Spinal Stenosis: Factors That Influence Patients' Decision to Undergo Surgery.

STUDY DESIGN: Prospective noninterventional observation. OBJECTIVE: To examine factors that influence a patient's real decision to accept the offer of surgery for lumbar spinal stenosis in a relatively controlled situation. SUMMARY OF BACKGROUND DATA: A patient's decision to undergo spine surgery might be influenced by factors other than pathology. However, there is limited research exploring the decision. METHODS: A study performed for other purposes recruited persons aged 55-90 years with medical record evidence of an offer of surgery for spinal stenosis by a university faculty surgeon. Inclusion criteria included neurogenic claudication, subjectively positive imaging, and difficulty walking 200 yards. Potential subjects with additional disabling conditions (eg, lower limb amputation), conditions that might mimic stenosis (eg, polyneuropathy), or some contraindications to invasive treatment (eg, anticoagulation) were excluded. Subjects filled out questionnaires on function, quality of life, pain, and health, and were examined by a spine surgeon masked to diagnostic category (Other recruits had back pain or no symptoms). Telephone follow-up 6-12 months later determined whether surgery was done. RESULTS: Of 39 qualifying subjects, 20 followed through with surgery. A binary logistic regression revealed that significant factors that influence patient decision making included SF-36 measures of "Comparative Health" and "Role Limit Emotional" as well as the subject's overall perception of their quality of life. The combination of all 3 factors yielded a predictive model (P=0.031). Individually, however, only "Comparative Health" was significant and able to predict a decision to proceed with surgery (P=0.036). CONCLUSIONS: In this population with significant disability, uncomplicated medical history, and a relatively clear diagnosis, the decision to accept surgical intervention was influenced by issues of perceived overall health and quality of life. Interventions to change real or perceived overall health may impact patient acceptance of surgery.

Patient perception of pain versus observed pain behavior during a standardized electrodiagnostic test.

INTRODUCTION: Clinicians often assume that observations of pain behavior are adequate for assessment of patient pain perception during procedures. This has not been tested during a standardized electrodiagnostic experience. METHODS: During a prospective trial including extensive, standardized electrodiagnostic testing on persons with lumbar stenosis, vascular claudication, and asymptomatic volunteers, the subjects and an observer rated levels of pain. RESULTS: In 60 subjects, observers significantly under-rated pain (Visual Analog Scale 3.17 ± 2.23 vs. 4.38 ± 2.01, t = -4.577, df = 59, P < 0.001). Perceived pain during testing related to bodily pain as measured by the visual analog, McGill, Pain Disability, and Quebec scales, but not age, duration of symptoms, Tampa kinesiphobia, Center for Epidemiological Studies Depression scale, or SF-36 health quality of life. CONCLUSIONS: Persons with worse pain syndromes may perceive more pain during testing than others. Clinicians and researchers should understand that patients may have more pain than they recognize.

Reliability of the clinical examination in the diagnosis of neurogenic versus vascular claudication.

BACKGROUND CONTEXT: As research increasingly challenges the diagnostic accuracy of advanced imaging for lumbar spinal stenosis, the impression gleaned from the office evaluation becomes more important. Neurogenic claudication is a hallmark of lumbar spinal stenosis, but the reliability of clinical impression of claudication has not been studied. PURPOSE: To determine the reliability of the clinical examination for neurogenic claudication in an idealized setting. STUDY DESIGN: Prospective masked controlled trial. PATIENT SAMPLE: Persons aged 55 to 90 years were recruited to form three groups: those offered surgery for spinal stenosis by academic spine surgeons, those who had peripheral vascular symptoms and positive ankle-brachial index (ABI), and those who were asymptomatic. All were extensively screened against confounding diseases. Forty-three neurogenic, 12 vascular, and 35 asymptomatic recruits were tested. OUTCOME MEASURES: Clinical impression of neurogenic claudication. METHODS: A neurosurgeon and a vascular surgeon, masked to each other's findings, imaging, and recruitment status, performed a codified but unconstrained comprehensive spine and vascular history and physical examination for each subject. The surgeon's impression was recorded. RESULTS: Masked surgeons strongly agreed with the recruitment diagnosis (neurosurgeon kappa 0.761, vascular surgeon kappa 0.803, both p<.001) and with each other (kappa 0.717, p<.001). However, disagreements did occur between examiners and recruitment diagnosis (neurosurgeon n=13 cases, vascular surgeon n=10) and between examiners (n=14 cases). Pain level and marginally some measures of disability related to the agreement, but specific aspects of the physical examination, showed poor interrater reliability and did not contribute to the agreement. CONCLUSIONS: The clinical impression of neurogenic claudication is a reliable construct. The history, but not the poorly reproduced physical examination, contributes to reliability. The level of disagreement between experts in this simplified, yet severely involved, population raises concern about the risk of misdiagnosis in individual cases. Thus, surgical and other consequential decisions about diagnosis may require ancillary tests such as electromyography or ABI.

