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Emergency and Acute Medicine - Subarachnoid Hemorrhage
Subarachnoid hemorrhage (SAH) is bleeding into the subarachnoid space and cerebrospinal fluid, most commonly due to rupture of a cerebral aneurysm. It is a life-threatening neurologic emergency with high mortality, ranging from 30–50%. It typically affects adults, with peak incidence in the sixth decade, and is rare before the third decade. Important risk factors include hypertension, smoking, alcohol abuse, stimulant drug use such as cocaine, female sex, and a family history of SAH. Certain genetic conditions, including polycystic kidney disease and connective tissue disorders, further increase risk.
The most common cause of spontaneous SAH is rupture of a saccular (berry) aneurysm, accounting for 80–90% of cases, usually occurring at arterial bifurcations within the circle of Willis. Other causes include arteriovenous malformations, arterial dissections, intracranial tumors, and mycotic aneurysms. Traumatic SAH is also seen in severe head injuries.
Patients classically present with a sudden, severe headache often described as a “thunderclap headache” or the “worst headache of life,” reaching maximal intensity within seconds. This headache is typically different from prior headaches. Associated features include vomiting, transient loss of consciousness, seizures, neck stiffness, and focal neurologic deficits. A “sentinel headache,” representing a minor bleed, may occur days to weeks before the major event in up to half of patients.
On examination, patients may have nuchal rigidity, altered mental status, and focal neurologic deficits. Cranial nerve involvement, particularly third nerve palsy presenting as a “down and out” eye, may be seen. Retinal hemorrhage can occasionally be the only clue, especially in comatose patients.
Diagnosis begins with an emergent noncontrast CT scan of the head, which detects SAH in up to 98% of cases if performed within 12 hours of symptom onset. If the CT scan is negative but clinical suspicion remains high, a lumbar puncture must be performed. The presence of red blood cells in the cerebrospinal fluid or xanthochromia confirms the diagnosis. Further imaging, such as CT angiography or digital subtraction angiography, is used to identify the source of bleeding, while transcranial Doppler may be used to monitor for vasospasm.
Management is focused on rapid stabilization and prevention of complications. Initial priorities include airway protection, oxygenation, cardiac monitoring, and establishing intravenous access. Blood pressure must be carefully controlled to reduce the risk of rebleeding while maintaining adequate cerebral perfusion, with a target systolic pressure below 160 mmHg. Measures to reduce intracranial pressure include head elevation, avoidance of straining, and use of antiemetics and stool softeners. In selected cases, mannitol and controlled ventilation may be required.
All patients should receive Nimodipine to reduce the risk of delayed cerebral vasospasm and improve neurologic outcomes. Seizures should be treated promptly with benzodiazepines, and metabolic abnormalities should be corrected. Definitive management involves urgent neurosurgical intervention, either by surgical clipping or endovascular coiling of the aneurysm.
All patients with confirmed or suspected SAH require admission to an intensive care unit. Early recognition and treatment are critical, as mortality is high and many patients deteriorate rapidly. A key pitfall is failure to consider SAH in patients presenting with acute severe headache, or stopping evaluation after a negative CT scan without proceeding to lumbar puncture when indicated.
Subarachnoid hemorrhage (SAH) is bleeding into the subarachnoid space and cerebrospinal fluid, most commonly due to rupture of a cerebral aneurysm. It is a life-threatening neurologic emergency with high mortality, ranging from 30–50%. It typically affects adults, with peak incidence in the sixth decade, and is rare before the third decade. Important risk factors include hypertension, smoking, alcohol abuse, stimulant drug use such as cocaine, female sex, and a family history of SAH. Certain genetic conditions, including polycystic kidney disease and connective tissue disorders, further increase risk.
The most common cause of spontaneous SAH is rupture of a saccular (berry) aneurysm, accounting for 80–90% of cases, usually occurring at arterial bifurcations within the circle of Willis. Other causes include arteriovenous malformations, arterial dissections, intracranial tumors, and mycotic aneurysms. Traumatic SAH is also seen in severe head injuries.
Patients classically present with a sudden, severe headache often described as a “thunderclap headache” or the “worst headache of life,” reaching maximal intensity within seconds. This headache is typically different from prior headaches. Associated features include vomiting, transient loss of consciousness, seizures, neck stiffness, and focal neurologic deficits. A “sentinel headache,” representing a minor bleed, may occur days to weeks before the major event in up to half of patients.
On examination, patients may have nuchal rigidity, altered mental status, and focal neurologic deficits. Cranial nerve involvement, particularly third nerve palsy presenting as a “down and out” eye, may be seen. Retinal hemorrhage can occasionally be the only clue, especially in comatose patients.
Diagnosis begins with an emergent noncontrast CT scan of the head, which detects SAH in up to 98% of cases if performed within 12 hours of symptom onset. If the CT scan is negative but clinical suspicion remains high, a lumbar puncture must be performed. The presence of red blood cells in the cerebrospinal fluid or xanthochromia confirms the diagnosis. Further imaging, such as CT angiography or digital subtraction angiography, is used to identify the source of bleeding, while transcranial Doppler may be used to monitor for vasospasm.
Management is focused on rapid stabilization and prevention of complications. Initial priorities include airway protection, oxygenation, cardiac monitoring, and establishing intravenous access. Blood pressure must be carefully controlled to reduce the risk of rebleeding while maintaining adequate cerebral perfusion, with a target systolic pressure below 160 mmHg. Measures to reduce intracranial pressure include head elevation, avoidance of straining, and use of antiemetics and stool softeners. In selected cases, mannitol and controlled ventilation may be required.
All patients should receive Nimodipine to reduce the risk of delayed cerebral vasospasm and improve neurologic outcomes. Seizures should be treated promptly with benzodiazepines, and metabolic abnormalities should be corrected. Definitive management involves urgent neurosurgical intervention, either by surgical clipping or endovascular coiling of the aneurysm.
All patients with confirmed or suspected SAH require admission to an intensive care unit. Early recognition and treatment are critical, as mortality is high and many patients deteriorate rapidly. A key pitfall is failure to consider SAH in patients presenting with acute severe headache, or stopping evaluation after a negative CT scan without proceeding to lumbar puncture when indicated.
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