老年下背痛患者应考虑到椎关节骨关节炎可能

佛罗里达州德斯坦——华盛顿大学康复医学系的Alfred C. Gellhorn医生在临床风湿病学大会（CCR）上报告称，在被归为“非特异性”的下背痛中，可能有相当多是椎关节骨关节炎。

“令人诧异且扼腕的是，腰椎关节在文献中得到的关注确实非常少。”每10名美国人中就有8名会在一生中的某段时间遭遇下背痛；下背痛的发生率仅次于普通感冒居第二位，是无法工作的最常见原因，每年的社会成本超过1000亿美元。多达85%的患者从未获得过明确诊断，而是被归类为非特异性疼痛。

可能有相当一部分下背痛与椎关节有关。关节软骨中没有神经，但软骨下骨、滑膜襞和关节囊中存在大量伤害感受器。一旦被滑膜炎症或机械因素（如骨小梁微骨折、关节囊扩张、关节负重增加时软骨下骨受压，或髓内高压）激活，这些伤害感受器可能引起椎旁肌继发反射性收缩。患者会报告发生痉挛，可扪及椎旁肌收缩。椎关节内和周围的长期炎症可导致中枢敏化、神经元可塑性变化和慢性下背痛的发生。

椎关节骨关节炎不同于椎间盘退行性变，但这两种疾病是相互依存的。椎间盘退行性变的影像学特征包括椎间隙高度减少、脱水和终板硬化，而椎关节骨关节炎的影像学特征椎关节空间缩窄、关节突骨赘增生、关节突肥大、硬化、软骨下侵蚀和软骨下囊肿。

以往的研究通过比较影像与症状发现，椎关节骨关节炎与下背痛之间无关联或仅有很小关联，但这些研究分析的是年轻或中年受试者的轻至中度骨关节炎。Gellhorn医生指出：“这些研究的做法是错误的。轻度椎关节骨关节炎在中年人中’本来就普遍存在’，而中至重度骨关节炎的症状更明显，主要影响老年人。应当针对老年人的中至重度骨关节炎开展研究。”

近期一项研究纳入了252例患者，平均年龄为67岁，均来自Framingham心脏研究。分析结果显示，累及椎关节的重度骨关节炎与频繁下背痛显著相关[比值比（OR），2.2]。在这些患者中，椎间隙高度缩小与下背痛无关（Osteoarthritis Cartilage 2013;21:1199-206）。这项研究得出了与既往研究不同的结果，可能是由于其受试者的年龄更大。潜在机制可能是，随着年龄增大，被归为“非特异性”的疼痛逐渐从椎间盘性疼痛转为椎关节性疼痛。

Gellhorn医生指出，针对中青年人椎间盘病理与下背痛的研究结果似乎支持这一假设。例如，在一项针对平均年龄49岁患者的研究中，下背痛与椎间隙高度减少和纤维环撕裂的风险倍增有关。在一项针对18~50岁患者的研究中，中度椎间隙高度减少与下背痛风险倍增有关。在另一项针对平均年龄50岁患者的研究中，晚期椎间隙高度减少与下背痛患病率增加2倍有关。

还有一项研究显示，重度椎间隙缩窄与60岁以下者的下背痛患病率增加2倍有关，而在60岁以上人群中未观察到这一现象。

尽管我们已经知道重度椎关节骨关节炎与下背痛有关，但事实上其阳性预测值仍然有限。Gellhorn医生指出：“很多老年重度椎关节骨关节炎患者在影像学检查中并无明显症状。”

不过，另外还有一些影像学特征。单光子发射计算机断层扫描（SPECT）/CT或液体敏感、脂肪抑制序列MRI可以清楚地显示症状性椎关节骨关节炎。而且一项研究显示，64%的可疑椎关节疼痛患者在短T1反转恢复（STIR）MRI中显示出骨髓病变，这类病变与疼痛侧有良好的关联性。目前尚无针对椎关节骨关节炎的血清生物标志物。

除了老年和上述影像学特征之外，与椎关节骨关节炎相关的危险因素和相关因素包括：性别（女性患椎关节骨关节炎的几率是男性的1.5~1.9倍）、种族（非裔美国人患椎关节骨关节炎的几率比美国白人低）和高体重指数（与BMI低于25 kg/m²相比，BMI介于25~30 kg/m²和30~35 kg/m²分别与椎关节骨关节炎相关腰痛风险增加2倍和5倍有关）。腹主动脉钙化和关节更偏矢状方向（vs. 冠状方向）也与椎关节骨关节炎相关。

随着研究的深入，这些因素或许将有助于阐释非特异性下背痛。“我认为我们正在逐步接近这一目标。”

