The neuro-otology of Susac syndrome

Phenotyping vestibulocochlear manifestations in Susac syndrome: a cohort study

PURPOSE

To characterize vestibulocochlear involvement in patients with Susac syndrome (SuS), a rare immune-mediated endotheliopathy of cerebral, retinal and inner ear microvasculature causing a triad of encephalopathy, branch retinal artery occlusions and sensorineural hearing loss.

METHODS

The electronic patient files of 21 patients with SuS are reviewed for data on demography, clinical presentation, disease course and audiovestibular testing.

RESULTS

All 21 patients experienced some form of audiovestibular complaints during the disease course, with vertigo and instability being most frequently reported, followed by hearing loss, tinnitus and aural fullness. These audiovestibular symptoms did not always coincide. Fifteen patients had objectified predominant low- to midfrequency sensorineural hearing loss and 8 out of 18 patients showed abnormalities on vestibular testing, most frequently vestibular evoked myogenic potential-abnormalities, indicating otolith dysfunction. Treatment protocols consisted of uniformly extensive immunosuppressive therapy and hearing loss remained mostly mild.

CONCLUSION

Audiovestibular involvement is very common in patients with SuS. Characteristic findings include a "reverse-slope" configuration on audiological testing and otolith dysfunction on vestibular testing. Aggressive immunosuppression may prevent severe audiovestibular dysfunction. Symptoms as aural fullness and otolith dysfunction may indicate an underlying hydrops. Further investigations are necessary to elucidate the histopathological mechanisms underlying these preferentially involved cochleovestibular areas. Early recognition and treatment of SuS are important to stabilize or decrease disease activity and might also have beneficial effects on inner ear outcome. THE SUBMITTED MANUSCRIPT REPORTS DATA DERIVED FROM CLINICAL OBSERVATIONS IN HUMANS: Consent for the research was provided by the Ethics Committee of Ghent University hospital (application number 2019/1443, registration date 31/12/2021, principal investigator Guy Laureys).

Fatal Presentation of Susac Syndrome in a Congenitally Deaf Patient With a Cochlear Implant

OBJECTIVE

To report a fatal case of Susac syndrome in a congenitally deaf patient with a cochlear implant and a history of migraines, emphasizing the diagnostic challenges in patients with preexisting conditions.

PATIENT

A 33-year-old male with congenital hearing loss, a cochlear implant, and chronic migraines who presented with mild subacute auditory disturbance and headaches that later progressed to severe encephalopathy.

INTERVENTION

Explantation of a non-magnetic resonance imaging (MRI) compatible cochlear implant followed by MRI, fundoscopy, and the administration of immunosuppressive medications.

MAIN OUTCOME MEASURES

Diagnosis was confirmed by characteristic MRI appearance and the presence of a hemi-retinal artery occlusion.

RESULTS

After weeks of immunosuppressive treatment, the patient died of a global cerebral ischemic event of unknown origin.

CONCLUSIONS

For patients with preexisting sensorineural hearing loss and cochlear implants, Susac syndrome poses a diagnostic challenge. Auditory disturbances in the absence of cochlear implant failure should prompt further evaluation for visual disturbances and encephalopathy. MRI and fundoscopy should be performed to detect other features of the disease.

Clinical Characterization and Ancillary Tests in Susac Syndrome: A Systematic Review

Susac syndrome (SuS) is an orphan microangiopathic disease characterized by a triad of encephalopathy, visual disturbances due to branch retinal artery occlusions, and sensorineuronal hearing loss. Our previous systematic review on all cases of SuS reported until 2012 allowed for a better understanding of clinical presentation and diagnostic findings. Based on these data, we suggested diagnostic criteria in 2016 to allow early diagnosis and treatment of SuS. In view of the accumulation of new SuS cases reported in the last 10 years and improved diagnostic tools, we here aimed at updating the demographic and clinical features of SuS and to review the updated ancillary tests being used for SuS diagnosis. Therefore, based on the 2016 criteria, we systematically collected and evaluated data on SuS published from January 2013 to March 2022.

Diffuse Cerebral Edema With Uncal Herniation Leading to Brain Death in Patient With Fulminant Susac syndrome: Rare Complication of Rare Disease

Susac Syndrome was first described as an inflammatory microangiopathy of the brain and retina. Since then, multiple articles have been published in attempts to improve the understanding of this rare disease. Clinically Susac Syndrome is known to present with triad of encephalopathy, sensorineural hearing loss and branch of retinal artery occlusion (BRAO), along with characteristic "snowball" or "spoke" appearing white matter lesions of the corpus callosum. It has been characterized by vast heterogeneity in terms of its presenting symptoms, severity, and clinical course. Although subset of patients present with severe forms of Susac Syndrome and can develop prominent residual neurologic deficits, it has been reported to be mostly non-life-threatening and only few fatal cases have been described in the literature. Based on the available case reports with fatal outcome, mortality has been related to the systemic complications either during acute disease flare or during chronic-progressive phase. We describe a case of fulminant Susac Syndrome complicated by the sudden and rapid progression of diffuse cerebral edema leading to brain herniation and ultimate brain death, in order to increase awareness of this rare and catastrophic complication.

