Subdural Space

The subdural space (from Latin: sub- — beneath and dura — dura mater) is a potential anatomic cleft space in the cranial cavity. It is located between the inner surface of the dura mater and the outer surface of the arachnoid mater.

Etiology and pathophysiology

In a healthy organism, this space effectively does not exist. Both layers are completely smooth and tightly pressed against each other. Between them lies only a very thin capillary layer that prevents friction of the membranes during brain pulsations.

However, these membranes do not have rigid connective tissue links or adhesions. Therefore, when traumatic vessel rupture occurs, the spilled blood (or fluid) easily separates them. The pathological mass acts as a hydraulic wedge, dissects the membranes, and creates a wide pocket.

Clinical significance

It is in this dissected space that highly dangerous traumatic pathologies form: subdural hematomas (accumulation of venous blood) and subdural hygromas (accumulation of leaked cerebrospinal fluid).

The most significant clinical feature of this space lies in its continuity. As a result, the leaked blood does not accumulate as a local clot but freely spreads across the hemisphere surface in a thin crescent- or half-moon-shaped layer. This leads to extensive and severe compression of the entire cerebral cortex.