Lumbar Differential Diagnosis

Original Editor - Nick Rainey based on the course by Nick Rainey
Top Contributors - Jess Bell, Carin Hunter, Jorge Rodríguez Palomino and Ewa Jaraczewska

Introduction

Low back pain is a common presenting condition in physiotherapy clinics. The physiotherapy assessment aims to screen for serious spinal conditions and identify impairments that may have contributed to the onset of the pain, or which increase the likelihood of an individual developing persistent pain. These include biological factors (eg. weakness, stiffness), psychological factors (eg. depression, fear of movement and catastrophisation) and social factors (eg. work environment).

Once serious spinal pathology and specific causes of back pain have been ruled out, an individual is classified as having non-specific low back pain. If no serious pathology is suspected, there is no indication imaging unless the results may change / guide the management protocol.

90% of patients presenting to primary care with low back pain are classified as having non-specific low back pain. Non-specific low back pain is defined as "low back pain not attributable to a recognizable, known specific pathology (eg, infection, tumor, osteoporosis, lumbar spine fracture, structural deformity, inflammatory disorder, radicular syndrome, or cauda equina syndrome)" Non-specific does not mean that there is no tissue causing nociception, just that it is not as clear and not as concerning.

Non-specific low back pain is usually categorised into three subtypes: acute, sub-acute and chronic low back pain. This subdivision is based on how long the individual has had low back pain. Acute low back pain is an episode of low back pain that has been present for less than 6 weeks, sub-acute low back pain has been present for between 6 and 12 weeks and chronic low back pain has been present for 12 weeks or more.

Diagnosis versus Classification

Diagnosis and classification are defined in more detail here. Typically when we discuss diagnoses, we are talking about pathoanatomical diagnoses. There are also many classification systems for low back pain, some more commonly used than others. The goal of a classification system is to guide treatment, and ensure that clinicians don't treat all cases of back pain the same.

Imaging

For more information on referring for imaging, please see Practical Decision Making in Physiotherapy Practice, but key points to consider are as follows:

• imaging is needed if red flags are present or if there is no improvement with conservative care within 6 weeks - if you are unsure about a red flag, you can often treat the patient a little to see if they improve
• imaging is recommended if it will change the course of treatment
• a lot of imaging findings correlate with low back pain. This doesn’t mean that everyone with imaging findings will have pain, but often, the more findings there are on imaging, the higher the chance that the person will have pain. We can still help these people though!

Potential Conditions to Consider in a Differential Diagnosis

Differential diagnosis is a key part of the physiotherapy assessment process. After a comprehensive lumbar assessment, you can triage the patient, as explained in the Lumbar Assessment page (see figure below).

You will need knowledge of red flags and to consider a range of conditions (see linked pages for more information).

• Specific Low Back Pain
  • an identified specific cause of back pain such as fracture, disc herniation, infection, tumour
• Cauda Equina Syndrome
  • a rare but serious neurological condition which affects the bundle of nerve roots at the lower end of the spinal cord - considered an urgent red flag condition
  • symptoms include bladder and bowel changes and saddle anaesthesia
• Lumbar Radiculopathy
  • compression of the nerve roots as they exit the spine
  • can result in tingling, radiating pain, numbness, paraesthesia, and shooting pain
• Disc Herniation
  • the nucleus pulposus is displaced from intervertebral space
  • results in low back pain and radicular sciatica, sometimes with sensory and/or motor deficits
• Spinal Stenosis
  • degenerative condition where there is reduced space available for the neural / vascular elements in the lumbar spine
  • spinal stenosis syndrome is associated with reduced walking distances (neurogenic intermittent claudication), pain which refers to both legs, and possible sensory and motor changes
• Spondylolisthesis
  • Slippage of one vertebral body in relation to the adjacent vertebral body, which results in mechanical or radicular symptoms
• Piriformis Syndrome
  • a clinical condition where there is sciatic nerve entrapment at the level of the ischial tuberosity
  • associated with gluteal pain, that may be described as shooting, burning, or aching
  • there may also be numbness in the buttocks and tingling along the sciatic nerve distribution
• Sacroiliac Joint Pain (not dysfunction)
  • the sacroiliac joint is a potential nociceptive source of back pain
  • please listen to this podcast to learn more: The Back Pain Podcast: Is my pain from my sacroiliac joint?
• Osteoarthritis
  • a significant cause of chronic low back pain
  • likely has a multifactorial pathogenesis
• Sciatica
  • causes pain and paraesthesias along the sciatic nerve distribution or associated lumbosacral nerve root
• Thoraco-Lumbar Junction Syndrome (also called Maigne syndrome)
  • an often unrecognised cause of low back pain
  • there are two types:
    • central variant caused by "nerve afferent input secondary to changes of facet joint arthropathy at the thoracolumbar junction"
    • peripheral variant caused by "impingement of the medial branch of the superior cluneal nerve"

