Spinal Structure :

Back pain is a common reason for absence from work and for seeking medical treatment. It can be uncomfortable and debilitating.
It can result from injury, activity and some medical conditions. Back pain can affect people of any age, for different reasons. As people get older, the chance of developing lower back pain increases, due to factors such as previous occupation and degenerative disk disease.
Lower back pain may be linked to the bony lumbar spine, discs between the vertebrae, ligaments around the spine and discs, spinal cord and nerves, lower back muscles, abdominal and pelvic internal organs, and the skin around the lumbar area.

With our knowledge & experience of operating under local anesthesia, we know precisely where the pain is coming from. To make it simple pain is sensation carried by nerves, so there cannot be a pain without involvement of nerve.
Pain in the upper back may be due to disorders of the aorta, tumors in the chest, and spine inflammation.

Due to various factors like lack of nutrition, obesity, smoking, vibration, repetitive stress etc this disc degenerates & the outer fibrous ring develops cracks & tears this gives rise to Back discomfort & pain.

As the tears extend to periphery & start leaking the central annular jelly. This causes the nerves to swell & back pain becomes intense & goes down the leg along the nerve.

Also one can experience burning senses, tingling or numbness in the legs with time tear enlarges in size or heals.If the tear enlarges then the back pain aggravates & the soft nucleus herniates out & there can be numbness & weakness in the part of the leg supplied by the nerve.Sudden compression at higher level can also cause disturbance in bowel & bladder function.

Now with herniation the disc collapses & this changes the mechanics & puts more stress on the bony facet joints causing their arthritis & it gives rise to back pain on sides. All this narrows this canal & facet bones impinge on the nerves giving rise to claudication( tingling & numbness in the legs on walking).Due to all these changes there is narrowing of the Spinal Canal.