Back pain is a generalized term used for pain in neck, mid back or lower back. Trauma, injuries or diseases involving soft tissue and skeletal system causes back pain. Back pain is been described in history over 1000 B.C. Back pain is seen in all profession and jobs. Severe backache in younger population is more often seen after sport injury, auto injury and work accident. Back pain is also observed more frequently in older patients. In the past, low back pain in older patient was thought to be cause by rheumatoid or osteo-arthritis. Scientific data and studies during last 50 years had defined back pain in greater details. Diagnosis of back pain is most often supported by image studies. Backache was one of the major complaints during Second World War among the soldiers because of back strain. Aggressive research and development of advanced image studies has directed clinician to come to precise diagnosis and treatment.

 

Causes of Back Pain:

A. Traumatic Injuries of Vertebral Column

Trauma such as fall, auto accident and work accident causes injuries of muscles, ligaments, disk, vertebral body and facet joint. 

  • Muscle injuries - tear or contusion.
  • Tendon - tear, fracture or dislocation of ligament.
  • Disk injury - result in bulge disk or herniated disk. 
  • Vertebral body injury - results in subluxation, dislocation or fracture of vertebral body. 

 

B. Diseases of Vertebral Column

Diseases such as arthritis, degenerative disease, cancer and osteoporosis cause backache. Symptoms depend on anatomical structure affected by disease.  Diseases of vertebral column results in backache are as follows:

  • Cervical, Thoracic or Lumbar Disc Diseases  
    1. Degenerative disk disease
    2. Disc infection
  • Vertebral Body 
    1. Primary cancer of vertebral body
    2. Metastasis of vertebral body
    3. Osteoporosis causing fracture of vertebral body
  • Facet Joint
    1. Hypertrophy
    2. Facet joint arthritis
    3. Osteoporosis causing Facet joint fracture or dislocation
  • Paravertebral Muscle Disease
    1. Muscle spasm
    2. Myofascial disease
    3. Fibromyalgia

 

Pathophysiology of Back Pain

Back pain originates from ligaments, paravertebral muscles, vertebrae and disc. Vertebral column is divided in to cervical, thoracic, lumbar, sacral and caudal segments. Ligaments associated with spinal canal are attached to vertebrae, disc and facet joints.Tear or inflammation of ligaments causes severe pain. Paravertebral muscle spasm, myofascial pain and pain cause by fibromyalgia are example of wide spread backache. Disc diseases and disc trauma results bulge or herniated disc. Bulge or herniated disc causes radicular pain, tingling, numbness and weakness because of irritation or pinch of spinal nerve or spinal cord. Vertebral body injury causes fracture of vertebrae or subluxation of vertebral column. Subluxation of vertebrae can cause mild to severe pressure on spinal cord resulting in pain, weakness or spinal cord injury. Spinal cord injury in neck can cause quadriplegia and in lumbar segment paraplegia. 

Vertebral column is divided into anterior and posterior segments.

 

Pathophysiology of Symptoms Originating from Anterior Segment

Anterior segment includes vertebral body, disk and anterior longitunal ligament.Disease or trauma of anterior segment causes symptoms like pain, tingling, numbness and weakness. Symptoms are observed over neck, upper extremity, chest, lower back or lower leg.

Dermatomal distribution of symptom depends on level of vertebral column affected by trauma or disease. 

A. Trauma 

Whiplash injury, work accident or fall can cause severe injury to anterior segment of vertebral column. Back pain and paravertebral muscle spasm is associated with skeletal muscle injuries as well as fracture or subluxation of lumbar vertebrae. Anterior longitudinal ligament is the strong ligament, which holds vertebral body. Ligament is spread from neck to sacrum at the back of vertebral body and disc. Injury of ligament can cause severe regional pain in neck, mid back or lower back.

