European Journal of Cardiovascular Medicine

Traumatic brain injury (TBI) represents a significant global health challenge, contributing substantially to mortality and long-term disability among survivors. Despite advancements in neurocritical care, the management of severe TBI, particularly in patients who develop refractory intracranial hypertension despite maximal medical therapy, remains a daunting task. Decompressive craniectomy (DC) has emerged as a pivotal surgical intervention aimed at reducing intracranial pressure (ICP), mitigating secondary brain injury, and improving patient outcomes. However, the decision to perform DC is complex, and its timing and indications are subjects of ongoing debate. This complexity is further compounded by the need to predict outcomes in patients undergoing this procedure, which is crucial for guiding clinical decisions and counseling patients and families. Among the predictors of outcome, neurological and radiological parameters have shown particular promise[1-3].

Neurological predictors encompass a range of clinical findings, including the initial Glasgow Coma Scale (GCS) score, pupillary response, and motor posturing, which have been correlated with patient outcomes following TBI. The GCS score, in particular, has been extensively studied and is universally applied in the assessment of consciousness level following traumatic injury. Its value in predicting outcomes post-DC, however, is influenced by various factors, including the presence of additional injuries, the patient's age, and the timing of the assessment[4,5]. Pupillary response and motor posturing provide immediate, clinically relevant information about brainstem function and the extent of diffuse axonal injury, respectively, offering additional prognostic value[6,7].

Radiological predictors, primarily assessed through computed tomography (CT) and magnetic resonance imaging (MRI), offer crucial insights into the structural impact of TBI. Features such as midline shift, compression of basal cisterns, and the presence of traumatic subarachnoid hemorrhage or contusions are associated with outcome prognostication. The role of advanced imaging techniques, including diffusion tensor imaging (DTI) and susceptibility-weighted imaging (SWI), in predicting outcomes post-DC is an area of growing interest. These modalities provide detailed information on white matter integrity and microhemorrhages, respectively, which are not readily apparent on conventional imaging[8,9].

Recent studies have focused on integrating neurological and radiological predictors into comprehensive models to enhance the accuracy of outcome predictions following DC in TBI patients. The development of predictive algorithms and scoring systems based on these parameters aims to refine patient selection for surgery, optimize timing, and ultimately, improve clinical outcomes. However, the variability in study methodologies, patient populations, and outcome measures poses challenges to synthesizing the available evidence into clear guidelines[10,11].

In addition to clinical and radiological predictors, biomarkers have emerged as potential tools for outcome prediction in TBI. The measurement of serum levels of neuronal and glial proteins, such as S100B, neuron-specific enolase (NSE), and glial fibrillary acidic protein (GFAP), has been proposed to correlate with the extent of brain injury and predict long-term outcomes. While promising, the integration of biomarkers with neurological and radiological predictors requires further validation[12,13].

This review aims to synthesize current knowledge on neurological and radiological predictors of outcome in TBI patients undergoing DC, highlighting their prognostic value and discussing the implications for clinical practice. By understanding the interplay between these predictors and patient outcomes, clinicians can make more informed decisions regarding the management of severe TBI, ultimately improving the quality of care for this vulnerable patient population.

The study was designed as an observational, prospective cohort analysis conducted at the Medical College Hospital (MCH) in Thiruvananthapuram. The research focused on evaluating the neurological and radiological predictors of outcomes in TBI patients who underwent DC.

The study encompassed decompressive craniectomies performed from July 2020 to December 2020, with a follow-up duration extending up to 3 months, concluding in March 2021. The patient population included all individuals undergoing DC for TBI at the Government Medical College, Trivandrum, admitted within 24 hours of sustaining the injury.

Sample Size

Using data from a previous study by Cianchi et al. on late DC in TBI and its outcomes at 6 months using the Glasgow Outcome Scale (GOS), the sample size was calculated employing the formula N= (Z(1-α/2)+ Z(1-β))^2(S1^2+S2^2)/(μ1-μ2)^2. With a set confidence level of 95% and power of 80%, the sample size required for each group was determined to be 123.

Inclusion and Exclusion Criteria

Inclusion Criteria: Patients aged 18-70 diagnosed with moderate to severe TBI and admitted within 24 hours of injury were included.

Exclusion Criteria: Excluded were patients younger than 18 or older than 70, those with prior neurological conditions with residual disability, polytraumas, primary brain stem injury on initial CT, refusal to participate, GCS 3 with non-reactive pupils, absent brainstem reflexes, and diffuse brain injury.

Data Collection

Data were collected using a predefined proforma at the time of presentation, in the post-operative period, and during serial follow-up. Variables included demographic details, clinical and imaging findings, and the Extended Glasgow Outcome Scale (GOS-E) at discharge, one month post-discharge, and three months post-discharge. Data were entered into a Microsoft Excel sheet for analysis.

