Short Follow-up Bias Confounds Estimates of the “Typical” Clinical Course of Susac Syndrome

Clinical characteristics and treatment approaches in patients with Susac syndrome: a scoping review of cases

BACKGROUND

Susac syndrome (SuS) is a rare disease characterized by encephalopathy, hearing impairment and visual disturbances. Immunosuppressive treatments are used based on the hypothesis that an autoimmune endotheliopathy drives the disease. However, a solid evidence-based treatment approach is lacking. The aim of this review is to provide an overview of patient characteristics, disease course and treatment patterns related to successful outcome that have been reported in literature since 2013.

METHODS

Three reviewers conducted a systematic literature search in February 2022. The primary outcome was treatment used, derived from cases classified as probable or definite SuS, describing successful treatment outcome (i.e. no signs of disease activity for ≥ 1 month). Secondary outcomes were time-to-relapse and follow-up time. Published case reports and case series were included. Various clinical characteristics and treatment(s) were extracted and categorized into different phases of treatment.

RESULTS

A total of 810 records was identified. 120 articles met inclusion criteria and 161 cases were extracted. Of these, 151 cases were classified as probable or definite SuS and included in the final analysis. Number of combinations of treatments used per treatment phase were: 6 empirically, 35 after confirmed diagnosis, 43 for maintenance treatment, 22 after relapse, 18 during maintenance post-relapse. Median follow-up time was 12.3 months (0.5; 120) and median time to relapse was 4 months (1; 120).

CONCLUSION

This scoping review summarizes treatment approaches in patients with SuS, highlighting variability. International efforts to collect clinical, imaging and treatment data from patients with SuS in registries are needed, in order to provide less biased and long-term follow-up information on treatment response, predictors of relapse and patient outcomes. This may lead to more evidence-based therapeutic approaches.

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.

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.

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.

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.

Acute Susac Syndrome in a Recent User of Adulterated Cocaine: Levamisole as a Triggering Factor?

Susac syndrome (SS) is a central nervous system vasculitis characterized by the clinical triad of encephalopathy, sensorineural hearing loss, and visual disturbance caused by branch retinal artery occlusion. It is considered as an inflammatory disorder, and an autoimmune etiology is suggested. A 29-year-old man with a history of recent cocaine abuse developed the clinical features of SS. Toxicological analysis including hair testing revealed that cocaine had been adulterated with levamisole. After an initial clinical improvement following corticosteroid therapy, the introduction of mycophenolate mofetil was justified a few weeks later by the progression (or relapse) of the retinal injury, followed by complete recovery. The presence of levamisole has been documented in patients with multifocal inflammatory leukoencephalopathy (MIL). Further investigations are needed to determine if levamisole as an adulterant of cocaine could also play a role in the development of rapidly progressive leukoencephalopathy in young men, with Susac or Susac-like syndromes as possible variants of MIL.

Progressive sensorineural hearing loss many years preceding completion of Susac's syndrome triad: A case report

Susac's syndrome (SuS) is a rare disorder with a clinical triad of encephalopathy, sensorineural hearing loss, and branch retinal artery occlusions. We report a 7-year-old girl who presented with chronic, progressive sensorineural hearing loss, who, years later, presented with encephalopathy and vision loss. Such prolonged period between symptoms is unusual and to our knowledge, this is the longest interval between onset of hearing loss and completion of the full triad in SuS. In addition, she had a protracted disease course, requiring multiple immune therapies for disease control.