Department of Neurosurgery, Maison Blanche Hospital, University of Reims, France.
J Neurosurg. 2011 Sep;115(3):647-58. doi: 10.3171/2010.11.JNS102148. Epub 2011 Feb 4.
The aim of this paper was to measure the posterior fossa (PF) volume increase resulting from a given-sized occipital craniectomy in Chiari malformation Type I surgery and to analyze its correlations with the PF size and the treatment response, with the perspective of tailoring the amount of bone removal to the patient-specific PF dimensions.
Between January 2005 and June 2006, 11 adult patients with symptomatic Chiari malformation Type I underwent a standardized PF decompression. A prospective evaluation with clinical examination, functional grading, and MR imaging measurement protocols was performed pre- and postoperatively. A method is reported for the measurement of PF volume (PFV) after surgery. The degree of PFV increase was compared with the preoperative size of the PF and with the clinical outcome.
All 11 patients improved postoperatively, with complete and partial recovery in 4 and 7 patients, respectively. No postoperative complication occurred after a mean follow-up period of 45 months. The mean relative increase in PFV accounted for 10% (range 1.5%-19.7%) of the initial PFV; the increase was greater in cases in which the PF was small (r = -0.52, p = 0.09) and the basiocciput was short (r = -0.37, p = 0.2). A statistically significant positive correlation was found between the degree of PFV increase and the treatment response (p = 0.014); complete recovery was observed with a PFV increase of 15% and partial recovery with an increase of 7%.
The treatment response is significantly influenced by the degree of PFV increase, which is dependent on the size of the PF and the extent of the craniectomy, suggesting that the optimal patient-specific PFV increase could be predicted on the basis of preoperative MR imaging and enhancing the perspective that the craniectomy size could be tailored to the individual PFV.
本研究旨在测量 Chiari 畸形 I 型手术中枕骨大孔后颅窝（PF）体积增加量，并分析其与 PF 大小和治疗反应的相关性，以期根据患者 PF 尺寸的个体差异来调整骨切除量。
2005 年 1 月至 2006 年 6 月，11 例有症状 Chiari 畸形 I 型患者接受了标准的 PF 减压。采用临床检查、功能分级和磁共振成像测量方案进行术前和术后前瞻性评估。报告了一种用于测量术后 PF 体积（PFV）的方法。将 PFV 增加程度与术前 PF 大小和临床结果进行比较。
11 例患者术后均有改善，4 例完全恢复，7 例部分恢复。平均随访 45 个月后无术后并发症发生。PFV 的平均相对增加量占初始 PFV 的 10%（范围 1.5%-19.7%）；PF 较小（r = -0.52，p = 0.09）和基底部较短（r = -0.37，p = 0.2）的病例中增加幅度较大。PFV 增加程度与治疗反应呈显著正相关（p = 0.014）；PFV 增加 15%时完全恢复，增加 7%时部分恢复。
PFV 增加程度显著影响治疗反应，这取决于 PF 的大小和颅后窝减压的程度，提示可以根据术前磁共振成像预测最佳的患者特异性 PFV 增加量，并增强了根据个体 PFV 来调整颅后窝减压程度的观点。