Chronic back pain caused by disk herniation or bulge disk following back injury often associated with tingling, numbness or weakness of the affected anatomical segment. Disk bulge or herniation causes irritation or pinch of spinal nerve within foramina or spinal canal. Skeletal injuries of anterior segment caused by trauma are as follows 

  • Tear or contusion of posterior longitudinal ligament
  • Fracture of vertebral body 
  • Subluxation of vertebrae
  • Dislocation of vertebrae
  • Disk herniation
  • Bulge disk

 

B. Diseases Affecting Anterior Segments 

Vertebral body tumor or metastasis is rare and result in severe intractable pain. Tumor mass may encroached into spinal foramina causing radicular pain, numbness and weakness along the affected nerve. Tumor mass spreading into spinal canal can cause spinal stenosis resulting in severe pressure on spinal cord.  Pressure will induce ischemic changes on spinal cord and cause severe spinal cord injury. Spinal cord injury in neck can result in quadriplegia and lumbar area paraplegia. Disk disease like thinning of disk cause by degenerative disk disease can cause foramina stenosis and result in radiculopathy. Radiculopathy cause by pinch nerve result in pain, tingling, numbness and weakness along the nerve, which is pinched.

  1. Vertebral Body Disease
    • Cancer of the vertebral body- Cancer may be primary or secondary, secondary cancer is metastasis from primary cancer of colon or lungs.
    • Osteoporosis - causes fracture of vertebral body.
  2. Disk Diseases - Disk lies between two vertebrae and is the softer component of the weight bearing structure. Herniation or bulge of the disk causes disruption of the weight bearing system.
    • Disk disease - bulge disk or herniated disk causes pain secondary to pinch nerve or pressure on spinal cord. If disk is herniated in to foramina the disease is known as foraminal stenosis. 
    • Foraminal stenosis - Foraminal stenosis causes pinch of nerve in foramina. Symptom is predominantly radicular pain associated with numbness and weakness. 
    • Spinal stenosis - Disk if bulge or herniated into spinal canal causes pressure on spinal cord, which is known as spinal stenosis. Symptoms of spinal stenosis are pain and weakness. 
    • Cauda Equina Syndrome - Significant bulge or herniated disk in lower back or lumbar segment causes pressure on bundle of nerves called Cauda equina. Pressure on cauda equina caused symptoms such as pain, numbness, tingling and weaknessin lower leg. Cauda equina pain is also known as cauda equina syndrome. Cauda equina syndrome also present with bowel and bladder dysfunction like incontinence of stool and urine. 
  3. Anterior Longitudinal Ligaments (ACL) - ACL inflammation is rare but result in severe back pain.

 

B. Pathophysiology of Symptoms Originating from Posterior Segment

Trauma or disease of posterior component of the vertebrae causes pain mostly localized over the neck, mid back or lower back. Whiplash injury often results in neck pain secondary to disk or facet joint injury. Lower back pain is common among elderly patients secondary to degenerative disk disease. Degenerative disease affects disk and facet joint. Facet joint disease results in inflammatory disease such as facet joint arthritis or hypertrophy of facet joint. Chronic back pain could also be secondary to muscle injury or spasm. Paravertebral muscle is predominantly situated on side of vertebral body and facet joint.

 

Posterior segment consist of

  • Facet joint 
  • Ligamentum flavum 
  • Posterior longitudinal ligament 
  • Inter-spinal ligament and 
  • Paravertebral muscles

 

a. Trauma - causes following injuries.

  • Fracture of facet joint
  • Subluxation or dislocation of facet joint
  • Paravertebral muscle tear
  • Tear of ligaments of vertebral column

 

b. Diseases - Following diseases may cause pain from posterior segment of vertebral column

  • Muscle diseases -
    1. Fibromyalgia, 
    2. Myofascial syndrome or myositis and 
    3. Muscle spasm
  • Facet joint disease - 
    1. Facet joint arthritis,
    2. Facet joint hypertrophy and
    3. Facet joint osteoporosis
  • Ligamental disease -
    1. Ligamentum flavum hypertrophy

 

Low back pain is one of the common pain symptom experienced by most of the adults sometime in their life. Epidemiology studies suggest 6 to 15 percent of population experience low back pain at least once a year.


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