Pamphlett R, Murray N, Louda C
Department of Pathology, University of Sydney, NSW, Australia.
Acta Neuropathol. 1996;91(4):422-6. doi: 10.1007/s004010050445.
It has been suggested that delayed development in either the peripheral or central nervous system could underlie the sudden infant death syndrome (SIDS). We studied the phrenic nerve in an attempt to find if maturation in this nerve was delayed in SIDS, and to see if fiber size differences could explain the paucity of type I muscle fibers described in SIDS diaphragms. Samples of phrenic nerves were taken at post mortem from 11 SIDS and 10 control infants. Myelinated fibers were quantitated in 1-micron silver-stained resin sections using a semi-automatic image analysis system. The numbers and sizes of all myelinated fibers in the right phrenic nerve were compared between SIDS and control groups. The proportion of small (less than 6-microns diameter) phrenic nerve fibers was similar in SIDS (53.1%, SD 12.8%) and control (53.6%, SD 14.0%) cases. The proportion of small fibers decreased with increasing age at an equivalent rate in both SIDS and control groups. Total numbers of myelinated fibers were similar in the right phrenic nerves of SIDS (3429, SD 440) and control (3457, SD 507) infants, but varied widely between cases and were not correlated with age. Maturation of the phrenic nerve, as judged by increasing size of myelinated fibers, is therefore similar in SIDS and control infants. This argues against a widespread development delay in SIDS. No changes in phrenic nerve fiber sizes were found to account for the finding of fewer type I fibers in SIDS diaphragms.
有人提出，外周或中枢神经系统发育延迟可能是婴儿猝死综合征（SIDS）的潜在原因。我们研究了膈神经，试图确定SIDS患儿该神经的成熟是否延迟，并查看纤维大小差异能否解释SIDS患儿膈肌中I型肌纤维数量稀少的现象。在尸检时从11例SIDS患儿和10例对照婴儿身上获取膈神经样本。使用半自动图像分析系统对1微米厚的银染树脂切片中的有髓纤维进行定量分析。比较了SIDS组和对照组右侧膈神经中所有有髓纤维的数量和大小。SIDS组（53.1%，标准差12.8%）和对照组（53.6%，标准差14.0%）中小（直径小于6微米）膈神经纤维的比例相似。在SIDS组和对照组中，小纤维的比例均以相同速率随年龄增长而下降。SIDS患儿（3429，标准差440）和对照婴儿（3457，标准差507）右侧膈神经中有髓纤维的总数相似，但不同病例之间差异很大，且与年龄无关。因此，根据有髓纤维大小增加来判断，SIDS患儿和对照婴儿膈神经的成熟情况相似。这表明SIDS并非普遍存在发育延迟。未发现膈神经纤维大小的变化能解释SIDS患儿膈肌中I型纤维数量较少的现象。
