Igari Kota, Fujimaki Motoki, Mai Mera, Sakuma Moe, Saiki Shinji
Department of Neurology, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8575, Japan.
Center for Medical Education and Training, University of Tsukuba Hospital, Tsukuba, Ibaraki, Japan.
BMC Neurol. 2025 Jul 29;25(1):304. doi: 10.1186/s12883-025-04332-z.
Gait apraxia, characterized by difficulties initiating and coordinating walking despite preserved conceptual movement abilities, is a distinct entity from lower limb apraxia. Although gait apraxia has been associated with dysfunction of the frontal lobe, particularly the supplementary motor area (SMA), the specific associated somatotopic organization phenotype remains poorly understood. Corticobasal syndrome (CBS), a clinical phenotype of corticobasal degeneration, commonly presents with upper limb apraxia, while lower limb or gait apraxia has rarely been reported. Herein, we describe two rare cases of CBS presenting with gait apraxia shown to be caused by SMA dysfunction, based on regional cerebral blood flow (rCBF) reduction on single-photon emission computed tomography (SPECT).
Case 1 was of an 82-year-old man who exhibited right-sided apraxic gait with freezing and shuffling patterns, along with SMA hypoperfusion in both the dorsal and pre-SMA regions. Neurological examination revealed mild rigidity, right-sided Babinski sign, and clumsiness in mimicking leg movements. Gait patterns were inconsistent and unresponsive to levodopa treatment or sensory cues. Case 2 was of an 80-year-old man who demonstrated a peculiar gait characterized by exaggerated right leg movements and everted ankle positioning. Hypoperfusion was localized to the left dorsal SMA. Examination findings included rigidity and impaired hand weight perception. Sensory tricks and levodopa provided no benefit.
These cases highlight the role of SMA dysfunction in the pathogenesis of gait apraxia. Variations in rCBF reduction correlated with distinct gait patterns. For example, the freezing gait shown in Case 1 likely resulted from pre-SMA impairment, which is critical for movement initiation, while the exaggerated leg movements in Case 2 reflected dorsal SMA dysfunction, involved in motor execution. These results indicate that gait apraxia, which is often underdiagnosed, should be recognized as a potential early indicator of CBS. Further, these cases suggest that SMA dysfunction, identified through SPECT imaging, underlies the distinct gait patterns seen in CBS patients with apraxic gait. Recognizing these symptoms, even in the absence of weakness or limb apraxia, may aid in early CBS diagnosis and improve clinical management.
步态失用症的特征是尽管概念性运动能力保留，但在启动和协调行走方面存在困难，它是一种与下肢失用症不同的病症。尽管步态失用症与额叶功能障碍有关，特别是辅助运动区（SMA），但其具体相关的躯体定位组织表型仍知之甚少。皮质基底节综合征（CBS）是皮质基底节变性的一种临床表型，通常表现为上肢失用症，而下肢或步态失用症很少被报道。在此，我们描述了两例罕见的CBS病例，其表现为步态失用症，基于单光子发射计算机断层扫描（SPECT）上局部脑血流量（rCBF）减少，显示为由SMA功能障碍引起。
病例1是一名82岁男性，表现为右侧失用性步态，伴有冻结和拖曳模式，同时在背侧和SMA前区均存在SMA灌注不足。神经系统检查发现轻度强直、右侧巴宾斯基征以及模仿腿部动作笨拙。步态模式不一致，对左旋多巴治疗或感觉提示无反应。病例2是一名80岁男性，表现出一种特殊步态，其特征为右腿动作夸张且脚踝外翻。灌注不足局限于左侧背侧SMA。检查结果包括强直和手部重量感知受损。感觉技巧和左旋多巴均无益处。
这些病例突出了SMA功能障碍在步态失用症发病机制中的作用。rCBF减少的变化与不同的步态模式相关。例如，病例1中显示的冻结步态可能是由于SMA前区受损所致，该区域对运动启动至关重要，而病例2中夸张的腿部动作反映了背侧SMA功能障碍，其参与运动执行。这些结果表明，常被漏诊的步态失用症应被视为CBS的潜在早期指标。此外，这些病例表明，通过SPECT成像识别出的SMA功能障碍是CBS患者出现失用性步态时不同步态模式的基础。即使在没有无力或肢体失用症的情况下识别这些症状，也可能有助于CBS的早期诊断并改善临床管理。