Defining the clinical syndrome of lumbar spinal stenosis: a recursive specialist survey process.

BACKGROUND: Lumbar spinal stenosis has evolved from an anatomic concept to a poorly defined clinical syndrome. Rules for such a syndrome need to be informed by the experience and beliefs of expert clinicians. The level of certainty is seldom considered in defining criteria for a syndrome. OBJECTIVE: To design an innovative online recursive survey technique to seek out information that is valued by specialists and to measure the impact of this evidence on their strength of conviction regarding the diagnosis of spinal stenosis. DESIGN: Prospective online survey. SETTING: University-based project. PARTICIPANTS: American physiatrists recruited by online postings and postcards. INTERVENTIONS: A recursive process presented a scenario that allowed clinicians to choose 1 of 10 clinical factors and then asked their level of certainty about diagnosis when that factor is true. Subsequent questions build on that assumption by adding other factors. MAIN OUTCOME MEASURES: Certainty regarding the diagnosis of clinical lumbar spinal stenosis. RESULTS: Of a total of 97 participants, 80 completed 3 or more iterations. "Leg pain while walking" (66%), "must sit down or bend" (66%), and "flex forward while walking" (49%) were the most commonly selected questions. "Normal foot pulses" (19%), "back pain" (16%), "leg pain" (15%), "relief with rest" (14%), and "sensory deficits" (12%) were of intermediate value, whereas "problems with balance," "have fallen recently," and "the sacroiliac joint is not the main pain generator" were all chosen less than 5% of the time. Statistically significant (P < .05) change in certainty ceased after 6 questions at 86.2% certainty. CONCLUSIONS: A recursive approach to diagnostic certainty is valuable. Within 5 questions, clinicians become almost 90% certain that a person has clinical spinal stenosis. This question set provides one pragmatic clinical criterion for the syndrome of lumbar spinal stenosis.

The risk of hematoma following extensive electromyography of the lumbar paraspinal muscles.

INTRODUCTION: The purpose of this study is to provide a controlled trial looking at the risk of paraspinal hematoma formation following extensive paraspinal muscle electromyography. METHODS: 54 subjects ages 55-80 underwent MRI of the lumbar spine before or shortly after electromyography using the paraspinal mapping technique. A neuroradiologist, blinded to the temporal relationship between the EMG and MRI, reviewed the MRIs to look for hematomas in or around the paraspinal muscles. RESULTS: Two MRIs demonstrated definite paraspinal hematomas, while 10 were found to have possible hematomas. All hematomas were < 15 mm, and none were close to any neural structures. There was no relationship between MRI evidence of hematoma and either the timing of the EMG or the use of aspirin or other nonsteroidal anti-inflammatory drugs. CONCLUSIONS: Paraspinal electromyography can be considered safe in the general population and those taking nonsteroidal anti-inflammatory drugs.

Fear of movement/(re)injury and activity avoidance in persons with neurogenic versus vascular claudication.

