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

Clinical Characterization and Prognostic Risk Factors of Susac Syndrome: A Retrospective Multicenter Study

BACKGROUND AND OBJECTIVES

Susac syndrome (SuS) is a rare disorder characterized by encephalopathy, branch retinal artery occlusion, and sensorineural hearing loss, often accompanied by vertigo. Recent updates to diagnostic criteria and treatment guidelines have been made. This study examines clinical manifestations; disease activity; and risk factors of disability, dependency, and return to work in patients with SuS.

METHODS

A retrospective multicenter study was conducted on 20 consecutive patients with SuS with at least 2 years of follow-up. Clinical and paraclinical activities were assessed and rated according to the severity at onset and the end of follow-up. Cognitive function was assessed using the Montreal Cognitive Assessment while disability and dependence in daily activities were measured using the modified Rankin Scale. Employment status was graded.

RESULTS

The mean age at onset was 38.9 years, with a mean follow-up of 55.9 months. The female-to-male ratio was 1.86, and 45% of patients had the complete clinical triad. Severe cerebral involvement at onset was associated with a higher risk of cerebral exacerbations within the first year and with an increased long-term disability and dependency. Cognitive function improved in 75% of patients during follow-up. At disease onset, hearing loss excluding low frequencies occurred in 46.7%. Relapse of hearing loss was associated with greater impairment in daily activities. Male sex and elevated CSF protein levels were linked to poorer prognosis. Cerebral and inner ear exacerbations were most common in the first year while retinal exacerbations occurred more frequently, mainly within the first 2 years. Approximately 50% of patients resumed employment while 25% did not return to work.

DISCUSSION

Current treatment strategies for SuS do not fully prevent relapses. Severe brain manifestation at onset, male sex, and high CSF protein levels are risk factors of a worse prognosis of disability and dependence, indicating the need for intensive treatment. High-frequency hearing loss does not exclude SuS diagnosis.

Immunosuppressive agents or intravenous immunoglobulin in addition to glucocorticoids in the treatment of Susac syndrome: a French national cohort study

BACKGROUND

Susac syndrome is a rare disease affecting mainly young women and is characterised by an occlusive microvessel disease limited to the brain, retina, and inner ear. No randomised controlled trial has been published or declared as ongoing to investigate treatments for Susac syndrome. We aimed to compare the effect of glucocorticoids given alone or in combination with immunosuppressive agents or intravenous immunoglobulin for the prevention of relapse in patients with Susac syndrome.

METHODS

The Phenotypic and Etiological Characterization of Susac Syndrome-National Clinical Research Hospital Program study is a prospective national cohort study that started enrolling on Nov 29, 2011, and included all consecutive patients aged 18 years or older with Susac syndrome who were referred to the French reference centre (Department of Internal Medicine, Bichat-Claude Bernard Hospital, Paris). Susac syndrome was defined by either the triad of encephalopathy with typical brain MRI abnormalities, cochleo-vestibular damage, and multiple occlusions of retinal central artery branches, or at least two of the three criteria without any alternative diagnosis. Collected data included fundoscopy, retinal angiography, audiometry, cerebrospinal fluid, brain MRI, and treatment received at diagnosis; months 1, 3, 6, and 12 after diagnosis; and then annually for 5 years or in the case of a relapse. The primary outcome was defined as the first relapse occurring within a 36-month follow-up period from the first day of treatment, characterised by new clinical symptoms or signs, and new abnormalities observed on retinal angiography, audiometry, or brain MRI, necessitating treatment intensification. There was no involvement of people with lived experience at any stage. The study is registered at ClinicalTrials.gov, NCT01481662.

FINDINGS

Between Nov 29, 2011, and Dec 2, 2022, 64 patients were included in the study, with a mean age at diagnosis of 35 years (SD 11); 41 (64%) were women and 23 (36%) were men. At diagnosis, 60 patients received glucocorticoids; 40 (63%) of 64 patients received glucocorticoids alone as a first-line therapy while 20 (31%) received glucocorticoids in combination with immunosuppressive agents or intravenous immunoglobulin. Overall, 46 (72%) of 64 patients had a first relapse with a median relapse-free survival time of 3·96 months (95% CI 2·24-16·07). Comparison of relapse-free survival showed no significant difference between the two treatment strategies (hazard ratio [HR] 1·11 [95% CI 0·56-2·17], p=0·76), compared with glucocorticoids alone as the reference group. In patients who first relapsed while treated with glucocorticoids alone, there was no significant difference in second relapse-free survival between those who did or did not receive immunosuppressive agents or intravenous immunoglobulin as a second-line therapy (HR 2·66 [95% CI 0·63-11·18], p=0·18).

