General Overview of the Lumbar Spine
Pain experienced in the low back can not only come from a variety of places but also can be due to multiple sources. Whether primary or secondary, here is a brief list of differentials to review:
Neurogenic: Radicular pain, radiculopathy, peripheral entrapments, disc innervations, joint innervations
Discogenic: neuropathy, annular fibers, chemical nucleus, SOL
Vascular: chemical, abdominal vessels
Muscles: Erector spinae, transversopinalis, gluteal, abdominal, pelvic floor
Sclerotogenous: IVD, facet joint
Radicular pain is an irritation & pain without neurologic impairment. There is a dermatome distribution (so presents at the level of insult) and is often caused at the dorsal root ganglion (DRG) or spine.
Radiculopathy is impaired conduction and symptoms depend on the type of nerve involved. Sensory cell bodies in the DRG (spinothalamic tract) will present with numbness. Motor cell bodies in ventral horn spine (corticospinal tract) will present with motor weakness.
It’s all Greek
The ICD coding of spine pain has always been laughable. The currently adopted standards are improved but still often fall short of supporting the highest level diagnosis of a patient. Specifically to spine pain, they are written as Cervicalgia, Pain in Thoracic Spine, and Lumbago. Formally, the suffixes -ago and -algia mean abnormal condition and suffering; respectively. From a manual therapist perspective however we often translate these to presenting pain and pain which the doctor can elicit; respectively. The later is not to the extreme of tactile allodynia (normal input producing abnormal responses) which can accompany Central Sensitization. Simply a point which is often considered in the chiropractic office.
Facet Joint (Lsp): Synovial joints oriented in the sagittal plane. They are supplied by medial branches of dorsal rami and recurrent meningeal nerves. Pain with loading (think extension maneuvers and standing). Kemp’s will cause local pain when aspects of the facet are irritated, and radiate pain to at least the superior gluteal area if the nerve root is also irritated. [When performing Kemp’s, ensure to “wind-up” to increase tension and compression forced]
Spondylolisthesis: Basically a “slippage” of one vertebra relative to another. May contribute to Facet Joint issues. There are five (5) grades based on approx. percentage of slippage (1-up to 25%, 2-upt to 50%, 3-up to 75%, 4-up to 100%, 5-completely fallen off). There are also five (5) TYPES (Dysplastic, Isthmic, Degenerative, Traumatic, Pathologic). “Spondys” may or may not cause pain, nerve symptoms, and/or be unstable, but an increase in lordosis is often seen with accompanying muscle spasm. If suspecting pars fracture, stork test (1-leg standing extension test) is a quick screen, but flexion & extension radiographs likely needed to rule-out instability.
SacroIliac Joint: See SIJ blog
Stenosis: Normal lumbar canal measures 15-27mm in diameter. Stenosis is diagnostic if less than 10mm. It will likely present with midline back pain (usually some significant length of the spine) and may be present with radiculopathies. Neurogenic claudication is a common finding. Activity-wise flexion, lying, & sitting can all be palliative while long-term standing and downhill walking is provocative. Some stenosis presentations may be from vertebral disc material. This presentation is the most common cause and significant rationale for back surgeries.
Discogenic: The first consideration here is Degenerative Disc Disease (DDD). Pain with DDD is specifically associated with increased nerve growth deep into the annulus and/or riddled with damage associated molecules. This is a PRO-INFLAMMATORY presentation and must be treated to reduce symptoms.
The second consideration is that dicogenic pain can be secondary to disc herniations (types discussed in other blog) or altered spinal mechanics/loading/movements. To assess and treat here it’s best to consider postures of ADLs and end-range loading approaches (MDT)
Neurogenic: The extent of nerve pain can be extensive. While there are many, an article by Miller combines nerve tension/Slump 8/Maitland-type screening followed by appropriate structural differentiation. Other blogs will review radiculopathies and common entrapments of nerves but always consider double crush patterns as sensitized nerves will be likely aggravated in multiple areas.
*Remember different levels of nerve injury: Neuropraxia, Axonotmesis, Neurotmesis*
Muscular: Muscles typically respond and compensate to pain in other areas. Their involvement can certainly hinder therapy. O’donahue’s performed to the region and isolated palpation and muscle testing will expose the likely culprits. While my preferred approach is to address the anatomical sensitivities of the region and use active care, others may use passive therapies to diminish their influence. Either way, it’s necessary to at least address their symptoms and treatment success increases significantly when applied to the appropriate structures!