BACKGROUND CONTEXT: Activity avoidance and fear of movement/(re)injury are increasingly being recognized as important factors in the rehabilitation of persons suffering from chronic low back pain, yet these factors have not been thoroughly explored in persons suffering from neurogenic claudication resulting from lumbar spinal stenosis. PURPOSE: To determine, compare, and explain differences in the degree of fear of movement/(re)injury and activity avoidance in persons with neurogenic claudication, vascular claudication, and asymptomatic volunteers. STUDY DESIGN: Prospective controlled cohort study at an academic medical center. PATIENT SAMPLE: Eighty-two adults aged between 55 and 90 years with neurogenic claudication, vascular claudication, or no back and leg symptoms. METHODS: Subjects completed a visual analog scale for pain, the Center for Epidemiological Studies Depression Scale, the Quebec Back Pain Disability Scale, Short Form 36 (SF-36), and the 13-item version of the Tampa Scale for Kinesiophobia (Tampa). They were also asked to estimate their maximum walking distance. OUTCOME MEASURES: The difference in the level of fear of movement/(re)injury and activity avoidance in the two symptomatic populations, as well as the predictive validity of self-reported measures such as pain level, functional impairment, and depression in determining fear avoidance. RESULTS: The total Tampa score was significantly higher in individuals with neurogenic claudication (M=31.68; standard deviation [SD]=7.56; N=39) than vascular claudication (M=24.07; SD=6.57; N=15) (p=.002), whereas both symptomatic groups were significantly different from controls (M=18.71; SD=6.3; N=28) (p<.001 vs. neurogenic; p<.05 vs. vascular). Tampa scores were strongly correlated to the Center for Epidemiological Studies Depression Scale score (r=0.515; p<.001), SF-36 Physical Functioning score (r=-0.632; p<.001), and the visual analog scale average level of pain in a week (r=0.461; p<.001). Using a standard multiple regression model (R²=0.406; F(3,62)=13.47; p<.001), the amount of functional impairment, that is, the SF-36 Physical Functioning score, was the strongest contributor to the variance in the Tampa total score (ß=-0.371; p=.014). The average level of pain did not make a significant or unique contribution in predicting the Tampa total score. Functional impairment as measured by the SF-36 Physical Functioning was strongly correlated with both pain (r=-0.740; p<.001) and depression (r=-0.488; p<.001). CONCLUSIONS: Persons with neurogenic claudication have important elevations in fear and avoidance, higher than those with claudication from another source (vascular insufficiency). The impact of fear and avoidance along with other factors such as depression on pain, disability, and quality of life for persons with claudication and spinal stenosis need to be explored.

Construct validity of language independent functional evaluation as used by Spanish-speaking clinicians to evaluate persons with developmental delays.

OBJECTIVE: This study aimed to establish the utility of Language Independent Functional Evaluation (LIFE) as used by clinicians. DESIGN: This study was a prospective trial involving 100 Spanish-speaking rehabilitation clients between the ages of 9 and 45 yrs with cognitive disability and 2 rehabilitation clinicians who cared for them at a Colombian inpatient and outpatient rehabilitation facility. Clinicians who had worked with clients for more than 2 mos rated their function using the LIFE and the Spanish-translated Barthel index. RESULTS: Overall LIFE scores correlated well with Barthel scores (r[98] = 0.793, P < 0.0001) and also on an item-to-item basis in all activities except grooming, bowel continence, and bladder continence. CONCLUSIONS: The LIFE is a reliable tool for clinicians to use in the assessment of persons with cognitive disability, regardless of the clinician's language.

The ligamentum flavum at L4-5: relationship with anthropomorphic factors and clinical findings in older persons with and without spinal disorders.

