Natural History ofRadiculopathy

Ellen Casey, MD

KEYWORDS

� Radiculopathy � Radicular pain � Natural history

Approximately two-thirdsof adults suffer fromneckand lowbackpain.1Axial spinepainis often accompanied by radicular pain or radiculopathy, which is defined as spinalnerve root dysfunction causing dermatomal pain and parasthesias, myotomal weak-ness, and/or impaireddeep tendon reflexes.Mixer andBarr first introduced theconceptof herniated discmaterial leading to radiculopathy in 1934.2 Since that landmark study,extensive research hasbeenconductedon thepathogenesis, clinical presentation, andtreatment of radiculopathy. An understanding of the natural history of radiculopathy iscrucial because it better enables health care providers to counsel patients, recommendtreatments, and assess outcomes of specific interventions. Although it can bechallenging to sort through the available information given the vast differences in diag-nostic criteria, length of follow-up periods, and exposure ofmany patients to some typeof conservative management, this article aims to combine the findings from severallandmark papers to provide a concise summary of the natural evolution ofradiculopathy.

EPIDEMIOLOGY

The estimated prevalence of radiculopathy is 9.8 per 1000 and 3.5 cases per 1000 in thelumbosacral andcervical spine, respectively.3,4Patientswith lumbosacral radiculopathytend to present in the late 1920s to 1940s, whereas the peak age of presentation forcervical radiculopathy is in the sixth decade.5,6 Various risk factors have beeninvestigated for a causative role in the development of radiculopathy, including gender,prior episodes of neck or back pain, and occupational or recreational factors. Althoughsome studies suggest that radiculopathy occurs more frequently in men, others haveshown equal rates between genders.5–7 Previous history of axial low back pain isa well-established risk factor for lumbosacral radiculopathy, and a prior history oflumbosacral radiculopathy has been found in patients presenting with cervicalradiculopathy. Additionally, prior history of trauma was found in approximately 15% ofcases of cervical radiculopathy but this association has not been documented in the

The author has nothing to disclose.Sports & Spine Rehabilitation, Rehabilitation Institute of Chicago/Northwestern UniversityFeinberg School of Medicine, 1030 North Clark Street, Suite 500, Chicago, IL 60610, USAE-mail address: ecasey@ric.org

Phys Med Rehabil Clin N Am 22 (2011) 1–5doi:10.1016/j.pmr.2010.10.001 pmr.theclinics.com1047-9651/11/$ – see front matter � 2011 Elsevier Inc. All rights reserved.

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lumbar spine. Although there is a correlation between a higher bodymass and low backpain, the same relationship does not appear to exist in radiculopathy.7 Multiple studieshave shown a genetic linkage for spinal canal size as well as occurrence of discherniation and subsequent radiculopathy.8–10 In regards to occupational factors,lumbosacral radiculopathy occurs more frequently in patients who have performedjobs requiring manual labor, and who work in positions of sustained lumbar flexion orrotation and who engage in prolonged driving.11–13

NATURAL HISTORYLumbosacral Radiculopathy

The first study to follow the clinical course of patients with lumbosacral radiculopathywas written by Hakelius14 in 1970. Of the 38 patients with a clinical presentationconsistent with radiculopathy and a disc herniation demonstrated on myelography,88% reported that they were symptom-free after 6 months. In 1983, Weber7 publisheda paper documenting a prospective study of 126 patients with “sciatica”. Thesepatients were randomized to surgery or conservative management and followed for10 years. The primary treatment given to the 66 patients in the conservative groupwas bed rest and paracetamol. Some patients also received physical therapy, butthe type and frequency was not documented. Sixty-seven percent of patients in theconservative group reported good to fair outcomes at 1 year, 4 years and 10 years.Saal and Saal15 conducted another prospective study that was published in 1989.They followed 58 patients with a diagnosis of radiculopathy based on physical exam-ination, imaging, and electrodiagnostic testing. The patients were exposed to minimaltreatment, including back school and stabilization exercises. At the conclusion of the31-week follow-up period, 92% reported a good to excellent outcome and 92% hadreturned to work. Another paper by Weber and colleagues 16 focused on the short-term evolution of lumbosacral radiculopathy in 208 patients. These patients wereplaced on bed rest for one week, and then allowed to gradually resume activity.None of the patients underwent physical therapy. After 4 weeks, 70% of patientshad marked reduction in pain, which corresponded to functional improvement, and60% had returned to work. Weber’s studies have also investigated prognostic riskfactors of recovery as well as recurrence. The factors that correlated with a pooroutcome or prolonged recovery included female gender, psychosocial problems,greater than 3 months sick leave before presentation, and a prior history of radiculop-athy. A recurrence of symptoms occurs in approximately 20% of patients.7,16