临床上，椎关节骨关节炎常表现为局部背痛或C5~C6水平颈痛并部分放射至肩胛部位。“腰椎的情况则不那么明确，尽管人们几乎总是有腰部疼痛，并且疼痛几乎总是放射至臀部。”他指出，放射至大腿前部或侧面的疼痛可与椎关节骨关节炎相关，但延伸至膝盖以下的疼痛更可能来自神经根。目前尚无特异性检查可用于确诊或辅助诊断这种疾病。

很重要的一点是必须意识到，很多患者将出现脊椎滑脱症、椎间盘退行性变、脊柱侧凸、肌萎缩和椎管狭窄等相关问题。“面对这些情况，临床医生容易感到不知所措，但我希望同行们不要失去信心，而仍要去试着解决下背痛问题。”

尽管麻醉阻滞内侧支神经被认为是诊断的金标准方法，但仍存在争议，原因是单次阻滞假阳性率过高导致可能需要对比阻滞，而后者需要多次脊髓注射。“我认为，对1例患者进行30次脊髓注射才能确诊，这恐怕不是最好的方式。”

椎关节骨关节炎的治疗通常涉及体力活动。由于很少有高质量研究评估确诊椎关节疼痛的非干预性治疗，对该病的治疗通常类似慢性非特异性下背痛和膝骨关节炎的治疗。有证据表明，在慢性非特异性下背痛患者和膝骨关节炎患者中，运动均有助于增强力量和减轻疼痛、残疾。

一篇Cochrane综述显示，运动治疗可带来轻至中度获益。另有研究显示，早期推荐老年下背痛患者接受物理治疗可轻度改善12个月时的功能，提示物理治疗可比多种其他疗法带来更持久的获益。而且，Gellhorn医生在近期研究中发现，接受物理治疗的患者对腰椎注射、就诊和腰椎手术的需求趋于减少。“因此，推荐椎关节骨关节炎患者接受物理治疗是非常合理的做法。”

假如不适宜进行体力活动，其他可能对椎关节骨关节炎患者有益的治疗包括关节内类固醇注射和射频去神经支配术。

在以SPECT为纳入标准的研究中，关节内类固醇注射的3个月时效果优于内侧支神经阻滞，并且 1个月和3个月时效果均优于不以SPECT为纳入标准的研究中的注射效果。在以体格检查或诊断性神经阻滞为纳入标准的研究中，关节内类固醇注射似乎无效。“因此，假如你以代谢活性为评价标准，那么可能会发现注射疗效理想。”

颈椎射频去神经支配术的效果有优于腰椎的趋势，但在临床实践中难以证实这一点，原因是如果要比较就需要进行内侧支神经阻滞，或者进行双重甚至三重阻滞以尽可能提高成功率，而且伴随多种潜在并发症（如多裂肌丧失神经支配）。

Gellhorn医生介绍，在临床上遇到下背痛患者时，他首先会寻找危险迹象，然后进行X线检查，如果X线特征和临床表现相符，就会考虑到疼痛可能是由椎关节骨关节炎引起的。然后他会与患者沟通并推荐患者接受经验性物理治疗，用或不用镇痛药物（泰诺林或NSAIDs）。如果患者在6~8周内功能改善、症状缓解，他会建议患者开始进行（比家庭物理治疗方案）更有趣的运动计划，例如瑜伽或普拉提，以提高患者的依从性；假如患者仍有症状，就会进行影像学检查。假如椎关节骨关节炎的可能性很大，他倾向于首选SPECT/CT而非MRI。如果检查结果为阳性，他会考虑给予关节内类固醇注射。假如注射治疗有效，他会建议患者练习瑜伽和/或普拉提以维持疗效。对于注射治疗无效的个别患者，他考虑采取更积极的治疗方案，例如内侧支神经阻滞或射频去神经支配术。

Gellhorn医生指出，尽管在对椎关节骨关节炎的认识方面进展缓慢，但确实已取得了一些成果。例如，SPECT/CT和STIR MRI的应用使我们掌握了更好的诊断和试验入组标准，或许还有助于监测治疗应答。另外，血清、尿和遗传学标志物是有希望的研究方向。尚需开展更多研究来评价保守治疗，比较不同的运动计划。富血小板血浆和自体干细胞等再生治疗也是引人注目的研究领域。

Gellhorn医生无利益冲突披露。

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By: SHARON WORCESTER, Clinical Neurology News

DESTIN, FLA. – Facet joint osteoarthritis likely accounts for much of what is classified as "nonspecific" low back pain, according to Dr. Alfred C. Gellhorn.