OBJECTIVE: To examine the relationship between ligamentum flavum thickness and clinical spinal stenosis. DESIGN: A validation study. SETTING: Clinical research laboratory. PATIENTS: A total of 119 subjects from the Michigan Spinal Stenosis Study (MSSS). METHODS: Two new measurement techniques were compared by use of magnetic resonance images of 4 asymptomatic subjects by 2 examiners. The technique with the best interrater reliability was then used to measure the ligamentum flavum at L4-L5 in 119 subjects in the MSSS who, on the basis of clinical examination without imaging, were thought to have lumbar stenosis, mechanical back pain, or no pain. These findings were related to other radiologic findings, demographics, clinical severity, and electrodiagnostic findings. MAIN OUTCOME MEASUREMENTS: Perpendicular on the inside of the spinal canal from the deepest point of concavity of the lamina to the edge of the ligament. RESULTS: The ligamentum flavum width measurement had high interrater (r = 0.774) and intrarater (r = 0.768) reliability. In 28 asymptomatic volunteers, ligamentum flavum width averaged 5.72 ± 0.95 mm, with the left side significantly thinner than the right (t = 2.117, P = .044), and thicker ligaments with age (r = 0.653, P < .001). Asymptomatic persons whom radiologists thought had stenosis had thicker ligaments (t = 2.273, P = .032). Persons with clinical stenosis (n = 48) and mechanical pain (n = 43) had ligament thickness similar to that of asymptomatic volunteers. Among patients with clinical stenosis, ligamentum flavum thickness did not relate to symptom severity (pedometer and laboratory ambulation tests, Pain Disability Index, and visual analog scale for pain). Most neurophysiological findings had no relationship with ligamentum flavum width, except the presence of limb fibrillation potentials related to a thinner ligament (t = 2.915, P = .004). CONCLUSIONS: The measurement technique is standardized for the ligamentum flavum for future use. Although the ligamentum flavum appears to get thicker with age, other factors, including clinical diagnosis, pain, and function, do not appear to relate to the ligamentum flavum width.

Construct validation of the Language Independent Functional Evaluation versus the Barthel Index in a Mongolian community.

PURPOSE: Differences in language and literacy impede our understanding of the impact of disability around the world. Since function is primarily action, the computer-animated Language Independent Functional Evaluation (L.I.F.E.) might bypass the use of written or verbal scales. This study validates L.I.F.E. in a developing world population. METHODS: Families were randomly chosen from the city centre, suburban 'ger' districts and countryside of Arvaikheer, Mongolia. The L.I.F.E. and cross-translated Mongolian Barthel Index were administered in random order. Demographics including subjective observation of disability were gathered. L.I.F.E. scores were converted to Barthel equivalents. RESULTS: One hundred forty-four persons completed the test, 24 answered for other persons. Persons with observed disability had lower L.I.F.E. scores (64.55 vs. 94.53, p < 0.001). L.I.F.E. and Barthel scores related well. (Spearman's rho = 0.757, p < 0.001; for persons with observed disability Pearson r = 0.820, p < 0.001). Individual functions all had high interclass correlations (>0.75), except bowel and bladder, which had moderate correlations. Qualitative inquiry found the L.I.F.E. was preferred over the Barthel. CONCLUSIONS: Using L.I.F.E., function can be measured without language or literacy. L.I.F.E. expands our ability to measure and compare the prevalence of disability and the impact of rehabilitation across regions perhaps leading to more rational allocation of resources.

A prospective, masked 18-month minimum follow-up on neurophysiologic changes in persons with spinal stenosis, low back pain, and no symptoms.

OBJECTIVES: To describe neurophysiologic changes over time in persons with and without spinal complaints and to assess whether paraspinal denervation predicts change in stenosis on magnetic resonance imaging (MRI) and clinical course. DESIGN: Prospective, controlled, masked trial. SETTING: University spine program. PARTICIPANTS: Persons aged 55 to 80 years, screened for polyneuropathy and determined on clinical examination to have spinal stenosis, mechanical low back pain, or no spinal symptoms. INTERVENTIONS: A comprehensive codified history was obtained and subjects underwent physical examination, ambulation testing, masked electrodiagnostic testing including paraspinal mapping, and MRI, repeated at greater than 18 months. This study presents detailed technical information and additional analyses not reported previously. MAIN OUTCOME MEASUREMENTS: Change in electrodiagnostic findings. Among persons with clinical stenosis, relationship of change in paraspinal mapping scores to MRI findings and clinical changes. RESULTS: Of 149 initial subjects, 83 (79.3% of eligible subjects) repeated testing at 20 (+/-2 SDs) months. No significant change in limb muscle spontaneous activity or motor unit pathology was noted in any group. In 23 persons with initial diagnosis of stenosis, paraspinal mapping electromyography related to change in diagnosis over time (analysis of variance F = 3.77, P = .037), but not to most initial magnetic resonance imaging measurements or to change in spinal canal diameter. CONCLUSIONS: Clinical spinal stenosis is neurophysiologically stable in most persons. Paraspinal electromyographic changes reflect large changes in clinical course, but neither neurophysiologic nor clinical changes relate to change in spinal geometry over 20 months.

