Back Pain – By Peter J. Moley – 2017

This article describes and suggests certain treatments for 6 different types of back pain:

It has been calculated that up to 80% of the population will complain of low back pain at some point during their lifetime, with spontaneous resolution within 6 weeks in another 80-90% of the cases.

However, chronic low back pain can be a disabling and complicated condition to deal with.

Given the complexity of the lumbar spine, deciphering the pathology that is generating a patient’s symptoms can be difficult to identify, and more difficult to treat.

Lumbosacral radiculopathy

Patients affected by lumbosacral radiculopathies generally complain of low back pain with radiating symptoms into the lower limb, usually following a dermatomal distribution pattern associated with the nerve root being affected. Symptoms tend to be unilateral as opposed to the bilateral symptoms found in spinal stenosis.

The frequently affected L5 and S1 nerve roots produce symptoms radiating into the buttock region, down the posterolateral thigh and lower leg, and frequently into the foot. An L5 lesion will frequently cross into the anterior aspect of the lower leg and into the dorsum of the foot, whereas an S1 lesion will remain posterior and lateral into the foot.

Upper lumbar lesions (L2-L4) will generally radiate into the anterior thigh region, with L4 radiculopathies radiating into the anteromedial aspect of the lower leg. Patients may often complain of numbness and tingling in similar distribution patterns associated with affected nerve roots. Additionally, myodermal weakness may be noted, although this may be subtler, and less likely to be reported.

Weakness of lower limb muscles affiliated with certain nerve roots, in conjunction with sensory deficits along dermatomal distribution can help identify a radiculopathy originating from a specific nerve root. Additionally, asymmetrical hyporeflexia on deep tendon reflex testing can aide in pinpointing a lesion (L2-4: patellar tendon reflex, L5: medial hamstring reflex, S1: Achilles tendon reflex). Dural tension testing is also a crucial aspect of the physical examination for lumbosacral radiculopathy.

In upper lumbar injuries (L2-L4), a femoral nerve stretch test (reverse straight leg raise) can be used to evaluate for reproduction of anterior thigh symptoms. Conversely, in lower lumbosacral injuries (L5-S1), Straight Leg Raising Test and Slump Test can be used to stress the affected nerve roots, recreating their radicular complaints.

Although the straight leg raise has generally been used more frequently in practice, the slump test has been shown to be more sensitive with similar specificities in the identification of L5and S1 radiculopathies.

Facet (zygapophyseal) arthropathy

The identification of facet joint pain using conventional history, physical examination, and imaging studies has been proven to be inconsistent and difficult to diagnose. Lumbar facet mediated pain has generally been described as axial low back pain, with referral patterns identified into the groin, posterolateral thigh, and buttock regions.

Patients will frequently complain of exacerbation of pain with standing, as well as transitional movements from sitting to standing positions

As structures located in the posterior elements of the lumbar spine, many have described a painful response to loading of the facet joints to be associated with facet-mediated pain. Again, studies have shown no consistent data to corroborate any specific physical exam findings to be associated with objectively diagnosed facet mediated low back pain.

Spondylolysis

Although the vast majority of individuals with spondylolysis remain asymptomatic and undetected, this is a frequent culprit in adolescent low back pain, responsible for up to 47% of low back pain in this population. Patients may present complaining of insidious onset of cramping, aching low back pain with referral into the buttock and posterior thigh region being described.

Symptoms may generally be exacerbated with prolonged standing and lumbar extension. Neurologic deficits are generally absent without any associated weakness, numbness, or tingling.

On physical examination, these patients are frequently found to have tenderness in the lumbar paraspinal region, with exacerbation of pain on lumbar hyperextension and a positive “stork test” (one-legged lumbar hyperextension) on the affected side.

Hamstring tightness has been noted to be one of the most common physical exam findings, with popliteal angles greater than 30-45 degrees considered a positive finding in this population. Neurologic evaluation is generally unremarkable with normal motor, sensory, reflexes, and dural tension signs.

Spondylolisthesis

Patients with spondylolisthesis often complain of chronic, axial low back pain, with referral into the posterolateral thighs frequently reported.

These patients may complain of radicular pain with associated numbness and tingling into bilateral lower limbs, with reports of neurogenic claudication upon ambulation. Radicular symptoms may follow the L4 and L5 nerve root distributions into the lower limbs, as these are the roots most likely to be affected.

Symptoms may be relieved with rest as well as maintaining a forward flexed position (shopping cart sign). In more advanced cases, patients may report associated bowel and bladder incontinence.

On physical examination, physicians may notice a step-off while palpating the lumbar spinal processes, indicating a slippage of the vertebral segments. Patients may complain of paraspinal tenderness upon palpation.

Neurologic examination may be variable depending on presence and extent of spinal stenosis, with diminished motor strength, sensation, and deep tendon reflexes present.

Spinal stenosis

Spinal stenosis results from compression of the nerve roots lying within the spinal canal due to central canal narrowing. Subsequently, patients often complain of symptoms associated with nerve root compression or irritation, leading to radiating pain, numbness, tingling, or weakness in the lower limbs.

Symptoms are frequently present in the L4 and L5 distribution, as these are the nerve roots most commonly affected. Unlike lumbar radiculopathy, which is generally a unilateral process associated with an isolated nerve root impingement, patients with spinal stenosis complain of bilateral lower limb complaints.

Patients frequently report exacerbation of pain with lumbar extension, as this further compromises the area within the spinal canal. This is particularly evident during ambulation and walking down stairs or down a hill, which places patients in increased lumbar extension. This is frequently called neurogenic claudication.

