Back pain overview

# Overview
Back pain is one of the most common cause of primary care and emergency department visit. On the basis of origin, back pain can be broadly classified into three categories: axial, referred, and radicular. Back pain can also be classified on the basis of its underlying etiology into mechanical and non-mechanical. On the basis of pathogenesis, back pain can be broadly classified into inflammatory, mechanical, degenerative, oncologic and infectious. Genes involved include HLA-B27, SOX5, CCDC26/GSDMC, DCC. Conditions associated with back pain are, heavy lifting, ligaments and muscle strain, back injuries/fractures, arthritis, osteoporosis, metastatic cancer, abnormal posturing, degenerative disc disease, depression, pregnancy, fibromyalgia, sciatica, spinal disc herniation, spinal stenosis.The causes of back pain can be stratified according to age. Common causes of back pain in adults under the age of 50 years include, ligament strain, nerve root irritation, spinal disc herniation, degenerative disc disease and isthmic spondylolisthesis. Common causes in adults over the age of 50 years include osteoarthritis (degenerative joint disease), spinal stenosis, trauma, cancer, infection, fractures, and inflammatory disease.  Non-anatomical factors can also lead to back pain, such as stress, repressed anger, or depression. Even if an anatomical cause for the pain is present, a coexistent depression should be treated concurrently. The prevalence of back pain in adult population is around ten to thirty percent in the US. Lifetime prevalence in US adult population is estimated to be 65-80 percent. Prevalence of back pain is higher in smokers as compared to non-smokers. Risk factors for back pain include poor posture, obesity, pregnancy, cancer, weight lifting, psychological stress, smoking, sedentary lifestyle, lack of exercise, autoimmune disease, arthritis and trauma.There is no single diagnostic study of choice for the diagnosis of back pain. Back pain is a symptom of an underlying condition, emphasis should be made in identifying the etiology. The diagnostic plan should include, a detailed history, physical examination, identification of red flags, imaging (preferably an MRI) and laboratory evaluation (CBC, ESR, CRP, ANA, RF, LDH, uric acid, HLA-B27). MRI is helpful in the diagnosis of the underlying cause of back pain. Findings on MRI suggestive of the cause of back pain include soft tissue lesions, nerve compression, malignancy, and/or inflammatory  lesions. MRI is indicated in back pain if any of following red flags are present, history of cancer, unexplained weight loss, significant trauma, motor weakness, sensory loss, urinary/fecal incontinence. Other diagnostic studies for back pain  include electromyography, nerve conduction studies, somatosensory evoked potentials, and/or diagnostics injections. Treatment depends on the underlying cause, co-morbidities, age of the patient and chronicity of the pain. A treatment plan including a combination of medical and non-medical therapy should be formulated. Medical therapy includes, muscle relaxants, narcotics, non-steroidal anti-inflammatory drugs (NSAIDs/NSAIAs), acetaminophen, amitriptyline, tramadol, pregabalin, corticosteroids. Non-Medical therapy include heat massage, physical therapy, exercise, psychotherapy, massages, joint manipulation, managing ergonomics, acupuncture. Surgery is rarely needed for back pain. Surgery may be required in patients with lumbar disc herniation, degenerative disc disease, spinal stenosis,  spondylolisthesis, scoliosis, compression fracture. Surgical procedure include, diskectomy, laminectomy, joint fusion, artificial disks, interlaminar implant, vertebroplasty, kyphoplasty, and nucleoplasty.

# Historical Perspective
Norton Hadler has written that back pain was not a common complaint in the United States till it emerged between the two world wars. He poses reasons for the medicalization of this complaint in the United States. Back pain is one of humanity's most frequent complaints. In the U.S., acute low back pain (also called lumbago) is the fifth most common reason for all physician visits. About nine out of ten adults experience back pain at some point in their life and five out of ten working adults have back pain every year. Bone scan, SPECT scan, DEXA scan and thermography may be helpful in identifying the cause of back pain.