"Amazingly – and I think sadly for us – the lumbar facet joints really have received very little attention in the literature," Dr. Gellhorn, who works in the department of rehabilitation medicine at the University of Washington, Seattle, said at the annual Congress of Clinical Rheumatology.

Eight of every ten American will experience low back pain at some point during their lifetime; low back pain is second only to the common cold in frequency, is the most common reason for time off work, and has a total social cost of more than $100 billion annually. Up to 85% of patients never receive a definitive diagnosis and are classified has having nonspecific pain, he said.

 

The facet joints may be responsible for a significant proportion of that pain.

Facet joint cartilage is aneural, but a number of nociceptors exist in the subchondral bone, the synovial folds, and the capsule. Once activated – by synovial inflammation or mechanical factors such as trabecular microfractures, capsular distention, pressure on the subchondral bone as joint load increases, or intramedullary hypertension, for example – the nociceptors may cause secondary reflex contraction of paraspinal muscles.

Patients will report this as spasms, and the contractions can be palpated, Dr. Gellhorn said, noting that prolonged inflammation in and around the facet joints can lead to central sensitization, neuronal plasticity, and development of chronic low back pain.

Facet joint osteoarthritis (OA) is distinct from disc degeneration, but the two conditions are interdependent. Radiographic hallmarks of disc degeneration include disc height loss, dehydration, and endplate sclerosis, whereas radiographic hallmarks of facet joint OA include narrowing of the facet joint space, osteophytosis of articular processes, hypertrophy of articular processes, sclerosis, subchondral erosion, and subchondral cysts.

Older studies that looked at facet joint OA by comparing findings on imaging and symptoms found either no association or only minimal association between facet joint OA and low back pain, but the threshold used in those studies was mild to moderate OA in young and middle-aged subjects.

"That’s the wrong criterion to use," Dr. Gellhorn said, noting that mild facet joint OA is "essentially ubiquitous" by middle age. Moderate to severe facet OA, however, is more symptomatic, and predominantly affects older adults – and should be the criterion used in studies of the condition.

In a recent study of 252 patients with a mean age of 67 years who were participants in the Framingham heart study, severe OA affecting the facet joint was significantly associated with frequent low back pain (odds ratio, 2.2). Disc height narrowing was not associated with low back pain in these patients (Osteoarthritis Cartilage 2013;21:1199-206).

The findings contrast with those from prior studies, likely because the cohort was older (mean age of 67 years vs. 30s to 50s), he said.

It may be that with age, back pain classified as "nonspecific" shifts from discogenic pain in younger adults to facetogenic pain in older adults, he suggested.

Findings with respect to disc pathology and low back pain in young and middle-aged adults seem to support this hypothesis, he noted.

For example, in a study of patients with a mean age of 49 years, low back pain was associated with a twofold increased likelihood of disc height loss and annular tears, and in a study of patients aged 18-50 years, moderate disc height loss was also associated with a twofold increased likelihood of low back pain. In another study of patients with a mean age of 50 years, advanced disc height loss was associated with a threefold increased likelihood of prevalent low back pain.

In another study, severe disc height narrowing was associated with a threefold increase in the odds of low back pain in those younger than age 60 years but not in those over age 60 years.

There are markers for symptomatic facet joint OA. Despite the known association between severe facet joint OA and low back pain, "the truth is there is still limited positive predictive value for that," he said.

"Many older adults with severe facet joint OA on imaging are relatively asymptomatic," he added.

There are some additional imaging makers, however. Symptomatic facet join OA is apparent on single-photon emission computed tomography/computed tomography (SPECT/CT) or fluid-sensitive, fat-suppressed MRI. Also, 64% of patients with suspected facet joint pain in one study had bone marrow lesions on short T1 inversion recovery (STIR) MRI, which were well correlated to the side of pain, he said.

There are no serum biomarkers for the condition at present, he noted.

In addition to older age and these findings on imaging, other risk factors and correlates for facet joint OA include sex (women are 1.5-1.9 times more likely than men to have facet joint OA), race (African Americans are about 60% less likely than white Americans to have facet joint OA), and high body mass index (those with BMI of 25-30 and 30-35 have a three- and fivefold increased risk of lumbar pain associated with facet joint OA, respectively, compared with those with BMI below 25).

Abdominal aortic calcifications and more sagittal orientation of the joints (vs. coronal orientation), also are associated with facet joint OA, Dr. Gellhorn said.

With additional research, these factors could be useful for "disambiguating nonspecific low back pain," he said.

"I think we’re getting closer. We’re not there yet, but we’re getting closer," he said.

Clinically, facet joint OA often presents as localized back or neck pain at C5-C6 with some radiation into the scapular region.

