Outcomes in patients admitted for rehabilitation with spinal cord or cauda equina lesions following degenerative spinal stenosis

Transcription

1 Disability and Rehabilitation, 2005; 27(11): RESEARCH PAPER Outcomes in patients admitted for rehabilitation with spinal cord or cauda equina lesions following degenerative spinal stenosis JACOB RONEN 1,2, DIANA GOLDIN 3, MALKA ITZKOVICH 1,2, VADIM BLUVSHTEIN 1, ILANA GELERNTER 4, ARKADY LIVSHITZ 5, YORAM FOLMAN 2,6, & AMIRAM CATZ 1,2 1 Loewenstein Rehabilitation Hospital, Raanana, 2 Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, 3 Tel Aviv Medical Center, Tel Aviv, 4 The Statistical Laboratory, School of Mathematics, Tel Aviv University, Tel Aviv, 5 Sapir Medical Center, Kfar Sava, and 6 Hylel-Yaffe hospital, Hadera, Israel Abstract Purpose. To evaluate outcome measures and the factors affecting them in patients treated between 1962 and 2000 at Loewenstein Rehabilitation Hospital, Israel. Method. This retrospective cohort study included 262 patients with spinal neurological lesions (spinal cord or cauda equina lesions) following degenerative spinal stenosis. Data were collected retrospectively. Survival was assessed using the Kaplan- Meier method and the relative mortality risk by the Cox model. Neurological recovery was evaluated by the change in Frankel grades, and factors that affect it were assessed by logistic regression. Associations of length of stay in rehabilitation were analyzed with ANOVA. Results. Median age at lesion onset was 61 years and median survival 17.6 years. Age at spinal neurological lesion onset was found to be the only factor with a significant effect on survival. Of the 148 patients who had Frankel grades A, B, or C on admission, 58% achieved recovery to grades D and E. Frankel grade at admission, age, and spinal neurological level had a significant effect on recovery. The mean length of stay was 99.7 days, and only Frankel grade had a significant effect on length of stay. Conclusions. Patients with spinal stenosis and disabling spinal neurological lesions can achieve significant neurological recovery and survive for many years. They require adequate care in a specialist rehabilitation system. Keywords: Spinal cord lesion, cauda equina lesions, spinal stenosis, survival, recovery, length of stay Introduction Spinal stenosis (SS) is the etiology of a substantial portion of non-traumatic spinal neurological lesions (SNL) among patients admitted to inpatient rehabilitation [1 5]. The term SS refers to narrowing of the entire cross-sectional area of the vertebral canal, nerve root canals, or intervertebral foramina due to spondylosis and degenerative disc disease. The process usually occurs in the cervical and lumbar spine, and less frequently in the thoracic spine. Patients usually become symptomatic at age 50 or older. Cervical stenosis usually presents with cervical radiculopathy; patients complain of radiating arm pain with numbness and paresthesia and/or weakness in the muscles supplied by that nerve root. In severe stenosis of the central canal, patients may present with signs and symptoms of myelopathy: numbness in the fingers and toes and difficulty in walking. In more severe cases, bowel and bladder control dysfunction may appear. Lumbar stenosis usually presents with symptoms of low back pain (LBP) and radiating leg pain, sometimes with bladder and bowel difficulties. The classic presentation, radiating leg pain associated with walking and relieved by rest, is neurogenic claudication; it is rarely accompanied by neurological deficit. When it is, the deficit may represent cauda equina impairment (if the central canal is compressed) or a pure lumbar radiculopathy (if the compression is lateral). Stenosis of the thoracic spine may result in Correspondence: Amiram Catz, MD, Medical Director, Department IV, Spinal Rehabilitation, Loewenstein Rehabilitation Hospital, 278 Ahuza St., P.O. Box 3, Raanana 43100, Israel. amcatz@post.tau.ac.il Accepted October ISSN print/issn online # 2005 Taylor & Francis Group Ltd DOI: /

2 612 J. Ronen et al. myelopathy [6]. Treatment can be conservative or surgical. Many studies have assessed the management of SS [6 16], but most of them include many patients without SNL and outcomes are usually described in terms of reduction of pain and improvement in function. Only scant information is available about SS outcomes that are important for patients with SNL, such as survival, neurological recovery, and length of stay (LOS) in hospital. The present study concentrated on patients with a neurological deficit and assessed these outcome measures in patients admitted to rehabilitation with spinal cord or cauda equina lesion following SS (SSSNL). Methods The study included 262 patients with SSSNL, admitted between 1962 and 2000 to Loewenstein Rehabilitation Hospital, the premier referral center for rehabilitation medicine for hospitals throughout Israel. Most of the patients were admitted to rehabilitation following decompressive surgery, but