# Classification
On the basis of origin, back pain can be broadly classified into three categories: axial, referred, and radicular. Back pain can also be classified on the basis of its underlying etiology into mechanical and non-mechanical.

# Pathophysiology
On the basis of pathogenesis, back pain can be broadly classified into inflammatory, mechanical, degenerative, oncologic and infectious. Genes involved include HLA-B27, SOX5, CCDC26/GSDMC, DCC. Conditions associated with back pain are, heavy lifting, ligaments and muscle strain, back injuries/fractures, arthritis, osteoporosis, metastatic cancer, abnormal posturing, degenerative disc disease, depression, pregnancy, fibromyalgia, sciatica, spinal disc herniation, spinal stenosis.

# Causes
The causes of back pain can be stratified according to age. Common causes of back pain in adults under the age of 50 years include, ligament strain, nerve root irritation, spinal disc herniation, degenerative disc disease and isthmic spondylolisthesis. Common causes in adults over the age of 50 years include osteoarthritis (degenerative joint disease), spinal stenosis, trauma, cancer, infection, fractures, and inflammatory disease.  Non-anatomical factors can also lead to back pain, such as stress, repressed anger, or depression. Even if an anatomical cause for the pain is present, a coexistent depression should be treated concurrently.

# Differentiating Back Pain from other Diseases
There are several life-threatening causes of back pain, including spinal cord or cauda equina compression, aortic dissection, aortic aneurysm, vertebral osteomyelitis, epidural abscess, and metastatic cancer. These should be evaluated alongside other possible causes of back pain by carefully assessing the nature of the pain, and obtaining a thorough patient history.

# Epidemiology and Demographics
The prevalence of back pain in adult population is around ten to thirty percent in the US. Lifetime prevalence in US adult population is estimated to be 65-80 percent. Prevalence of back pain is higher in smokers as compared to non-smokers. Studies suggest that for as many as 85% of cases, no physiological cause for the pain has been identified. Race can be a factor in back problems. African American women, for example, are two to three times more likely than white women to develop spondylolisthesis, a condition in which a vertebra of the lumbar spine slips out of place. Back pain prevalence have been observed to be higher in females than males.

# Risk Factors
Risk factors for back pain include poor posture, obesity, pregnancy, cancer, weight lifting, psychological stress, smoking, sedentary lifestyle, lack of exercise, autoimmune disease, arthritis and trauma.

# Screening
There is insufficient evidence to recommend routine screening for back pain.

# Natural history, Complications and Prognosis
Natural history, complications and prognosis largely depend on the underlying cause of back pain. Back pain progresses and presents varialbly depending on the pathology. Back pain of any origin can lead to deformity, disability, depression, weight gain, social isolation, decreased quality of life, and sleep disturbances. Prognosis varies according to the underlying etiology, most patients will recover with within weeks. Recurrent and chronic cases are more resistant to treatment.

# Diagnosis

## Diagnostic Study of Choice
There is no single diagnostic study of choice for the diagnosis of back pain. Back pain is a symptom of an underlying condition, emphasis should be made in identifying the etiology. The diagnostic plan should include, a detailed history, physical examination, identification of red flags, imaging (preferably an MRI) and laboratory evaluation (CBC, ESR, CRP, ANA, RF, LDH, uric acid, HLA-B27).

## History and Symptoms
Important history question for patients presenting with back pain should focus on, pain onset, duration, radiation, aggravating or relieving factors, intensity, preceding event (surgery, intense exercise, trauma), and associated symptoms including, bowel incontinence, bladder incontinence, progressive weakness in legs, sleep interrupted due to severe back pain, fever, unexplained weight loss.