"It’s less clear in the lumbar spine, but almost always people will have pain in the lumbar region, and almost always they will have pain that radiates into the buttocks," he said, noting that pain radiating into the anterior or lateral thighs can be associated with facet joint OA, but pain that extends below the knees is more likely to be radicular.

There are no specific examination maneuvers that are pathognomonic – or even particularly helpful – for the condition, he added.

It is important to keep in mind that many patients will have associated conditions, including spondylolisthesis, disc degeneration, scoliosis, muscle atrophy, and spinal stenosis.

"It’s easy to get overwhelmed in the face of this, but I would urge you not to, and to still try to disentangle some of these concepts of low back pain without throwing up your hands," he said.

Although anesthetic blockade of the medial branches of the dorsal primary ramus (or "medial branch blocks,") are considered the gold standard for diagnosis, they are controversial, have an unacceptably high rate of false-positive results with a single block, and thus may require comparative blocks, which can result in numerous spinal injections.

This is problematic; there is no good way to make the diagnosis before doing more rational, conservative treatment, he said.

"I think that there are probably better things than doing 30 injections into someone’s spine to establish a diagnosis," he said.

In fact, treatment for facet joint OA generally involves physical activity.

"You don’t want to push these people to their limits, but certainly it is important to have them move and to have them keep the strength in their spine," he said.

In the absence of good studies evaluating noninterventional therapy for confirmed facet joint pain, treatment is generally based on findings in patients with chronic nonspecific low back pain and knee OA, and there is evidence in both of those settings that suggest exercise is helpful for increasing strength and decreasing pain and disability.

A Cochrane review showed that exercise therapy provides mild to moderate benefit. Additional studies have suggested that early referral to physical therapy results in modest improvement in function at 12 months in older adults, suggesting physical therapy provides longer-term results than many other interventions for low back pain, which tend to provide only short-term relief, he noted.

Furthermore, patients who have physical therapy tend to require fewer interventions. Dr. Gellhorn found in a recent study that physical therapy in a Medicare population with low back pain was associated with fewer lumbar injections, physician office visits, and lumbar surgeries.

"So it’s very reasonable to send your patients with facet joint OA to PT," he said.

Other treatments that may have some benefit if physical activity is inadequate include intra-articular steroid injections and radiofrequency denervation.

In studies that used SPECT for inclusion criteria, intra-articular injections were better than medial branch blocks at 3 months, and were more effective at 1 month and 3 months than were injections used in studies that did not use SPECT for inclusion, he said.

Injections were not useful in studies that used physical examination or diagnostic block for inclusion.

"So if you’re basing it on metabolic activity, you’re likely to have a good outcome from your injection," he said.

Radiofrequency denervation tends to work better in the cervical spine than in the lumbar spine, but it is difficult to justify in practice because it requires medial branch block, or double or even triple block to optimize success, and because it is associated with a number of potential complications, such as loss of innervation to the multifidus muscles.

In his practice he first screens for red flags in patients who present with low back pain. Next, he gets an X-ray to look for alignment issues, and he "heavily considers – if the clinical picture fits" – whether facet joint OA might be the cause of the pain.

"I’ll talk to them about it, and then almost always, I’ll send them for an empiric trial of physical therapy plus or minus some analgesics – Tylenol or NSAIDs," he said.

If patients experience improved function and a decrease in symptoms within 6-8 weeks, he recommends that they begin a more interesting (than their home physical therapy regimen) exercise program, such as yoga or Pilates to help them maintain those gains; if they remain symptomatic, he images them.

He starts with SPECT/CT rather than MRI if facet joint OA is high on his differential list for the patient, and if that’s positive, he will consider intra-articular steroid injections. If the injections are effective he recommends yoga and/or Pilates for maintaining the gains.

In rare cases a patient doesn’t respond to the injections, and then he will consider more aggressive treatment, such as medial branch block or radiofrequency denervation.

Understanding of facet joint OA has been slow to emerge, but progress is being made, Dr. Gellhorn said.

For example, the work with SPECT/CT and STIR MRI is very exciting, he said.

"I think this is going to give us a number of things to work with: first and foremost, it’s going to give us better criteria to diagnose patients and enroll them in treatment studies," he said.

Serum, urine, and genetic biomarkers, on the other hand, are interesting and on the horizon, "but we’re not really there yet," he added.

"But I think we will be able to at least use imaging studies to monitor some response to treatment," he said.

Additional study is also needed with respect to conservative treatments. Studies comparing different exercise programs, including studies comparing strength vs. flexibility and extension vs. flexion, are needed.

Regenerative treatments, such as platelet rich plasma and autologous stem cells are another area of interest, he said.

Dr. Gellhorn reported having no disclosures.