Subgaleal hematoma

Subgaleal hematoma (from Latin sub- — under, galea — helmet, and Greek haematoma — blood tumor) is an extensive pathological accumulation of liquid blood in the space of loose connective tissue, strictly located between the tendinous helmet and the periosteum of the skull.

Etiology and pathophysiology

This areolar space (layer ‘L’ in the structure of the scalp) is absolutely free. It lacks any fascial septa or barriers, therefore it anatomically encompasses the entire calvaria from the supraorbital ridges anteriorly to the superior nuchal line posteriorly.

Hemorrhage in this zone most often occurs with a strong tangential blow to the head, traction injury (for example, grabbing the hair), or the use of a vacuum extractor in complicated childbirth. The source of massive bleeding is the damaged emissary veins — vessels passing through the bones of the cranium and connecting external tissues with intracranial venous sinuses.

Clinical significance

Due to the lack of anatomical constraints, the subgaleal hematoma is capable of containing an enormous volume of blood. In adults, the volume of hemorrhage can reach several hundred milliliters, while in newborns, blood loss into this space can quickly lead to life-threatening hemorrhagic shock.

Visually, the hematoma spreads across the entire head. Under the influence of gravity, blood often descends to the facial region, forming extensive secondary hemorrhages around the eyes (“raccoon eye” symptom). On palpation, a distinct fluctuation symptom is determined — a wave-like rolling of the fluid under the fingers. Unlike cephalohematoma, the subgaleal blood collection freely crosses cranial suture lines. Treatment requires careful monitoring, control of blood parameters, and, in rare cases, puncture removal of fluid.