Chronic Subdural Hematoma

Slow extravasation of blood into the subdural space between the dura and arachnoid membranes. Commonly seen neurosurgical condition associated with high morbidity and mortality


  • Slow extravasation of blood into the subdural space between the dura and arachnoid membranes
  • Commonly seen neurosurgical condition associated with high morbidity and mortality


  • Worldwide Incidence
    • 3-4/100,000/year in patients <65 years of age
    • 8-58/100,000/year in patients >65 years of age
    • 286/100,000/year in patients >80 years of age
    • May occur after weeks of minor head injury (usually >3 weeks)
  • Usually affects elderly and those on anticoagulant therapy
  • Estimated to affect 60,000 US population >65 years of age annually by 2030
  • Male to female ratio: 3:1
  • Bilateral in 20%


  • Rupture of bridging veins
  • Risk factors
    • Old age
    • Anticoagulant/antiplatelet therapy
    • Male gender
    • History of falls
    • Minor head trauma
    • Bleeding disorders
    • Seizure history
    • Alcohol use

Figure 1: Chronic Subdural Hematoma on CT

notion image
Case courtesy of UoE Radiology, Radiopaedia.org, rID: 34063


  • Initial trauma to the subarachnoid space leading to acute SDH→ fibrin accumulates→ organization, dissolution of fibrin and subdural hematoma→ activate inflammatory changes lead to collagen and fibroblast formation→ subdural neomembrane formation in more than 2 weeks→ formation of weak vascular capillaries that promote subsequent chronic subdural hematoma
  • Subdural hygroma: accumulation of CSF in the subdural space→ new blood vessel formation takes place→ bleeding from these newly formed vessels lead to the development of chronic subdural hematoma

Clinical Features

  • Headache
  • Nausea/vomiting
  • Mental status changes
    • Disorientation.
    • Lethargy
    • Cognitive dysfunction (a cause of reversible dementia-like symptoms)
    • Delirium
    • Coma
  • Seizures
  • Focal neurological deficits
    • Motor weakness
    • Hemiparesis
    • Hemisensory loss
    • Speech problems
  • Difficulty walking
  • Stroke

Clinical progression

  • The early period of injury
    • Traumatic brain injury causes hematoma development, also known as “seed” for chronic SDH
  • The latent period of hematoma growth
    • Hematoma grows slowly
    • Volume expansion
    • Significant neovascularization
    • Lasts weeks to years
    • Usually asymptomatic
  • The Period of clinical appearance
    • Clinical manifestations from raised intracranial pressure by enlarging hematoma.
    • Seizures
    • Coma
    • Brain herniation

Differential Diagnosis

  • Lymphoma
  • Metastasis
  • Sarcoma
  • Infectious
    • Neurocysticercosis
    • Bacterial empyema
  • Autoimmune disorders:
    • Wegener granulomatosis
    • Rosai-Dorfmann disease
    • Polyarteritis nodosa


  • CT Scan of Head: hypodense crescent-shaped mass but can be isodense or hyperdense
  • Additional CT findings
    • Grey-white junction shifts medially
    • Convexity sulci do not extend to the inner part of the skull
  • MRI of Brain
    • May be used when alternative diagnoses are suspected


  • Focused physical examination
  • Pupillary examination and GCS assessment
  • Emergent resuscitation with assessment of airway, breathing, and circulation., followed by emergent neuroimaging (CT head without contrast)
  • Neurosurgical consultation
  • Adequate intravenous access
  • Coagulopathy correction/reversal
  • Steroids medications
  • Antiepileptic medications: Phenytoin/fosphenytoin or Levetiracetam
  • Non-operative treatment: indicated in
    • Asymptomatic patients with small hematoma
    • Moribund patients with poor baseline function
  • Indication for Surgical intervention
    • Any size that is symptomatic
    • Radiological signs of significant brain compression
    • Radiological signs of impending midline shift
    • Radiologically more than 2mm
  • Surgical Technique
    • Burr hole craniotomy
      • Most commonly used.
      • Drilling burr hole over cerebral convexity.
      • 2 burr holes 5-8cm apart are drilled.
      • Dura is entered and irrigated with normal saline.
      • Silicone drainage is placed into the subdural space and drainage is done by connecting to a drainage system.
      • Drain removed after 48 hours.
      • Done under general anesthesia.
    • Twist drill craniotomy.
      • Relatively safe and less invasive method.
      • A small craniotomy is made using a hand drill.
      • Done under local anesthesia.
      • Higher recurrence rate.
    • Craniotomy.
      • Most invasive method used in the past.
      • Used for old, organized, multiseptated SDH.
      • Large bone flap is separated followed by irrigation and evacuation of the hematoma.
      • Higher morbidity than other surgical procedures.


