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Abstract This study examined the roles of microglia and monocytes in myelin destruction in patients with early multiple sclerosis (MS). Twenty-two cases were studied; the clinical duration was <9 weeks in 10 cases. Twenty myeloid cell subtypes or categories were identified including 2 cell types not known previously to occur in demyelinating diseases. Commencing myelin breakdown in plaques and in perivascular and subpial tissues occurred in the immediate presence of infiltrating monocytes and was effected by a homogeneous population of IgG-positive Fc receptor-bearing early phagocytes interacting with abnormal myelin. Oligodendrocyte apoptosis was observed in intact myelinated tissue bordering areas of active demyelination. Capillaries in the cerebral cortex plugged by large numbers of monocytes were common in acute cases of MS and in a patient with a neuromyelitis optica variant and extreme systemic recruitment of monocytes. In an MS patient with progressive disease, microglial nodules centered on MHC-II-positive capillaries plugged by monocytes were present in the cerebral cortex. This constitutes a new gray matter lesion in MS.

Background: A serum antibody directed against astrocytes is present in a high proportion of patients with neuromyelitis optica (NMO). The pathogenicity of the antibody is uncertain because no consistent astrocyte lesion is known to occur in NMO. Objective: To determine whether there is an astrocyte lesion in NMO and if this differs from astrocyte changes in multiple sclerosis (MS). Methods: Astrocyte pathology in early (still-myelinated) lesions and subacute NMO and MS lesions was examined immunohistochemically and in sections stained for astrocytes using routine histological techniques. Results: Demyelination in early NMO lesions is accompanied by oligodendrocyte apoptosis in a pattern identical to that seen in MS and this is preceded by an abrupt destruction of perivascular astrocytes. Reparative astrogliosis is effected by a population of unipolar, new astrocytes. Evidence of a different type of astrocyte lesion was found in MS. Discussion: The findings add to experimental evidence that the antibody is pathogenic. They also raise the possibility that demyelination in MS may be a bystander effect of an astrocyte lesion, i.e. that MS is not a disease primarily of myelin and oligodendrocytes.

Susac’s syndrome is a rare and debilitating disease characterized by the triad of encephalopathy, branch retinal artery occlusions, and sensorineural hearing loss. All manifestations may not be clinically apparent at presentation resulting in delayed diagnosis. Early recognition of the syndrome may prevent disease sequelae such as permanent cognitive, visual, and hearing loss. We present such a case of Susac’s syndrome that was also refractory to conventionally prescribed combination of immunosuppressive treatments including high-dose potent corticosteroids, intravenous cyclophosphamide, methotrexate, plasma exchange, rituximab, and mycophenolate. His disease was stabilized with infliximab in combination with a tapering course of low-dose prednisone. After 2 years of remission with TNF treatment, consideration is being given to ceasing therapy. He has the sequelae of bilateral sensorineural hearing loss but no visual impairment or cognitive deficits on follow-up with neuropsychometric testing. This is the first case report to our knowledge of the successful use of infliximab for a patient with Susac’s syndrome that was necessary following treatment with cyclophosphamide and then rituximab.

Objective We characterised the clinical and neuro-otological characteristics of patients with Susac syndrome. Methods The medical records of 30 patients with Susac syndrome were reviewed for details of their clinical presentation and course, neuro-otological symptoms, investigation results including audiology and vestibular function tests, treatment and outcomes. Results Our findings demonstrate that 29 of our 30 patients with Susac syndrome developed neuro-otological symptoms such as hearing loss, disequilibrium, tinnitus or vertigo during their disease course. Hearing loss was the most common neuro-otological symptom occurring in 93% of patients. A rising configuration of low-frequency greater than the high-frequency sensorineural hearing loss was the most characteristic finding on audiological testing (37% of reviewed audiograms). Disproportionately poor speech discrimination was identified in 20% of cases, and one case demonstrated a retrocochlear pattern on electrophysiological testing. Four patients required hearing aids and a further two patients required a cochlear implant due to severe hearing loss. Two out of two treated patients had improvements in hearing after the prompt administration of corticosteroids, indicating the potential for recoverable hearing loss if relapses are treated early. Effects on vestibular function were variable in ten patients who were tested, with most showing preservation of function despite significant hearing loss. Conclusions Neuro-otological symptoms in Susac syndrome are almost universal. In the correct clinical context, a rising configuration of low to high-frequency sensorineural hearing loss should prompt consideration of Susac syndrome. Treatment of inner ear symptoms in Susac syndrome requires further research as early immunotherapy may be beneficial.

