title: Helmetlike skull deformity with a large arachnoid cyst.
abstract: BACKGROUND
  It is not difficult to find localized skull ballooning or macrocrania in patients with intracranial arachnoid cysts. However, there have been no previous reports regarding large localized skull protuberant deformities resembling a war helmet. The authors report with a review of literature a case of an adult with helmetlike skull deformity resulting from a large supratentorial arachnoid cyst.
  
  
  METHODS
  A 35-year-old man presented with a large head deformity since his early childhood that had been the result of gradual progression from infantile macrocrania. He also had mental retardation, sixth cranial nerve palsy with recent aggravation of headache, reduced activity, poor voiding control, and walking disturbance. Magnetic resonance imaging of the head showed hydrocephalus with a large supratentorial arachnoid cyst located in the bilateral parietooccipital area compressing the hemisphere anteriorly, and the tentorium and cerebellum inferiorly. Magnetic resonance venogram demonstrated low-lying short transverse and lateral sinuses, and the superior sagittal sinus and falx were displaced to the right side. Radioisotopic cisternogram showed nonfilling of the isotope in the bilateral parietooccipital area. Cerebrospinal fluid pressure measured by lumbar puncture was 17 cm H(2)O. We tentatively diagnosed the condition as normopressure hydrocephalus with a large supratentorial arachnoid cyst. His headache, reduced activity, poor voiding control, and walking disturbance improved after a cystoperitoneal shunt.
  
  
  CONCLUSIONS
  This might suggest that large arachnoid cysts found in childhood should be treated for prevention of skull deformity and late aggravation of increased intracranial pressure.
authors.affiliation: Department of Neurosurgery, Kangwon National University College of Medicine, Chunchon 200-701, Korea.
authors.forename: Seoung Woo
authors.initials: SW
authors.lastname: Park
authors.forename: Ki Hong
authors.initials: KH
authors.lastname: Cho
authors.forename: Yong Sam
authors.initials: YS
authors.lastname: Shin
authors.forename: Se Hyuk
authors.initials: SH
authors.lastname: Kim
authors.forename: Young Hwan
authors.initials: YH
authors.lastname: Ahn
authors.forename: Kyung Gi
authors.initials: KG
authors.lastname: Cho
authors.forename: Ji Soon
authors.initials: JS
authors.lastname: Huh
authors.forename: Soo Han
authors.initials: SH
authors.lastname: Yoon
mesh_terms: D000328:Adult; D016080:Arachnoid Cysts / Q000000981:diagnostic imaging / Q000473:pathology*; D006801:Humans; D006849:Hydrocephalus / Q000000981:diagnostic imaging / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D011877:Radionuclide Imaging; D012886:Skull / Q000000981:diagnostic imaging / Q000473:pathology*