Traumatic Subarachnoid Hemorrhage
Traumatic subarachnoid hemorrhage (tSAH) is bleeding into the subarachnoid space surrounding the brain surface (the space containing cerebrospinal fluid) following head trauma. It is the most common type of bleeding in moderate-to-severe head injury. The course is usually good with isolated, thin bleeds, but can be more serious when accompanied by other lesions.
最終更新: 2026-06-07
Definition
Traumatic subarachnoid hemorrhage is the leakage of blood, after head trauma, into the subarachnoid space between the arachnoid membrane and the pia mater, which contains cerebrospinal fluid. It occurs in a substantial proportion of moderate-to-severe head injuries and is the most common type of traumatic intracranial bleeding. The blood usually collects in the surface folds of the brain (sulci), in the fissures and in the basal cisterns. Distinguishing it from spontaneous subarachnoid hemorrhage caused by a ruptured aneurysm, based on the distribution of the bleeding, is important.
Causes and Mechanism
A direct impact or acceleration-deceleration injury tears the small vessels on the brain surface (pial arteries, capillaries, cortical veins), causing bleeding into the subarachnoid space. The bleed is often associated with areas of brain contusion and laceration and may accompany diffuse axonal injury. Possible complications include acute hydrocephalus from blood obstructing cerebrospinal fluid circulation, relatively rare and mild vascular spasm (vasospasm), late chronic hydrocephalus and seizures.
Symptoms
In isolated, thin traumatic subarachnoid hemorrhage the patient is usually alert; signs of meningeal irritation such as a sudden headache, neck stiffness, nausea and vomiting and sensitivity to light (photophobia) may be present. In moderate-to-severe cases with accompanying lesions, impairment of consciousness, focal neurological signs such as weakness on one side of the body and seizures may develop. In the later period, neurological deterioration due to vascular spasm, or headache, cognitive slowing and gait disturbance due to chronic hydrocephalus may occur.
Diagnosis
Non-contrast brain CT is the gold standard; hyperdense (bright) blood is seen in the subarachnoid space within the sulci, fissures and basal cisterns. If the history of trauma is unclear or the distribution of bleeding suggests an aneurysm, CT angiography is used to look for an aneurysm and, if needed, digital subtraction angiography (DSA) is performed. Magnetic resonance imaging is more sensitive in the subacute-chronic phase and for showing accompanying diffuse axonal injury. Lumbar puncture is not appropriate in this setting because of the risk of raised intracranial pressure and herniation.
Treatment Options
A conservative approach is sufficient in most cases. In mild, isolated traumatic subarachnoid hemorrhage, close neurological observation, pain management and supportive care are provided. Where accompanying lesions are present, seizure prophylaxis may be considered in the early period. If acute obstructive hydrocephalus develops, an external ventricular drain may be needed to drain cerebrospinal fluid; in the later period a shunt may be placed for persistent hydrocephalus. In severe cases, intracranial pressure monitoring and, where required, decompression with osmotic therapy are considered. Management of vascular spasm is undertaken selectively.
Course and Recovery
The course of traumatic subarachnoid hemorrhage depends on the amount of bleeding and the accompanying brain lesions. Recovery is generally good with isolated, thin bleeds, and most patients can return to their previous functional level. With widespread bleeding or accompanying contusion, subdural hematoma or diffuse axonal injury, the course can be more severe, and persistent problems such as cognitive slowing, headache and fatigue may occur. Younger age, a high level of consciousness on presentation and an isolated lesion are associated with a more favorable course. Outcomes vary from patient to patient and cannot be guaranteed.
参考文献
- Greenberg MS. Greenberg's Handbook of Neurosurgery. 10th ed. Thieme; 2023:1006-1019.
- Carney N, Totten AM, O'Reilly C, et al. Guidelines for the Management of Severe Traumatic Brain Injury. 4th ed. Neurosurgery. 2017;80(1):6-15.
- Mata-Mbemba D, Mugikura S, Nakagawa A, et al. Traumatic midline subarachnoid hemorrhage on initial computed tomography as a marker of severe diffuse axonal injury. J Neurosurg. 2018;129(5):1317-1324.
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