P2.M249: Pneumocephalus and Meningitis in a Previously Healthy Female

Introduction: Anterior sacral meningocele (ASM) is a rare congenital defect that presents as a cystic lesion protruding through the anterior sacrum. Of the few hundred cases of ASM reported, less than ten were associated with the rare complication of a recto-thecal fistula. These cases usually have a medical history suggestive of surgical manipulation of the abdominopelvic cavity or chronic constipation. None of the previously reported cases, however, reported air within the cranial cavity or spinal cord.

Case Description: An 18-year-old female with a recent diagnosis of meningitis (6 weeks prior) presented to the emergency department for headache, nuchal rigidity, back pain, and peri-orbital rash. She was afebrile with stable vital signs but physical exam was concerning for meningitis. A CT of the brain and orbits was performed revealing gas within the frontal horns of the lateral ventricles and along the posterior aspect of the right thalamus. A subsequent MRI of the brain and spine redemonstrated the gas within the ventricles in addition to a tethered cord and sacral defect with a large anterior meningocele. CT chest, abdomen and pelvis were obtained demonstrating additional foci of gas within the thoracic spinal canal. Given the history of recent presumed meningitis, new peri-orbital vesicular rash, persistent headache and back pain with new findings of pneumocephalus, tethered cord, and sacral defect, she was started on broad spectrum antibiotics and Acyclovir. She was admitted to the hospital with a diagnosis of meningitis.
After a more extensive history, she reported experiencing the sensation of fluid leaking from her anus when voiding. An MRI pelvis was obtained and an ano-thecal fistula was demonstrated along the infero-lateral aspect of the meningocele near the anus. She was transferred to an outside hospital for definitive surgical management of her anatomic anomaly.

Discussion: The initial differential included recurrence of bacterial meningitis, herpetic meningitis, or orbital cellulitis with intracranial complications. However, with CT findings of pneumocephalus and pneumorachis and the added history of anal leakage, a fistula between the CNS and the rectum was considered. The MRI findings of an ano-thecal fistula confirmed the conduit for bacteria and air introduction into the CNS leading to her recurrent meningitis.

Conclusion: Few cases have been reported of a recto-thecal fistula from an ASM with meningitis complicated by either pneumocephalus, rectorrhea, or both. This is the first reported case of a patient with meningitis, pneumocephalus, pneumorachis, and rectorrhea, due to an ano-thecal fistula from an ASM. This case enhances the literature on severe complications due fistulas from ASM in previously healthy individuals.