Methodology

Patients were managed according to the institute's protocol for TBI, which is based on state guidelines and the Brain Trauma Foundation guidelines. The management included immediate surgery or conservative treatment, with specific procedures detailed for DC, including the size of the bone flap and post-operative care. Conservative management strategies were also outlined, including medication, physiological monitoring, and support measures.

Statistical Analysis

Categorical variables were presented as numbers and percentages, and quantitative data as means ± SD or median with interquartile range. The Kolmogorov-Smirnov test assessed data normality. Non-parametric tests were used for non-normal data, including the Mann-Whitney Test for two groups, Kruskal Wallis test for more than two groups, and Wilcoxon signed rank test for follow-up comparisons. Chi-Square and Fisher’s exact tests analyzed qualitative variables. SPSS software version 21.0 was used for statistical analyses, with a p-value of less than 0.05 considered significant.

Ethical Considerations

Institutional ethical committee approval was obtained before the study commenced. Informed consent was acquired from all participants or their legal guardians, ensuring confidentiality and adherence to ethical standards throughout the research process.

The study was conducted in Department of Neurosurgery, Government Medical College, Thiruvananthapuram. 174 patients between the age group 18-70 who were diagnosed with Moderate to Severe Traumatic Brain Injury and were admitted within 24 hours of Injury were included in the study with 87 patients of early decompressive craniectomy and 87 patients of late decompressive craniectomy.

Distribution of age(years) was comparable between early and late decompressive craniectomy. (<=20 years:- 3.49% vs 4.65% respectively, 21-30 years:- 8.14% vs 11.63% respectively, 31-40 years:- 17.44% vs 23.26% respectively, 41-50 years:- 31.40% vs 12.79% respectively, >50 years:- 39.53% vs 47.67% respectively) (p value=0.062).

Median(25th-75th percentile) of age(years) in early decompressive craniectomy was 48(39.25-55) and late decompressive craniectomy was 50(37-61.5) with no significant difference between them. (p value=0.41)

Distribution of gender was comparable between early and late decompressive craniectomy. (Female:- 19.54% vs 19.54% respectively, Male:- 80.46% vs 80.46% respectively) (p value=1).

RTA was significantly higher in early decompressive craniectomy as compared to late decompressive craniectomy. (RTA:- 82.76% vs 48.28% respectively). Proportion of patients with mode of injury:- fall was significantly lower in early decompressive craniectomy as compared to late decompressive craniectomy. (Fall:- 17.24% vs 51.72% respectively). (p value <0.0001)

The study meticulously examined the influence of pre-operative neurological status, radiological findings, and post-operative recovery on the functional outcomes of traumatic brain injury (TBI) patients undergoing decompressive craniectomy (DC). The cohort comprised 174 patients, evenly divided into early and late intervention groups based on the timing of surgery relative to injury.

Pre-operative Anisocoria as a Predictor of Outcomes

The presence of pre-operative anisocoria was significantly more common in the late DC group compared to the early DC group, with 95.40% of late DC patients showing no anisocoria versus 27.59% in the early DC group. This stark contrast (p<.0001) underscores the potential of pre-operative anisocoria as a critical predictor of the need for timely surgical intervention.

CT Findings and Surgical Outcomes

CT findings related to the side of injury revealed significant disparities between the groups. Notably, bifrontal contusions were exclusively observed in the late DC group (10.34%), absent in the early DC group, indicating a potential correlation between injury patterns and the decision-making process for the timing of DC (p<.0001). The distribution of injuries—57.47% on the left and 42.53% on the right in the early group versus 19.54% on the left and 70.11% on the right in the late group—further highlighted the complexity of TBI presentations and their implications for surgical outcomes.

Post-operative Anisocoria

The evolution of post-operative anisocoria presented a compelling narrative of recovery, with a marked decrease from 37.93% on day 1 to 35.80% by day 7 in the early group, while completely absent in the late group throughout the observation period. This persistent anisocoria in the early group versus its absence in the late group (p<.0001 on all days) may reflect differences in the severity of brain injuries or the effectiveness of surgical intervention.

Glasgow Coma Scale (GCS) Improvement

GCS improvement from pre-operation to day 7 and at discharge provided insights into neurological recovery. Although the mean improvement in GCS at day 7 did not significantly differ between the groups (p=0.185), the early group exhibited a more pronounced mean improvement at discharge (2.83 ± 3.54) compared to the late group (1.45 ± 4.13), with statistical significance (p=0.043). This suggests a nuanced benefit of early DC in enhancing neurological recovery.

