[A case report: abscess of the cavum septi pellucidi]

A rare case of an abscess in the cavum septi pellucidi (CSP) is described and previously reported cases are reviewed. A 60-year-old male was admitted to the hospital because a diagnosis of cerebellar hemisphere infarction was made on CT scan. Seven years earlier, the patient had undergone a craniotomy for aneurysm clipping, and a ventriculo-peritoneal shunt was installed for normal pressure hydrocephalus 14 days after the aneurysmal rupture. On his second hospitalization CT scan also demonstrated CSP but this was not associated with ventriculomegaly. He was placed on a rehabilitation regimen and his hospital course was uneventful. Two months later, however, he developed hyponatremia due to the syndrome of inappropriate secretion of antidiuretic hormone. After analysis of CSF obtained from the shunting device, a diagnosis of meningitis was made and CSF culture revealed E. coli infection. A part of the peritoneal tubing was torn and missing when the tube was removed from the peritoneal cavity and converted to outer drainage. Being treated with intrathecal and intravenous antibiotics administration, the meningitis subsided. However, CT scan taken twelve days after the onset of the infection showed an abscess in CSP which showed ring enhancement after contrast media. Therefore, the patient continued to receive intravenous antibiotics to counter the mass effect due to the abscess. The abscess had disappeared on follow-up CT scan obtained ten days later. The patient, however, eventually expired after iatrogenic hypernatremia associated with acute renal failure. The patient was submitted to an autopsy. The authors speculate that the abscess developed through a retrograde cisternal route after infection which had originated from bowel perforation by the peritoneal shunt tube.