data collection on the operative procedures was beyond the scope of this study. Demographic and clinical data were collected by reviewing the hospital charts. Mortality data were collected from the Population Registry of the Israel Ministry of Internal Affairs. Survival rates were estimated using the product limit (Kaplan-Meier) method, and differences between subgroups were analyzed by logrank test (univariate analysis). The Cox proportional hazard model was employed to determine the probability of mortality ( hazard ) in the presence of specific risk factors (multivariate analysis) [17]. The time of SNL onset was defined as the earliest time of SSSNL symptoms and signs mentioned in the hospital records. The severity of neurological deficit below the spinal level of injury was graded according to Frankel et al [18]. as described in a previous publication on recovery of spinal cord injury [19]. In most cases, Frankel grades had not been assigned during hospitalization, so for purposes of the study they were assigned retroactively on the basis of the examination protocols. The degree of neurological recovery or regression in each patient was determined by comparing the Frankel grade of neurological deficit at first admission for rehabilitation (initial Frankel grade) with the grade at discharge from the same hospitalization. Recovery rate was assessed either as any recovery, namely a recovery of at least one Frankel grade from a grade of A, B, C or D, or as useful recovery, namely a recovery from Frankel grades A, B, or C at admission to grades D or E at discharge. In the authors opinion, the change from a non-functional status represented by Frankel grades A, B and C, to a functional status, represented by grades D and E, is an important aspect of recovery from the point of view of rehabilitation medicine. Other studies have also used such an assessment of recovery [19,20]. The assessment of useful recovery did not include patients with an initial Frankel grade of D or E. Logistic regressions were used to examine the association between various affecting factors and recovery [17]. Analyses of the LOS in hospital for rehabilitation due to SSSNL were performed after a square root transformation to approach a normal distribution. The associations of LOS with potentially affecting factors were analyzed by ANOVA: one-way ANOVA for multiple comparisons between decade of admission and SNL severity, and 3-way ANOVA for age, gender, and Frankel grade. Statistical significance was defined by p Data were analyzed by SPSS for Windows, version 11 (SPSS Inc., USA). Results Demographic and clinical data The patients included in the study were 180 men (69%) and 82 women (31%), with a median age of 61 years and a mean age of 58.6 years (SD = 11.9 years) at lesion onset. The SNL was cervical in 163 patients (62%), thoracic in 41 (16%), and lumbar in 58 (22%). The mean time from SNL onset to rehabilitation was 34.5 months (SD = 47.9 months). Initial Frankel grade was A in 2 patients (0.8%), B in 22 patients (8.4%), C in 124 patients (47.3%), and D in 114 patients (43.5%). The initial Frankel grade for thoracic SNL was C in 59% of the lesions and D in 32%; for cervical or lumbar SNL it was C or D in about 45% of the lesions; it was B in about 8% at all SNL levels. Eighteen patients were admitted before 1970, 28 between 1971 and 1980, 83 between 1981 and 1990, and 133 between 1991 and Outcome Survival. Mortality data were available in 261 of the 262 patients. One hundred and seventy of them (65%) survived at the end of the follow-up period (May 2001). The longest survival at that time was 35 years. The accumulated survival was 92.7% (SE = 1.7%) 5 years after the SNL onset, 80.4% (SE = 2.8%) 10 years after the SNL onset, 61% (SE = 4.1%) 15 years after the SNL onset, 42.1% (SE = 5.0%) 20 years after the SNL onset, and 32% (SE = 5.5%) 25 years after the SNL onset (Figure 1). Median survival time was 17.6 years. After controlling for gender, initial Frankel grade, SNL level, and decade of SNL onset, the mortality risk was 1.08 times higher for every additional year of

3 Outcomes of spinal neurological lesions caused by spinal stenosis 613 Table I. Changes in the severity of neurological damage by Frankel grade between admission for rehabilitation and discharge from hospitalization, in percent of patients (N = 262). Total of A, B, and C grades at admission (56.5%) minus total at discharge (23.7%) = 32.8%, representing 58% of 56.5%. Frankel Grade Relative proportion of the grade on admission (%) Relative proportion of the grade at discharge (%) Change in the relative proportion of the grade (%) A B C D E Figure 1. Survival following spinal neurological lesions due to spinal stenosis. Acc. survival = Accumulated survival rate. Time = - Time from lesion onset to death or end of follow-up. age at SNL onset (p ; 95% confidence interval: ). The effects of gender, initial Frankel grade, SNL level, and decade of SNL onset on the risk of mortality were not statistically significant