Neurosurgery notes/Trauma/Primary head Injury/Subdural haematoma (SDH)/Chronic SDH

Chronic SDH

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Subdural haematoma (SDH)

General

  • >21 days post-injury
  • Hypodense
  • May not present symptomatically until the collection has expanded significantly and signs of compression appear
  • Presents specific demographic (elderly patients or those with cerebral atrophy) as a specific clinical syndrome

Mechanism

  • A minor head injury → Tearing of the stretched bridging veins that span the subdural space → Small haematoma
    • Cerebral atrophy: stretched bridging veins
  • The initial small volume haematoma may be asymptomatic and the initial insult is often forgotten.
  • Inflammatory neo-membrane
    • Form in some patient
    • Potentiates
      • Ongoing haemorrhage
      • Breakdown of blood products → development of an osmotic gradient across the neo-membrane → swelling of the enclosed haematoma
        • This process takes time hence it is chronic
        • Clinical presentation several weeks after the initial injury
  • Location
    • Convexity
      • Most commonly
    • Inter-hemispheric fissure
    • Tentorium cerebelli
    • Rarely the posterior fossa
  • CSDH arises at the dural border cell layer (between the dura mater and arachnoid mater) which is prone to separation creating a “subdural space,” particularly in those with cerebral atrophy (e.g. elderly, alcoholics).

Radiological

  • SDH hypodense to brain.
  • Presence of membranes
  • The haematoma may nonetheless show areas of acute haemorrhage from repeated haemorrhages, presumably from the inflammatory neomembrane.

Clinical features of CSDH

  • Headache
  • Hemiparesis
  • Speech disturbance (dominant hemisphere)
  • Behavioural disturbances (e.g. emotional outbursts, lack of concentration, manic and depressive states),
  • Coma
    • If large and untreated.
  • Bilateral CSDH are more likely to progress to coma rapidly and consequently are treated at a smaller absolute volume.

Management

General

Conservative

  • Steroids
    • Miah et al 2023
      • Trial stopped early
      • Dexamethasone treatment
          • Was not found to be noninferior to burr-hole drainage with respect to functional outcomes
          • But had
            • More complications (59% dexamethasone group vs 32% surgery group)
            • A greater likelihood of later surgery 55% dexamethasone group and 6% surgery group)
          notion image
    • Hutchinson 2020
        • Multicentre RCT
        • 2 week tapering course of PO dexamethasone vs placebo
        • Decision whether to surgically evacuate made by treating clinician
        • Primary outcome was mRS 0-3 at 6 months (i.e. favorable outcome)
        • Results:
          • Mean age 74
          • 94% had surgery during index admission
          • Modified intention to treat analysis: 83.9% favorable outcome dexamethasone vs 90.3% Placebo group
          • Repeat surgery 1.7% dexamethasone group vs 7.1% placebo group
          • More adverse effects in dexamethasone group
        notion image
         

Surgery

  • Options
    • Burr hole craniostomy (BHC)
    • Minicraniotomy (MC)
    • Twist drill craniostomy (TDC)
  • Which option is the best:
    • Duerinck et al 2002
      • 3 techniques are effective at treating patients with CSDH with eventual 6-month outcome being similar. Although not reaching statistical significance in our study, BHC offers the lowest recurrence rate combined with manageable complication rate.
  • Drains > No drains
    • Peng et al 2016 and
      • Significant reduction in the risk of recurrence with subdural drains (RR 0.45)
      • No strong evidence of any increase in
        • Complications (RR 1.15),
        • Mortality (RR 0.78),
        • Poor functional outcome (which included deaths) (RR 0.68)
    • Santarius et al 2009
      • RCT
      • Randomised: drain vs no drain
      • Reduce recurrence with placement of a soft drain into the subdural space for 48 hours
      • Inclusion: age>18, symptomatic cSDH confirmed on CT
      • Exclusion:
        • Indication for surgery other than burr holes,
        • Insertion Of CSF shunt same side as in preceding 6 months,
        • Surgeon deemed drain unsafe
      • Results
        • Study stopped early due to significant benefit with drain
        • Recurrence in
          • 9.3% with a drain
          • 24% without a drain
        • Mortality at 6 months
          • 8.6% with a drain
          • 18.1% without a drain
        • No significance in complication rate
      • Critique
        • Single centre study
  • Subperiosteal vs subdural drains
    • Ding et al 2020
      • No difference in
        • Subdural haematoma recurrence
        • Favourable outcome
      • Subperiosteal drains have lower risk of parenchymal injuries
  • Risks
    • Infection of the subdural space
    • Seizures
    • Recurrence
      • Proliferating microcapillaries in the capsule of SDH are implicated in bleed recurrence due to marked mitotic potential of endothelial cells and vascular permeability.

Interventional radiology

  • Middle meningeal artery embolization
    • Sattari et al 2023 - meta analysis
        • MMA embolization vs
          • Burr hole (single or dual)
          • Craniotomy
          • Twist drill craniotomy
        • MMA embolization decreases treatment failure and the need for surgical rescue without furthering the risk of morbidity and mortality
        • Definition
          • Treatment failure (residual hematoma ≥10 mm and/or reaccumulating hematoma ≥10 mm[ie, recurrence]
          • Surgical rescue [ie, surgical drainage of the symptomatic residual or re-accumulated hematoma])
        • The relative risk of treatment failure in MMA embolization was significantly lower compared with conventional management (5.6% vs 22.2%, RR = 0.34
        • The relative risk of surgical rescue was significantly lower after MMA embolization vs conventional management (4.1% vs16.1%, RR = 0.33 [0.14-0.77