The Spine Journal - (2013) -

Clinical Study

Reliability of the clinical examination in the diagnosis of neurogenicversus vascular claudication

Andrew J. Haig, MDa,*, Paul Park, MDb, Peter K. Henke, MDc, Karen S.J. Yamakawa, MSa,Christy Tomkins-Lane, PhDd, Juan Valdivia, MDb, Sierra Loar, MPAa

aDepartment of Physical Medicine and Rehabilitation, University of Michigan Health System, 1500 E. Medical Center Dr, Ann Arbor, MI 48109, USAbDepartment of Neurological Surgery, University of Michigan Health System, 1500 E. Medical Center Dr, Ann Arbor, MI 48109, USA

cDepartment of Vascular Surgery, University of Michigan Health System, 1500 E. Medical Center Dr, Ann Arbor, MI 48109, USAdMount Royal University, 4825 Mount Royal Gate SW, Calgary, Alberta T3E 6K6, Canada

Received 11 November 2011; revised 10 October 2012; accepted 1 June 2013

Abstract BACKGROUND CONTEXT: As research i

FDA device/drug

nance Imaging, Arter

Author disclosure

employer); Support fo

NIH (H, Paid directly

viewing the manuscr

Private Investments:

hospitals, Payorst Hea

ing Arrangements: Mi

related to the study: N

sulting: Globus Medi

(B, Paid directly to

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http://dx.doi.org/10.10

ncreasingly challenges the diagnostic accuracy ofadvanced imaging for lumbar spinal stenosis, the impression gleaned from the office evaluationbecomes more important. Neurogenic claudication is a hallmark of lumbar spinal stenosis, butthe reliability of clinical impression of claudication has not been studied.PURPOSE: To determine the reliability of the clinical examination for neurogenic claudication inan idealized setting.STUDY DESIGN: Prospective masked controlled trial.PATIENT SAMPLE: Persons aged 55 to 90 years were recruited to form three groups: those of-fered surgery for spinal stenosis by academic spine surgeons, those who had peripheral vascularsymptoms and positive ankle-brachial index (ABI), and those who were asymptomatic. All wereextensively screened against confounding diseases. Forty-three neurogenic, 12 vascular, and 35asymptomatic 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 spineand vascular history and physical examination for each subject. The surgeon’s impression wasrecorded.RESULTS: Masked surgeons strongly agreed with the recruitment diagnosis (neurosurgeon kappa0.761, 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 (neurosurgeonn513 cases, vascular surgeon n510) and between examiners (n514 cases). Pain level and margin-ally some measures of disability related to the agreement, but specific aspects of the physical ex-amination, showed poor interrater reliability and did not contribute to the agreement.CONCLUSIONS: The clinical impression of neurogenic claudication is a reliable construct. Thehistory, but not the poorly reproduced physical examination, contributes to reliability. The level ofdisagreement between experts in this simplified, yet severely involved, population raises concern

status: Approved (Electromyogram, Magnetic Reso-

ial doppler machine).

s: AJH: Grants: NIH (H, Paid directly to institution/

r travel to meetings for the study or other purposes:

to institution/employer); Payment for writing or re-

ipt: NIH (H, Paid directly to institution/employer),

President, Haig et al.; Consulting (consulting with

lthcare Systems 100% owing, D); Speaking/Teach-

scellaneous Academic Organizations (B). PP: Grant

IH (C, Paid directly to institution/employer); Con-

cal (D), Medtronic (C), Depuy (B); Grants: SMISS

institution/employer), Congress of Neurological

Surgeons (C, Paid directly to institution/employer), Grant: NIH (B, Paid

directly to institution/employer). PKH: Endowments: Endowed Professor-

ship (none); Grant: NIH (H, Paid directly to institution/employer). KSJY:

Nothing to disclose. CT-L: Nothing to disclose. JV: Nothing to disclose.

SL: Nothing to disclose.

The disclosure key can be found on the Table of Contents and at www.

TheSpineJournalOnline.com.

* Corresponding author. Department of Physical Medicine and Reha-

bilitation, The University of Michigan, 325 E. Eisenhower, Ann Arbor,

MI 48108, USA. Tel.: (734) 763-4200; fax: (734) 615-1770.