Magnetic resonance imaging vs. electrodiagnostic root compromise in lumbar spinal stenosis: a masked controlled study.

OBJECTIVE: The high false-positive rate of magnetic resonance imaging (MRI) makes it a less-than-reliable tool for evaluating clinically significant stenosis. Finding MRI changes that correlate with electrodiagnostic abnormalities might lead to more successful treatment decision making. The purpose of this study was to identify MRI changes that correlate with neurologic abnormalities measured by electrodiagnosis in patients with spinal stenosis. DESIGN: One hundred fifty persons with and without back pain between the ages of 55 and 79 yrs participated in this prospective, blinded, controlled study. Exclusion criteria included previous spine surgery or known neuropathy. Needle electromyography of the limb, nerve conduction studies, including peroneal F-wave and tibial H-wave, and noncontrast lumbo-sacral spine MRI were completed. A codified physical medicine and rehabilitation history and physical examination was completed to differentiate symptomatic lumbar stenosis patients from asymptomatic controls. The relationship between lumbar MRI measurements and extremity electromyography findings was studied. RESULTS: MRI measurements did not differ significantly with respect to extremity needle electromyography findings in the entire population or in patients with clinical signs of lumbar stenosis. In the entire population, an absent tibial H-wave corresponded to the interfacet ligament distance at L5-S1 and anterior to posterior canal size at L4-5. In patients clinically evaluated as having lumbar stenosis, peroneal F-wave latency correlated with anteroposterior canal size at L4-5 and interfacet ligament and anterior to posterior lateral recess narrowing at L5-S1. In patients with clinical signs and symptoms of lumbar stenosis, limb electromyography findings did not correlate with MRI measurements, although H-wave and F-wave testing correlated with relevant locations of stenosis. CONCLUSIONS: Needle electromyography does not differentiate patients with symptomatic mild or moderate lumbar stenosis. However, H-wave and F-wave correlated to specific anatomical changes on MRI in this patient population.

Spinal canal size and clinical symptoms among persons diagnosed with lumbar spinal stenosis.

OBJECTIVE: Clinical symptoms associated with lumbar spinal stenosis (LSS) are believed to be due to neurogenic claudication caused by narrowing of the central and lateral spinal canals. However, there is a paucity of published data on these relationships. The purpose of the present study was to examine the relationship between clinical symptoms associated with LSS and osseous anterior-posterior (AP) spinal canal diameter as measured on axial magnetic resonance imaging. DESIGN: Cross-sectional study conducted at a University Spine Program. Fifty persons with a clinical diagnosis of LSS were administered measures of clinical pain and perceived function. Walking distance in the laboratory and community was also assessed. Participants also underwent magnetic resonance imaging of the spine. RESULTS: Using recommended upper limits from the literature, patients with smaller canals reported greater perceived disability, but no other group differences emerged. In the entire sample, AP spinal canal diameter was not significantly associated with any of the clinical symptom measures examined. Body mass index was found to be significantly related to walking distance, but not perceived function or pain. CONCLUSIONS: AP spinal canal diameter is not predictive of clinical symptoms associated with LSS. The findings also suggest that body mass may play a significant role in functional limitations observed in this population.

Needle EMG has a lower false positive rate than MRI in asymptomatic older adults being evaluated for lumbar spinal stenosis.

