Curnes J T, Oakes W J, Boyko O B
Department of Radiology, Duke University Medical Center, Durham, NC 27710.
AJNR Am J Neuroradiol. 1989 Mar-Apr;10(2):293-302.
We examined the MR appearance of the hindbrain deformity, including the upper cervical spinal canal and craniovertebral junction, in 33 patients with Chiari II malformation. In this disorder, there is impaction at birth of the medulla and cerebellar vermis into the upper cervical spine, resulting in obliteration of the subarachnoid space and scalloping of the dens. Spinal canal enlargement during the child's growth, combined with dorsal displacement of neural tissue, eventually causes marked widening of the precervical subarachnoid space. This enlargement may simulate an intradural mass. Our series documents the changes seen at birth and the progression of the widened precervical space through the first and second decades. Twelve (36%) of the 33 patients studied were symptomatic, with brainstem or longtract symptomatology, and 11 of these required surgery. This group was compared with the remaining 21 asymptomatic Chiari II patients to identify MR features associated with clinical deterioration. The level of descent of the hindbrain hernia was critical; eight of 12 symptomatic patients had a cervicomedullary kink at C4 or lower, while no asymptomatic patients had a fourth ventricle, medulla, or kink below C3-C4. The precervical cord subarachnoid space was slightly wider in asymptomatic patients, although there was great overlap. In five patients with follow-up scans, this space was seen to increase in width after laminectomy. A CSF flow void was present in the precervical space in about 25% of patients in both groups. In nine of 12 symptomatic patients, C1 arch indentation of the dura (causing significant compression) was confirmed surgically. However, seven (33%) of the 21 asymptomatic patients also had this appearance. Absolute measurement of the anteroposterior diameter of the canal at C1 ranged from 11 to 25 mm in both groups. Retrocollis, which persisted despite sedation for MR, was seen in two patients, both symptomatic. Recognition of the vermis, medullary kink, cervical cord, C1 arch, fourth ventricle, and precervical space in Chiari II patients is fundamental to the analysis of symptoms in
我们研究了33例Chiari II型畸形患者后脑畸形的磁共振成像表现，包括上颈椎管和颅颈交界区。在这种疾病中，出生时延髓和小脑蚓部嵌入上颈椎，导致蛛网膜下腔闭塞和齿状突扇贝样改变。儿童生长过程中椎管扩大，加上神经组织背侧移位，最终导致颈前蛛网膜下腔明显增宽。这种增宽可能类似硬膜内肿块。我们的系列研究记录了出生时的所见变化以及颈前间隙在第一个和第二个十年的进展情况。33例研究患者中有12例（36%）有症状，表现为脑干或长束症状，其中11例需要手术治疗。将这组患者与其余21例无症状的Chiari II型患者进行比较，以确定与临床恶化相关的磁共振特征。后脑疝下降的水平至关重要；12例有症状的患者中有8例在C4或更低水平有颈髓扭结，而无症状患者中没有在C3 - C4以下有第四脑室、延髓或扭结的情况。无症状患者的颈前脊髓蛛网膜下腔略宽，尽管有很大重叠。在5例进行了随访扫描的患者中，椎板切除术后该间隙宽度增加。两组中约25%的患者颈前间隙存在脑脊液流动空洞。12例有症状的患者中有9例经手术证实有C1弓对硬脑膜的压迹（导致明显压迫）。然而，21例无症状患者中有7例（33%）也有这种表现。两组中C1处椎管前后径的绝对测量值范围为11至25毫米。在2例有症状的患者中，尽管在磁共振检查时使用了镇静剂，但仍可见持续性斜颈。认识Chiari II型患者的蚓部、髓扭结、颈髓、C1弓、第四脑室和颈前间隙对于分析症状至关重要
