Background: Cerebellar mutism syndrome (CMS) is a postoperative syndrome of decreased speech seen in children associated with neurobehavioral abnormalities, the incidence of which is up to 40%.

Objectives: To evaluate pediatric patients with posterior fossa tumors for incidence, clinical characteristics, pathophysiology, risk factors, and neuroradiographic features of this syndrome.

Materials and methods: The study included 60 pediatric patients with a posterior fossa tumor who underwent surgery by a telovelar approach. Detailed pre- and postoperative clinical and radiological evaluations were done. Patients with CMS were analyzed and compared with those without mutism to find risk factors for CMS. The presentation and characteristics of cerebellar mutism were studied along with the following risk factors:Clinical-age, sex, cranial nerve deficit, and adjuvant treatment.Radiological-tumor location, hydrocephalus, brainstem invasion, extent of tumor resection, peduncular and brainstem edema, and atrophy of posterior fossa structures.Pathological-histopathology of tumor.The preoperative, immediate postoperative, and 1-year postoperative imaging results were reviewed to assess the neuroradiographic features in the two groups.

Results: The incidence of this syndrome was 20%. The mutism was accompanied by some neurobehavioral abnormalities ( p -value = 0.05). The most significant finding was the presence of a period of cerebellar dysarthria after the resolution of the muteness ( p -value < 0.001) in all cases. Brainstem and related structures' involvement was the most significant risk factor ( p -value = 0.03). The presence of brainstem and peduncular edema in the immediate postoperative period ( p -value = 0.04) and gross atrophy of posterior fossa structures at 1 year ( p -value = 0.01) showed significance toward the development of CMS. There was delayed neurological recovery in patients with CMS with a poor Glasgow Outcome Score at 1 year of follow-up.

Conclusion: The clinical presentation of this syndrome in context with neuroradiographic features suggests that it results from transient impairment of the afferent and/or efferent pathways of dentate nuclei that are involved in initiating complex volitional movements and are associated with brainstem involvement of tumor and poor functional outcome.

Keywords: dysarthria; mutism; neurobehavioral; posterior fossa syndrome; posterior fossa tumors in children.

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背景： 小脑缄默症（CMS）是一种在儿童神经外科手术后出现的综合征，表现为语言减少和神经行为异常，发病率高达40%。

目的： 评估后颅窝肿瘤患儿中CMS的发生率、临床特征、病理生理学、危险因素及神经影像学特点。

材料与方法： 本研究纳入了60名接受顶小脑幕切口手术的后颅窝肿瘤儿童患者，对他们进行了详细的术前和术后临床以及放射学评估。分析并比较有CMS症状的患儿与其他没有语言沉默症状的患儿，以确定CMS的风险因素。CMS的症状表现及其特点与以下风险因素相关：临床年龄、性别、颅神经缺陷及辅助治疗；影像学方面包括肿瘤位置、脑积水、延髓侵犯程度、肿瘤切除范围、小脑脚和延髓水肿以及后颅窝结构萎缩；病理学方面包括肿瘤的组织病理学。对术前、术后立即以及术后1年期的成像结果进行审查，以评估两组之间的神经影像学特征。

结果： 该综合征的发生率为20%。语言沉默伴随一些神经行为异常（P值=0.05）。最显著的是，在所有病例中，当言语沉默期结束之后都会出现一段小脑构音障碍时期（P值

结论： 根据临床表现及神经影像学特征，在肿瘤及其延髓受累的情况下，该综合征可能是由于齿状核投射通路（参与启动复杂的意志运动）的短暂受损所导致，并与功能预后较差相关联。

关键词： 构音障碍；缄默症；神经行为异常；后颅窝综合症；儿童后颅窝肿瘤。