Susac syndrome: neurological update (clinical features, long-term observational follow-up and management of sixteen patients)

Susac syndrome is a likely autoimmune microangiopathy affecting the brain, retina and inner ear. Due to the rarity of this condition, diagnosis and treatment can be challenging. Diagnosis is based on the presence of the clinical triad of central nervous system dysfunction, branch retinal artery occlusions and sensorineural hearing loss. Typical MRI findings of callosal and peri-callosal lesions may assist in diagnosis. Clinical course can be monophasic, polycyclic or chronic continuous. It is important to look out for red flags to attain an accurate diagnosis and follow a therapeutic algorithm based on severity of the disease and response to treatment. Patients are treated with steroids and immunosuppressive agents with a variable response. Early aggressive treatment especially in severe cases, may help in preventing relapses and morbidity/disability. This study highlights important diagnostic features and proposes a treatment algorithm based on clinical experience from management of 16 patients from 2 neuroscience centres in the UK since 2007, who were followed up over a long period of 3-15 years.

Behavioral Impairment and Amnesia at the Onset of Susac Syndrome

Susac syndrome (SS) is an autoimmune microangiopathy that affects the brain, retina, and inner ear, causing a wide range of clinical manifestations. The triad of encephalopathy, visual disturbances, and hearing loss constitute the classic disease presentation. We describe an original clinical case of a young male with a definitive diagnosis of SS, who presented with disordered behavior and amnesia, initially manifested as a dissociative or anxiety disorder but with a fulminant evolution toward severe encephalopathy associated with retinal infarcts and sensorineural hearing loss. After the diagnosis of SS, aggressive immunosuppressive treatment was started with significant neurological improvement and favorable evolution during the follow-up period. SS is a rare but potentially devastating disease that can cause great disability if not properly diagnosed and treated. The onset of SS with behavioral or psychiatric manifestation can be misleading, causing a diagnostic delay.

Cervical and Ocular Vestibular Evoked Myogenic Potential Recovery in Susac Syndrome: A Case Report

Purpose:

Susac syndrome (SS) is a rare autoimmune disorder that affects the brain and the retina and causes unilateral or bilateral sensorineural hearing loss. Although vestibular dysfunction is reported in SS, limited information is available underlying the vestibular pathophysiology.

Method:

The diagnosis of SS was established based on symptoms and diagnostic tools such as magnetic resonance imaging and fundus fluorescein angiography. The audiovestibular evaluation was done on the seventh day of admission (Session 1) into the emergency unit, whereas the second and third evaluations were done at 3-month (Session 2) and 8-month (Session 3) follow-ups after discharge, respectively. The audiovestibular test battery consisted of routine audiological tests, auditory brainstem response, and vestibular evoked myogenic potentials (VEMPs; both cervical and ocular).

Results:

We found unilateral sensorineural hearing loss and absent cervical VEMPs(cVEMPs) when testing the left ear during Session 1. In the following sessions, the unilateral hearing loss did not recover; however, cVEMPs were present bilaterally. The ocular VEMPs showed an increase in amplitude during Sessions 2 and 3.

Conclusions:

SS can selectively disrupt auditory and vestibular structures. It may present with unique findings of audiovestibular tests. A detailed audiovestibular evaluation may be essential in patients with SS.

Supplemental Material:

https://doi.org/10.23641/asha.21513843

Susac Syndrome: A Case Series

BACKGROUND

Susac syndrome (SS) is an autoimmune disorder that involves the eyes, the brain, and the ears. It is a rare cause of recurrent branch retinal artery occlusion. The purpose of this study was to report cases of SS, highlighting the clinical presentations, therapeutic options, and their outcome.

PATIENTS AND METHODS

Retrospective case series of patients seen at our institution for SS between 2005 and 2020. Demographics, clinical characteristics, treatment, and outcome were studied.

RESULTS

Four patients (3 females, mean age 29 years old) were included in the study. According to the recently revised diagnostic criteria, three patients had definite and one patient had probable SS (distinctive ophthalmological and brain involvement without ear involvement). Initial visual acuity (VA) was normal in all eyes, but two patients had unilateral visual field impairment. Gass plaques (defined as yellow-white plaques found in the arteriolar wall away from arterial bifurcations) were observed on fundus examination in all patients. Fluorescein angiography revealed arteriolar wall hyperfluorescence and branch retinal arterial occlusions (BRAOs) in the absence of other signs of intraocular inflammation in all patients. Initial treatment consisted of a high-dose corticosteroid (intravenous or oral) with additional immunosuppressive therapy (azathioprine, intravenous immunoglobulins, mycophenolate mofetil, and/or cyclophosphamide). Residual symptoms were present in all patients and included scotoma (n = 2) and hearing loss (n = 3).

CONCLUSION

SS is a rare disease with characteristic ophthalmological manifestation. The majority of patients present a crude form of the triad, and retinal findings may be the first initial manifestation. Ophthalmologists should consider the possibility of an SS in all young patients presenting with BRAOs.

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.

[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.

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.