Chronic Subdural Hematoma

A chronic subdural hematoma is a collection of old blood and fluid between the surface of the brain and its outermost covering (the dura). It typically affects older adults and develops slowly over weeks or months, often after a seemingly minor head bump. As it expands, it compresses the brain and can cause progressive neurological and cognitive symptoms.

What Is Chronic Subdural Hematoma?

A chronic subdural hematoma (cSDH) occurs when bridging veins tear, usually due to mild trauma. Because the brain normally shrinks slightly with age (atrophy), these veins are stretched and more easily broken. The initial small bleed slowly liquefies, and an inflammatory membrane forms around it. This membrane repeatedly leaks fluid and microscopic amounts of new blood, causing the hematoma to gradually enlarge and compress the underlying brain tissue.

At a Glance

Most common in adults over 60, often developing weeks to months after a minor head injury
Risk factors include advanced age, blood thinners and frequent falls
Symptoms often mimic dementia, stroke, or Parkinson's disease, including confusion and weakness
Diagnosis is quickly confirmed with a non-contrast CT scan of the head
Treatment ranges from observation for small bleeds to surgical drainage (burr holes) for symptomatic collections

Symptoms

Diagnosis

Non-contrast CT scan — the gold standard; shows a crescent-shaped, hypodense (dark) or isodense (gray) fluid collection pressing on the brain.
MRI of the brain — may be used to identify smaller or complex hematomas and evaluate the exact age of the blood products.
Neurological exam — assesses cognitive function, balance and focal weakness to determine the severity of brain compression.

Types

Treatment

Observation — for small, asymptomatic hematomas. Includes serial CT scans and possibly adjusting blood-thinning medications.
Burr Hole Evacuation — the standard surgical treatment. One or two small holes are drilled in the skull to drain the fluid, and a temporary drain is often left in place for 24-48 hours to prevent fluid re-accumulation.
Mini-Craniotomy — opening a slightly larger window of bone to remove thick or multi-loculated (compartmentalized) hematomas.
Middle Meningeal Artery (MMA) Embolization — a newer, minimally invasive endovascular procedure that blocks the blood supply to the hematoma's inflammatory membrane, halting its growth and promoting natural absorption.

Outcomes

Treatment	Efficacy	Notes
Burr Hole Evacuation	Highly effective (~80-90% success)	Recurrence rate is ~10-20%, sometimes requiring repeat drainage
MMA Embolization	Promising for reducing recurrence	Often used as an adjunct to surgery or as a primary treatment for mild cases
Observation	Variable	Only safe for small, asymptomatic collections; requires close monitoring

References

Our Specialists

Paramita Das, MD, MS

Neurosurgery

P.B. Raksin, MD

Neurosurgery

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