Dr Stephanie Tilston, Anaesthetic SpR KCH March 2007 Management of Severe Raised ICP in Traumatic Brain Injury & the Role of Decompressive Craniectomy Dr Stephanie Tilston, Anaesthetic SpR KCH March 2007

Traumatic Brain Injury Major cause of morbidity and mortality worldwide Trauma is leading cause of death in first 4 decades of life Head injury implicated in at least half Recent advances in care at several levels

But morbidity and mortality remain high High ICP is the most frequent cause of death and disability after severe traumatic brain injury (TBI) controversy continues about fundamental treatment and specific therapies.

Raised ICP Fundamental principles credited to Professors Monro (1783) and Kelly (1824) States that 1) cranium is non-expandable 2) brain parenchyma is nearly incompressible 3) volume of blood therefore nearly constant 4) continuous venous outflow required for continuous arterial flow

Relationship Between ICP and Intracranial Volume

Fundamental Pathophysiology

Management of raised ICP Once first line measures fail only a few therapeutic options are available unless evacuable mass lesions are found at CT. Second tier management include: High dose barbiturates Hypertensive management Mild/moderate hypothermia Osmotherapy ?Intensive hyperventilation Decompressive craniectomy

Of these only barbitutates reached level of ‘guidance’ Others considered ‘options’ Brain Trauma Foundation Guidelines

However Cochrane collaboration found no evidence that barbiturates improve outcome in severe TBI May reduce ICP but this reduction not associated with lower mortality or improved outcome.

Decompressive Craniectomy Increases cranial volume by removing bone and opening duramater. Converting skull from ‘a closed box with finite volume into an open one’ First detailed report by Cushing in 1905 (used decompression to alleviate high ICP secondary to inoperable brain tumours.)

Classification Primary/Prophylactic decompression Aim not to control refractory ICP but to avoid expected increases. Secondary decompressive craniectomy- Any decompressive surgery performed to control ICP refractory to maximal medical management

Concerns About Decompressive Craniotomy May convert brain stem death into PVS Confounding small observational studies but no large RCT Systematic review of >2000 patients (Bazarian 2002) showed benefit but heterogeniety of study

Controversies Variability in surgical technique Extent of bone removed directly related to fall in ICP. Should extend beyond coronal suture Unilateral or bilateral Open the dura (or scarify?or keep closed?) Sectioning of the falx ? Quality of teqnique and dissection Vascular tunnels ?

Complications of Craniectomy At surgery More commonly after bone replacement Increased brain oedema Subdural collections CSF leakage Hydrocephalus Brain infarctions Epidural collections Infections Bone resorption

Decompressive Craniectomy For Refractory ICP in TBI-Cochrane Systematic Review (October 2005) Randomised/quasi randomised trails assessing patients over 12 months No evidence to support routine use of secondary DC to reduce unfavourable outcome in adults. But reduces risk of death and unfavourable outcome in paediatric population (NB limitations of study)

To date no RCT to confirm or refute effectiveness of DC in adults However results of non RCT and controlled trails with historical controls involving adults suggest DC may be useful option. Two ongoing RCT may allow further conclusions ResueICP DECRA (ANZICS)

RescueICP Trial International prospective multi-centre RCT comparing efficacy of DC v optimal medical management for treatment of refractory intracranial hypertension following brain trauma Collaboration between Cambridge NeuroSx/NeuroITU and European Brain Injury Consortium. KCH is a recruiting centre

Hypothesis DC results in improved Extended Glasgow Outcome Score cf optimal medical management DC results in improved surrogate endpoint measures cf optimal medical management

Rational of Trial Establish class I evidence Establish incidence of complications Recruit from centres experienced in ITU management of head injury

Inclusion Criteria Patients aged 10-65 Abnormal CT Requiring ICP monitoring ICP > 25mmhg for >1-12 hrs Refractory to initial medical measures May have initial op for mass lesion Hepato/renal/immuno compromise included but type and extent documented

Exclusion Criteria Bilateral fixed dilated pupils Bleeding diathesis Survival not expected >24hrs Follow up not possible ICPmonitoring not possible Patients treated on Lund Protocol Primary decompression Barbiturates pre randomisation Brainstem involvement

Power Originally 400 patients in total (200 each arm) to detect 15% difference in outcome Ie increase favourable outcome from 45% to 60% As a result of pilot study increased to 500 (due to crossover from medical to surgical arm)

Outcome measures Primary endpoints Assessment of outcome at discharge (Glasgow Outcome Score) and 6 months (Extended Glasgow Outcome Score) Secondary endpoints SF-36 questionnaire ICP control Time in ITU Time to discharge from ITU

Current Recommendations Servadei et al Curr Op Critical Care 2007, 13:163-168 (WHO Neurotrauma Collaboration) Given dismal outcome of patients with refractive high ICP, reasonable to include DC as last resort in protocol driven Mx Conventional therapeutic measures failed Operable masses ruled out Patient has possibility of functional outcome

Exclude devastating neurological injury & predictable poor outcome (signs of brainstem damage, very severe diffuse axonal injury)

Recommendations - Technique Bifrontal craniectomy with large bilateral bone flap extending beyond coronal suture and including most basl part of temporal bone to base of cranium Wide dural opening with anterior division of the falx cerebri Vascular tunnels may be helpful to protect veins at bony edges