Neuroinflammation is often associated with blood-brain-barrier dysfunction, which contributes to neurological tissue damage. Here, we reveal the pathophysiology of Susac syndrome (SuS), an enigmatic neuroinflammatory disease with central nervous system (CNS) endotheliopathy. By investigating immune cells from the blood, cerebrospinal fluid, and CNS of SuS patients, we demonstrate oligoclonal expansion of terminally differentiated activated cytotoxic CD8 + T cells (CTLs). Neuropathological data derived from both SuS patients and a newly-developed transgenic mouse model recapitulating the disease indicate that CTLs adhere to CNS microvessels in distinct areas and polarize granzyme B, which most likely results in the observed endothelial cell injury and microhemorrhages. Blocking T-cell adhesion by anti-α4 integrin-intervention ameliorates the disease in the preclinical model. Similarly, disease severity decreases in four SuS patients treated with natalizumab along with other therapy. Our study identifies CD8 + T-cell-mediated endotheliopathy as a key disease mechanism in SuS and highlights therapeutic opportunities. Susac syndrome is an inflammatory pathology of the brain endothelium. Here the authors show that the pathology is driven by CD8 T cells attacking the endothelium, and that blocking T cell-endothelial adhesion ameliorates the disease in a mouse model, and associates with improved clinical score in 4 patients.

Objectives Recent studies suggested that the expansion of long‐standing multiple sclerosis (MS) lesions and an enlargement of choroid plexus may be linked to chronic inflammation and microglial activation. We investigated the potential association between plexus volume and subsequent lesion expansion in patients with relapsing‐remitting MS. Methods Pre‐ and post‐gadolinium 3D‐T1, 3D FLAIR and diffusion tensor images were acquired from 49 patients. Choroid plexus (CP) volume (normalised by Total Intracranial Volume, TIV) and lesion activity were analysed between baseline and 48 months. In addition, plexus volume was measured in 40 healthy controls of similar age and gender. Results Baseline CP/TIV ratio was significantly larger in RRMS patients compared to normal controls (p < 0.001). CP/TIV ratio remained stable in RRMS patients during follow‐up period. There was a strong correlation between baseline CP/TIV ratio and subsequent rate of chronic lesion expansion (p < 0.001), which was stronger in close proximity to CSF. A cut‐off of 98 × 10−5 CP/TIV ratio predicted future lesion expansion with a sensitivity of 85% and specificity of 76%. CP/TIV ratio larger than a cut‐off was associated with >8‐fold increased risk of chronic lesion expansion. Baseline CP/TIV ratio was also associated with change in Mean Diffusivity (MD) inside of chronic lesions. Furthermore, baseline CP/TIV ratio significantly correlated with central brain atrophy. There was, however, no correlation between CP/TIV ratio and volume of new lesions. Interpretation Our data demonstrate that baseline CP/TIV ratio predicts subsequent expansion of chronic periventricular MS lesions and associated tissue damage within and outside of chronic lesions.

ObjectivesWe have undertaken a clinic-based survey of neuromyelitis optica spectrum disorders (NMOSDs) in Australia and New Zealand to establish incidence and prevalence across the region and in populations of differing ancestry.BackgroundNMOSD is a recently defined demyelinating disease of the central nervous system (CNS). The incidence and prevalence of NMOSD in Australia and New Zealand has not been established.MethodsCentres managing patients with demyelinating disease of the CNS across Australia and New Zealand reported patients with clinical and laboratory features that were suspicious for NMOSD. Testing for aquaporin 4 antibodies was undertaken in all suspected cases. From this group, cases were identified who fulfilled the 2015 Wingerchuk diagnostic criteria for NMOSD. A capture–recapture methodology was used to estimate incidence and prevalence, based on additional laboratory identified cases.ResultsNMOSD was confirmed in 81/170 (48%) cases referred. Capture–recapture analysis gave an adjusted incidence estimate of 0.37 (95% CI 0.35 to 0.39) per million per year and a prevalence estimate for NMOSD of 0.70 (95% CI 0.61 to 0.78) per 100 000. NMOSD was three times more common in the Asian population (1.57 (95% CI 1.15 to 1.98) per 100 000) compared with the remainder of the population (0.57 (95% CI 0.50 to 0.65) per 100 000). The latitudinal gradient evident in multiple sclerosis was not seen in NMOSD.ConclusionsNMOSD incidence and prevalence in Australia and New Zealand are comparable with figures from other populations of largely European ancestry. We found NMOSD to be more common in the population with Asian ancestry.

