Subdural Hematoma

Introduction

• Subdural hematoma (SDH) is usually secondary to traumatic head injury
• Subdural hematomas have been classified based on the time they become clinically symptomatic following injury into acute, subacute and chronic subdural hematomas
• A typical clinical scenario includes a patient with history of head injury that is followed by worsening neurological state
• CT shows a crescent shaped collection of blood that DOES cross the suture lines. The midline might shift in some cases

Classifications Based on Timing

• Acute subdural hematoma — less than 3 days
• Subacute subdural hematoma — 4 - 21 days
• Chronic subdural hematoma — more than 21 days

Classifications Based on CT scan

• This classification depends on the density of the hematoma in relation to the adjacent brain tissue
• Acute SDH is hyperdense (white)
• Chronic SDH is hypodense

Acute Subdural Hematoma

• Motor vehicle accidents are common causes of aSDH in children and young adults; older adults, especially those on anticoagulants and antiplatelet agents, may present after a minor fall
• Acute SDH are bilateral in approximately one-third of cases (epidural hematomas are only bilateral in 3% of cases only)
• It is accompanied by a fracture in the cranial vault or base of the skull in nearly 80% of cases
• Treatment of acute SDH requires evacuation of the hematoma (a craniotomy is nearly always necessary for this condition)

Clinical Presentation in Acute SDH

• An acute SDH should be suspected in a patient who presents with a severe head injury whose neurological state is either failing to improve or deteriorating
• An acute SDH must be distinguished from epidural hematomas that usually have a lucid interval of improvement

Acute SDH Prognosis

• Many factors may influence outcome of patients such as patient age and size of the hematoma
• Mortality rates in patients younger than 40 years were nearly 20%, whereas age 40 - 80 years was associated with a mortality rate of 65%. Patients older than 80 years had a mortality rate of nearly 88%
• Many patients do not regain their previous levels of functioning, especially after an acute subdural hematoma that was very severe and required surgical intervention
• Poor prognostic indicators include low Glasgow coma score on admission (less than 5), pupillary abnormalities, alcohol use, and difficulty in controlling intracranial pressure

Chronic Subdural Hematoma

• One-third of patients have no definite history of preceding head trauma
• Non-traumatic chronic SDH is related to rupture of fragile bridging veins in a relatively atrophic brain (patients are usually over 50 years)
• Shrinkage of the brain (due to atrophy) allows the brain to move more freely. A relatively minor injury can lead to movement of the brain and subsequent rupture of the bridging veins
• Chronic SDH is mainly concerning for patients who are on anticoagulant therapy. They are prone to develop SDH after a relatively minor trauma
• Treatment of chronic SDH requires evacuation of the hematoma (through burr holes or craniotomy)

Clinical Presentation in Chronic SDH

• The predominant characteristic symptom is a decline in the level of consciousness and the patient might become abruptly unconscious
• A progressive dementia (might be mistaken for Alzheimer’s disease). However, the course of the dementia in chronic SDH cases is usually more rapid and progressive

Chronic SDH Prognosis

• Morbidity and mortality rates with surgical treatment of chronic subdural hematoma are estimated at 11% and 5%
• No clear prognostic indicators are associated with chronic SDH. However, early diagnosis and intervention before significant neurological deterioration may be related with a more favorable prognosis

Diagnosis

• CT scan is the radiological investigation of choice
• Acute SDH is hyperdense (white)
• Chronic SDH is hypodense

Treatment

• Treatment of subdural hematoma is craniotomy to evacuate the collection of blood

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