E-mail address: andyhaig@umich.edu (A.J. Haig)

nt matter � 2013 Elsevier Inc. All rights reserved.

16/j.spinee.2013.06.021

2 A.J. Haig et al. / The Spine Journal - (2013) -

about the risk of misdiagnosis in individual cases. Thus, surgical and other consequential decisionsabout diagnosis may require ancillary tests such as electromyography or ABI. � 2013 ElsevierInc. All rights reserved.

Keywords: Physical examination; Neurogenic claudication; Vascular claudication; Interrater reliability

Introduction

Lumbar spinal stenosis is the most common reasonfor older people to undergo spine surgery. In the UnitedStates, the operation rate is both escalating and highly var-ied across regions [1]. For decades, various researchers, re-viewers, and consensus committees have accepted thegeneral concept that lumbar spinal stenosis is a syndromeof clinical presentation associated with radiological evi-dence. However, a number of recent studies have chal-lenged the relationship between imaging results and theclinical syndrome [2–5]. The latter half of the definition,a ‘‘clinical syndrome,’’ has never been defined in a quantifi-able or reproducible manner. In fact, it is widely recognizedthat people who have clinical stenosis may or may not havea number of different presentations, ranging from back painto leg pain to painless weakness to ataxia, each of whichcan be caused by other disorders [6].

Neurogenic claudication is the feature most identifiedwith spinal stenosis. Characteristically, it is described asback or leg pain that worsens with ambulation or prolongedstanding, reaching a point where the sufferer cannot con-tinue without resting, typically with the trunk flexed [6].Animal and human studies have created strong pathophys-iological ties between compromise within the spinal canaland claudication [7,8]. A recent review concluded that per-sons without neurogenic claudication were one-fourth aslikely to have spinal stenosis, although it should be notedthat the review used a somewhat circuitous reference stan-dard of ‘‘expert opinion with radiographic or anatomic con-firmation’’ [9].

Vascular claudication is a common symptom that pres-ents in a way similar to neurogenic claudication [10,11].One common test for the cause of vascular claudication, pe-ripheral vascular disease, is the ankle-brachial index (ABI).The ABI is a simple test in which blood pressure cuffs areinflated in the arms and legs and a ratio of blood pressuresis created. It is highly sensitive and specific to the presenceof peripheral vascular disease [12]. However, as demon-strated in the Framingham Offspring Study, only about halfof people with positive ABIs have symptoms of vascularclaudication [13]. Thus, in a conundrum similar to that en-countered by spine physicians, vascular physicians cannotrely on a simple test to prove that claudicatory symptomsare coming from the arteries.

In light of this information, the validity of the clinician’simpression that a person has neurogenic claudication hastaken on new importance, especially when the clinician isa surgeon who might offer invasive treatment. This articleis designed to examine the reliability of a surgeon’s

diagnostic impression of neurogenic or vascular claudica-tion based on an extensive history and physical examina-tion, performed under the most optimal circumstances.

Methods

Subjects

In an ethical review board–approved study, three groupsof persons aged 55 to 90 years were recruited. The Figureshows the recruitment and testing process. A neurogenicclaudication group was identified from the review of thecomputerized medical record of neurosurgery and orthope-dic surgery spine clinics for persons who were diagnosedwith spinal stenosis, had difficulty walking 200 yards(~200 m), and were offered surgery. The vascular claudica-tion group was identified through the review of the recordsof the vascular surgery, vascular medicine, and vascular di-agnostic laboratory for persons who complained of leg painwith ambulation that their doctor attributed to vascularclaudication and who also had a positive ABI. Asymptom-atic volunteers were recruited from postings seeking per-sons without back pain or vascular disease from thecommunity. Placement in each of these groups will be re-ferred to as the ‘‘recruitment diagnosis.’’

Through the review of medical record and interviews,potential subjects were excluded from the study if theyhad previous back surgery, cardiopulmonary precautionsfor ambulation testing, or risk factors for neuromusculardisease (diabetes, alcohol O12 drinks per week, personalor family history of neuromuscular disease, or history ofsignificant focal lower limb nerve injury). Because a laterphase of the study involved imaging and electrodiagnostictesting, contraindications to magnetic resonance imagingscanning (metal, obesity, unmanageable claustrophobia),relative contraindications or technical issues related toEMG testing (previous lumbar surgery, coumadinization,severe immune disorder, extreme obesity, 3þ pittingedema, or implanted electrodes such as defibrillators),were exclusions. Among the groups with the recruitmentdiagnoses of neurogenic or vascular claudication, anyonewho had another disorder that, in the investigator’s opin-ion, might be limiting ambulation more than the vascularor neurogenic claudication was eliminated. This provisionincluded persons with severe osteoarthritis or other unfore-seen diagnoses. Subjects were required to be competentand willing to travel to the testing appointments at theirown expense. All subjects were compensated for theirefforts.

