Demographics of the patients. Demographics of the patients. Twenty-three patients were admitted during the study period. The mean age was 67.7 (range 29–91) years, and 19 (83%) of the patients were over 60 years old. Fourteen patients were transported by HEMS (61%, group H), seven patients were transported by ambulances (30%, group A), and two patients transported themselves (9%, group T). Upon admission, the AIS grade was A in nine patients, C in four, D in five, and E in three, and two were in cardio-pulmonary arrest (CPA). The average ISSs of group H, group A, and group T were 30.6, 18.6 and 12.5, respectively (Fig. 2a).
The travelled distance in group H (mean 64.5 km, range 41–134 km) was significantly longer than that in group A (mean 24.7 km, range 3.7–47.9 km) (Fig. 2b), but group H was admitted slightly earlier (mean 159.4 min, ranged 50–885 min) than group A (mean 163.6 min, raged 67–419 min) (Fig. 2c). Except for delayed transport due to night occurrence (885 min), the average time to admission in group H was 100.0 min. More than 24 h passed between the trauma and admission in both patients in group T.
Mountainous areas account for approximately 90% of the prefecture, and highway passing areas are limited in this region; most highways are single lanes in the eastern area. Fifty percent of the travelled distances in group H were longer than 50 km, and HEMS also covered topographically isolated areas (Fig. 2d). Five of the patients in group H (36%) were admitted via another medical institution as follows: one patient via rendezvous with a helicopter and four patient transfers from a medical institution. The doctors and nurses started prehospital medicine after an average of 25.5 min (range 11–71 min) after the request for HEMS. The reasons why helicopter transport was not chosen in group A were occurrence time (58%), occurrence at a short distance (29%), and a need for urgent cardiopulmonary resuscitation at the closest hospital (14%). Four patients in group A (57%) were transferred from another medical institution.
Closed reduction by craniocervical traction. Although the trauma experienced in group H was significantly more severe than that in group A, craniocervical traction in group H (mean 52.2, range 21–121 min) was started as soon after admission as that in group A (mean 53.2, range 28–90 min). Traction could be performed on 20 of the 23 patients, and their details are shown in Table 1. In two CPA patients and one AIS A patient with unstable vitality, immediate traction was difficult.
The success rate of closed reduction was 95%, and all the reductions were confirmed within 1 h. The average traction time, including ring connection, was 30.3 min (range 7–60 min), and the average traction weight for reduction was 16.3 kg (range 5–30 kg, average 10% (range 3%-19%) of body weight). No significantly strong correlations were observed between the patients’ body weight or height and the traction weight or time (Fig. 3a). In addition, there were no significant differences in traction weight and time, ketamine usage or the addition of ring rotation for reduction among the fracture-dislocation types (bilateral/unilateral, complete dislocations/locked facets and with/without facet fractures, Fig. 3b, c). The only closed reduction failure case was two levels of unilateral dislocations (complete dislocation and locked facet) with facet fractures (Table 1).
Eighteen patients had tolerance for MRI after the reduction. Herniated discs were found at dislocation levels in five patients (28%), and the average occupation rate of bulging or herniated discs and haematoma in the canal space was 31.1% (range 12%-48%). All cases of inner fixation and direct decompression of the spinal cord were treated via the posterior approach an average of 5.7 days (range 0–13 days) after admission.
Neurological prognosis. The AIS grade prognoses of the 20 patients who underwent craniocervical traction are shown in Fig. 4. The average follow-up duration of the patients who survived was 613 days (range 159–1381 days). Excluding group T, the rates of reduction within 4, 6 and 8 h after the injuries in nine AIS C-E patients were 44%, 78% and 89%, respectively. The corresponding rates of reduction in the eight AIS A patients, including a closed reduction failure case, were 75%, 75%, and 100%, respectively. Importantly, neurological deterioration following traction was not observed in any cases. Including group T, the AIS grade improved in four of nine AIS C-D patients (44%) immediately after successful reduction, and all nine patients (100%) had improved at the latest follow-up even when reduction was delayed. Three of the seven (43%) AIS A patients had an improved grade immediately after successful reduction, and the reduction in these three patients was confirmed within 4 h after the injuries. One of the three improved to AIS E (normal), one to D (could walk by themselves), and one to C (could walk with devises and auxiliary). In contrast, two AIS A patients who did not improve neurologically after reduction died within two months of injury.
The rates of reduction within 4, 6 and 8 h were 79%, 86% and 93%, respectively, in group H and 33%, 67% and 100%, respectively, in group A. Although the sample size was small and there were no statistically significant differences (chi-squared test), the outcomes of early reduction within 4–6 h in group H, which included a delayed transport case and a closed reduction failure case, were better than those in group A.