## Physical Examination
Patients with back pain have variable presentation depending on the severity of pain and associated signs and symptoms. If fever is present then infectious cause should be investigated. Signs of trauma should be observed, including, contusions, abrasions, point tenderness. Restricted range of motion and muscular tenderness are observed in patients with lumbosacral muscle strains/sprains. Pain on extension and rotation of hips may be present in patients with lumbar spondylosis along with pain radiating to hips. Point tenderness can be seen in patients with vertebral compression fracture. ] examination of patients with back pain is usually normal. However, if any abnormality is recognized further investigation must be done to rule-out a more serious condition. Paresthesia, sensory deficit, decreased muscular strength or diminished reflexes may be observed in patients with herniated disc. Straight leg raise (SLR) should be done to investigate for lumbar disk herniation. Motor deficit in legs and sensory loss is also seen in patients with spinal stenosis. One leg hyperextension test looks for pars interarticularis defect as a cause of back pain.

## Laboratory Findings
There are no diagnostic laboratory findings associated with back pain. However, to investigate the underlying cause of back pain it is crucial to look for the following, complete blood count (CBC), erythrocyte sedimentation rate, C-reactive protein, HLA-B27, antinuclear antibody (ANA), rheumatoid factor, lactate dehydrogenase (LDH), uric acid.

## Electrocardiogram
Patients with atypical back pain should undergo an ECG to rule out or investigate life threatening causes of back pain such as thoracic aortic dissection, myocardial ischemia.

## X Ray
X-ray imaging includes conventional and enhanced methods that can help diagnose the cause and site of back pain. A conventional x-ray is often the first imaging technique used, it looks for fractured bones, degenerative changes, and vertebral misalignment. Tissues such as injured muscles and ligaments or painful conditions such as a bulging disc are not visible on conventional x-rays. Myelogram enhances the diagnostic imaging of an x-ray. In this procedure, the contrast dye is injected into the spinal canal, allowing spinal cord and nerve compression caused by herniated disc or fractures to be seen on an x-ray.

## Echocardiography and Ultrasound
There are no echocardiography/ultrasound findings associated with back pain.

## CT
Computerized tomography (CT) is considered when MRI is not an option. It is used if disc rupture, spinal stenosis, or damage to vertebrae is suspected as a cause of back pain. CT scan can be paired with a myelogram by injecting contrast dye in the spinal cord. PET/CT can be used together to increase anatomical accuracy especially in adults with persistent back pain.

## MRI
MRI is helpful in the diagnosis of the underlying cause of back pain. Findings on MRI suggestive of the cause of back pain include soft tissue lesions, nerve compression, malignancy, and/or inflammatory  lesions. MRI is indicated in back pain if any of following red flags are present, history of cancer, unexplained weight loss, significant trauma, motor weakness, sensory loss, urinary/fecal incontinence.

## Other Imaging Findings
Bone scan, SPECT scan, DEXA scan and thermography may be helpful in identifying the cause of back pain.

## Other Diagnostic Studies
Other diagnostic studies for back pain  include electromyography, nerve conduction studies, somatosensory evoked potentials, and/or diagnostics injections.

# Treatment

## Medical Therapy
Treatment depends on the underlying cause, co-morbidities, age of the patient and chronicity of the pain. A treatment plan including a combination of medical and non-medical therapy should be formulated. Medical therapy includes, muscle relaxants, narcotics, non-steroidal anti-inflammatory drugs (NSAIDs/NSAIAs), acetaminophen, amitriptyline, tramadol, pregabalin, corticosteroids. Non-Medical therapy include heat massage, physical therapy, exercise, psychotherapy, massages, joint manipulation, managing ergonomics, acupuncture.

## Surgery
Surgery is rarely needed for back pain. Surgery may be required in patients with lumbar disc herniation, degenerative disc disease, spinal stenosis,  spondylolisthesis, scoliosis, compression fracture. Surgical procedure include, diskectomy, laminectomy, joint fusion, artificial disks, interlaminar implant, vertebroplasty, kyphoplasty, and nucleoplasty.

## Primary Prevention
Effective measures for the primary prevention of back pain include, improved posture, proper lifting techniques of heavy objects, avoiding trauma, balanced diet, active lifestyle, stress management, avoid smoking.

## Secondary Prevention
Effective measures for the secondary prevention of back pain include, treatment of the underlying cause, posture correction, balanced nutrition and active lifestyle, physical therapy, psychosocial therapy, stress management, improved sleep quality.