Epidemiology of the Spinal Cord and Cauda Equina Injury in Korea -Multicenter Study-

Recently, the number of patients suffering from spinal cord injuries (SCI) from industrial and traffic accidents, due mainly to the rapid industrialization and explosive growth in vehicle traffic, have increased significantly.1) According to international statistics, the annual occurrence rate of SCI is 721 case for 1 million people with a 6% fatality rate. Since over 50% of SCI results in paralysis of the limbs or paralysis of the lower limbs, these injuries inflict not only mental and physical pains but also cause an increase in the societal costs as well.

Although, in the mid 1990s, the Korea Ministry of Health and Welfare and the Korea Institute for Health and Social Affairs conducted studies on the occurrence rate of complications from the after-effects of SCI for the disabled persons and their epidemiology, these studies were conducted without an accurate registration system; these studies reported that, among all the disabled persons in Korea, 67,204 cases (9.2%) were paralyzed in the lower limbs, and 32,827 cases (4.5%) were paralyzed in all four limbs; Nah et al.2) reported that the full paralysis cases, rather than partial paralysis cases, comprised the majority of all paralyses; these were pretty much the extent of these studies. In contrast, in Europe, Australia or the U.S., annually or during a planned period, studies of SCI patients and various items such as complication occurrence rates, early treatment methods, recovery after injury, length of hospital stay, and treatment costs are being conducted on a continual basis, and the huge amounts of data collected from these studies are being amassed and utilized as valuable materials for establishing clinical guidelines or welfare policies.

Up until now in Korea, the pathophysiology and epidemiological information or data for SCI have been insufficient, and the criteria for the diagnosis and treatment of SCI has been vague.1-3) With the sponsorship of the Spine Research Society at the Korean and Society of Spine Surgery, we, in conjunction with a number of universities jointly, wanted to provide the basic material to be utilized in the future as the basic material for the overall research regarding SCI in Korea, by conducting analyses of the overall history, characteristics, treatment status of SCI, and by having discussions about various literature.

Among the 987 spinal trauma injury patients who visited and received treatment, during the period from September 1, 2006 through August 31, 2009, at the hospitals of Chungnam National University, Yonsei University, Chosun University, Hallim University, Wongwang University, Catholic University, and Soonchunhyang University, 47 cases were retrospectively studied. 17 items that could be used to identify the patient's injury-to-treatment process were prepared, made into a questionnaire, and distributed (Fig. 1). This questionnaire was distributed to orthopedic spine surgeons at each of these institutions to be completed, and using the medical information systems at each location, the record of these patients were retrieved and their medical records and radiographic findings were discussed and prepared.

Fig. 1
Multi-center study, questionnaire survey. 17 contents asked of 6 university spine surgeons.

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The average age of spinal cord injury patients was 48.4-years-old, which was relatively young enough to work, and the male-to-female ratio was 33:14. The causes of injuries were falls in 22 cases (47%) and traffic accidents in 15 cases; the injury sites were the lumbar spine in 19 cases (40%) which was the most frequent, thoracolumbar in 11 cases (23%), cervical spine in 7 cases (14%), thoracic in 5 cases (11%), cervical spine and thoracolumbar combination damage in 5 cases (11%). On spinal injuries, unstable bursting fractures were the most with 24 cases (51%), and the next most common was fracture-dislocation in 12 cases (26%). Full paralysis and partial paralysis were, respectively, in 19 cases (40%) and in 28 cases (60%); among the partial paralysis cases, the cauda equina syndrome was most common with 10 cases, and anterior spinal cord syndrome was 5 cases and Brown-Sequard syndrome was 5 cases. Based on the injury level classifications of the American Society of Spinal Cord Injury (ASIA scale), ASIA A (complete injury; complete loss of all motor and sensory functions including sacral nerve roots 4-5) was in 19 cases, and in partial paralysis cases, ASIA D was the most with 12 cases (26%). After the diagnosis, high-dose steroids were administered in 25 cases (54%); among these 25 cases, in 14 cases medicine was administered within 8-hours of injury. In terms of the injection protocol, the NASCIS (National Acute Spinal Cord Injury Study) II was used in 16 cases, and NASCIS III was used in 9 cases. There were complications in 14 cases: respiratory complications like pneumonia or atelectasis occurred in 5 cases; pressure sores occurred in 5 cases, gastrointestinal bleeding occurred in 1 case; 2 cases of urinary tract infection; and 1 case of deep vein thrombosis.

