Safety Optimization of Injections in Specific Areas of the Scalp: A Cadaveric and 3D-CT Analysis of Arterial Distribution.

Background: An injection method called cranial ceiling elevation is used in Asian countries to reduce facial proportions. Scalp injections carry risks such as arterial embolism or compression, leading to adverse events including scalp necrosis and hair loss.

Objective: No arterial studies or injection recommendations exist for the injection of specific scalp regions. We aimed to examine blood vessel types and distributions to identify relatively safe areas for scalp injections.

Methods: Computed tomography scans were used to evaluate the blood vessels in the scalp of 50 cadaver heads and anatomical studies were performed. Each scalp was divided into two segments (L1/L2) and six areas (S1/S1'-S3/S3'). The total number of arteries and the probability of each named artery occurring in each section were recorded.

Results: The total number of arteries in L1 was higher than that in L2 (L1, 78.76 ± 31.07; L2, 75.28 ± 28.68). The most frequently distributed artery in both L1 and L2 was the parietal branch of the superficial temporal artery. No significant difference was observed between the total number of arteries and the number of each named artery in the S1/S1'-S3/S3' segments. Except for S2' and S3', the number of named arteries in L1 was higher than that in L2.

Conclusions: Large-volume scalp injections are not recommended. For injections within 30° above the ear, it is advisable to inject at L2. For other regions, it is also recommended to inject at L2. The periosteal layer should be selected for injection.