Decompressive craniectomy for severe traumatic brain injury: The relationship between surgical complications and the prediction of an unfavourable outcome

Abstract

Object

To assess the impact that injury severity has on complications in patients who have had a decompressive craniectomy for severe traumatic brain injury (TBI).

Methods

This prospective observational cohort study included all patients who underwent a decompressive craniectomy following severe TBI at the two major trauma hospitals in Western Australia from 2004 to 2012. All complications were recorded during this period. The clinical and radiological data of the patients on initial presentation were entered into a web-based model prognostic model, the CRASH (Corticosteroid Randomization After Significant Head injury) collaborators prediction model, to obtain the predicted risk of an unfavourable outcome which was used as a measure of injury severity.

Results

Complications after decompressive craniectomy for severe TBI were common. The predicted risk of unfavourable outcome was strongly associated with the development of neurological complications such as herniation of the brain outside the skull bone defects (median predicted risk of unfavourable outcome for herniation 72% vs. 57% without herniation, p = 0.001), subdural effusion (median predicted risk of unfavourable outcome 67% with an effusion vs. 57% for those without an effusion, p = 0.03), hydrocephalus requiring ventriculo-peritoneal shunt (median predicted risk of unfavourable outcome 86% for those with hydrocephalus vs. 59% for those without hydrocephalus, p = 0.001), but not infection (p = 0.251) or resorption of bone flap (p = 0.697) and seizures (0.987). We did not observe any associations between timing of cranioplasty and risk of infection or resorption of bone flap after cranioplasty.

Conclusions

Mechanical complications after decompressive craniectomy including herniation of the brain outside the skull bone defects, subdural effusion, and hydrocephalus requiring ventriculo-peritoneal shunt were more common in patients with a more severe form of TBI when quantified by the CRASH predicted risk of unfavourable outcome. The CRASH predicted risk of unfavourable outcome represents a useful baseline characteristic of patients in observational and interventional trials involving patients with severe TBI requiring decompressive craniectomy.

Introduction

Surgical intervention in the context of trauma can take many forms whether it is to arrest catastrophic haemorrhage, repair a ruptured viscus or to fixate a fractured limb. In most instances the decision to surgically intervene is based on the premise that any benefit provided in terms of outcome is not offset by the morbidity of the surgical procedure. A contemporary illustration of this problem is seen when considering decompressive craniectomy in the management of severe traumatic brain injury. The procedure is technically straightforward and can be performed either unilaterally or bilaterally (or bifrontally). A unilateral decompression is usually performed following evacuation of a mass lesion such as a subdural haematoma or when the cerebral swelling is localized to one hemisphere. A bilateral or bifrontal craniectomy is usually performed when there is diffuse cerebral swelling.

Use of the procedure initially gained popularity in the early 1970s [1] only to fall into disrepute due to a combination of poor clinical outcomes [2] and experimental studies that suggested that decompression may actually worsen cerebral oedema [3] and this led to use of the procedure being almost abandoned. However, throughout the 1980s its popularity returned as an increasing number of studies demonstrated that surgical decompression could reliably lower the intracranial pressure and there would appear to be little doubt that in the context of intractable intracranial hypertension, surgery can represent a lifesaving intervention [4], [5], [6]. However despite many assertions to the contrary [7] evidence that the well documented reduction in ICP that occurs following surgical decompression is translated into an improvement in outcome is far less forthcoming.

The DECRA (Decompressive Craniectomy in Patients with Severe Traumatic Brain Injury) compared early decompressive craniectomy for diffuse traumatic brain injury with standard medical therapy and found that patients in the surgical arm of the trial had worse outcomes than those treated medically [8]. Notwithstanding a number of criticisms [9], [10] the trial unequivocally demonstrated that at the particular ICP threshold at which these patients were enrolled there was insufficient ongoing secondary brain injury and therefore any benefit obtained by lowering the ICP was offset by surgical morbidity [11]. Indeed it is becoming increasingly apparent that use of the procedure exposes patients to significant morbidity not only from the initial decompression but also from the subsequent cranioplasty [12], [13], [14], [15].

The aim of this study was to determine what features predispose patients to the development of complications and most notably whether injury severity was a contributing factor.