when controlling for the other affecting factors. Neurological recovery. Eighty six patients, representing 58% of the 148 patients who had initial Frankel grades of A, B, or C and 32.8% of all SSSNL patients, achieved useful recovery and showed an improvement during the course of rehabilitation to Frankel grades D and E (Table I). Eighty eight of them (59%), and 116 of all patients with SSSNL (44.3%), showed any recovery (partial or complete). The frequency of any recovery in patients who had initial Frankel grades of A, B, or C was inversely related to the severity of the original deficit (Table 2). When controlling each initial Frankel grade, age at admission to rehabilitation, gender, SNL level, and decade of admission to rehabilitation for all the other listed variables, the initial Frankel grade, age, and SNL level had a significant effect on useful recovery and on any recovery (p ), while gender and decade did not have a significant effect on recovery. The odds of useful recovery during rehabilitation were 4.6 times higher for initial Frankel grade C versus A or B, and 5% lower for each additional year of age. The odds of useful recovery were also lower for thoracic and cervical versus lumbar SNL (Table 3). The effects of thoracic and cervical SNL on recovery were not statistically different. The odds of any recovery were 2.7 times higher (95% confidence interval = CI = ) for initial grade C versus A or B (p = 0.038), and 4% lower (CI = 2% 7 7%) for each additional year of age at admission to rehabilitation (p = 0.001). The odds of any recovery for thoracic SNL were 76% lower versus lumbar SNL (p ), and 65% lower (CI = 18% 7 85%) versus cervical SNL (p = 0.016), Table II. Relationship between severity of neurological damage and recovery. Changes in Frankel grade between admission for rehabilitation and discharge from hospitalization, in percent of initial number of patients for each grade (N). Frankel grade at discharge Frankel grade on admission (N) A (%) B (%) C (%) D (%) E (%) A (2) B (22) C (124) D (114) Table III. Odds of useful recovery during rehabilitation, controlling for affecting factors. SNL severity by Frankel grading. Age and decade at rehabilitation. For age, the odds are for each additional year. Each decade is compared to % confidence interval Affecting factor Odds p lower upper SNL severity Age SNL level 0.01 C vs L T vs L Gender Decade SNL = spinal neurological lesion, C = cervical SNL, L = Lumbar SNL, T = thoracic SNL, vs = versus. while those for cervical were not significantly different from those for lumbar SNL (p = 0.359). The odds of any recovery from initial grade D were not significantly different from those of any recovery from initial grade A or B (p = 0.066). LOS. The mean LOS was 99.7 days (SD = 65.7 days; range = days). When controlling for two age

4 614 J. Ronen et al. groups at rehabilitation ( 4 60 years or 5 61 years), gender, and initial Frankel grade (A, B, and C or D), only Frankel grade had a significant effect on LOS (p 5 001), while the effects of age and gender were not significant (p = and 0.693). Mean LOS decreased through the decades, but the decrease was not statistically significant (p = 0.6). The differences in LOS between SNL levels were also non-significant (p = 0.3) (Table 4). Discussion Although SS may be followed by pre- or postoperative SNL, which may cause morbidity and death, the orthopedic and rehabilitation medicine literature pays little attention to outcomes of neurological complications of SS or its treatment. Studies of SS rarely delve into the consequences of the related myelopathy, and most SNL studies focus on traumatic spinal cord lesions (TSCL). But although the number of patients with TSCL admitted to rehabilitation has remained approximately constant over the last four decades in our practice [19,21], the number of patients with SSSNL is continually increasing. More SSSNL patients were admitted in the last 10 years before the conclusion of the study than during the preceding 3 decades. The increase in admissions probably reflects the increase in public and professional awareness of the role of rehabilitation in the treatment of SNL. It is of interest, therefore, to examine the characteristics and outcomes in this group of patients. SSSNL characteristics As in other studies, patients with SSSNL in the present study are older than patients with either TSCL or non-traumatic SNL of other etiologies [4 5, 19 26], and the SSSNL is usually incomplete [4,23,26], C being the prevailing Frankel grade on Table IV. LOS by Frankel grade, decade of admission to rehabilitation, and SNL level. Mean LOS (days) SD (days) Frankel grade A Frankel grade B Frankel grade C Frankel grade D Admission before Admission between Admission between Admission between Cervical SNL Thoracic SNL Lumbar SNL SNL: spinal neurological lesion. admission. But unlike other studies, the present research includes mainly cervical SSSNL (62% vs 31% or less) [4,5,23]. SSSNL outcome Survival. Survival appears shorter