Cranial CT scan evaluation of morphological variations and location of pterion in Pakistani male population for lateral neurosurgical approach.

Objective: To determine the morphological variations and location of pterion in Pakistani male population.

Methods: This retrospective observational study was carried out in the Department of Radiology, Shifa International Hospital from December 2018 to June 2019. The sample size was calculated by Open Epi web-based calculator. Fifty-three cranial CT scans with slice thickness of 0.5mm; consecutive scans of males were randomly selected. The patients with no craniofacial fracture and ages from 25 to 45 years were included. The dataset was obtained from Toshiba Aquilion One, 360-slice MDCT. The images were imported into the imaging software PACS (WFM), and analyzed in maximum intensity projection mode with three dimensional multiplanar reconstruction viewers. Measurements were taken in lateral projections of skull in Frankfurt plane, as horizontal and vertical distance from the posterolateral margin of frontozygomatic suture to center of pterion. Vertical distance from the superior border of zygomaticotemporal arch to the center of pterion. The morphological types were also recognized.

Results: The type of pterion on right side was 94.3% sphenoparietal 5.6% epipteric whereas left side was (90.5%) sphenoparietal (3.7%) epipteric, (3.7%) stellate type, (1.8%) frontotemporal type. The mean horizontal and vertical frontozygomatic measurements on right side were 2.23 ± 0.22cm and 1.25±0.219 cm respectively. The same measurements on the left side were 2.27-±0.25 cm and 1.226-±0.22 cm respectively. The mean zygomaticotemporal measurements on the right and left sides were 3.45 ±0.29cm and 3.44 ±0.25 cm respectively. The mean distance on right and left side of skull was statistically insignificant.

Conclusion: The study provides useful data for position and location of pterion for safe neurosurgical procedures via pterion. Moreover, the knowledge about different morphological types of pterion help the radiologist to differentiate between a fracture line and normal morphological variety.