Figure. Subject recruitment and testing. ABI, ankle-brachial index.

3A.J. Haig et al. / The Spine Journal - (2013) -

Testing protocol

Subjects completed the lengthy standard university spineprogram questionnaire. This includes basic demographic,medical, social, family, and spine history and an extensivereview of systems. Standardized measures analyzed in thepresent study include a 10-cm Visual Analog Scale (VAS)for pain [14], the Pain Disability Index [15], the McGillPain Scale [16], and the Quebec Back Pain Disability Scale[17]. Other validated scales administered included theSwiss Stenosis Questionnaire [18], the Walking ImpairmentQuestionnaire [19], the Multidimensional Pain Inventory[20], and the Short-Form 36 [21].

All subjects underwent ABI testing as per the protocoldescribed by McDermott [22], using a hand-held Dopplerprobe (Nicolet Vascular Pocket Dop II, Golden, CO,USA). The ABI was done to ensure that neurogenic and

asymptomatic volunteers did not have coincident vasculardisease and to ensure that the clinically performed ABIson the vascular patients were reproducibly abnormal. Thosewhose ABI results did not match their recruitment diagno-sis were eliminated. Specifically, neurogenic and normalsubjects were eliminated for a positive ABI, and vascularsubjects were eliminated for a negative study.

Each subject underwent a history and physical examina-tion by one of the three faculty spine neurosurgeons anda single vascular surgeon. The history included a requiredreview of the extensive questionnaires. Afterward, the clini-cians were also asked to obtain a spine symptom history asthey would in clinic, with the exception that they were notallowed to ask about diagnostic tests, treatments, or thenames or specialties of physician consultants. They were al-lowed to ask about other medical problems and symptoms;however, aside from the questionnaire, no specific ques-tions were required. During the physical examination, thesurgeons were required to observe for spinal deformity, hairloss, varicosities, and pain provocation with testing of rangeof motion and palpation. In addition, they performed a de-tailed lower limb test for strength and deep tendon reflexes,plantar reflex, sensation at the great toe, nerve tensionsigns, and capillary refill and dorsalis pedis pulse and ob-served for pain reproduction on hip range of motion. Thephysicians were not constrained by this extensive historyand physical examination and were encouraged to ask ques-tions and perform maneuvers as needed to clarify theirimpression.

Masking was achieved by first having a research assis-tant coach the subjects to provide truthful informationabout all aspects of their complaints and medical historybut not to provide any information about specialists, tests,or treatments related to their claudication complaint. Thesurgeons were instructed not to seek such information.The research assistant was present in the room to enforcethis rule and observe any violations. After testing, the sur-geon rated any potential unmasking events.

The main outcome from the examination was a singlebottom-line choice of neurogenic claudication, vascularclaudication, both, or neither. In addition, the clinicians’rated certainty and severity of each of these diagnoses ona 100-mm visual analog scale. To ensure that no other con-founding diagnoses could be detected, the clinicians wererequired to rate the possibility of three other causes forleg pain, venous insufficiency, painful limb arthritis, andpolyneuropathy on 100-mm VAS scales, and were askedto write in any other pertinent diagnoses.

Statistical analysis

After importiong, the cleaned data from an Excelspreadsheet, PASW Statistics 18 (SPSS, Inc., Chicago, IL,USA), were used for checking duplicate records and ana-lyzing data. Chi-square tests were performed to examinethe relationship among categorical variables. One-way

4 A.J. Haig et al. / The Spine Journal - (2013) -

analysis of variance was used to compare group mean dif-ferences, with a Tukey HSD adjustment for multiple pair-wise comparisons between group means. Cohen kappatest was used to examine the strength of association be-tween the opinions on diagnostic and the clinical findingsof different specialists (eg, neurosurgeon and vascular sur-geon). Kappa statistics are appropriate for looking at asso-ciations among categorical variables that have the samenumber of categories. Significant results indicate that thetwo variables of interest are somehow associated. We adop-ted Fleiss [23] interpretations of kappa 0.75 as excellent,0.40 to 0.75 as fair to good, and below 0.40 as poor. Inall the analyses, a p value of less than or equal to .05was considered as statistically significant.

