Two-year Mortality and Functional Outcomes in Combat-related Penetrating Brain Injury: Battlefield Through Rehabilitation

M. Benjamin Larkin, MD, PharmD; Erin K. M. Graves, MD, MA; Jason H. Boulter, MD; Nicholas S. Szuflita, MD, MPH; R. Michael Meyer, MD; Michael E. Porambo, MD; John J. Delaney, MD; Randy S. Bell, MD

Disclosures

Neurosurg Focus. 2019;45(6):e4 

In This Article

Results

Patient Population

The neurosurgery service at KAF received requests for consultations on 908 cases during the study period. Among them, 156 (17%) involved US service members for whom follow-up data were available. The remaining consultations involved NATO allied and non–NATO allied military members, enemy combatants, and local civilians. Among the US service members, a total of 80 (51%) were found to have sustained a PBI (Table 1).

All patients were male; their mean age was 24.9 years, and the majority were seriously injured (mean admission GCS score 8.5 [SD 5.56], n = 64; mean admission ISS 26.7 [SD 10.2], n = 80). The most common mechanism of injury was blast-related (73%). The most common injuries sustained included intraparenchymal hemorrhage, subarachnoid hemorrhage, and subdural hemorrhage. Surgical intervention was undertaken for 47% of patients, and the overall cohort mortality rate was low at 21% (17 patients) (34% in the group presenting with an admission GCS score of 3–5; Table 1). Of the 17 patients who died, 11 presented with an admission GCS score ≤ 5, and in the remaining 6 cases, no admission GCS score was recorded. All patients in the study cohort who presented with an admission GCS score > 6 survived. No patients were lost to follow-up during the study period.

GOS Scores

Overall, the cohort demonstrated no significant improvement in GOS scores over the study period (mean 3.58 [SD 1.51] at 6 months, 3.80 [1.56] at 12 months, and 3.96 [1.60] at 24 months, p = 0.29; Figure 1). Segregation of patients by admission GCS score demonstrated significantly higher GOS scores at all time points for patients with an admission GCS score ≥ 6 (mean 4.56 [SD 0.66] vs 2.84 [1.48] at 6 months, 4.75 [0.51] vs 3.16 [1.69] at 12 months, and 4.91 [0.30] vs 3.38 [1.81] at 24 months, p < 0.01 at all time points) but no difference between GOS scores over time within each admission GCS score group (Figure 2). Patients who presented with an admission GCS score of 6–15 demonstrated a significant increase in GOS score at 24 months when compared to their GOS score at 6 months (mean 4.91 [SD 0.30] vs 4.56 [0.67], p = 0.01). Additionally, when patients who died were removed from the admission GCS score 3–5 cohort, there was a significant increase in mean GOS score from 6 to 12 months (3.81 [SD 0.75] vs 4.29 [0.72], respectively, p = 0.04) and from 6 to 24 months (3.81 [SD 0.75] vs 4.62 [0.59], respectively, p < 0.01), although there was no significant difference in mean GOS score between 12 and 24 months (4.29 [SD 0.72] vs 4.62 [0.59], respectively, p = 0.11). Similarly, patients with an admission ISS ≤ 25 demonstrated higher mean GOS scores at all time points than those with an aISS ≥ 26 (4.03 [SD 1.20] vs 3.22 [1.64] at 6 months, p = 0.02; 4.29 [1.18] vs 3.42 [1.73] at 12 months, p = 0.01; and 4.51 [1.15] vs 3.53 [1.78] at 24 months, p = 0.01) with no difference over time within any of the groups (Figure 3). PBI secondary to blast injury also resulted in a more favorable GOS score at all time points when compared to GSWH (mean 3.91 [SD 1.37] vs 2.68 [1.52] at 6 months, 4.10 [1.37] vs 3.00 [1.77] at 12 months, and 4.28 [1.37] vs 3.14 [1.88] at 24 months, p < 0.01 at all time points), again with no significant difference in GOS score over time for either group (Figure 4).

Figure 1.

GOS scores over time for study population.

Figure 2.

Mean GOS scores over time stratified by admission GCS score. Error bars indicate SDs. *p < 0.05.

Figure 3.

Mean GOS scores over time stratified by admission ISS. Error bars indicate SDs. *p < 0.05.

Figure 4.

Mean GOS scores over time stratified by mechanism of injury. Error bars indicate SDs. *p < 0.05.

Of the injury characteristics observed, only herniation at presentation was associated with a significantly worse GOS score at all time points (poor outcome in 93% at 6 months, 93% at 12 months, and 87% at 24 months, p < 0.01 at all time points; Table 2). There was no significant association with GOS score for any other injury characteristic.

Interestingly, no difference in mean GOS score at any time point was found between those who underwent surgical intervention and those who did not (3.45 [SD 1.39] vs 3.69 [1.62] at 6 months, p = 0.47; 3.71 [1.45] vs 3.88 [1.67] at 12 months, p = 0.63; 3.95 [1.51] vs 3.98 [1.70] at 24 months, p = 0.94) despite the fact that the average admission GCS score in the group who underwent surgical intervention was lower than that in the group who did not (5.41 [SD 4.22] vs 11.00 [5.31], respectively, p < 0.01; Figure 5).

Figure 5.

Mean GOS scores over time stratified by presence or absence of neurosurgical intervention. Error bars indicate SDs.

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