"Have a hypothesis. The more thoughtful you are, the better you’ll become." - Nick Rainey

Sources of Pain

When completing a lumbar differential diagnosis, you will need to consider if there is extremity pain or just spinal pain. Then you will need to determine if the spine is contributing to the extremity pain (i.e. spinogenic) or if the extremity is the source.

A few key factors to consider when looking for the source of pain:

• if there are movement restrictions in the spine, there is a higher chance that distal symptoms are from the spine
• there is a higher likelihood that the spine is the source of pain if the extremity has full range of motion
• "current spinal pain" raises the pre-test probability that extremity pain has a spinal source from 10% to 19% overall 
• a high percentage of people who have pain in their hip, thigh or leg have spinogenic pain
• paraesthesia more commonly arises from the spine than the extremities
• if a change in posture affects symptoms, pain is more likely coming from the spine

For more information, please see these articles:

• Exploring indicators of extremity pain of spinal source as identified by Mechanical Diagnosis and Therapy (MDT): a secondary analysis of a prospective cohort study
• A study exploring the prevalence of Extremity Pain of Spinal Source (EXPOSS)

During an assessment, it is important to remember that while neurological testing isn't exact, it is close. "We just need to figure out where do we need to treat and what gets those distal symptoms better."

Pathoanatomical Approach Compared to a Signs and Symptoms Approach

"A pathoanatomical approach means that you are treating to improve anatomy while a signs and symptoms approach means you test signs and ask for symptoms, treat, and then retest to assess for progress." - Nick Rainey

After our assessment, we should consider the asterisk signs that we have made note of throughout our examination and use these to help decide how to treat using a "signs and symptoms" treatment approach.

An asterisk sign is also known as a comparable sign. It is something that you can reproduce/retest that often reflects the primary complaint. It can be functional or movement specific. It is used to measure if symptoms are improving or worsening.

Differentiating between Hip and Lumbar Pain

This video shows a patient examination aiming to differentiate between hip and lumbar pain.

The following tables detail a range of conditions associated with low back pain.

Types of low back pain associated with physical findings of no clear pathoanatomical significance

Syndrome	Findings	Assessment/Plan
Facet syndrome	History and physical examination: local and pseudoradicular symptoms and signs pain on movement facet tenderness pain on reclination positive injection test joint dysfunction on manual diagnosis Radiological findings (not indicated on intial evaluation): differentiation from high-grade or activated spondylarthrosis (possibly, juxtaforaminal cyst) axial spondylarthritis	Differential diagnosis: major joint dysfunction (blockage) activated spondylarthrosis Treatment: analgesics (1–3 days) muscle stabilization manual medicine facet injection if indicated
Sacro-iliac joint syndrome	History and physical examination: sactro-iliac joint symptoms, positive provocation test functional leg length discrepancy injection test Radiological findings (not indicated on intial evaluation): – Differential diagnosis: inflammation (sacro-iliitis in seronegative spondylarthritis)	Functional disturbance: muscular imbalance Treatment: stabilizing exercises analgesics (1–3 days) if needed manual medicine sacro-iliac joint injection if indicated
Myofascial pain syndrome	History and physical examination: muscle trigger points: local pain with peripheral radiation peripheral and central sensitization Radiological and histological findings: not indicated no clear evidence from MRI or biopsy	pathogenesis and definitive diagnosis still unclear (low intra- and interrater reliability) Local treatment: active physiotherapy manual therapy infiltration acupuncture
Functional instability	History and physical examination: “snapping” feeling generalized deconditioning pain on movement, possibly accompanied by sensory and motor deficits (reversible) impaired proprioception Radiological findings: no direct evidence	unclear pathogenesis and definition treatment with manual medicine physiotherapeutic stabilization program caveat: surgery differential diagnosis structural instability

