Neurology · Traumatic Brain Injury
The facts most likely to be tested
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Subdural hematomas result from the rupture of bridging veins that traverse the subdural space.
Non-contrast CT of the head reveals a crescent-shaped hyperdensity that crosses suture lines.
Elderly patients and chronic alcoholics are at highest risk due to cerebral atrophy, which increases the length and tension of bridging veins.
Clinical presentation often involves a fluctuating level of consciousness or a gradual decline in mental status following minor head trauma.
Chronic subdural hematomas appear hypodense or isodense on CT due to the breakdown of blood products over several weeks.
Infants presenting with a subdural hematoma in the absence of significant trauma should raise immediate suspicion for non-accidental trauma or shaken baby syndrome.
Surgical intervention via burr hole craniostomy or craniotomy is indicated for symptomatic patients or those with a midline shift greater than 5 mm.
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A 78-year-old male is brought to the emergency department by his daughter due to increasing confusion and lethargy over the past two weeks. The patient has a history of hypertension and alcohol use disorder. He reports a minor fall where he bumped his head on a door frame approximately three weeks ago, but he did not lose consciousness at that time. On physical examination, he is oriented only to person and exhibits a mild left-sided hemiparesis. A non-contrast head CT shows a crescent-shaped, hypodense collection along the right cerebral hemisphere that crosses suture lines and causes a midline shift.
What is the most likely diagnosis?
Chronic subdural hematoma
The patient's presentation of a gradual decline in mental status following minor trauma, combined with the classic crescent-shaped lesion that crosses suture lines on CT, is pathognomonic for a subdural hematoma.
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Etiology / Epidemiology
Caused by tearing of bridging veins; most common in elderly and alcoholics due to brain atrophy.
Clinical Manifestations
Presents with fluctuating consciousness and progressive headache/focal deficits; a lucid interval is classically associated with epidural hematoma (though it can occasionally occur with subdural).
Diagnosis
Non-contrast CT head shows a crescent-shaped hyperdensity that crosses suture lines.
Treatment
Small bleeds managed with observation; large or symptomatic bleeds require surgical evacuation.
Prognosis
High mortality in elderly; monitor for increased intracranial pressure and herniation.
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Epidemiology & Etiology
Common in patients with brain atrophy (elderly, chronic alcohol use) which increases the length of bridging veins. Often follows minor head trauma that may be forgotten by the patient. Anticoagulant use is a major risk factor for expansion.
Pertinent Anatomy
Bleeding occurs between the dura mater and the arachnoid mater. The hematoma is not limited by suture lines, allowing it to spread over the entire hemisphere.
Pathophysiology
Shearing forces rupture the bridging veins that drain the cerebral cortex into the dural venous sinuses. The resulting venous bleed is typically slower than arterial bleeds, leading to a subacute or chronic clinical course. As the hematoma ages, it may liquefy and expand due to osmotic pressure.
Clinical Manifestations
Patients often present with altered mental status, focal neurological deficits, or a lucid interval followed by decline. Cushing's triad (bradycardia, hypertension, irregular respirations) indicates impending herniation. Chronic cases may present with vague symptoms like personality changes or gait instability.
Diagnosis
Non-contrast CT head is the gold standard for initial evaluation. The hematoma appears as a crescent-shaped hyperdensity that crosses suture lines. If the CT is negative but suspicion remains high, MRI is more sensitive for subacute or isodense chronic hematomas.
Treatment
Small, asymptomatic hematomas with minimal midline shift are managed with serial CT scans and observation. Symptomatic patients or those with midline shift > 5mm require surgical evacuation via burr hole or craniotomy. Avoid anticoagulants and manage increased intracranial pressure with head elevation and hyperventilation if necessary.
Prognosis
Prognosis depends on the Glasgow Coma Scale score at presentation and the presence of underlying brain injury. Chronic subdural hematomas have a high rate of recurrence, requiring close follow-up. Seizures are a common long-term complication.
Differential Diagnosis
Epidural Hematoma: lens-shaped, does not cross suture lines, usually arterial
Subarachnoid Hemorrhage: thunderclap headache, blood in cisterns
Intracerebral Hemorrhage: focal deficits, often hypertensive origin
Meningitis: fever, nuchal rigidity, altered mental status
Dementia: chronic cognitive decline without acute trauma history