OBJECTIVE: False positive imaging tests--disk herniation or spinal stenosis--occur in a significant number of asymptomatic persons, increasing with age. A similar or greater prevalence probably occurs in people who present to physicians with mechanical back pain, potentially causing therapeutic misadventure. Electrodiagnostic testing may be normal in persons with asymptomatic pathology, but has not been directly tested. METHODS: As part of a larger study of older persons with lumbar stenosis, 35 asymptomatic adults were evaluated by an extensive questionnaire, codified history and physical examination, masked electrodiagnostic testing, and masked lumbar magnetic resonance imaging, with repeated procedure at 18 months. Thirty-two subjects remained after removal of three with neuromuscular disease. RESULTS: The radiologist characterized 18 (56%) asymptomatic subjects as having spinal stenosis. There was no relationship between electrodiagnostician diagnosis and radiologist diagnoses. Among the 13 whom the electrodiagnostician identified as abnormal, 2 had technical data within normal limits and the only abnormality in 5 was >2/10 polyphasic motor units (considered a 'soft' finding by many). One muscle in 1 subject had abnormal spontaneous activity, and 3 persons scored >4 on paraspinal mapping. Electrodiagnostic findings were normal in the 5 (16%) who had disk herniations. None of the 22 re-examined acquired symptoms over 18 months and follow-up electrodiagnosis was essentially normal (one muscle in 1 subject had 3/10 polyphasic motor units). CONCLUSIONS: MRI changes, motor unit changes on EMG needle examination, and low paraspinal mapping scores are not uncommon in asymptomatic older adults with spinal stenosis or disk herniation and may lead to false positive tests. The stricter criterion of abnormal spontaneous activity on needle examination and paraspinal mapping scores greater than 6 offered in this paper lowers the risk of false positive EMG testing. SIGNIFICANCE: EMG is less likely to be abnormal (false positive) in asymptomatic adults than MRI.

Electromyographic and magnetic resonance imaging to predict lumbar stenosis, low-back pain, and no back symptoms.

BACKGROUND: Magnetic resonance imaging is commonly used to diagnose lumbar spinal stenosis. Some persons without symptoms have a small lumbar spinal canal. Electrodiagnosis has been used to diagnose spinal stenosis for over sixty years, but we are aware of no masked, controlled trials of the use of electrodiagnosis for that purpose. This study was performed to evaluate the relationships of magnetic resonance imaging measures and electrodiagnostic data with the clinical syndrome of spinal stenosis. METHODS: One hundred and fifty persons between the ages of fifty-five and eighty years old, including asymptomatic volunteers and persons referred for lumbar magnetic resonance imaging, underwent clinical examination, electrodiagnosis, and magnetic resonance imaging. Subjects were excluded if they had neuromuscular disease, sacral cancer, or inadequate test results, which left 126 subjects for the final analysis. The final cohort was divided into three groups--no back pain, mechanical back pain, and clinical spinal stenosis--on the basis of the impression of the examining physician, for whom the results of the magnetic resonance imaging and electrodiagnostic testing were masked. A spine surgeon also reviewed both the imaging and clinical examination data. RESULTS: The examining physician's diagnosis of clinical spinal stenosis was significantly related to the neurological findings on examination (p < 0.05) and to the spine surgeon's diagnosis (p < 0.001). The diagnosis of clinical spinal stenosis was also significantly related to the presence of fibrillations on electrodiagnostic testing (p < or = 0.003), the minimum anteroposterior diameter of the spinal canal on the magnetic resonance images (p = 0.016), and the average of the two smallest spinal canal diameters (p = 0.008) on the images. Measurements on magnetic resonance imaging did not differentiate subjects with clinical spinal stenosis from controls better than chance, whereas paraspinal mapping electrodiagnosis scores did. CONCLUSIONS: This prospective, controlled, masked study of electrodiagnosis and magnetic resonance imaging for older subjects showed that imaging does not differentiate symptomatic from asymptomatic persons, whereas electrodiagnosis does. We believe that radiographic findings alone are insufficient to justify treatment for spinal stenosis.

Comparing pain severity and functional status of older adults without spinal symptoms, with lumbar spinal stenosis, and with axial low back pain.

