title: Subarachnoid hemorrhage emanating from a ruptured infundibulum: case report and literature review.
abstract: BACKGROUND
  Infundibula are frequently regarded as incidental anatomical variants that are of no pathogenetic significance.
  
  
  METHODS
  A 51-year-old man presented with a sudden onset of severe occipital headache. Computed tomographic scan revealed a predominantly perimesencephalic pattern of SAH with a slight bias toward the left side. Angiography demonstrated a left PCo-A IF as the sole abnormality. At craniotomy, the left PCo-A IF was found to represent the sole abnormality. The IF was markedly reddened posteriorly, contained a capping clot, and lay immediately adjacent to a mass of xanthochromatous tissue. The PCo-A was hypoplastic and lacked perforating vessels; therefore, the IF base was successfully clipped with a straight Sugita clip parallel to the left ICA. At discharge and at clinical follow-up, our patient was asymptomatic and lacked neurologic signs.
  
  
  CONCLUSIONS
  Infundibula may rarely represent a direct source of rupture and SAH. Exploratory craniotomy is required to establish the diagnosis and to provide definitive treatment. To label a case of SAH as angiogram-negative may be unwise when an IF potentially colocalizes to the SAH source.
authors.affiliation: Department of Neurosurgery, North Staffordshire Royal Infirmary, Hartshill, Stoke-on-Trent, Staffordshire, UK.
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Coupe
authors.forename: Rupinder K
authors.initials: RK
authors.lastname: Athwal
authors.forename: Laurence A G
authors.initials: LA
authors.lastname: Marshman
authors.forename: Howard L
authors.initials: HL
authors.lastname: Brydon
mesh_terms: D015901:Angiography, Digital Subtraction; D002941:Circle of Willis / Q000002:abnormalities* / Q000000981:diagnostic imaging / Q000473:pathology*; D006801:Humans; D002532:Intracranial Aneurysm / Q000150:complications* / Q000000981:diagnostic imaging / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D019635:Neurosurgical Procedures; D012422:Rupture, Spontaneous; D013345:Subarachnoid Hemorrhage / Q000473:pathology* / Q000503:physiopathology; D013525:Surgical Instruments; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D014656:Vascular Surgical Procedures