Neurology · Cerebrovascular Disease
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The classic presentation of a subarachnoid hemorrhage is a thunderclap headache described as the worst headache of life reaching maximal intensity within seconds.
The initial diagnostic test of choice for a suspected subarachnoid hemorrhage is a non-contrast head CT to identify acute blood in the subarachnoid space.
A lumbar puncture is mandatory if the non-contrast head CT is negative but clinical suspicion remains high, looking for xanthochromia or elevated red blood cell count that does not clear between tubes.
The most common underlying etiology of a non-traumatic subarachnoid hemorrhage is the rupture of a saccular (berry) aneurysm.
Patients with autosomal dominant polycystic kidney disease (ADPKD) and Ehlers-Danlos syndrome are at significantly increased risk for berry aneurysm formation and subsequent rupture.
Nimodipine is the standard of care administered to prevent delayed cerebral ischemia caused by vasospasm, which typically occurs 3 to 10 days after the initial bleed.
Cerebral angiography (digital subtraction angiography) is the gold standard for identifying the location and morphology of the aneurysm for surgical or endovascular intervention.
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A 48-year-old female presents to the emergency department after experiencing a sudden, severe headache while exercising. She describes the pain as the worst headache of her life, which reached peak intensity within seconds. On physical exam, she is alert but has mild nuchal rigidity and photophobia. A non-contrast head CT is performed and is negative for acute hemorrhage. Her blood pressure is 145/90 mmHg.
What is the most appropriate next step in the management of this patient?
Lumbar puncture
This patient presents with a classic thunderclap headache, and a negative non-contrast CT does not rule out a subarachnoid hemorrhage, necessitating a lumbar puncture to evaluate for xanthochromia.
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High yield triage
Etiology / Epidemiology
Most commonly caused by ruptured berry aneurysm at the Circle of Willis. Smoking and hypertension are primary modifiable risk factors.
Clinical Manifestations
Sudden onset thunderclap headache described as the worst headache of life. May present with nuchal rigidity and photophobia.
Diagnosis
Non-contrast CT head is the initial test of choice. If negative, lumbar puncture is required to look for xanthochromia.
Treatment
Maintain systolic BP < 160 mmHg using nicardipine. Administer nimodipine to prevent delayed cerebral ischemia.
Prognosis
High mortality rate; rebleeding is a major risk within the first 24-48 hours. Vasospasm is the leading cause of morbidity.
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Epidemiology & Etiology
Peak incidence occurs between ages 50-60. Autosomal dominant polycystic kidney disease and Ehlers-Danlos syndrome are high-yield genetic associations. Rupture of a saccular (berry) aneurysm accounts for 80% of non-traumatic cases.
Pertinent Anatomy
Aneurysms typically arise at arterial bifurcations within the Circle of Willis, most commonly the anterior communicating artery. Bleeding occurs into the subarachnoid space, causing rapid elevation of intracranial pressure.
Pathophysiology
Arterial wall weakness leads to aneurysm formation and subsequent rupture under high-pressure stress. Blood extravasation causes meningeal irritation and acute hydrocephalus. Secondary vasospasm occurs 3-14 days post-bleed due to breakdown of blood products.
Clinical Manifestations
Patients report a thunderclap headache reaching peak intensity within seconds. Red flags include loss of consciousness, seizures, and focal neurologic deficits. Physical exam may reveal Kernig's or Brudzinski's signs indicating meningeal irritation.
Diagnosis
Perform non-contrast CT head immediately; sensitivity is near 100% within 6 hours of onset. If CT is negative but suspicion remains high, lumbar puncture is the gold standard to detect xanthochromia (yellowish CSF due to bilirubin). Cerebral angiography is required to localize the aneurysm for surgical planning.
Treatment
Stabilize airway and control blood pressure with nicardipine or labetalol. Avoid anticoagulants and manage intracranial pressure. Initiate nimodipine to reduce neurological deficits from vasospasm. Surgical clipping or endovascular coiling is definitive management.
Prognosis
Significant risk of rebleeding and delayed cerebral ischemia. Patients require strict ICU monitoring for vasospasm and hydrocephalus. Long-term outcomes are often poor, with high rates of permanent neurological disability.
Differential Diagnosis
Migraine: usually recurrent with aura
Meningitis: associated with fever and leukocytosis
Cervical artery dissection: associated with neck pain and trauma
Pituitary apoplexy: associated with visual field defects
Intracerebral hemorrhage: usually presents with focal deficits