susac syndrome are discussed in detail in this review, summarizing the most recent updated information.

SUMMARY

Susac syndrome is a rare, underdiagnosed, and often misdiagnosed disease that can lead to severe complications such as deafness, vision loss, dementia, and death. It involves the central nervous system and may mimic other neurological and neuro-ophthalmological diseases.

Increased incidence of Susac syndrome: a case series study

BACKGROUND

Susac syndrome (SuS) is a rare condition characterized by a clinical triad of sensorineural hearing loss, branch artery occlusion and encephalopathy. This study reports an increased incidence of SuS in Israel. We describe the clinical characteristics of these patients, diagnostic procedures and the use and subsequent outcomes of newly published treatment guidelines.

METHODS

This is a single center retrospective study. Patients who were diagnosed with SuS between July 2017 and August 2018 were enrolled in this study.

RESULTS

Seven patients were diagnosed with SuS according to the diagnostic criteria in a time period of 13 months. The annual incidence was recently evaluated in Austria to be 0.024/100000, therefore, our case series represent at least a 5.4- fold increase in the annual incidence of SuS expected in Israel and a 7-fold increase in the annual incidence expected in our medical center. Mean time from the onset of the symptoms to diagnosis was three weeks and follow-up time was twenty four months. Recent exposure to cytomegalovirus was serologically evident in three patients and one patient had high titer of anti-streptolysin antibody. All patients underwent brain MRI, fluorescein angiography and audiometry. All patients were treated according to the newly recommended guidelines. All patients achieved clinical and radiological stability.

CONCLUSIONS

We report of an increased incidence of SuS in Israel. Infectious serological findings may imply a post infectious mechanism. The use of the recommended diagnostic procedures reduced the time to diagnosis. Newly published treatment guidelines led to favorable clinical outcomes.

Retinal vasculitis: A framework and proposal for a classification system

Retinal vasculitis, a poorly understood process involving inflammation or ischemia of the retinal vessel wall, may occur in association with a systemic process, although it can also be isolated to the retina. Because of the limited ability to perform histopathological studies on retinal vessels, there is no gold standard for diagnosis. Thus, there is utility in creating a classification system for retinal vasculitis and improving diagnostic strategies for this disease. We provide a framework for understanding retinal vasculitis based on size, location, and etiology. We hope that this information can be implemented in the clinical setting to provide some diagnostic strategies for this often confusing entity.