GCS and CT Findings in Relation to GOSE Outcomes

The analysis of Glasgow Coma Scale scores and CT findings in relation to Glasgow Outcome Scale Extended (GOSE) at discharge illuminated the prognostic utility of these metrics. In the early DC group, right-sided injuries were significantly more likely to result in favorable outcomes (GOSE 5 to 8) compared to left-sided injuries (p=0.033). Furthermore, both pre-operative and post-operative day 7 GCS scores were significantly higher in patients with favorable outcomes, underscoring the predictive value of neurological status for functional recovery (p<.0001).

Midline Shift, GCS, and GOSE Outcomes in Late DC

In the late DC group, a midline shift of ≤8 mm was overwhelmingly associated with both favorable and unfavorable outcomes, suggesting its limited predictive value alone. However, when combined with GCS improvements, a significant correlation emerged, especially noted in post-operative day 7 and at discharge evaluations (p<.0001), highlighting the complexity of factors influencing recovery trajectories.

Detailed GCS and CT Findings Analysis

Further dissecting the relationship between GCS trends, improvement, and CT findings revealed that patients with right-sided injuries in the early DC group exhibited significant GCS improvements from pre-operation to discharge (p<.0001). In contrast, in the late DC group, bifrontal contusions showed a noteworthy improvement in GCS, emphasizing the heterogeneity of TBI and the multifaceted nature of recovery (p=0.002).

This comprehensive analysis elucidates the intricate interplay between pre-operative neurological status, radiological findings, and post-operative recovery in determining functional outcomes for TBI patients. The findings accentuate the prognostic significance of pre-operative anisocoria, injury patterns as depicted by CT, post-operative anisocoria, and the trajectory of GCS improvement in predicting outcomes, thereby offering valuable insights for optimizing TBI management and enhancing patient care.

The intricate relationship between pre-operative neurological status, radiological findings, and the functional outcomes of patients undergoing decompressive craniectomy (DC) for traumatic brain injury (TBI) has been a focal point of neurosurgical research. This study's findings underscore the critical role of pre-operative anisocoria, CT findings relating to the side of injury, post-operative anisocoria, and the improvement in Glasgow Coma Scale (GCS) scores as predictors of outcome following DC.

Pre-operative Anisocoria

The significant association between pre-operative anisocoria and patient outcomes aligns with prior research suggesting that pupillary reactivity is a crucial indicator of neurological function and potential recovery post-TBI[14]. The stark contrast in the prevalence of anisocoria between the early and late DC groups (p<.0001) emphasizes its prognostic value. This finding corroborates with studies indicating that the absence of anisocoria is associated with better outcomes in TBI patients, likely reflecting less severe brainstem involvement or diffuse axonal injury[15].

CT Findings and Surgical Outcomes

The distribution of injuries, as evidenced by CT findings, revealed a significant impact on the timing of DC and subsequent outcomes. The presence of bifrontal contusions exclusively in the late DC group suggests a pattern of injury that may evolve over time, necessitating delayed surgical intervention[16]. This evolution aligns with the understanding that the pathophysiology of TBI can progress, influencing the decision-making process regarding the timing of DC[17]. The lateralization of injury (left vs. right) and its association with outcomes may reflect differences in cerebral dominance and the resilience of brain networks, which warrants further investigation[18].

Post-operative Anisocoria

The persistence of post-operative anisocoria in the early group and its complete absence in the late group throughout the observation period (p<.0001) could indicate the severity of initial injury and the effectiveness of DC in mitigating secondary brain injury. This observation suggests that early surgical intervention might not always preempt the development of complications that manifest as anisocoria, underscoring the need for a nuanced approach to surgical timing[19].

GCS Improvement and Functional Outcomes

The observed improvement in GCS scores from pre-operation to discharge underscores the prognostic importance of neurological status in predicting outcomes. The significant improvement in the early DC group suggests that timely surgical intervention can facilitate neurological recovery, a finding that supports existing literature advocating for early DC in selected patients to improve outcomes[20]. However, the differential improvement based on the side of injury and the presence of bifrontal contusions highlights the heterogeneity of TBI and the multifactorial nature of recovery trajectories[21].

Implications for Clinical Practice

These findings suggest several implications for clinical practice. First, the assessment of pre-operative anisocoria can provide valuable prognostic information. Second, understanding the evolution of CT findings and their impact on surgical outcomes can guide the timing of DC. Finally, monitoring post-operative neurological status, especially changes in anisocoria and GCS scores, can inform post-operative care and rehabilitation efforts.

In conclusion, this study reaffirms the prognostic value of pre-operative anisocoria, CT findings, post-operative anisocoria, and GCS score improvements in predicting outcomes following DC for TBI. These findings highlight the need for a comprehensive, individualized approach to the management of TBI patients, integrating clinical and radiological assessments to optimize surgical timing and improve patient outcomes.

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