Beware the ischiorectal abscess

Abstract

Introduction: Ischiorectal abscesses have been shown to form sinuses with various deep structures but continuity with the spinal canal is extremely rare.

Presentation of case: A previously healthy sixty-five year old man presented emergently with rectal pain, weight loss and recurrent severe tension headaches. He had systemic sepsis and resultant coagulapathy (INR 3.4) which precluded investigation of neurological symptoms by lumbar puncture. MRI rectum demonstrated a well circumscribed fluid collection with direct connection to the spinal canal and containing meningeal tissue. It extended inferiorly to the right ischiorectal fossa and abutted the natal cleft. A radiological diagnosis of ischiorectal abscess which had become continuous with a previously existing anterior sacral myelomeningocoele (ASM) was made. He was treated with broad spectrum antibiotics and a neurosurgical opinion was sought. He remained clinically unwell (septic and coagulopathic) until the abscess fistulated through the perianal skin, draining pus mixed with clear fluid (likely CSF) at which point he improved systemically.

Discussion: Few general surgeons would be faced with acute management of complicated ASM. Paucity of literature made application of evidence based medicine difficult. In fit healthy patients surgery is the mainstay of treatment as myelomengingoceles do not regress spontaneously. Conservative management is associated with up to 30% mortality (largely due to bacterial meningitis). The patient in this case was adamant that he did not consent to definitive surgical intervention.

Conclusion: This case highlights challenges encountered in the management of complicated ASM in a general hospital.

Fig. 1

Saggital section of the CT abdomen and pelvis demonstrating anterior displacement of the rectum by a large cystic mass contiguous with the neural canal.

Fig. 2

MRI rectum demonstrating a well circumscribed fluid collection with direct connection to the spinal canal and containing meningeal tissue. It extends inferiorly to the right ischiorectal fossa and abutts the natal cleft.

Fig. 3

(a) MRI (saggital section) demonstrating rectum sandwiched between the anterior sacral myelomeningocele and urinary bladder which is grossly distended in keeping with acute urinary retention. (b) Repeat MRI (4 weeks after initial presentation). Anterior sacral myelomeningocele has halved in size and only remnants of the ischiorectal abscess remain.