Unilateral relapsing primary central nervous system vasculitis (UR-PCNSV) is a scarcely reported subtype of PCNSV. It is characterised by frequent relapses with lesions confined to a single hemisphere. Herein, we expand the phenotype of UR-PCNSV, adding three cases to the existing 13 in the literature. A retrospective review of clinic databases at two adult tertiary referral centres in New South Wales, Australia, was undertaken to identify cases of UR-PCNSV. Predefined inclusion criteria were (1) biopsy-proven PCNSV, (2) lesions confined to a single hemisphere, and (3) two or more relapses as evidenced by new enhancing lesions on MRI. Three cases of biopsy-proven UR-PCNSV were identified. All demonstrated three or more relapses with new lesions confined to the same hemisphere. The mean age was 34.5 (± 8.6) years, and the median delay to diagnosis was 12 months (IQR 7.5-21). Headache was the first symptom in all patients, and they developed unilateral motor and sensory deficits. Cognitive impairment was a prominent feature in one and none developed seizures. CT and/or MR angiography showed normal results. MRI head showed both subcortical and cortical lesions with parenchymal and leptomeningeal enhancement. The protein level was normal in all patients, and one had a mildly raised white cell count (9 × 10 /L). Biopsy in all three demonstrated a T-cell predominant perivascular lymphocytic infiltrate with areas of transmural inflammation and infarct-like necrosis. Despite treatment with anti-CD20 monoclonal antibodies, relapses occurred after steroid withdrawal in all. Prolonged steroid with additional immunosuppression was required to maintain remission. All patients demonstrated hemiatrophy within 12 months of presentation. Compared with typical PCNSV, this rare unilateral, relapsing subtype has a younger age of onset, lower prevalence of angiographic abnormalities, and frequent relapses. Our patients had persisting lesion enhancement despite anti-CD20 mAb monotherapy and demonstrated hemiatrophy within the first year, indicating high inflammatory activity and a requirement for additional immunosuppression. This case series additionally highlights the overlapping clinical and radiological features of PCNSV and CNS demyelination, which may contribute to diagnostic delay.

BackgroundB-cell depleting monoclonal antibodies are highly effective treatment for multiple sclerosis (MS) but have rarely been associated with seronegative arthritis. We report the findings in four cases of seronegative arthritis occurring in this context.MethodsPatients were identified from the Royal North Shore Hospital MS database and clinical and radiological data aggregated through review of the medical records.ResultsThree female and one male patient were identified. The mean age was 49.5 years (SD 12) and MS disease duration, 17 years (SD 18). Two female patients had a prior diagnosis of mild to moderate psoriasis, one of whom had previously received treatment for psoriatic arthritis but was in remission. Two patients were treated with ocrelizumab and two with ofatumumumab. The median time to joint symptoms was 3.5 months (Range 1 to 12). All patients experienced increasing axial and limb joint pain, with two patients suffering disfigurement of joints. Three patients discontinued the anti-CD 20 and started an interleukin- 17a inhibitor which was effective for arthritis. One patient remained on ocrelizumab with Sulphasalazine added for arthritis. All 4 patients showed no evidence of disease activity (NEDA) over the ensuing 2-year follow-up.ConclusionIt is important to consider a history of psoriasis and seronegative spondyloarthritis prior to commencing B-cell depleting monoclonal antibodies in patients with multiple sclerosis, and to monitor for this rare complication. More data is required to determine optimal treatment strategies, particularly interleukin-17A inhibitors given their safety, and potential benefit, in MS.