Results

The process of screening is documented in Table 1.Among persons contacted, proportionally fewer vascularrecruits agreed or qualified to participate. Anticoagulationwas a frequent reason for exclusion. Table 2 describes thecharacteristics of the three populations included in the finalanalysis. A one-way analysis of variance was used to testfor differences in demographic, pain, and disability vari-ables among the three groups (neurogenic claudication,vascular claudication, and asymptomatic). Significant dif-ferences among the groups were found for age, McGill totalscore, Pain Disability Index, VAS pain average, and QuebecBack Pain Disability Scale. The asymptomatic volunteerswere significantly younger (Tukey post hoc comparisonM561.7 years, 95% confidence interval [CI]559.6, 63.8)than the vascular group (M568.9 years, 95% CI563.1,74.6, p5.024). As expected, they also had lower pain anddisability scores than the other groups, all p!.01. The neu-rogenic claudication group had significantly higher PainDisability Index (p5.014) and VAS pain average(p5.021) than the vascular claudication group.

Table 1

Subject recruitment and classification

Screening completed Total

Vascular impression

and þABI

Cases screened 403 128

Preliminarily qualified 124 21

Screened (%) 30.8 16.4

Contacted and consented 98 15

Qualified (%) 79.0 71.4

Neurosurgeon examination 94 13

Qualified (%) 75.8 61.9

Vascular surgeon examination 96 15

Qualified (%) 77.4 71.4

Study ABI 94 14

Qualified (%) 75.8 66.7

Both surgeons and ABI done 90 12

Qualified (%) 72.6 57.1

ABI, ankle-brachial index.

* Significant at the .01 level (two tailed).

Study surgeon agreement with recruitment diagnosiswas excellent [23], with kappa values of 0.761 and 0.803for the neurosurgeons and vascular surgeon, respectively(p!.001). The neurosurgeons and vascular surgeon dis-agreed with recruitment diagnosis in 14% and 12% ofcases; however, six cases that the vascular surgeon felthad ‘‘both’’ diagnoses were excluded from the analysis.Five of these were recruited as neurogenic and one as vas-cular claudication (Table 3). The two masked surgeons whoexamined an individual agreed on diagnosis in 70/84 (83%)cases, with a kappa of 0.717 (p!.001) (Table 4). This anal-ysis did not include the six cases rated as ‘‘both’’ by thevascular surgeon, which would raise the potential rate ofdisagreement from 17% to 22%.

A number of aspects of the patient history related to thesurgeon’s diagnosis. There were significant group mean dif-ferences in VAS pain; persons whom the vascular surgeonand one of the three neurosurgeons agreed had neurogenicclaudication had higher pain than the agreed-on vascularcases (post hoc Tukey analysis M55.7, 95% CI54.8, 6.5vs. M52.6, 95% CI50.0, 5.2, p5.014). The asymptomaticsubjects were not included in this analysis (Table 5). Incontrast, Table 6 demonstrates that there was poor interraterreliability for most parts of the physical examination.

Discussion

This study found that the clinical impression of neuro-genic and vascular claudication is a valid construct, repro-ducible between the presenting diagnosis made by thetreating surgeon, one masked vascular and three maskedspine neurosurgeons at our institution. However, in thisvery carefully selected population of severely involved per-sons and completely asymptomatic persons with no otherconfounding disorders, there were also a number of dis-agreements among clinicians. This raises a concern thatthe discriminant value of the clinical impression of

Offered surgery

for stenosis

Asymptomatic

volunteer

Statistics

c2/F p Value

168 107

54 49 23.885 !.001*

32.1 45.8

46 37 2.333 .311

85.2 75.5

45 36 4.027 .134

83.3 73.5

44 37 1.043 .594

81.5 75.5

44 36 2.051 .359

81.5 73.5

43 35 3.896 .143

79.6 71.4

Table 2

Descriptors of the final study population

Subject descriptor Total

Vascular impression

and þABI

Offered surgery

for stenosis

Asymptomatic

volunteer

Statistics

c2/F p Value

In the final population 90 12 43 35

Age (y) 64.768.3 68.969.0 66.068.9 61.766.1 4.588 .013*

Sex (%)

