Department of Neurology, Division of Speech-Language Pathology, Mayo Clinic, Rochester, MN, USA.
Department of Radiology, Division of Neuroradiology, Mayo Clinic, Rochester, MN, USA.
Cortex. 2018 Feb;99:358-374. doi: 10.1016/j.cortex.2017.12.021. Epub 2018 Jan 2.
Apraxia of speech is a motor speech disorder characterized by combinations of slow speaking rate, abnormal prosody, distorted sound substitutions, and trial-and-error articulatory movements. Apraxia of speech is due to abnormal planning and/or programming of speech production. It is referred to as primary progressive apraxia of speech (PPAOS) when it is the only symptom of a neurodegenerative condition. Past reports suggest an association of PPAOS with primary 4-repeat (4R) tau (e.g., progressive supranuclear palsy, corticobasal degeneration), rather than amyloid, pathology. The goal of the current study was to investigate the distribution of tau tracer uptake using [18F]AV-1451 positron emission tomography (PET) imaging in patients with PPAOS. Fourteen PPAOS patients underwent [18F]AV-1451 PET (tau-PET) imaging, [C11] Pittsburgh Compound B (PiB) PET and structural MRI and were matched 3:1 by age and sex to 42 cognitively normal controls. Tau-PET uptake was assessed at the region-of-interest (ROI) level and at the voxel-level. The PPAOS group (n = 14) showed increased tau-PET uptake in the precentral gyrus, supplementary motor area and Broca's area compared to controls. To examine whether tau deposition in Broca's area was related to the presence of aphasia, we examined a subgroup of the PPAOS patients who had predominant apraxia of speech, with concomitant aphasia (PPAOSa; n = 7). The PPAOSa patients showed tau-PET uptake in the same regions as the whole group. However, the remaining seven patients who did not have aphasia showed uptake only in superior premotor and precentral cortices, with no uptake observed in Broca's area. This cross-sectional study demonstrates that elevated tau tracer uptake is observed using [18F]AV-1451 in PPAOS. Further, it appears that [18F]AV-1451 is sensitive to the regional distribution of tau deposition in different stages of PPAOS, given the relationship between tau signal in Broca's area and the presence of aphasia.
言语失用症是一种运动性言语障碍，其特征为语速缓慢、韵律异常、声音扭曲替代、以及尝试-错误性的发音运动。言语失用症是由于言语产生的计划性和/或程序性异常所致。当它是神经退行性疾病的唯一症状时，被称为原发性进行性言语失用症（PPAOS）。过去的报告表明，PPAOS 与原发性 4 重复（4R）tau（例如进行性核上性麻痹、皮质基底节变性）而非淀粉样蛋白病理学有关。本研究的目的是使用[18F]AV-1451 正电子发射断层扫描（PET）成像研究 PPAOS 患者中 tau 示踪剂摄取的分布。14 名 PPAOS 患者接受了[18F]AV-1451 PET（tau-PET）成像、[C11]匹兹堡化合物 B（PiB）PET 和结构 MRI 检查，并按年龄和性别与 42 名认知正常对照进行了 3:1 匹配。在 ROI 水平和体素水平评估 tau-PET 摄取。与对照组相比，PPAOS 组（n=14）在前中央回、辅助运动区和布罗卡区显示出 tau-PET 摄取增加。为了研究布罗卡区的 tau 沉积是否与失语症的存在有关，我们检查了 PPAOS 患者亚组，这些患者主要表现为言语失用症伴伴发失语症（PPAOSa；n=7）。PPAOSa 患者在与整个组相同的区域显示 tau-PET 摄取。然而，其余 7 名没有失语症的患者仅在前运动皮质和中央前回显示摄取，而在布罗卡区没有摄取。这项横断面研究表明，在 PPAOS 中使用[18F]AV-1451 观察到 tau 示踪剂摄取增加。此外，鉴于布罗卡区 tau 信号与失语症的存在之间的关系，似乎[18F]AV-1451 对 PPAOS 不同阶段 tau 沉积的区域分布具有敏感性。
