Pain is categorized as acute or chronic based on the cause and duration:
- Acute pain is usually temporary, has a protective function, and resolves quickly. It is usually caused by injury or surgery. However, untreated or inadequately treated acute pain may progress on to chronic pain.
- Chronic pain is often defined as pain lasting more than 6 weeks, long after the initial injury has healed. The cause may be obvious: such as a broken bone; or not apparent, such as a nerve injury. An extensive work-up may need to be done to determine the cause of pain, such as MRI scans and diagnostic nerve blocks.
Common sources of pain are spinal pain, nerve pain, and headache:
Spinal pain may be due to:
- Herniated ("slipped") disc
- Spinal stenosis
- Degenerative disc disease
- Facet Syndrome
- Failed Back Surgery Syndrome
Nerve pain may be due to:
- Any of the causes of spinal pain (above)
- Neuropathy (diabetes or chemotherapy for example)
- Complex Regional Pain Syndrome (“RSD”)
- Shingles or post-herpetic neuralgia
- Nerve injury after surgery such as hernia or breast surgery
Headache may be due to:
- Cervical spine disease
- Tension or muscle spasm
- Medication overuse
Other common causes of pain include cancer pain, fibromyalgia, and degenerative joint disease.
Because there is overlap in the origins of many pain syndromes, diagnostic nerve blocks using local anesthetics are often necessary. Some nerve blocks may be done in an office setting, but others require real-time fluoroscopic imaging so that the medication can be observed going precisely to the target area or nerves. Examples of fluoroscopic guided blocks are facet injections, nerve root blocks, and diagnostic discography.