Male 49 (54.4) 8 (66.7) 26 (60.5) 15 (42.9) 3.246 .197

Race (%) —y —y

Black 7 (7.8) 1 (8.3) 4 (9.3) 2 (5.7)

White 79 (87.8) 11 (91.7) 39 (90.7) 29 (82.9)

Asian 4 (4.4) 0 (0.0) 0 (0.0) 4 (11.4)

BMI (N568) 30.766.1 33.169.7 31.764.8 29.266.3 1.813 .171

McGill total 14.5615.4 17.8614.6 23.6614.8 2.365.0 31.299 !.001z

PDI 18.5618.3 17.3617.0 30.6615.6 4.9610.6 31.625 !.001z

VAS pain average this week 3.062.9 3.062.6 5.062.3 0.661.4 42.429 !.001z

Quebec Back Pain Disability Scale 29.6625.3 30.3615.8 46.3621.3 7.6612.1 43.145 !.001z

ABI, ankle-brachial index; BMI, body mass index; PDI, pain disability index; VAS, visual analog scale.

* Significant at the .05 level (two tailed).y Statistical testing not performed because of expected count less than five in six cells.z Significant at the .01 level (two tailed).

5A.J. Haig et al. / The Spine Journal - (2013) -

claudication may not be adequate when the stakes are high,as is the case when spine surgery is considered.

The first descriptions of neurogenic and vascular claudi-cation are attributed to giants in the field of medicine, De-Jerine (1911) and Charcot (1858) cited by Gilfillan andBerry [11] more than half a century ago. Since then, thepossibility of confusion between neurogenic and vascularclaudication has been a common topic of discussion andteaching. However, we could find no rigorous researchcomparing the two. Dodge et al. [24] found that, of 172 pa-tients with symptoms of claudication and lumbar spinal ste-nosis ‘‘proved’’ by now disputed myelography or computedtomography criteria, 9 had peripheral vascular disease iden-tified with ultrasonography and arteriography. Fasih et al.[25] reviewed vascular surgical clinic records to show that,of 1,070 patients, 33 were diagnosed with a nonvascularproblem, including 28 who were thought to have spinal ste-nosis, again with debatable evidence.

Despite this work, the intersection between vascular andneurogenic claudication had not been adequately exploredbefore this study. We found that the masked study surgeons

Table 3

Study surgeon agreement with the patient’s unmasked clinical surgeon’s diagnos

Clinical diagnosis as recruited

Vascula

and þA

Masked examiner impression Neurosurgeon diagnosis (N590) n512

Vascular claudication 9

Neurogenic claudication 1

Asymptomatic 2

Vascular surgeon diagnosis (N584) n511

Artery disease 9

Spinal stenosis 0

Asymptomatic 2

ABI, ankle-brachial index.

demonstrated good or substantial agreement, matching eachother in 83% of cases. Factors that relate to agreement canbe explored to understand the relative value of different as-pects of the clinical encounter in making a final diagnosis.

Table 5 shows a number of strong relationships regard-ing the patient report of pain and disability. In contrast,poor, slight, and fair levels of agreement were found forfour pertinent components of the physical examination.This suggests that these physical examination findings werenot the factors used by surgeons in coming to agreement ondiagnosis, even where they may have added to certainty.The sample size was not sufficient to explore various spe-cific aspects of the physical examination or the extensivehistory and patient questionnaires; so, it is quite possiblethat some specific factors are highly diagnostic. It is alsopossible that a more careful orientation to the examination,such as training to ensure similar skill in performing thesebasic maneuvers or additional training to ensure similarscoring, might have increased the interrater reliability.Nevertheless, these findings suggest that listening to thepatient’s symptoms and the patient’s ability to provide

is

r impression

BI

Offered surgery

for stenosis

Asymptomatic

volunteer

Statistics

Kappa p Value

n543 n535 0.761 !.001

1 0

34 1

8 34

n538 n535 0.803 !.001

1 0

32 2

5 33

Table 4

Agreement between masked study surgeons on diagnosis

Total (N584)

Vascular surgeon diagnosis Statistics

Vascular

claudication (n510)

Neurogenic

claudication (n534)

Asymptomatic

(n540) Kappa p Value

Neurosurgeon diagnosis Vascular claudication 8 1 0 0.717 !.001

Neurogenic claudication 1 26 4

Asymptomatic 1 7 36

6 A.J. Haig et al. / The Spine Journal - (2013) -

a clear and rational description of their symptoms are crit-ical aspects of the diagnosis.