BACKGROUND: Functional status has been quantified in the adult low back pain (LBP) population, but has not been characterized for older adults with spinal symptoms. OBJECTIVES: To compare pain severity and functional status of older adults with and without spinal symptoms, and to determine what factors are associated with quality of life in the spinal stenosis and axial LBP groups. METHODS: In 24 subjects greater than 55-years old with lumbar spinal stenosis, 12 with LBP, and 12 without spinal symptoms, obtain the following: pain severity with 10-cm visual analog scale (VAS), 15-minute walk test, 7-day walking distance, Quebec Back Pain Disability Scale (QBPDS), and Pain Disability Index (PDI). RESULTS: The mean scores were worst for the stenosis group, were intermediate for the LBP group, and were the best for the asymptomatic group. Analysis of variance showed that the pain VAS (p < 0.001), 15-minute walk test (p = 0.01), 7-day walk (p = 0.02), QBPDS (p < 0.001), and PDI (p < 0.001) were different between at least two groups. All the variables in the stenosis group were worse than in the asymptomatic group, but only the pain VAS, QBPDS, and PDI in the LBP group were worse than in the asymptomatic group. In both the stenosis and LBP group the QBPDS and PDI were only related to pain VAS. CONCLUSION: Seniors with spinal stenosis and LBP have more disability than asymptomatic seniors. The 15-minute walking test with the stenosis group was slower than with the asymptomatic seniors. However, they compensate so that their 7-day walking distance is not as significantly decreased.

Predictors of pain and function in persons with spinal stenosis, low back pain, and no back pain.

STUDY DESIGN: Longitudinal masked, double-controlled cohort study. OBJECTIVES: To determine prognosis and predictors of function and pain in persons with spinal stenosis. SUMMARY OF BACKGROUND DATA: The clinical syndrome of spinal stenosis is common and disabling, but not clearly related to anatomic measures. Prognosis not well studied. METHODS: Persons 55 to 80 years of age with and without stenosis on preliminary review of magnetic resonance imaging (MRI), and asymptomatic volunteers underwent screening, questionnaires, physical examination, ambulation testing, masked electromyogram (EMG), and masked MRI scans; these were repeated at >18 months. RESULTS: Twenty-three asymptomatic, 28 back pain, and 32 clinically diagnosed stenosis subjects underwent follow-up. Although initial and follow-up diagnosis tended to agree (kappa = 0.394, P < 001), there were substantial shifts between the three groups. Among persons with clinically diagnosed stenosis, every measure trended for improvement, including significant changes in pain, ambulation, and EMG. Ambulation velocity and Pain Disability Index at follow-up were predicted by initial disability measures. Pain was predicted by initial sleep difficulty but not initial pain. EMG and MRI did not predict function or pain. CONCLUSION: Clinically recognized spinal stenosis is fluctuating and largely improving, and in continuum with back pain and no symptoms. Since anatomic and neurologic deficits do not predict future function, they should not be weighed heavily in surgical risk-benefit discussions.

Specificity of needle electromyography for lumbar radiculopathy and plexopathy in 55- to 79-year-old asymptomatic subjects.

OBJECTIVE: Determine specificity of needle electromyography for lumbar radiculopathy and plexopathy using a blinded study design. DESIGN: Asymptomatic community volunteers ages 55 and older, as part of a spinal stenosis study, were given a standardized electrodiagnostic evaluation by a blinded electromyographer. A monopolar needle was used to evaluate five leg muscles and the lumbar paraspinal muscles. The specificities of different diagnostic criteria for radiculopathy and plexopathy were then calculated. RESULTS: There were 30 subjects with a mean age of 65.4 yrs (SD 8.0). When only positive sharp waves or fibrillations were counted as abnormal, most of the diagnostic criteria (two limb muscles plus associated lumbar paraspinal muscle abnormal, two limb muscles abnormal, or one limb muscle plus associated lumbar paraspinal muscle abnormal) had 100% specificity. When we also included at least 30% polyphasia in the limb muscles as abnormal, the respective specificities were 97, 90, and 87%. When we also included at least 20% polyphasia in the limb muscles as abnormal, the respective specificities were 77, 60, and 60%. The specificity for plexopathy was 100% when only positive sharp waves or fibrillations were used, and it remained 100% when increased polyphasia was added. CONCLUSION: Needle electromyography has excellent specificity for lumbosacral radiculopathy and plexopathy when appropriate diagnostic criteria are used.

