肛管直肠周围肌组织感染的MRI表现及术后随访

  目的  分析肛管直肠周围肌组织脓肿长期被临床忽视的原因，并总结术后患者肛门功能的恢复情况。  方法  回顾性分析39例肛门外括约肌和/或耻骨直肠肌、肛提肌脓肿患者的MRI表现，并随访术后患者控便及排便能力。  结果  18例为单一肌组织脓肿，21例并发两组以上肌组织脓肿，其中存在肛门外括约肌深部脓肿28例，浅部脓肿26例，耻骨直肠肌脓肿9例，肛提肌脓肿4例，肛门外括约肌皮下部脓肿1例；感染肌组织肿胀增粗，基本保持解剖形态，其中外括约肌深部呈典型“U”形，肛提肌呈对称“蝴蝶翅膀样”表现；肛周脂肪间隙清晰34例，脂肪间隙结构不清5例，术中触及内口26例。35例未累及肛提肌患者术后控便和排便良好，3例肛提肌脓肿患者存在不同程度控便不良及排便无力，另1例失联。  结论  肛门外括约肌和/或耻骨直肠肌、肛提肌有时不能阻挡肛周感染的传播，甚至肌组织内部形成脓肿，肛门外括约肌及耻骨直肠肌脓肿术后患者肛门控便及排便功能很可能不受影响，肛提肌脓肿术后患者可能会出现肛门控便及排便功能不同程度降低。 

MRI findings and postoperative follow-up of perianorectal intramuscular infection

  Objective  To analyze the causes of long-term clinical neglect of perianorectal muscle tissue abscess, and summarize the recovery of anal function in patients after operation.  Methods  The MRI features of 39 patients with abscess of external anal sphincter and/or puborectalis muscle and levator ani muscle were analyzed retrospectively. The anal defecation control and defecation ability were followed up.  Results  There were 18 cases of single muscle tissue abscess and 21 cases of complicated with more than two groups of muscle tissue abscess. There were 28 cases of deep abscess of external anal sphincter, 26 cases of superficial abscess, 9 cases of puborectal abscess, 4 cases of levator ani abscess and 1 case of subcutaneous abscess of external anal sphincter. The infected muscle tissue swelled and thickened, basically maintaining the anatomical shape. The deep part of the external sphincter showed a typical "U" shape, and the levator ani muscle showed a symmetrical "butterfly wing" appearance. 34 cases had clear perianal fat space, 5 cases had unclear fat space and 26 cases had internal openings. 35 patients without involvement of levator ani muscle recovered well after operation. Three patients with abscess of levator ani muscle had different poor ability of fecal control and defecation after operation, and other patients with levator ani muscle abscess lost contact.  Conclusion  The external anal sphincter, puborectal muscle and levator ani muscle sometimes can not stop the spread of perianal infection, and even form an abscess inside the muscle tissue. The patients with external anal sphincter and puborectal muscle abscess have normal ability of fecal control and defecation after operation. Patients with levator ani abscess may have decreased ability of fecal control and defecation after operation.