The study needs to be interpreted in the light of its meth-odology. Research on the interrater reliability of the historyand physical examination requires some level of confidencethat the clinicians are sufficiently trained and experienced.These faculty surgeons were quite familiar with the dis-eases and with the history and physical examination com-ponents that they were required to perform. Theframework within which the surgeons decided on the diag-nosis is also important. Their agreement came only aftera requirement to review a patient questionnaire that in-cludes more data and more standardized testing than anyclinical surgical encounter that we know of, and their phys-ical examination requirements may also have been well be-yond the usual practice of a surgeon. The question theyknew they would be asked had only three possible answers,in great contrast with the differential diagnosis generated inthe real world. Both of these factors drive up the interraterreliability compared with other situations; so, any extrapo-lation from the present study would need to assume thata similar construct was applied.

Variations on this work can result in different informa-tion. A study that included more surgeons, surgeons withmore diverse training, experience, or practice patterns,might show different results. There might be value instudying reliability among other types of clinicians suchas physiatrists, neurologists, therapists, or primary carephysicians. These persons may even see the syndrome dif-ferently than our small number of surgeons. A study that

Table 5

Patient pain and function as related to disagreement between clinicians

Total (n554)

Agreed neurogenic

claudication (n526)

Agreed

claudica

Patient information

VAS pain average this week 5.762.0 2.662

PDI total score 32.7614.7 18.061

McGill total 26.2615.2 18.661

Quebec Back Pain Disability Scale 51.4618.1 30.861

PDI, pain disability index; VAS, visual analog scale.

* An examination of the nature of the 20 disagreements between the 2 clinici

example, neurogenic versus vascular claudication.y Disagreed either versus neither includes the following: six persons whom th

neurosurgeon thought were neurogenic [5] and vascular [1] subjects. Four person

rosurgeon thought had neurogenic claudication. Eight persons whom the neurosu

[7] and asymptomatic [1] subjects by the vascular surgeon.

included persons with disorders such as mechanical backpain would better represent the more complex and equivo-cal decision making in the community. There is value inperforming each of these studies, but the agreement be-tween surgeons is perhaps the clinically most important is-sue regarding reproducibility of the diagnosis becausesurgeon’s diagnostic impressions may drive a choice of in-vasive procedures.

The present study was designed to examine the questionof reliability in the most optimal and clinically obvious sit-uation. There is no gold standard for the diagnosis of steno-sis. For stenosis subjects, the offer of surgery by facultysurgeons represents a high level of certainty and severitythat exceeds the typical definition of stenosis, which spec-ifies only criteria of imaging evidence and clinical impres-sion. To our knowledge, no study overtly uses this asa criterion for diagnostic certainty or severity. However,this criterion means that the study population more closelymatches major trials such as the SPORT study, where pa-tients must be at a stage where they could reasonably berandomized or selected for surgery [26].

Statistical agreement is reassuring to scientists, who cannow use the clinical impression as a valid metric for inclu-sion in research studies. A caveat is that that the impressionmust be based on the exhaustive information gathered inthis study. In clinical care, an acceptable level of certaintyis more complex. It involves consideration of the risks andbenefits of whatever procedure is contemplated. For exam-ple, the eight subjects who were offered surgery for stenosisby surgeons who had seen their imaging tests, but who were

vascular

tion (n58)

Disagreed vascular versus

neurogenic* plus either

versus neithery (n520)

Statistics

F p Value

.5 4.162.5 5.185 .009

9.0 26.4616.9 2.680 .079

7.1 18.2613.3 1.909 .159

5.1 40.0623.2 3.143 .053

ans shows that they disagreed in 2 subjects on the type of claudication, for

e vascular surgeon thought had both types of claudication (either) whom the

s whom the vascular surgeon felt were asymptomatic (neither) but the neu-

rgeon felt were asymptomatic (neither) but who were felt to be neurogenic

Table 6

Reliability of the clinical examination between the two observers for the population as a whole and for persons thought to have neurogenic claudication

