title: Chemical analysis of fluid obtained from intracranial arachnoid cysts in pediatric patients.
abstract: OBJECTIVE
  The authors analyzed the chemical composition of intracranial arachnoid cyst fluid to gain greater understanding of potential causes of cyst growth.
  
  
  METHODS
  The authors studied 54 pediatric patients who underwent craniotomies for arachnoid cyst fenestration. Cyst fluid was analyzed and results were compared with expected values (EVs) for cerebrospinal fluid (CSF). The arachnoid cyst fluid values were as follows: protein (median 37 mg/dl, mean 178.2 mg/dl, and EV 25.6 mg/dl), osmolality (median 284 mOsm/kg, mean 285.5 mOsm/kg, and EV 287.2 mOsm/kg), potassium (median 2.6 mEq/L, mean 2.68 mEq/L, and EV 2.88 mEq/L), sodium (median 140 mEq/L, mean 142.2 mEq/L, and EV 143.3 mEq/L), and chloride (median 122 mEq/L, mean 120.77 mEq/L, and EV 120.3 mEq/L). Median glucose was 51 mg/dl (range 26-98 mg/dl). The median white blood cell count in cyst fluid was 1/mm3, and the median red blood cell (RBC) count was 1.5/mm3. All Gram stains and cultures were negative. No statistically significant correlations were found between arachnoid cyst fluid protein level and elevated RBC count, patient age, or the subsequent need for a shunt. Elevated RBC count in cyst fluid was also not associated with the subsequent need for a shunt.
  
  
  CONCLUSIONS
  Fluid from arachnoid cysts has a chemical composition similar to that of CSF, but some of them have significantly elevated protein levels. The authors hypothesize that elevated protein content may contribute to arachnoid cyst expansion in some patients.
authors.affiliation: Division of Neurosurgery, Childrens Hospital Los Angeles, California, USA.
authors.forename: David I
authors.initials: DI
authors.lastname: Sandberg
authors.forename: J Gordon
authors.initials: JG
authors.lastname: McComb
authors.forename: Mark D
authors.initials: MD
authors.lastname: Krieger
mesh_terms: D000293:Adolescent; D016080:Arachnoid Cysts / Q000737:chemistry* / Q000503:physiopathology / Q000601:surgery; D002555:Cerebrospinal Fluid / Q000737:chemistry*; D002648:Child; D002675:Child, Preschool; D003399:Craniotomy; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D019635:Neurosurgical Procedures; D011506:Proteins / Q000032:analysis
chemical_list: D011506:Proteins