Specific causes of low back pain that need immediate treatment (red flags)

Disease	Findings	Further Evaluation	Treatment
Fracture traumatic pathological osteoporotic	red flags acute or acutely exacerbated position-dependent pain pain and tenderness over spinous processes in some cases, iliocostal syndrome (12th rib)	Imaging studies: plain films/MRI/CT scintigraphy for pacemaker wearers bone densitometry (T score) Laboratory testing: inflammatory parameters (CBC + CRP) osteoporosis parameters	Conservative: treatment of pain (strong analgesics if needed) basis therapy (osteoporosis) physiotherapy stabilizing, activating corset Surgical: vertebro-/kyphoplasty pedicle-screw-based instrumentation, possibly with ventral interposition (cage, vertebral body replacement) Prevention: regular intake of calcium, vitamin D, and biphosphonates exercise
Massive disc herniation	red flags mutiple radicular deficits bladder/bowel dysfunction saddle anesthesia (cauda equina syndrome)	MRI/CT electrophysiology: EMG SSEP	Surgical: decompression with: sequestrectomy nucleotomy
Bacterial infection (spondylitis/ spondylodiscitis, epidural or paravertebral abscess)	red flags pain swelling signs of instability pain on plantar flexion bed-shaking test (peritoneal irritation) neurologic deficit(s)	inflammatory parameters MRI/CT with contrast medium plain films in two planes biopsy for pathogen identification optional: scintigraphy echocardiography	The indication for conservative vs. operative treatment (debridement, filling of defects, instrumentation) depends on: neurologic deficits stability abscess formation: intradiscal epidural paravertebral osseous muscular pathogen identification (specific/nonspecific)
Tumor	red flags pain swelling signs of instability pain on plantarflexion bed-shaking test (peritoneal irritation) neurologic deficit(s)	Imaging studies: local at first, then staging studies to rule out instability (SINS): entire spinal axis CT of thorax and abdomen scintigraphy Laboratory tests: CBC, ESR, CRP, etc. tumor markers, Karnofsky score Tissue biopsy (CT- or MRIguided, or open)	Neurologic deficit present: decompression and stabilization (dorsal or dorsoventral depending on overall findings) Neurologic deficit absent: discuss plan in interdisciplinary tumor board Conservative: treatment of pain (strong analgesics if needed) radiotherapy external stabilization (corset)