Agreement on clinical examinations

Neurologic and vascular examiners agreement on diagnosis

Total population

agreedþdisagreed

(N590), n (%)

Total population

agreed (N570), n (%)

Total population disagreed

(N520), n (%)

Agreed neurogenic

claudication (N526), n (%)

Strength*

Agreed deficit 4 (4.4) 3 (4.3) 1 (5.0) 3 (11.5)

Agreed no deficit 71 (78.9) 58 (82.9) 13 (65.0) 16 (61.5)

Disagreed deficit versus no deficit 15 (16.7) 9 (12.9) 6 (30.0) 7 (26.9)

Kappa 0.254y 0.331y 0.063 0.295

Reflexz

Agreed abnormal 11 (12.2) 9 (12.9) 2 (10.0) 8 (30.8)

Agreed normal 47 (52.2) 36 (51.4) 11 (55.0) 7 (26.9)

Disagreed abnormal versus normal 32 (35.5) 25 (35.7) 7 (35.0) 11 (42.3)

Kappa 0.220y 0.228y 0.186 0.210

Great toe sensation

Agreed abnormal 0 (0.0) 0 (0.0) 3 (15.0) 2 (7.7)

Agreed normal 81 (90.0) 64 (91.4) 17 (85.0) 24 (92.3)

Disagreed abnormal versus normal 9 (10.0) 6 (8.6) — —

Kappa �0.036 �0.040 —x —x

Standing lumbar tenderness (N589, 70, 19, 26)

Agreed tender (abnormal) 2 (2.2) 1 (1.4) 1 (5.3) 1 (3.8)

Agreed normal 75 (84.3) 61 (87.1) 14 (73.7) 17 (65.4)

Disagreed abnormal versus normal 12 (13.5) 8 (11.4) 4 (21.1) 8 (30.7)

Kappa 0.187 0.141 0.269 0.019

* Strength: right and left toe dorsiflexion and plantar flexion, ankle dorsiflexion and plantar flexion, knee extension, and hip flexion and internal rotation.y Kappa significant at!0.05.z Reflex: right and left patellar and achilles.x Statistic not computed because of at least one variable in a two-way table is a constant.

7A.J. Haig et al. / The Spine Journal - (2013) -

seen as asymptomatic volunteers by our expert neurosur-geon, may have wished for more certainty.

Although surgery may be highly effective for personswho have failed aggressive conservative intervention, itcannot be taken lightly. A meta-analysis of surgical compli-cations from spinal stenosis surgery [27] noted a 12% com-plication rate, including 1% chance of deep infection, 2.8%chance of deep venous thrombosis, and 0.32% chance ofperioperative death. Reoperation rates are quoted at 6%to 18% over periods of 1 to 4 years [28].

One hopeful answer is electrodiagnostic testing. Two stud-ies have shown nearly 100% specificity of a certain electro-diagnostic protocol for clinically apparent stenosis and,depending on the severity of presentation, moderate to excel-lent sensitivity for the clinical impression of spinal stenosis,while detecting commonneuromuscular diseases that can con-found the diagnostic impression [2]. In caseswhere diagnosticcertainty is important, including persons who have anythingbut a classical clinical diagnosis and are being consideredfor surgery, this electrodiagnostic protocol is indicated.

Finally, there is the question of terminology. Lumbar spi-nal stenosis is often called a syndrome, but in fact, it is a dis-ease. A disease is defined by certain pathophysiologicalchanges. In the case of lumbar stenosis, the disease is de-fined by pathophysiological changes to the nerve roots ofthe lumbar spine that occur as a result of insufficient space.A syndrome is a constellation of findings that some group ofexperts agrees on. The people who define a syndrome often

hope that this set of rules is specific enough that others canuse them with good reproducibility. They frequently seekout evidence that the syndrome approximates the disease,so that they can design research and clinical interventionsthat affect the disease.