INTERPRETATION

The combination of glucocorticoids with immunosuppressive agents or intravenous immunoglobulin did not appear to reduce the risk of Susac syndrome relapse compared with glucocorticoids alone. Our findings did not support the systematic use of immunosuppressive agents in Susac syndrome.

FUNDING

French Ministry of Health.

Brain microstructural damage through serial diffusion tensor imaging and outcomes in Susac syndrome: A prospective cohort study

BACKGROUND

Susac syndrome (SuS) is a rare immune-mediated microangiopathy with potential disabling evolution. We aimed to analyze brain microstructural damage through diffusion tensor imaging (DTI) in SuS and determine its association with poor outcomes.

METHOD

CarESS study is a prospective multicenter national cohort study of patients with SuS. Patients included at the principal investigator's center with at least two available brain magnetic resonance imaging (MRI) with DTI were analyzed. Mean diffusivity (MD) and fractional anisotropy (FA) were measured in fibers crossing three regions of interest (ROIs): the corpus callosum as a whole, the genu of the corpus callosum, and the splenium of the corpus callosum. The primary outcome was work resumption.

RESULTS

Twenty-two patients (36 (25;42) years, 16 (73%) females) were studied. The triad (i.e., brain, eye, and ear involvement) was complete in 21 (95%) patients. All but one patients received steroids alone or in combination with immunosuppressive drugs (n = 11) and/or IVIg (n = 7). Over a median follow-up of 6 (5;8) years, 15 (68%) patients went back to work. FA and MD were longitudinally measured in 123 DTI MRI accounting for a median of 5.6 [4.2; 7] MRI per patient. Microstructural damages in the corpus callosum as a whole, the genu of the corpus callosum, and the splenium of the corpus callosum increased during follow-up and were significantly associated with the inability to return to work.

CONCLUSION

Brain DTI identified microstructural damage in fibers crossing the corpus callosum that are associated with long-term disability in SuS.

TRIAL REGISTRATION

ClinicalTrials.gov portal identifier: NCT01481662 (https://clinicaltrials.gov/ct2/show/NCT01481662?term=caress&draw=2&rank=5).

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.

Risk factors for severe hearing loss in Susac syndrome: A national cohort study

BACKGROUND

Nonreversible hearing loss (HL) is the main sequelae of Susac syndrome (SuS). We aimed to identify risk factors for HL in SuS.

METHODS

The CARESS study is a prospective national cohort study that started in December 2011, including all consecutive patients with SuS referred to the French reference center. The CARESS study was designed with a follow-up including fundoscopy, audiometry, and brain magnetic resonance imaging at 1, 3, 6, and 12 months after diagnosis and then annually for 5 years. The primary outcome was the occurrence at last follow-up of severe HL defined as the loss of 70 dB in at least one ear on audiometry or the need for hearing aids.

RESULTS

Thirty-six patients (female 66.7%, median age 37.5 [range 24.5-42.5] years) included in the clinical study were analyzed for the primary outcome. Thirty-three patients (91.7%) had cochleovestibular involvement at SuS diagnosis including HL >20 dB in at least one ear in 25 cases. At diagnosis, 32 (88.9%), 11 (30.6%), and 7 (19.4%) patients had received steroids, intravenous immunoglobulin, and/or immunosuppressive (IS) drugs, respectively. After a median follow-up of 51.8 [range 29.2-77.6] months, 19 patients (52.8%) experienced severe HL that occurred a median of 13 [range 1.5-29.5] months after diagnosis. Multivariable analysis showed that the odds of severe HL were lower in patients who received IS drugs at diagnosis (OR 0.15, 95% CI 0.01-1.07, p = 0.058).

CONCLUSIONS

Severe HL in SuS is associated with the absence of IS drugs given at diagnosis. Our findings support the systematic use of IS drugs in SuS.