骶管囊肿文献导读：非动脉瘤性中脑周围蛛网膜下腔出血导致症状性骶管囊肿

原文：Multiple Sacral Perineurial Cysts Presented Symptoms Triggered by Nonaneurysmal Perimesencephalic Subarachnoid Hemorrhage

作者：Keitaro Yamagami, Tadahisa Shono, and Koji Iihara

Department of Neurosurgery, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Fukuoka, Japan（日本 福冈）

编译：沈霖  杨敏   审校：郑学胜

Case Report

A 48-year-old male presented with a severe headache of sudden onset. Brain computed tomography (CT) demonstrated a SAH mainly located around the mesencephalon without a hematoma in the interhemispheric and lateral Sylvian fissures (Fig. 1A). Three-dimensional CT, MR, and conventional angiography were performed to determine the cause of the SAH; however, no abnormal vascular lesion was detected. Conservative treatment and careful observation were conducted, and the patient was gradually relieved of the headache. Four days after the onset of the SAH, he suffered from pain in the left buttock. The symptoms were aggravated by postural change, sitting and walking. Eight days after the onset of the SAH, urinary and bowel dysfunction occurred. He complained of paresthesia in the left S2 and S3 dermatomes, urinary retention and severe constipation. Lumbosacral MR imaging detected multiple cystic lesions at the sacral roots (Fig. 1B). The cyst at the S1 level had low signal intensity on T1-weighted images and high signal intensity on T2-weighted images, which were similar to those of cerebrospinal fluid (CSF). In contrast, the two cysts at the S2 level had high signal intensity on both T1- and T2-weighted images (Figs. 2A–2D). Additionally, the CT value of those cysts at S2 level was higher than that of normal CSF (Fig. 2E), suggesting the content of the cyst included a hematoma. No other abnormal radiological findings that could explain the symptoms were found.

一位48岁男性，突发性剧烈头痛入院。脑计算机断层扫描（CT）显示蛛网膜下腔出血主要位于中脑周围，大脑半球间和外侧裂无血肿（图1A）。该患者完善了三维CT、MR和常规血管造影检查以明确自发性蛛网膜下腔出血的病因，但未发现异常血管病变。经过保守治疗和仔细观察，病人的头痛逐渐减轻。蛛网膜下腔出血起病四天后，他出现左臀部疼痛。体位改变、坐立行走等症状加重。发病后8天，患者出现排便功能障碍。患者主诉左侧S2和S3神经支配区域皮肤感觉异常，尿潴留和严重便秘。腰骶部磁共振成像在骶神经根处发现多发性囊性病变（图1B）。S1囊肿T1加权像低信号，T2加权像高信号，与脑脊液（CSF）相似。相反，S2的两个囊肿在T1和T2加权图像上都为高信号强度（图2A–2D）。此外，这些囊肿在S2水平的CT值高于正常脑脊液（图2E），提示囊肿内含有血液成分。此外，没有发现其他可以解释症状的异常放射学表现。

He was treated with a 10-day course of intravenous injection of steroids (betamethasone, tapering from 4 to 1 mg). Six days after the start of the medical treatment, his symptoms began to improve. He recovered completely from the symptoms in 2 months. Follow-up MR imaging at 2 months revealed remarkable shrinkage of the cysts. The two cysts at the S2 level, which had high signal intensity on both T1- and T2-weighted images with the initial MR imaging, changed to low signal intensity on both T1- and T2-weighted images (Figs. 3A–3D).

患者接受了为期10天的静脉注射类固醇治疗（倍他米松，从4毫克逐渐减少到1毫克）。开始治疗6天后，他的症状开始好转。他的症状在两个月内完全康复。术后2个月复查磁共振显示囊肿明显缩小。S2的两个囊肿，在T1和T2加权图像上都为高信号强度，在T1和T2加权图像上都变为低信号（图。3A–3D）。

专家点评：郑学胜主任指出自从1938年Tarlov报道了第一个神经根周围囊肿的病例以来，许多专家及学者对囊肿的起源和发病机制进行了推测，包括神经根鞘内炎症导致脑脊液流入、神经根袖周围蛛网膜增生、外伤后蛛网膜下腔出血导致神经根周围和神经内静脉引流不畅形成囊肿，以及先天性发育起源等原因，但目前仍尚无明确定论。典型的神经周围囊肿磁共振影像学表现为脑脊液信号特征，即T1加权像呈低信号，T2加权像呈高信号。而本例患者S2水平两个囊肿在T1和T2加权像上均呈高信号，提示其囊肿内囊液中包括蛛网膜下腔出血，蛛网膜下腔出血后脑脊液压力增高导致脑脊液进入囊肿内，并使得原本无症状的骶管囊肿出现症状，且骶神经根的机械性压迫和扩张的骶管囊肿刺激骶神经根是引起症状的原因。通过本病例报告及其发展过程也印证了我们中心提出的骶管囊肿模型的正确性。同时，如果患者在蛛网膜下腔出血后出现腰痛或骶神经根病，则应考虑将症状性骶管囊肿列入鉴别诊断之中。