Strik Myrte, Clough Meaghan, Solly Emma J, Glarin Rebecca, White Owen B, Kolbe Scott C, Fielding Joanne
Melbourne Brain Centre Imaging Unit, Department of Radiology, Melbourne Medical School, University of Melbourne, Melbourne, VIC 3010, Australia.
Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC 3004, Australia.
Brain Commun. 2022 Jun 23;4(4):fcac164. doi: 10.1093/braincomms/fcac164. eCollection 2022.
Visual snow syndrome is a neurological condition characterized by continuous visual disturbance and a range of non-visual symptoms, including tinnitus and migraine. Little is known about the pathological mechanisms underlying visual snow syndrome. Here, we assessed brain morphometry and microstructure in visual snow syndrome patients using high-resolution structural and quantitative MRI. Forty visual snow syndrome patients (22 with migraine) and 43 controls underwent 7-Tesla MRI (MP2RAGE, 0.75 mm isotropic resolution). Volumetric and quantitative T1 values were extracted for white and grey matter regions and compared between groups. Where regions were significantly different between groups (false discovery rate corrected for multiple comparisons), comparisons were examined between patients with and without migraine. For visual snow syndrome patients, significant MRI variables were correlated with clinical severity (number of visual symptoms, perceived visual snow intensity, disruptiveness, fatigue and quality of life) and psychiatric symptoms prevalent in visual snow syndrome (depression, anxiety and depersonalization). Finally, cortical regions and individual thalamic nuclei were studied. Compared with controls, visual snow syndrome patients demonstrated a trend towards larger brain and white matter volumes and significantly lower T1 values for the entire cortex ( < 0.001), thalamus ( = 0.001) and pallidum ( = 0.001). For the patient group, thalamic T1 correlated with number of visual symptoms ( = 0.019, = 0.390) and perceived disruptiveness of visual snow ( = 0.010, = 0.424). These correlations did not survive multiple comparison corrections. As for specificity in visual snow syndrome group, T1 changes were most evident in caudal regions (occipital cortices) followed by parietal, temporal and prefrontal cortices. T1 values differed between groups for most individual thalamic nuclei. No differences were revealed between patients with and without migraine. In visual snow syndrome patients, we observed no changes in morphometry, instead widespread changes in grey matter microstructure, which followed a caudal-rostral pattern and affected the occipital cortices most profoundly. Migraine did not appear to independently affect these changes. Lower T1 values may potentially result from higher neurite density, myelination or increased iron levels in the visual snow syndrome brain. Further investigation of these changes may enhance our understanding of the pathogenesis of visual snow syndrome, ultimately leading to new treatment strategies.
视觉雪综合征是一种神经系统疾病，其特征为持续性视觉障碍以及一系列非视觉症状，包括耳鸣和偏头痛。目前对视觉雪综合征背后的病理机制知之甚少。在此，我们使用高分辨率结构和定量磁共振成像（MRI）评估了视觉雪综合征患者的脑形态学和微观结构。40名视觉雪综合征患者（22名伴有偏头痛）和43名对照者接受了7特斯拉MRI检查（MP2RAGE序列，各向同性分辨率为0.75毫米）。提取白质和灰质区域的体积和定量T1值，并在组间进行比较。在组间存在显著差异的区域（经多重比较校正后的错误发现率），对有偏头痛和无偏头痛的患者进行比较。对于视觉雪综合征患者，显著的MRI变量与临床严重程度（视觉症状数量、感知到的视觉雪强度、干扰性、疲劳和生活质量）以及视觉雪综合征中普遍存在的精神症状（抑郁、焦虑和人格解体）相关。最后，研究了皮质区域和各个丘脑核。与对照组相比，视觉雪综合征患者的大脑和白质体积有增大的趋势，整个皮质（<0.001）、丘脑（=0.001）和苍白球（=0.001）的T1值显著降低。对于患者组，丘脑T1与视觉症状数量（=0.019，=0.390）和视觉雪的感知干扰性（=0.010，=0.424）相关。这些相关性在多重比较校正后未通过检验。至于视觉雪综合征组的特异性，T1变化在尾侧区域（枕叶皮质）最为明显，其次是顶叶、颞叶和额叶皮质。大多数单个丘脑核的T1值在组间存在差异。有偏头痛和无偏头痛的患者之间未发现差异。在视觉雪综合征患者中，我们未观察到形态学变化，而是灰质微观结构出现广泛变化，这种变化呈尾侧-头侧模式，对枕叶皮质影响最为深远。偏头痛似乎并未独立影响这些变化。较低的T1值可能是由于视觉雪综合征大脑中较高的神经突密度、髓鞘形成或铁含量增加所致。对这些变化的进一步研究可能会增进我们对视觉雪综合征发病机制的理解，最终带来新的治疗策略。
