Traumatic subarachnoid hemorrhage

Traumatic subarachnoid hemorrhage (from Latin sub- — under and Greek arachne — web, haima — blood) is a pathological accumulation of leaked blood in the space between the pia mater and arachnoid membranes of the brain.

This condition is caused by a mechanical impact to the head and is one of the most common consequences of brain contusion.

Etiology and pathophysiology

Normally, the subarachnoid space is filled with clear cerebrospinal fluid that circulates around the brain. With severe impact, friction of brain tissue against the bone protuberances of the skull or crushing of the cerebral cortex causes rupture of the small superficial pial blood vessels.

Blood under pressure enters the subarachnoid space, mixes with cerebrospinal fluid, and quickly spreads along the sulci and basal cisterns of the brain. Unlike spontaneous hemorrhage (which occurs due to an aneurysm rupture), the traumatic type is invariably associated with primary mechanical damage to the brain tissue itself. Breakdown products of erythrocytes have a strong chemical irritant effect on the meninges and cause their acute aseptic inflammation.

Clinical significance

The clinical picture is characterized by unbearable headache, photophobia, and repeated vomiting. A rapidly developing syndrome, known as meningeal syndrome, is noted, the main feature of which is pronounced rigidity (tension) of the neck muscles – the patient physically cannot bend the chin to the chest.

This condition does not require surgical removal of the blood itself, as it is distributed in a thin layer across the entire brain. However, it is dangerous due to severe delayed complications. Blood clots may obstruct the pathways for cerebrospinal fluid outflow, causing post-traumatic hydrocephalus (water on the brain). Additionally, the chemical effect of blood on the major arteries at the base of the brain often provokes their persistent spasm (vasospasm), leading to secondary ischemic stroke several days post-injury.