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A common neurologic disorder that affects mainly older individuals.

It has been increasing in prevalence, owing to the aging of the population, and the widespread use of anticoagulant medications.

Chronic subdural hematomas may begin as a subdural hygroma, which begins as a separation in the dura-arachnoid interface.

This space is then filled by CSF and the dural border cells proliferate around this fluid collection producing a neomembrane into which blood vessels grow, and which can hemorrhage with the growth of a chronic subdural hematoma.

It is characterized by a collection of blood and blood breakdown products in the intracranial subdural space that overtime liquefies.

Chronic subdural hematomas may also evolve from the liquefaction of an acute bleed.

it is postulated that an inflammatory response occurs as a reaction to fluid collection, which leads to expansion of the clot and clinical symptoms.

Liquefaction of an acute subdural hematoma usually occurs after 1-3 weeks, with the hematoma appearing hypodense on a CT scan.

Chronic SDHs may have membranes between the dura and hematoma at 1 week and between the brain and hematoma at 3 weeks.

The chronic phase begins about 2-3 weeks after acute injury.

Minor head trauma often precedes the development of the hematoma, however, the disorder can occur in the absence of trauma.

Men have a higher incidence of chronic SDH with the male-to-female ratio 2:1.

Most adults with chronic SDH are older than 50 years.

The inciting event is often a minor head trauma, and subsequently inflammation may play a role in the pathogenesis.

Its time of onset is often unknown.

Its incidence is increasing owing to an aging population, the use of anticoagulant and antiplatelet medications.

It is projected to become one of the most common cranial neurosurgical procedures among adults.

One quarter to one half of patients with chronic SDH have no history of head trauma, and if there is a history of such trauma it is mild.

The average time between the occurrence of the head trauma and the diagnosis of a chronic subdural hematoma is between 4-5 weeks.

Presentation for chronic SDH is often insidious.

Symptoms include:headache, impaired level of consciousness, impaired gait or balance, cognitive impairment, motor deficits, or aphasia.

Patients with subdural hematoma may present with Parkinsonism or acutely as well.

Reported to be bilateral in 8.7-32% of cases.

Two-thirds of cases occurring in patients over the age of 65 and 40% in those aged over 75.

In younger patients it generally occurs in patients with premature cerebral atrophy and/or a propensity to minor head injuries-either in patients with epilepsy or in alcoholics.

Diagnosis is made on the basis of cranial imaging.

Surgery for chronic subdural hematoma may be indicated if the patient is symptomatic or it is producing significant mass effect.

A chronic SDH with minimal or no mass effect and no neurological symptoms or signs can often observed with serial scans and it may resolve without surgery.

Surgical evaluation is the main treatment approach for symptomatic patients, but hematoma occurs in 10-20% of surgically treated patients.

Surgical evacuation of the hematoma by means of a burr hole craniotomy often combine with the placement of a subdural or subperiosteal drain is the mainstay of treatment, for symptomatic patients.

Surgical drainage has a risk of death, and up to 10% of patients have recurrence of the sub dural collection of fluid.

In a randomized placebo controlled trial assessing the effectiveness of dexamethasone in patients with symptomatic chronic subdural hematoma, most who have undergone surgery, results in fewer favorable outcomes and more adverse events than placebo at six months, but is associated with fewer repeat operations (Hutchinson PJ).

Dexamethasone potentially blocks inflammatory changes in the subdural space, impeding hematoma, persistence, and growth.

In a trial involving patients with chronic subdur hematoma, dexamethasone treatment was not found to be non-inferior to burr hole drainage with respect to functional outcomes, and was associated with more complications in greater likelihood of later surgery (DECSA collaborators.)

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