Cerebral palsy (CP) involves a wide range of clinical presentations. Therefore, it is useful to categorize individuals into groups for clinical, research, and service provision purposes. Cerebellar diplegia or congenital cerebellar ataxia was first described in 1903 by Frederick Batten, who differentiated it from hereditary cerebellar ataxia, but the term ‘ataxic CP’ is currently used in various ways. According to the Surveillance of Cerebral Palsy in Europe, individuals with ataxic CP show generalized hypotonia with loss of orderly muscle coordination so that movements are performed with ‘abnormal’ force, rhythm, and accuracy. Other schemes do not require the presence of hypotonia. Experience (and perhaps my own clinical practice bias) suggests that poor balance and intention tremor are typical, gross motor function is generally less impaired than in other types of bilateral CP, individuals are less likely to develop contractures, and intellectual disability and speech impairment are quite common. However, there is a lack of description of motor and non-motor features in the literature, making the diagnosis problematic. Indeed, early-onset ataxia can signal a host of genetic disorders that are often progressive (thus not CP) with poor outcomes. For example, ataxia-telangiectasia, spinocerebellar ataxia (SCA), and Joubert syndrome can mimic ataxic CP in early life. Developmental impairment of motor coordination as seen in developmental coordination disorder (DCD) is much more prevalent than these conditions, and in many children one cannot distinguish between motor phenotypes of DCD and degenerative ataxias, not to mention ataxic CP. Admittedly, assessing motor disorders in developing children is challenging, and one cannot rely on widely shared experience as in spastic and dyskinetic CP. Ataxic CP is the least common CP type, accounting for less than 1 in 10 individuals with CP. Moreover, a higher proportion of children see their diagnosis reassigned to non-CP conditions by age 5 years, indicating incorrect initial diagnosis. Thus, more consequentially than in other presentations, it must be stressed that the diagnosis of CP, even when accurate, is essentially descriptive, calling for a comprehensive aetiological work-up. A genetic origin does not rule out the diagnosis, and it carries counselling implications. Further complexity arises as some responsible genes are better known to cause nonCP disorders. KCNC3 mutations are usually found in SCA13, but some can be associated with an early-onset stable course consistent with ataxic CP. So can SPTBN2 mutations, though they are usually associated with SCA5, or ITPR1 mutations, some of which cause SCA15 and SCA29, and Gillepsie syndrome, a congenital hypotonia-ataxia syndrome with aniridia and intellectual disability. Neuroimaging also fails to show abnormalities much more commonly than in other CP types. Eventual changes are rarely lesional, but rather indicate hypoplasia or other malformations of the cerebellum. Yet, cerebellar malformations do not necessarily manifest themselves with ataxia (or CP). Associations between clinical and neuroimaging features have been far less documented than in spastic and dyskinetic CP. In contrast with those CP types, no causal pathways have been suggested that might improve understanding of the condition and provide at least hypothetical targets for prevention. In sum, ataxic CP currently appears too heterogeneous and uncertain to be as conceptually useful as other CP types. This may stem from the relatively late development of motor coordination and maturation of the cerebellum, including into the postnatal period. There has also been little intersection between CP, early-onset ataxia, and DCD research, resulting in lack of scrutiny of the overlap between these conditions. The clinical, functional, and pathophysiological picture must be clarified based on studies bringing together phenomenology, neuroimaging, genetics, and epidemiology to improve the definition and understanding of the implications of the diagnosis. Given the low estimated prevalence, such an effort will require worldwide collaboration, ideally involving all major CP registries and groups studying degenerative childhoodonset ataxia, DCD, and typical development.

中文翻译：

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共济失调性脑瘫的诊断有多大用处？

脑瘫 (CP) 涉及广泛的临床表现。因此，出于临床、研究和服务提供的目的，将个人分类为组是有用的。小脑双瘫或先天性小脑性共济失调于 1903 年由 Frederick Batten 首次描述，他将其与遗传性小脑性共济失调区分开来，但“共济失调性 CP”一词目前以多种方式使用。根据欧洲脑性麻痹的监测，患有共济失调性 CP 的个体表现出全身性张力减退，失去有序的肌肉协调，因此以“异常”的力量、节奏和准确性进行运动。其他方案不需要存在张力减退。经验（也许是我自己的临床实践偏见）表明平衡能力差和意向性震颤是典型的，与其他类型的双侧 CP 相比，粗大运动功能的受损程度通常较轻，个体发生挛缩的可能性较小，智力障碍和言语障碍很常见。然而，文献中缺乏对运动和非运动特征的描述，使得诊断存在问题。事实上，早发性共济失调可能预示着一系列遗传疾病，这些疾病通常是进行性的（因此不是 CP），结果不佳。例如，共济失调-毛细血管扩张症、脊髓小脑性共济失调 (SCA) 和 Joubert 综合征可以模拟生命早期的共济失调性脑瘫。发育性协调障碍 (DCD) 中所见的运动协调性发育障碍比这些病症更为普遍，并且在许多儿童中，人们无法区分 DCD 的运动表型和退行性共济失调，更不用说共济失调性 CP。诚然，评估发育中儿童的运动障碍具有挑战性，并且不能像痉挛和运动障碍 CP 那样依赖广泛共享的经验。共济失调型 CP 是最不常见的 CP 类型，每 10 名 CP 患者中不到 1 人。此外，更多的儿童在 5 岁时看到他们的诊断被重新分配到非 CP 疾病，这表明初始诊断不正确。因此，比其他报告更重要的是，必须强调 CP 的诊断，即使准确，本质上也是描述性的，需要全面的病因学检查。遗传起源不排除诊断，它具有咨询意义。由于一些负责任的基因会导致非 CP 疾病，因此更加复杂。KCNC3 突变通常在 SCA13 中发现，但有些可能与与共济失调 CP 一致的早发性稳定病程有关。SPTBN2 突变也是如此，尽管它们通常与 SCA5 或 ITPR1 突变有关，其中一些突变会导致 SCA15 和 SCA29，以及 Gillepsie 综合征，一种伴有无虹膜和智力障碍的先天性肌张力低下-共济失调综合征。神经影像学也无法比其他 CP 类型更常见地显示异常。最终的变化很少是病变的，而是表明小脑发育不全或其他畸形。然而，小脑畸形不一定表现为共济失调（或 CP）。与痉挛性和运动障碍 CP 相比，临床和神经影像学特征之间的关联性记录要少得多。与那些 CP 类型相比，没有提出可能提高对病情的了解并至少提供预防的假设目标的因果途径。总而言之，共济失调 CP 目前似乎过于多样化和不确定，在概念上与其他 CP 类型一样有用。这可能源于小脑运动协调和成熟的相对较晚的发展，包括进入产后时期。CP、早发性共济失调和 DCD 研究之间也几乎没有交集，导致缺乏对这些条件之间重叠的审查。必须根据将现象学、神经影像学、遗传学和流行病学相结合的研究来阐明临床、功能和病理生理学情况，以提高对诊断意义的定义和理解。鉴于估计流行率较低，