Conversely, alleviation of radiating symptoms can be elicited with opening the canal through lumbar flexion. Patients may report increased walking tolerance while leaning on a walker or shopping cart, leading to a positive “shopping cart sign”. They may also complain of axial low back pain, which may be due to concomitant degenerative spondylolisthesis, degenerative disc disease, or facet arthropathy leading to spinal stenosis. In the presence of cauda equina syndrome, patients may also report associated bowel or bladder incontinence.

On physical examination, patients may be noted to stand and walk in a forward flexed position, as this is their desired alignment for symptomatic relief.

Neurologic deficits such as decreased motor strength, sensory loss, and diminished deep tendon may be noted along the nerve root distributions affected by the stenosis.

Discogenic low back pain

Low back pain secondary to internal disc disruption can be difficult to diagnose based on history and physical examination alone. No specific factors in a patient’s history or physical exam have proven to be consistently present in the identification of discogenic low back pain.

Patients may report complaints of axial low back pain, with referral patterns described into the anterior thigh (L3-L4, L4-L5 disc lesions) as well as posterior thigh and leg regions (L4-5, L5-S1 discs), which can emulate radicular pain patterns without nerve root involvement. Pain exacerbation with prolonged sitting, particularly without support and in a forward flexed position has also been reported.

These complaints would seem to be consistent with reports of increased intradiscal pressures in these positions when compared with lying supine, standing, and a reclined position.

What tests to perform?

Lumbosacral radiculopathy

Imaging studies of the lumbar spine can be useful in the identification of lumbosacral disc herniations and nerve root compression, which may correlate with subjective complaints and objective findings on physical examination. Initial imaging studies should consist of AP and lateral plain films to evaluate for bony pathology, coronal and sagittal malalignment, and degeneration of intervertebral discs.

Subsequently, MRI can be used to identify structural lesions that may be compressing or irritating an affected nerve root, helping to make a clinical diagnosis of a lumbosacral radiculopathy. It can also be useful in identifying any potential masses or inflammation contributing to the reported symptoms.

imaging studies should not be used in isolation, as asymptomatic volunteers have been found to have a high proportion of lumbar disc herniations on imaging studies. Therefore, imaging should be used with caution to supplement clinical findings, with correlation to patient symptoms being used to verify its significance.

In patients with an unclear diagnosis or persistent weakness, Electromyography can subsequently be considered in patients to aide in localizing a lesion, while also assessing the function of the nerve.

Facet (zygapophyseal) arthropathy

Radiographic imaging studies provide inconclusive correlation with facet joint pain. CT and MRI studies have shown facet degeneration in 8-14% of asymptomatic volunteers. Nonetheless, severe osteoarthritis was not noted in any of the asymptomatic individuals, suggesting a possible association between radiographic findings of severe facet osteoarthritis with the likely pain generator.

However, studies using imaging studies to predict a positive response to intra-articular anesthetic blocks have provided conflicting data, limiting their reliability. At this time, the diagnostic imaging of choice would consist of MRI with the inclusion of STIR sequences to identify bony edema, while avoiding the misinterpretation of increased signal seen in fat.

Spondylolysis

Radiographic imaging studies have been noted to be quite useful in identifying pars defects, although false negative rates have proven to be unreasonably high. Plain radiographic images of the lumbar spine are useful in detecting a lucency within the region of the pars interarticularis, with collimated lateral views providing the most sensitive images.

Spondylolisthesis

Plain radiographs can be used to identify spondylolisthesis, as well as grading the severity of the translation. Using lateral spine x-rays, the extent of spondylolisthesis can be divided into grade one (0-25% slippage), grade two (25-50%), grade three (50-75%), and grade four (75-100%), with complete translation called spondyloptosis.

Spinal stenosis

Plain radiographs should be obtained initially to identify any bony pathology that may be leading to stenosis of the spinal canal. Findings of degenerative disc disease, degenerative spondylolisthesis, or facet hypertrophy may suggest a concomitant spinal stenosis. Reversal of lumbar lordosis may also be noted, given the avoidance of lumbar extension in these individuals.

MRI can subsequently be obtained to identify spinal canal narrowing.

On sagittal images, disc protrusions and ligamentum flavum hypertrophy can be identified impinging on the central canal.

On axial views, central disc protrusions, facet hypertrophy, and ligamentum flavum hypertrophy can be identified, leading to narrowing of the spinal canal

Discogenic low back pain

The use of MRI for the identification of annular tears through the presence of high intensity zones (HIZ) has been controversial, with some studies finding a positive predictive value of up to 86% when correlated with CT discography.

Conversely, more recent studies have found MRIs to have a low sensitivity in identifying annular tears. They should therefore be used as an initial diagnostic tool, with discography used to identify symptomatic discogenic pain.

CT discography is widely considered to be the most reliable tool in identifying intradiscal pathology responsible for discogenic low back pain

However, this too has been proven to be controversial in the literature, with some studies showing provocation of pain upon injection of discs with HIZ in 70% of patients, regardless of complaints of symptomatic low back pain.

The use of discography can be used to diagnose a specific disc as a pain generator, while helping guide further treatment and interventions.

How should patients with back pain be managed?

Lumbosacral radiculopathy

The natural history of lumbosacral radiculopathy shows spontaneous resolution of symptoms in 23-48% of patients, with approximately 30% complaining of continued symptoms after one year of onset.

Physical therapy focuses on pain reduction, maintaining pain free range of motion, and stabilization of the lumbar spine.

Interventional spinal injections have also proven to be of benefit in decreasing pain related to an acute lumbosacral radiculopathy.

The use of transforaminal epidural steroid injections has been shown to provide significant subjective and objective improvement of radicular pain in the short-term, without any long-term benefits noted compared to placebo.