All 46 cases except for 1 case (98%) underwent surgery; the 1 case without surgery was because of an internal illness which accompanied the patient's lumbar burst fracture at lumbar 1 and as a result emergency decompression procedure was not performed, but since after 72 hours of injury patient's conditions started showing improvement in his partial paralysis the patient was given a conservative treatment. 21 cases underwent surgery within 24-hours of injury (44%); 25 cases underwent surgery after 24-hours of injury (53%); 12 cases were brought to a hospital within 4-hours of injury (26%); 11 cases within 8-hours of injury (23 %); 5 cases within 8- to12-hours of injury (11%); 19 cases were brought to a hospital after 24-hour of injury (40%). Simple decompression was performed in 12 cases; decompression and fixation with device via posterior approach were performed in 27 cases; decompression and fixation with device via anterior approach were performed in 7 cases. Before arriving at a hospital, 25 cases received appropriate emergency treatment (53%; high-dosage steroid injection); after the final diagnosis, 30 cases (64%) clearly acknowledged spinal injury (Table 1).

Table 1
Summary of cases of spinal cord injury

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The average age of the spinal injury patients was 48.5-years-old, which was higher than the 40.2-year-old average age for Americans based on the National Spinal Cord Injury Center (NSCIC; the U.S.) statistical data of 2005 to 2007. This difference can be attributable to the fact that most Americans obtain their drivers license at 16 years of age, i.e., cultural and systematical differences. On the other hand, the average of American SCI patients was 27.8-years-old, based on the 1973-1979 statistical data; the research of Young et al.4) showed 28.7-years-old for the average age of SCI patients, which was similar to 27.8; and the reason for this rather young average age increasing to the current age can be reconciled by the fact that the life expectancy has increased since then and also the development of transportation system resulted in a greater number of drivers.5)

The male:female ratio for this study was 33:14 (70%:30%), and this was not that much different from the NSCIC statistic of 8:2 (80%:20%); we believe that this higher percentage for males is due males tend to have higher activity levels. Eric et al5) reported that, using the 1973-1998 NSCIC statistical data, the causes of SCIs were traffic accidents 34.3%, falls 19%, gunshots 17%, and diving accidents 7.3%. Stover et al6) reported that traffic accidents accounted for the most common cause of SCI; the NSCIC statistics also showed that traffic accidents accounted for 41% and falls 27%; however, in our study, falls accounted for the most of SCI causes; in addition, our study showed cervical spine in 7 cases (14%), thoracolumbar in 11 cases (23%), lumbar in 19 cases (40%). Typically, most foreign studies have shown that the most common cause of SCI is cervical spine. Among the patients in the 5-year follow-up research by Dustin et al.,7) 320 of 675 patients suffered cervical spins injury, 209 thoracic lumbar, and lumbar 46, i.e., cervical spine injury were the most. In our study, studying cauda equina syndrome along with spinal injury contributed to the showing of large number of lumbar injury. In this study, full paralysis and partial paralysis, respectively, were 19 cases (40%) and 28 cases (60%); and among the partial paralysis cases, the cauda equina syndrome was most common with 10 cases, and anterior spinal cord syndrome was 5 cases and Brown-Sequard syndrome was 5 cases. Based on the injury level classifications of the American Society of Spinal Cord Injury (ASIA scale), ASIA A (complete injury; complete loss of all motor and sensory functions including sacral nerve roots 4-5) was in 19 cases, and in partial paralysis cases, ASIA D was the most with 12 cases (26%). And also in the NSCIC statistics, there were more partial paralysis cases with full paralysis cases being 39.8% and partial paralysis cases 59.8%. Although anatomically cauda equina is not included in the spinal cord, in this study cauda equina cases were included with SCIs, and this was due to considering cauda equina syndrome as a syndrome that occurs in nerve damage situations and also due to the fact that textbooks categorize cauda equina syndrome as partial paralysis.

High-dose steroid was administered in 54% of the cases, and the reasons for not administering to the rest stemmed from the differences of opinions among the spine surgeons, priority given for the treatment of injury, association of the patients with internal medical illnesses.8-12) Among these 25 cases, in 14 cases medicine was administered within 8-hours of injury. In terms of the injection protocol, the NASCIS (National Acute Spinal Cord Injury Study) II was used in 16 cases, and NASCIS III was used in 9 cases. The high-dosage steroid use is much controversial worldwide regarding its effect. Although many clinicians have adhered to the use of high-dosage steroid, due to their peer reviews and legal issues, as reported by McCutcheon et al.13) there are studies that suggest the initial medical costs increase and the length of hospitalization prolonged; Ito et al.14) showed that the reality is that there are doubts about steroid use and neurological improvement, and that there are negative sides due to complications of pneumonia, urinary tract, wound infection, etc. The 2008 study done on Canadians by John15) reported about the results of an interesting reversal trend in the recent 5 years for "injection:non-injection" mainly influenced by the literatures of negative results of high-dosage steroid use; Peter et al.16) as well reported that statistically compliance by clinicians for the NASCIS III protocol has decreased, and that the reasons for this was unknown. Similar to the study by Eck17) which suggested that, although 90% of the spine surgeons are using steroids, only 24% believed that an improved clinical outcome would result from it, we believe that is unclear as to whether the spine surgeons in Korea are convinced of improved clinical outcome from steroid use.