For generations, various clinicians, scientists, and policymakers have used the term ‘‘syndrome’’ to describe steno-sis. Initially, the association of that word with stenosis waslikely an attempt to warn physicians away from treating ra-diological findings without clinical findings. However, thedefinitions of the syndrome have continued to be vague tothe point of uselessness. Typical definitions found in prac-tice guidelines and study inclusion criteria consist of theclinician’s impression based on (unspecified) history crite-ria plus radiological evidence based on no specific mea-surement. To meet this vague standard, the present studydoes include persons who could not walk a certain distance,had magnetic resonance imaging scans that their surgeonthought showed stenosis, and did not have other diseasesto explain the walking problem. The ‘‘offer to operate’’was imposed so that there would be little question thatthe nonstudy clinician felt that there was a disease ofconsequence.

One might wish for a more specific definition of the syn-drome. No group of experts has agreed on a viable or repro-ducible one. In fact, when researchers have attempted tomake the radiological criteria more specific—by definingcertain diameters or areas of the thecal sac or spinal canal,

8 A.J. Haig et al. / The Spine Journal - (2013) -

or even the radiologist’s gestalt impression—the syndromelost any meaningful relationship to the disease [3,4,29,30].Regarding the clinical impression of claudication, the pres-ent study shows that, after reviewing this study’s question-naires, asking clarifying questions, and performing thestated physical examination, a surgeon’s impression thata person has neurogenic claudication holds together fairlywell but not perfectly. Although words like neurogenicclaudication are often discussed in guidelines and otherdocuments, no strict rules for clinically labeling a patientas having neurogenic claudication have evolved. This pro-tocol may help.

Neurogenic claudication, however, does not seem tobe a sine qua non for the clinical side of stenosis. No guide-line to our knowledge excludes persons if they do not haveneurogenic claudication. Such a definition would excludefindings such as static neurologic deficit or even back painthat some experts believe reflect the pathophysiology of ste-nosis. A recent study took an innovative approach to illus-trating other variables that are actually considered byclinicians [31]. In a recursive online survey of 97 physicalmedicine and rehabilitation physicians, Sandella et al. [31]found ‘‘leg pain while walking’’ (66%), ‘‘must sit down orbend’’ (66%), and ‘‘flex forward while walking’’ (49%)were the most commonly selected questions. ‘‘Normal footpulses’’ (19%), ‘‘back pain’’ (16%), ‘‘leg pain’’ (15%), ‘‘re-lief with rest’’ (14%), and ‘‘sensory deficits’’ (12%) wereof intermediate values, whereas ‘‘problems with balance,’’‘‘haven fallen recently,’’ and ‘‘the sacroiliac joint is notthe main pain generator’’ were all chosen less than 5% ofthe time. Statistically significant (p!.05) change in cer-tainty ceased after five questions at 86.2% certainty. Thisis yet another method of seeking consensus before agreeingon a syndrome.

It is entirely possible that the expanding and varied useof surgery for stenosis can be traced to vague and never-validated radiological criteria combined with scarce evi-dence that any particular clinical presentation is specificor reliable. There are potential solutions. Faced with aneven more daunting lack of anatomic proof, the AmericanPsychiatric Association has gone far in advancing diagnosisand treatment of mental health problems throughits rigorous Diagnostic and Statistical Manual [32]. Thismanual is explicit about inclusion and exclusion from cer-tain psychiatric syndromes. Although it is revised as moreclinical knowledge evolves, and people may well have dis-eases but not qualify under the manual’s rules, the consen-sus on measurable and reproducible criteria has served thatfield well.

Perhaps, spine policy makers can make a decision thatwill allow spine care to emulate this success. Regardless,until research shows that some well-defined syndrome pre-cisely matches the disease, educators, researchers, and pol-icy makers must be careful to provide specific frameworkfor the complaints that they diagnose, research, and teach.More important, individual clinicians must recognize the

vulnerability of their judgment as they propose treatmentsthat have real risk and potential benefit.

Acknowledgments

Siera Goodnight, Derek Wood, and Danielle Sandellaassisted in testing and recruitment of the subjects. Theproject described was supported by Award NumberR01HD059259 from the Eunice Kennedy Shriver NationalInstitute of Child Health and Human Development. Thecontent is solely the responsibility of the authors and doesnot necessarily represent the official views of the EuniceKennedy Shriver National Institute of Child Health andHuman Development or the National Institutes of Health.

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