Definition

Herniated Nucleus Pulposus (HNP) is a condition where the intervertebral disc, which acts as a cushion for the vertebrae, shifts from its original position and compresses the spinal nerve. HNP is also known as a “pinched nerve.” The symptoms of a pinched nerve depend on its location, most commonly occurring in the lower back (lumbar) or the neck. HNP in the lower back is more common than in the neck.

Causes

HNP is caused by the weakening of the tissues in the spinal disc. As we age, the flexibility of the spinal disc decreases, making it more prone to injury. HNP can also occur after a fall or impact on the spine. Other causes of HNP include being overweight, lifting heavy objects with incorrect posture and support, bending, and twisting movements done suddenly or repetitively.

Risk factor

Risk factors that make people susceptible to HNP include:

• Jobs involving heavy lifting
• Intense physical activities
• Repetitive and prolonged activities like excessive bending or twisting
• Smoking
• Overweight, as it puts pressure on the lower back
• Aging, as older age increases the risk of HNP
• Genetic factors

Symptoms

HNP symptoms vary depending on its location, typically occurring in the neck and lower back.

If HNP or a pinched nerve occurs in the neck, symptoms may include:

• Neck stiffness
• Pain radiating from the neck to the shoulders and arms
• Pain worsened by coughing, sneezing, or changing positions
• Tingling, weakness, or muscle stiffness in one arm
• Burning sensation in the neck, shoulders, and arms

If HNP or a pinched nerve occurs in the lower back, it can cause symptoms such as:

• Lower back pain that worsens with movement
• Pain radiating to the tailbone, buttocks, thighs, calves, and feet
• Stabbing pain in the buttocks radiating to one leg
• Tingling or muscle weakness in the leg

In HNP cases, muscle weakness can interfere with daily activities and reduce the ability to lift or carry objects. Although rare, in some cases, lower back HNP can also cause incontinence.

Diagnosis

Diagnosing HNP requires a thorough interview (anamnesis) about symptoms such as neck or lower back pain, radiating pain, burning sensations, tingling, and weakness. It is essential to identify any triggers, such as trauma, job history, and posture. Other underlying conditions, such as partial limb weakness, nausea, vomiting, fever, and altered consciousness, should be ruled out. Physical examination includes measuring the patient’s weight, as obesity is a risk factor for HNP. Patients may be asked to lie down and move their legs in various positions to help identify the cause of the pain. The doctor will evaluate each vertebra to determine the HNP location and may perform neurological tests to check reflexes, muscle strength, walking ability, and sensation. In some HNP cases, physical examination and medical history are sufficient for diagnosis. However, if other conditions are suspected or specific nerve involvement needs to be identified, imaging tests such as X-rays, CT scans, MRIs, myelograms, and electromyography (EMG) can be used to measure nerve conduction.

Management

In some HNP cases, symptoms improve with conservative therapy without the need for surgery. For patients who do not improve with conservative therapy, invasive treatments such as steroid injections or surgery may be considered.

Pain relief in HNP, a common symptom of a pinched nerve, can be achieved with nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen and naproxen to reduce inflammation and pain. Corticosteroids may also be prescribed to reduce pain and swelling.

Surgery is performed if symptoms worsen and do not improve. The surgical procedure for HNP, called microdiscectomy, involves removing the protruding or damaged disc without removing the entire disc. The disc is then replaced with an artificial one, and the spine is fused in a procedure called laminectomy and spinal fusion.

Complications

Untreated HNP can lead to worsening pain, weakness, disrupted daily activities, incontinence, loss of sensation, and permanent nerve damage, potentially resulting in paralysis.

Prevention

To reduce the risk of HNP, engage in regular exercise such as swimming, maintain good posture when sitting or lifting objects, maintain an ideal weight to prevent excessive pressure on the spine, and quit smoking as smoking can reduce the oxygen supply to the spinal discs.

When to see a doctor? 

You should see a doctor if the pain persists, radiates to the leg, or causes tingling, muscle weakness, or numbness. Immediate medical attention is needed if pain causes incontinence, paralysis, or occurs after an injury. Seek emergency care if there is altered consciousness, nausea, vomiting, fever, partial limb weakness, or slurred speech.

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