The sensitivity and specificity of electrodiagnostic testing for the clinical syndrome of lumbar spinal stenosis.

STUDY DESIGN: Prospective, masked, double controlled diagnostic trial. OBJECTIVES: To determine the sensitivity and specificity of electrodiagnostic consultation (EDX) for the clinical syndrome of lumbar spinal stenosis. SUMMARY OF BACKGROUND DATA: EDX has been used for more than 50 years to diagnose spinal disorders but has not met the new standards of evidence-based medicine. METHODS: A total of 150 subjects (asymptomatic volunteers and patients with MRIs suggesting back pain or spinal stenosis; 55-80 years of age) underwent physiatrist history and physical examination, MRI, and review of this data by a neurosurgeon, with each clinician masked to any outside information, leading to a unanimous consensus on diagnosis in 55. After masked EDX testing, 7 subjects with undiagnosed neuromuscular disease were discovered. EDX findings were related to "clinical gold standard" diagnoses in 48 persons. RESULTS: Paraspinal mapping EMG score of >4 had 100% specificity and 30% sensitivity for stenosis compared with either the back pain or asymptomatic groups (each, P < 0.04). A composite limb and paraspinal fibrillation score had a sensitivity of 47.8% and specificity of 87.5% (P = 0.008), and H-wave sensitivity was 36.4, specificity 91.3 (P = 0.026) for stenosis versus all controls. CONCLUSIONS: This first masked study in the 60-year history of needle electromyography also introduces anatomically validated needle placement, quantified and reproducible examination of the paraspinal muscles, and dual control populations to EDX research in spinal disorders. EDX has statistically significant, clinically meaningful specificity for spinal stenosis and detects neuromuscular diseases that may masquerade as stenosis.

Paraspinal electromyography: age-correlated normative values in asymptomatic subjects.

STUDY DESIGN: Cross-sectional study. OBJECTIVES: To determine if the amount of lumbar paraspinal denervation increases with age and present normative data on the amount of denervation present in asymptomatic subjects. SUMMARY OF BACKGROUND DATA: To our knowledge, there are no data on the relationship of paraspinal denervation with age or normative data on the amount of denervation expected in asymptomatic older adults. METHODS: We combined the data from our current study of asymptomatic adults, age 55-79 years, and a previous study of asymptomatic adults, age 18-58 years, who underwent lumbar paraspinal muscle needle electromyography using a validated needle electromyography (MiniPM) technique. We then compared the results of the age group 55-79 to that of the age group 18-54. RESULTS: The older group scored significantly higher than the younger group by 1.7 (P = 0.008, 95% confidence interval 0.5-3.0). Linear regression showed that age was a significant predictor of the MiniPM score (beta = 0.04, and P = 0.04). For subjects 55 years and older, mean MiniPM score on one side was 2.3 (standard deviation 3.6). The upper range of the 95th percentile was 10. CONCLUSIONS: The amount of lumbar paraspinal muscle denervation does increase with age. Understanding the range of findings in asymptomatic subjects will help us interpret lumbar paraspinal needle electromyography findings in patients with spinal disorders.

Paraspinal electromyography that compares concentric with monopolar needles: a blinded study.

OBJECTIVE: To establish interrater reliability for paraspinal muscle needle electromyography study with both monopolar and concentric needles in symptomatic and asymptomatic persons and to further establish normative data for paraspinal needle study. DESIGN: At a university spine center, participants with and without radiating low back pain were evaluated with the mini-paraspinal mapping paraspinal needle technique by an unblinded and a blinded electromyographer. RESULTS: In the symptomatic group, the intraclass correlation coefficient between concentric and monopolar needles was 0.793; between monopolar needles, it was 0.876; and between concentric needles, it was 0.966. In the asymptomatic group, the mean total score was 0.25. CONCLUSIONS: The good interrater reliability with the same needle type helps support the validity of the needle electromyography study of the paraspinal muscles. The good correlation between the concentric and monopolar needles shows the data published using monopolar needle data also apply to studies using paraspinal needle electromyography with concentric needles. The low score with the asymptomatic group reaffirms that using a cutoff score of >2 as abnormal has a false-positive rate of <5%.