Multifrequency magnetic resonance elastography of the brain reveals tissue degeneration in neuromyelitis optica spectrum disorder.

OBJECTIVES: Application of multifrequency magnetic resonance elastography (MMRE) of the brain parenchyma in patients with neuromyelitis optica spectrum disorder (NMOSD) compared to age matched healthy controls (HC). METHODS: 15 NMOSD patients and 17 age- and gender-matched HC were examined using MMRE. Two three-dimensional viscoelastic parameter maps, the magnitude |G*| and phase angle φ of the complex shear modulus were reconstructed by simultaneous inversion of full wave-field data in 1.9-mm isotropic resolution at 7 harmonic drive frequencies from 30 to 60 Hz. RESULTS: In NMOSD patients, a significant reduction of |G*| was observed within the white matter fraction (p = 0.017), predominantly within the thalamic regions (p = 0.003), compared to HC. These parameters exceeded the reduction in brain volume measured in patients versus HC (p = 0.02 whole-brain volume reduction). Volumetric differences in white matter fraction and the thalami were not detectable between patients and HC. However, phase angle φ was decreased in patients within the white matter (p = 0.03) and both thalamic regions (p = 0.044). CONCLUSIONS: MMRE reveals global tissue degeneration with accelerated softening of the brain parenchyma in patients with NMOSD. The predominant reduction of stiffness is found within the thalamic region and related white matter tracts, presumably reflecting Wallerian degeneration. KEY POINTS: • Magnetic resonance elastography reveals diffuse cerebral tissue changes in patients with NMOSD. • Premature tissue softening in NMOSD patients indicates tissue degeneration. • Hypothesis of a widespread cerebral neurodegeneration in form of diffuse tissue alteration.

MOG-IgG in NMO and related disorders: a multicenter study of 50 patients. Part 4: Afferent visual system damage after optic neuritis in MOG-IgG-seropositive versus AQP4-IgG-seropositive patients.

BACKGROUND: Antibodies against myelin oligodendrocyte glycoprotein (MOG-IgG) have been reported in patients with aquaporin-4 antibody (AQP4-IgG)-negative neuromyelitis optica spectrum disorders (NMOSD). The objective of this study was to describe optic neuritis (ON)-induced neuro-axonal damage in the retina of MOG-IgG-positive patients in comparison with AQP4-IgG-positive NMOSD patients. METHODS: Afferent visual system damage following ON was bilaterally assessed in 16 MOG-IgG-positive patients with a history of ON and compared with that in 16 AQP4-IgG-positive NMOSD patients. In addition, 16 healthy controls matched for age, sex, and disease duration were analyzed. Study data included ON history, retinal optical coherence tomography, visual acuity, and visual evoked potentials. RESULTS: Eight MOG-IgG-positive patients had a previous diagnosis of AQP4-IgG-negative NMOSD with ON and myelitis, and eight of (mainly recurrent) ON. Twenty-nine of the 32 eyes of the MOG-IgG-positive patients had been affected by at least one episode of ON. Peripapillary retinal nerve fiber layer thickness (pRNFL) and ganglion cell and inner plexiform layer volume (GCIP) were significantly reduced in ON eyes of MOG-IgG-positive patients (pRNFL = 59 ± 23 µm; GCIP = 1.50 ± 0.34 mm3) compared with healthy controls (pRNFL = 99 ± 6 µm, p < 0.001; GCIP = 1.97 ± 0.11 mm3, p < 0.001). Visual acuity was impaired in eyes after ON in MOG-IgG-positive patients (0.35 ± 0.88 logMAR). There were no significant differences in any structural or functional visual parameters between MOG-IgG-positive and AQP4-IgG-positive patients (pRNFL: 59 ± 21 µm; GCIP: 1.41 ± 0.27 mm3; Visual acuity = 0.72 ± 1.09 logMAR). Importantly, MOG-IgG-positive patients had a significantly higher annual ON relapse rate than AQP4-IgG-positive patients (median 0.69 vs. 0.29 attacks/year, p = 0.004), meaning that on average a single ON episode caused less damage in MOG-IgG-positive than in AQP4-IgG-positive patients. pRNFL and GCIP loss correlated with the number of ON episodes in MOG-IgG-positive patients (p < 0.001), but not in AQP4-IgG-positive patients. CONCLUSIONS: Retinal neuro-axonal damage and visual impairment after ON in MOG-IgG-positive patients are as severe as in AQP4-IgG-positive NMOSD patients. In MOG-IgG-positive patients, damage accrual may be driven by higher relapse rates, whereas AQP4-IgG-positive patients showed fewer but more severe episodes of ON. Given the marked damage in some of our MOG-IgG-positive patients, early diagnosis and timely initiation and close monitoring of immunosuppressive therapy are important.

Normal volumes and microstructural integrity of deep gray matter structures in AQP4+ NMOSD.

OBJECTIVE: To assess volumes and microstructural integrity of deep gray matter structures in a homogeneous cohort of patients with neuromyelitis optica spectrum disorder (NMOSD). METHODS: This was a cross-sectional study including 36 aquaporin-4 antibody-positive (AQP4 Ab-positive) Caucasian patients with NMOSD and healthy controls matched for age, sex, and education. Volumetry of deep gray matter structures (DGM; thalamus, caudate, putamen, globus pallidus, hippocampus, amygdala, nucleus accumbens) was performed using 2 independent automated methods. Microstructural integrity was assessed based on diffusion tensor imaging. RESULTS: Both volumetric analysis methods consistently revealed similar volumes of DGM structures in patients and controls without significant group differences. Moreover, no differences in DGM microstructural integrity were observed between groups. CONCLUSIONS: Deep gray matter structures are not affected in AQP4 Ab-positive Caucasian patients with NMOSD. NMOSD imaging studies should be interpreted with respect to Ab status, educational background, and ethnicity of included patients.

Insufficient treatment of severe depression in neuromyelitis optica spectrum disorder.

OBJECTIVE: To investigate depression frequency, severity, current treatment, and interactions with somatic symptoms among patients with neuromyelitis optica spectrum disorder (NMOSD). METHODS: In this dual-center observational study, we included 71 patients diagnosed with NMOSD according to the International Panel for NMO Diagnosis 2015 criteria. The Beck Depression Inventory (BDI) was classified into severe, moderate, or minimal/no depressive state category. We used the Fatigue Severity Scale to evaluate fatigue. Scores from the Brief Pain Inventory and the PainDETECT Questionnaire were normalized to estimate neuropathic pain. Psychotropic, pain, and immunosuppressant medications were tabulated by established classes. RESULTS: Twenty-eight percent of patients with NMOSD (n = 20) had BDI scores indicative of moderate or severe depression; 48% of patients (n = 34) endorsed significant levels of neuropathic pain. Severity of depression was moderately associated with neuropathic pain (r = 0.341, p < 0.004) but this relationship was confounded by levels of fatigue. Furthermore, only 40% of patients with moderate or severe depressive symptoms received antidepressant medical treatment. Fifty percent of those treated reported persistent moderate to severe depressive symptoms under treatment. CONCLUSIONS: Moderate and severe depression in patients with NMOSD is associated with neuropathic pain and fatigue and is insufficiently treated. These results are consistent across 2 research centers and continents. Future research needs to address how depression can be effectively managed and treated in NMOSD.