  • Recurrence
  • Seizures
  • Subdural empyema
  • Intracerebral hemorrhage
  • Epidural hematoma
  • Pneumocephalus
  • Intracerebral abscess
  • Meningitis


  • Good clinical outcome after surgery in 80-90% of patients
  • Death rate: 0.5-4.3%
  • Recurrence rate nearly 70%
  • 10-20% of recurring cases require repeated surgical management


  • Asghar M, Adhiyaman V, Greenway MW, Bhowmick BK, Bates A. Chronic subdural haematoma in the elderly: a North Wales experience. J R Soc Med 2002;95:290–292.
  • Bourgeois P, Sleiman M, Louis E, et al. Chronic subdural hematoma in patients over 80 years of age [in French]. Neurochirurgie 1999;45:124–128.
  • Cousseau DH, Echevarria Martin G, Gaspari M, Gonorazky SE. Chronic and subacute subdural haematoma: an epidemiological study in a captive population [in Spanish]. Rev Neurol 2001;32:821–824.
  • Adhiyaman V, Asghar M, Ganeshram KN, Bhowmick BK. Chronic subdural haematoma in the elderly. Postgrad Med J 2002;78:71–5.
  • Santarius T, Kirkpatrick PJ, Ganesan D, Chia HL, Jalloh I, Smielewski P. Use of drains versus no drains after burr-hole evacuation of chronic subdural haematoma: a randomised controlled trial. Lancet (London, England) 2009;374:1067–73.
  • Asghar M, Adhiyaman V, Greenway M, Bhowmick BK, Bates A. Chronic subdural haematoma in the elderly—a North Wales experience. Journal of the royal society of medicine. 2002;95(6):290-2.
  • Miranda LB, Braxton E, Hobbs J, Quigley MR. Chronic subdural hematoma in the elderly: not a benign disease: clinical article. Journal of neurosurgery. 2011;114(1):72-6.
  • Kolias AG, Chari A, Santarius T, et al. Chronic subdural haematoma: modern management and emerging therapies. Nat Rev Neurol 2014;10(10):570–8.
  • Adhiyaman V, Asghar M, Ganeshram KN, et al. Chronic subdural haematoma in the elderly. Postgrad Med J 2002;78(916):71–5.
  • Mori K, Maeda M. Surgical treatment of chronic subdural hematoma in 500 consecutive cases: clinical characteristics, surgical outcome, complications, and recurrence rate. Neurol Med Chir (Tokyo) 2001;41(8):371–81.
  • Gelabert-Gonza´lez M, Iglesias-Pais M, Garcı´a-Allut A, et al. Chronic subdural haematoma: surgical treatment and outcome in 1000 cases. Clin Neurol Neurosurg 2005;107(3):223–9.
  • Ivamoto HS, Lemos HP, Atallah AN. Surgical treatments for chronic subdural hematomas: a comprehensive systematic review. World Neurosurg 2016; 86:399–418.
  • Iliescu IA, Constantinescu AI. Clinical evolutional aspects of chronic subdural haematomas - literature review. J Med Life 2015;8(Spec Issue):26–33.
  • Sambasivan M. An overview of chronic subdural hematoma: experience with 2300 cases. Surg Neurol 1997;47(5):418–22.