Cervical Radiculopathy

The course of clinical improvement of cervical radiculopathy is even less well docu-mented than that of lumbosacral radiculopathy. Spurling and Segerberg17 publishedone of the first papers that attempted to address this question in 1953. They followed110 patients with cervical radiculopathy who were primarily treated with 7 to 10 daysof bed rest and traction. The average follow-up period was 23 months, and the resultsshowed that 77% of patients had definite improvement. They noted that in the firstmonth, 12%of patientswere referred for surgicalmanagement, but none of the patientsthat showed a response to treatment in the first month required surgery. Lees andTurner18 conducted another early study in 1963. They followed 51 patients with cervicalspondylosis and radicular symptoms without myelopathy for 10 to 19 years. Somepatients were exposed to conservative treatments, including wearing a cervical collarand manipulation, whereas others did not receive any treatment. At the end of the 10years, 73% of patients reported having mild or no symptoms. DePlama and Subin19

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foundsignificantly different results in 384patientswith cervical radiculopathy. This studycompared surgical to nonsurgical outcomes and found that only 29% of conservativelytreated patients attained complete symptom relief. Gore and colleagues20 followeda group of 205 patients with neck pain, of whom 58% had radicular symptoms. Mostof the patients were exposed to one or more treatments, including hospitalization,cervical collar, and oral medications. At the completion of the 10-year follow-up, 43%were pain-free and 79% reported a reduction in symptoms. However, 32% reportedpersistent moderate to severe pain. Two additional studies from the physiatry literaturesuggest that 70% to 90%of patients with cervical radiculopathy have a good outcome.However, each of these studies included some type of conservative management,including traction.21,22 A more recent study of 563 patients who presented to theMayo Clinic from 1976 to 1990 also showed that 90% of patients had mild or nosymptoms after 4 to 5 years of follow-up. However, one-fifth of patients did not improveand ultimately underwent surgical treatment.5 Only one study specifically monitored forrecurrent symptoms and found that recurrences occurred in 12.5% of patients duringa follow-up period of 1 to 2 years.22

Evolution of Radiographic Findings

The advent of computed tomography (CT) and magnetic resonance imaging (MRI) hassignificantly impacted the ability to diagnose and monitor disc herniations in patientswith radiculopathy.These imaging studieshavealsomade itpossible to follow thenaturalcourse of disc herniations and compare the morphologic changes with symptomaticimprovement. Key was the first to document the spontaneous regression of a herniateddisc in the lumbar spinebymyelography in1945.23Thisphenomenonwasconfirmedwiththe use of follow-up CT scans in the lumbar and cervical spine in 1985.24 Saal andcolleagues25 published a subsequent study in 1990 of 12 patients with documentedlumbar herniations on CT. These patients were rescanned at an average of 25 monthsand the following findingswere documented: 46%of subjects had 75% to100% resorp-tion, 36%had 50% to 75%decrease in herniation size, and 11%had 0% to 50% regres-sion. They found that complete resorption was most frequently seen in the patients whohad the largest herniations. However, they did not find a significant correlation betweenclinical and morphologic improvement. Bozzo and colleagues26 had similar resultsregarding morphology of lumbar herniations on MRI: 48% of patients had greater than70% reduction in size, 15% had a 30% to 50% reduction in size, 29% had no change,and 8% had an increase in size. Overall, 64% of the 69 patients had a reduction inherniation size, and the largest degree of resorption was seen in those with mediumand large herniations. Maigne and Deligne27 established a similar relationship betweengreater spontaneous resolutions in larger herniations in the cervical spine. Cowan andcolleagues28 performed repeatCT scans on 106 patients one year after being diagnosedwith lumbosacral radiculopathy. Disc herniations that decreased or fully resolved wereseen in 76%ofpatients.However, only 26%ofdiscbulgesdecreasedor resolved.Masuiand colleagues29 found that disc herniation size decreased by 95% in 21 patients whohad follow-up MRI imaging 7 to 10 years after being diagnosed with disc herniationand radiculopathy. Cribb and colleagues30 focused on massive lumbar disc extrusionsthat obscured greater than 66% of the spinal canal at the time of diagnosis ofradiculopathy. They found that after 25 months, 14 out of 15 herniations had completelyresolved. Although Komori and colleagues31 did not find a correlation between clinicalsymptom and radiological improvement, this finding has been demonstrated in morerecent studies.32 Dellerud and Nakstad32 followed 92 patients over 14 months withfollow-up CT scans and found a strong association between clinical improvement andreduction in the size of the lumbar herniation. They also found that central herniations

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and disc bulges were less likely to resolve, and the reduction in size of disc bulges wasassociatedwith a lesser degree of symptomatic improvement thanwith disc herniations.

SUMMARY

Radicular pain is a frequent complaint of patients presenting to outpatient primarycare and musculoskeletal clinics. Based on a review of the literature, most cases ofradiculopathy seem to be self-limiting and symptoms seem to resolve over the courseof weeks to months. Advanced imaging has demonstrated the spontaneous resolutionof disc herniations, particularly in larger protrusions and extrusions, and clinicalimprovement seems to correlate with morphologic resolution. Knowledge of thenatural history of radiculopathy is crucial for the health care provider to appropriatelycounsel and treat patients with this disorder. Although each patient should bemanaged individually, the favorable prognosis of radiculopathy based on the naturalhistory supports a conservative approach for the initial weeks to months for mostpatients.

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