Specific types of low back pain that require further diagnostic evaluation

Disease	Findings	Further Evaluation	Treatment
Disk herniation	low back pain and radicular sciatica (worse in leg than in back), sometimes with sensory and/or motor deficits positive nerve-stretching test reflex asymmetry	Imaging studies: (DD herniation vs. stenosis vs. tumor) MRI, plain films (CT if MRI is contraindicated) Neurological/electrophysiological testing: EMG, SSEP, NCS in suspected cauda equina syndrome, examination of bladder and rectal function (post-void residual urine volume, sphincter tone)	Depending on the clinical findings: Conservative/interventional: analgesic and anti-inflammatory drugs physiotherapy periradicular/epidural injections Surgical: particularly in case of a motor deficit (strength grade 3 or less) sequestrectomy nucleotomy
Spinal canal stenosis / degenerative instability	spinal stenosis syndrome, limitation of walking distance (neurogenic intermittent claudication), pain radiating into both legs possibly, sensory and motor deficits	Abnormally flexed posture of trunk imaging studies: plain films functional myelography and post-myelographic CT Neurological/electrophysiological testing: ENG SSEP EMG	Depending on the clinical findings: Conservative: pain therapy physiotherapy Interventional: PDA sacral block Surgical: decompression decompression and fusion
Axial spondylitis and seronegative spondylo - arthropathy	Inflammatory back pain syndrome onset before age 45 back pain for more than 3 months morning stiffness >30° improvement with movement pain at night restriction of lateral bending sacro-iliac joint syndrome enthesitis (heel) insertion tendinitis	Imaging studies: plain films/MRI (sacro-iliac joint, STIR sequence) inflammatory parameters HLA-B27 Rheumatologic consultation	analgesic and anti-inflammatory drugs physiotherapy maintenance therapy with rheumatologic drugs if indicated
Deformities scoliosis: idiopathic structural neuromyopathic other idiopathic juvenile kyphosis (Scheuermann's disease) spondylolisthesis (dysplastic types)	Clinical features: pelvic tilt shoulder height discrepancy spinal misalignment asymmetry of waist forward bending test hunchback lumbar protrusion hyperkyphosis visible/palpable step in spine sacral kyphosis lumbar spine fixed in extension	Early detection in children! Imaging studies: biplanar imaging of the entire spine images on bending MRI (secondary scoliosis, intraspinal anomalies) CT if indicated	Depending on the patient’s age and on the cause and severity of the deformity: physiotherapy corset surgical correction
Herpes zoster	mono- or pluriradicular pain syndrome with sensory deficit (much less often, motor deficit) dermatomal rash (often arising some time after the pain)	Lumbar puncture and CSF examination: CSF pleocytosis positive CSF serology	oral or IV virostatic drugs (aciclovir, brivudine, famciclovir) analgesic drugs: cf. diabetic radiculopathy vaccination of patients at risk
Diabetic radiculopathy	painful sensory and motor radiculopathy	patient with diabetes mellitus other causes ruled out no rash CSF cell count normal, serology negative	Pharmacotherapy: metamizole, NSAIDs + TCA/SSNRI or gabapentin/pregabalin; for lancinating pain, carbamazepine/capsaicin 8% ointment; if necessary, high- or low-potency opioids
Neuroborreliosis	mono-/pluriradicular pain syndrome with sensory and motor deficits	Lumbar puncture and CSF examination: CSF pleocytosis, elevated CSF protein intrathecal Borrelia-specific AB	IV antibiotic treatment with ceftriaxone and cefotaxime for 14–21 days, along with steroid (prednisone 100 mg, decreasing dose) analgesic drugs: cf. diabetic radiculopathy
Spinal ischemia	at first, pain in thoracic or lumbar spine, followed by development of spinal cord transection syndrome	MRI / spiral CT / angiography	inhibition of platelet aggregation analgesic drugs (NSAIDs, high- or low- potency opioids) physiotherapy

Key to abbreviations:

• CBC: complete blood count
• CRP: C-reactive protein
• CT: computerized tomography
• EMG: electromyography
• ESR: erythrocyte sedimentation rate
• MRI: magnetic resonance imaging
• SINS: spinal instability in neoplastic disease
• SSEP: somatosensory evoked potentials
• AB: antibodies
• CT: computerized tomography
• CSF: cerebrospinal fluid
• DD: differential diagnosis
• ENG: electroneurography
• EMG: electromyography
• MRI: magnetic resonance imaging
• NCS: nerve conduction study
• NSAID: nonsteroidal anti-inflammatory drug
• PDA: peridural anesthesia
• SSEP: somatosensory evoked potentials
• SSNRI: selective serotonin-norepinephrine reuptake inhibitor
• TCA: tricyclic antidepressant

Additional Resources

Podcast Links:

• The Back Pain Podcast: Piriformis syndrome
• The Back Pain Podcast: Is my pain from my sacroiliac joint?
• Modern Pain Podcast: Lumbar Stenosis
• The Back Pain Podcast Episode 82: Flexion, Extension, Radicular Pain & Disc Pathology with Adam Meakins and Dr. Mark Laslett

Journal Articles and Books:

• Casser HR, Seddigh S, Rauschmann M. Acute lumbar back pain: investigation, differential diagnosis, and treatment. Deutsches Ärzteblatt International. 2016 Apr;113(13):223.
• Casiano VE, Dydyk AM, Varacallo M. Back pain.

Physiopedia Pages:

• Low Back Pain
• Lumbar Assessment
• Low Back Pain Guidelines
• Differentiating Inflammatory and Mechanical Back Pain
• Non Specific Low Back Pain
• Specific Low Back Pain