应用筛板压力失衡原理治疗颅骨纤维发育不良导致的视觉障碍

Theoretic explanation about visual disorder induced by fibrous dysplasia of skull： pressure disequilibrium between lamina cribrosa

目的 探讨纤维发育不良导致视神经管狭窄时视神经头部的改变及导致视觉障碍的原因.方法 12例患者经CT诊断纤维发育不良,行眼底像与光学相干断层扫描（OCT）,视神经管受病变累及者行视神经管狭窄减压术.以OCT矢状面断层示筛板位于视网膜色素上皮层（RPE）上方为暴露因子,视力下降或视乳头水肿,萎缩为发病,计算Fisher精确检验和比值比.结果 CT示视神经管受病变累及致狭窄18侧：8侧视力正常,其中6侧OCT示筛板位于RPE下方,经随访1侧筛板接近RPE,1侧OCT示筛板达RPE,视乳头正常;1侧筛板位于RPE上方,视乳头水肿.视觉下降10侧,视乳头正常2侧,视乳头萎缩8侧,OCT示筛板位于RPE上方,术后OCT示筛板位于RPE下方.术后7侧眼视力好转.Fisher精确检验,P＜0.01,比值比=∞.结论 视神经管狭窄导致筛板区后压力增高,筛板向RPE上方移位,通道变形,挤切视神经节细胞轴突,轴浆运输受阻,血运障碍,是导致视觉障碍的病因;手术后筛板区后压力下降,筛板恢复凹陷,通道变形恢复,视力改善.

Objective To investigate the causes for changes in optic nerve head and visual impairment caused by fibrous dysplasia （FD） of optic canal stenosis. Methods A total of 12 FD patients,diagnosed by CT, received the fundus and optical coherence tomography （OCT）. Those with FD involving optic canal underwent decompression. The examination of OCT showed that lamina cribrosa located at the top was the exposure factor for retinal pigment epithelium （RPE）. There were decreased vision or edematous optic nerve and atrophic lesion. Odds ratio was calculated by Fisher＇s exact test. Results The examination of CT showed the results of optic canal stenosis caused by lesions involving 18 sides ： 8-sides with normal vision.Among which, 6 showing that lamina cribrosa was located below RPE and a lamina cribrosa plate near RPE at follow-up, 1 side OCT showing lamina cribrosa above RPE with normal optic nerve; a lateral lamina cribrosa was located above RPE with edematous optic nerve. Visual impairment at 10 sides, normal papillary 2 sides, atrophic papillary 8 sides, OCT showed that lamina cribrosa was located above RPE,postoperatively OCT showed that lamina cribrosa below with 7 sides having improved visual acuity. Fisher＇s exact test was performed （ P = 0. 000, odds ratio = ∞ ）. Conclusion The optic canal stenosis causes a rising pressure of lamina cribrosa zone to shift above RPE. The channel becomes distorted so as to squeeze and cut the ganglion cell axons of optic nerve, block the axoplasmic transport and result in blood circulation disorder. The above factors are the etiologies of visual impairments. Postoperatively lamina eribrosa zone pressure drops so that depressed lamina cribrosa and channel deformation recover and visual acuity improves.