Menon et al.18) reported that, among the 55 patients who visited the hospital due to urinary tract infection, 31% were quadriplegia, 38% paraplegia, and 7% cauda equina syndrome; Young et al.4) reported that urinary tract infection among paraplegia was 66% and among quadriplegia 70%. Urinary tract infection has shown a gradually decreasing trend after the mid-90s, and we believe that this decrease is attributable to the availability of appropriate urination method choices and education.19) Paul et al.20) reported that complications of urinary tract infection have decreased. In our study, the complications of pressure sores and respiratory mechanisms were the most frequent with 5 cases each and urinary tract infections were in 2 cases.

21 cases underwent surgery within 24-hours of injury (44%); 25 cases underwent surgery after 24-hours of injury (53%); 12 cases were brought to a hospital within 4-hours of injury (26%); 11 cases within 8-hours of injury (23 %); 5 cases within 8- to12-hours of injury (11%); 19 cases were brought to a hospital after 24-hour of injury (40%). In other words, the cases that underwent surgery after 24-hour mostly were due to the delay in reaching the hospital after injury. It has not been reported that cases of undergoing surgery within 24-hours and after 24-hours are different in terms of the rehabilitation results or post-surgery results; only in studies using test animals it was shown that a decompression surgery within 24-hours resulted in more effective outcome for nerve regeneration; clinically, the critical time for surgical treatment has not been identified in any studies.21) This was merely a case of setting 24-hour period as a convenience metric. However, according a number of studies, based on the generally-accepted concept and as predicted by professional organizations, receiving appropriate treatment more quickly resulted in shorter period of hospitalization and lower treatment costs; considering surgical care as a category of treatment, arriving at a hospital more quickly has importance.7)

In other countries, full-fledged treatment for spinal cord patients began during the Second World War; the British Medical Council took special interests on the management of spinal cord injury patients, and instituted special care units for spinal injury patients at many hospitals.4) Under Guttmann's guidance in the 1940s, a new comprehensive spinal rehabilitation unit was installed in Aylesbury, and later this has developed into the Stoke-Mandeville National Spinal Injury Center.22) In the U.S., Munro23) created in the Boston Municipal Hospital a 10-bed spinal cord injury unit and started providing comprehensive rehabilitation; under the Federal Veterans Administration, 18 Spinal Cord Injury Centers and 17 Civilian Regional Spinal Injury Center were developed. In addition, in most European countries and in Australia, there are spinal cord injury centers; in Asia, Japan has an integrated spinal cord injury treatment center, however, there are no systemized specialized facilities in Korea that can treat spinal cord patients for early treatment (conservative progress monitoring or surgical treatment) from the time a patient is admitted. However, this study has found that, in more than half of the cases, emergency treatment (high-dose steroid therapy) until hospital arrival has been administered properly, and this is attributable to the upgrade and professionalization of emergency medical system personnel and advancements in equipment and in social cognition. As Sorensen et al.24) reported about the speed limit and seat belt legislations contributing to reduction in auto traffic accident-caused spinal cord injury, in order to reduce the incidence of spinal cord injury for drivers or industrial workers, the development and activation of training programs that target these individuals are needed, and the revamping of transportation and work environment are needed to reduce traffic accidents and industrial accidents. Tyroch et al.25) studied spinal cord disabled persons registered with spinal cord injury registration system and reported that 60-70% of the cases were preventable and social support was needed for this; Rish et al.26) conducted a 15-year follow-up observations of the disabled persons in the United States who were registered under the Vietnam Head and Spinal Cord Injury Registry and reported about not only the prevalence rates but mortality rates as well; in Denmark, through long-term follow-up studies, it was reported that the cause of death for people with disabilities was changing.27) In addition, Dustin et al.7) reported about the differences in treatment costs for 675 patients by dividing them based on spinal injury areas into cervical spine, thoracic, and lumbar; Johnson et al.28) contributed significantly to the welfare policy by producing the needed co-payments for treatment based on the degree of injury. As shown above, epidemiological studies based on database provide essential and systematic important materials about spinal cord disabled persons, and they are an essential social work for establishing welfare policies.

This study is significant for being a collaborative research by the multicenters of the Spine Research Society at the Korean and Society of Spine Surgery, and, if in future studies the number of participating institutions could be widened countrywide and amass data from a specific time period (annual or over many years), then similar to the U.S. and Europe it will be useful as the essential database for establishing policies for spinal cord injury patients.

This study is the first collaborative research by multicenters attempted in Korea for spinal cord injury, and also, as statistics for establishing a database, this study is expected to be used in the future as essential materials for spinal cord injury statistics and a standard for care.