Chronic Subdural Hematoma

Manish KC, MBBS1, Junaid Siddiqui, MD, MRCP2

1KIST Medical College & Teaching Hospital, Nepal.

2Department of Neurology, University of Missouri, Columbia, USA

Introduction

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

Epidemiology

  • 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%

Etiology

  • 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

Pathophysiology

  • 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
    • Hemisensoy 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

Figure 1: Chronic Subdural Hematoma

Differential Diagnosis

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

Diagnosis

  • 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

Treatment

  • 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.

Complications

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

Prognosis

  • 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

Bibliography

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