Human Arachnoid Granulation Topography

Quantification Significance for Idiopathic Intracranial Hypertension

Since arachnoid granulations help drain CSF into the venous circulation, the relationship between elevated CSF pressure and increased resistance across
the arachnoid membrane may be the mechanism behind intracranial hypertension.

Consequently, the number and distribution of arachnoid granulations is of great interest to IH researchers. Kapil Kapoor, B.S. and other investigators
at the Gryzbowski/Katz lab at Ohio State in Columbus, OH studied the topography of human arachnoid granulations. With a goal to physically map the areas where arachnoid granulations are present, Mr. Kapoor and his associates photographed and analyzed 33 brains. Two pictures, which depicted the two brain
hemispheres and the superior sagital sinus, were taken of each sample. The images were then transformed into segments, which enabled the researchers to identify the arachnoid granulations.

Mr. Kapoor and two independent investigators discovered that the arachnoid granulations were primarily distributed along the longitudinal fissure that separates the two hemispheres of the brain. Preliminary analysis revealed that that the average arachnoid granulation surface area for samples from the 38-53 year-old age group was 96.30mm.²  For ages 54-68, the surface area decreased to 74.14mm.², while for ages 68 years and older, the surface rose to 110.65mm².

A comparison of arachnoid granulation surface area as a proportion of total brain surface area was 0.006 for the 38-53 year-old group; 0.00677 for the 54-68 year-old group; and 0.008 for the 68+ year-old group. Total brain surface area by age was 1578 mm.² for the 38-53 year-old group; 1100 mm.² for the 54-68 year-old group; and 1218 mm.²  (It should be noted that total brain surface generally declines with age and must be considered when analyzing any of this data.)

Mr. Kapoor commented that additional data from more brain specimens will provide more robust statistics and further study of other variables that may affect the topographic distribution and quantity of arachnoid granulations including age, sex, race, height, weight and Body Mass Index (BMI).