than that of patients with TSCL and non-traumatic spinal cord lesions (NTSCL) described in other publications [1,21,27 29]. However, the median survival of 17.6 years found in SSSNL patients with a median age of 61 years at lesion onset is not far from expected survival at age 61 in the general population of Israel. It indicates that despite relatively old age and neurological compromise, these patients can live for many years; it is therefore necessary to ensure their maximal survival and the best possible quality of life during these years. Only age at lesion onset had a significant effect on survival in patients with SSSNL. The effects of SNL level and severity and that of the decade of lesion onset, which were significant following TSCL [21,27 29], were not significant in SSSNL. This is probably because of the distribution of the examined factors in SSSNL patients: most of the patients had Frankel Grade C or D, cervical SCL, and relatively recent lesion onset, so other grades, levels, or periods of lesion onset could hardly influence survival. Neurological recovery. Neurological recovery was remarkable. Almost 60% of the patients with Frankel grades A, B, or C showed useful recovery, and 44% of all SSSNL patients showed any recovery. For comparison, in previous studies useful recovery was found in 27% of TSCL [19] and 51% of mixed NTSCL [2], and any recovery in 34% of mixed SNL [23]. In SSSNL, recovery was inversely related to initial Frankel grade when the initial Frankel grade was A, B, or C. The effect of initial Frankel grade D on recovery, however, was not significantly different from that of initial Frankel grades A or B, which indicates that despite the high recovery rate, SSSNL patients tend to retain some neurological deficit. In addition to the initial Frankel grade, age at rehabilitation and SNL level had a significant effect on recovery. Recovery was more likely in cervical and lumbar than in thoracic SNL, but the advantage of cervical lesions was not sufficient for useful recovery, which was better only in lumbar SNL. The less reversible nature of thoracic SCL is probably related to the fact that a more prolonged pressure is involved in its pathogenesis, while the pathogenesis of cervical and lumbar SNL includes more fluctuations in pressure owing to the excess mobility of the cervical and lumbar spine. LOS. The LOS of the patients with SSSNL was within the range presented in European publications

5 Outcomes of spinal neurological lesions caused by spinal stenosis 615 describing patients with TSCL, and much longer than spinal cord lesions (SCL) LOS in American studies [4,5,22,23,26,30]. Only Frankel grade affected SSSNL LOS significantly. However, controlling for various potentially affecting factors, LOS was found shorter in patients with SSSNL than in patients with most other SNL etiologies, including trauma. This may suggest that although rehabilitation of SSSNL and TSCL patients was based on similar considerations of SNL severity and the achievement of expected function, patients with SSSNL achieved their expected functional results earlier than patients with TSCL, therefore requiring shorter LOS, because the expected functional outcome in patients with SSSNL is lower than that of the patients with TSCL. Similarly, in a previous study, the LOS of patients with non-traumatic spinal cord lesions was shorter than that of patients with TSCL who were admitted with similar FIM scores and had similar FIM efficiency [3]. Limitations. The study focused on patients with SNL that followed degenerative SS, and the results cannot be generalized to all SS patients. The clinical condition is described in terms of SNL severity and level, which are relevant for patients with spinal neurological deficits, and not in functional terms, such as walking ability, which are more relevant for other SS patients. In addition, the outcomes demonstrated in this retrospective study, which does not contain detailed data about the management procedures, does not allow any interpretation of the effect of surgery or rehabilitation. It does allow, however, inference from what is accepted for patients with TSCL with comparable outcomes, and may thereby contribute to the assessment of the role of rehabilitation medicine in the care of SSSNL. In conclusion, the findings of the present study indicate that despite their relatively old age and of comorbidities likely to be present at their age, patients with SSSNL who undergo decompressive surgery and rehabilitation may survive many years and achieve significant neurological recovery. However, many of them tend to remain with neurological deficits, which may be relatively mild but still cause a significant disability and lethal complications. Therefore, to ensure longevity and quality of life, patients with SSSNL require adequate care and functional restoration in a specialist rehabilitation system, similarly to TSCL patients with comparable neurological deficit. 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