Introduction

While cases of acquired Chiari I malformation following ventriculoperitoneal shunting for posthemorrhagic hydrocephalus have been reported, true disproportionate cerebellar growth is rare, with no previous cases requiring posterior fossa decompression reported.

Clinical presentation

We present a premature neonate who underwent ventriculoperitoneal shunt placement for suspected posthemorrhagic hydrocephalus. He subsequently developed a symptomatic Chiari I malformation with volumetric measurements demonstrating disproportionate growth of the cerebellum. He did not demonstrate thickening of the supratentorial or posterior fossa cranium. The patient underwent an extradural posterior fossa decompression, with resolution of symptoms.

Outcome and conclusions

We review the extant literature regarding the development of Chiari malformation type I as a manifestation of craniocerebral disproportion (CCD) following shunt placement for posthemorrhagic hydrocephalus of prematurity. Most previous reports reflect a mechanism that includes underdevelopment of the intracranial posterior fossa (or supratentorial) volume. The case presented in this report, as well as one additional case, indicates that there may exist a variant mechanism, characterized by rapid growth of the cerebellum itself, in the absence of one of the rare syndromes associated with primary macrocerebellum. While this case was effectively managed with extradural posterior fossa decompression, previous reports indicate that supratentorial cranial expansion procedures are preferable in some cases. As such, pediatric neurosurgeons should be able to distinguish the patterns of craniocerebral disproportion when considering treatment options for these patients. Further investigation regarding these uncommon patients may better describe the underlying mechanisms.

中文翻译：

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围产期脑室腹腔分流术后需要手术减压的“生长小脑”。

介绍

虽然已经报道了因脑室腹腔分流术治疗出血后脑积水后获得性 Chiari I 畸形的病例，但真正不成比例的小脑生长很少见，以前没有报道需要后颅窝减压的病例。

临床表现

我们介绍了一名因疑似出血后脑积水而接受脑室腹腔分流术的早产儿。随后，他出现了有症状的 Chiari I 畸形，体积测量显示小脑不成比例地生长。他没有表现出幕上或后颅窝颅骨增厚。患者接受了硬膜外后颅窝减压，症状得到缓解。

结果和结论

我们回顾了关于 Chiari 畸形 I 型发展的现有文献，作为早产儿出血后脑积水分流术后颅脑不比例 (CCD) 的表现。大多数以前的报告反映了一种机制，包括颅内后颅窝（或幕上）体积发育不足。本报告中介绍的案例以及另外一个案例表明，可能存在一种变异机制，其特征是小脑本身的快速生长，而没有一种与原发性大小脑相关的罕见综合征。虽然该病例通过硬膜外后颅窝减压得到了有效处理，但之前的报告表明，在某些情况下，幕上颅骨扩张手术更为可取。像这样，儿科神经外科医生在考虑这些患者的治疗方案时，应该能够区分颅脑比例失调的模式。对这些罕见患者的进一步调查可能会更好地描述潜在机制。