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The gel within the intervertebral disc begins to gradually lose its water content from our mid twenties onwards. In practice this can be likened to a car tyre gradually deflating. This results in the disc bulging outwards, and this may result in pressure on the nerves within the spinal canal. As the process of degeneration continues the outer fibrous capsule (annulus) is exposed to increasing stresses and strains and may tear as a result. Finally as the disc loses height, increasing pressure is placed on the facet joints. The facet joints are similar in structure to the hip or knee joint. The joint surfaces are covered in articular cartilage. This wears away gradually which can result in pain.
What is Sciatica?
Sciatica refers to symptoms of pain, changes in sensation and / or weakness in the leg as a result of compression of a nerve root. These symptoms radiate from the buttock down the leg. The specific area in the leg affected depends on the nerve or nerves involved. Disc herniation occurs when the outer disc capsule (annulus) tears allowing the gel contents to bulge outwards pressing on the involved nerve root.
There is evidence to suggest that the risk of disc herniation is higher in smokers, and in patients with a non-active lifestyle. Incorrect lifting techniques and poor posture may also contribute. However most of the changes seen are part of the natural process of degeneration, causing the gel in the nucleus to lose its water content over time and the disc to deflate as a result. The process of disc herniation can occur instantaneously or come on over a matter of weeks to months. The presence of a disc herniation may not result in pain. Some studies have shown that up to 80% of asymptomatic individuals have some abnormalities in their discs.
Interestingly not every herniated disc causes symptoms. Some people discover they have a bulging or herniated disc after undergoing investigations for an unrelated reason. However most of the time the patient’s symptoms prompt the patient to seek medical care.
A medical consultation usually includes a symptom evaluation and the history of treatments and medication the patient has tried, review of medical history followed by a physical and neurological exam. Imaging studies including a MRI or plain x-rays may often be required to fully assess the patient’s spinal anatomy.
Signs and Symptoms
A herniated or bulging disc is a common cause of leg and low back pain. Symptoms classically include leg pain, pins and needles or other sensory changes and muscle weakness in the leg. Other symptoms include muscle spasm or cramping and leg weakness. Patients occasionally walk with a limp as a result of pain or weakness. Sneezing, coughing, or bending usually intensifies the pain. In addition some patients note that sitting will exacerbate their leg pain.
Cauda Equina Syndrome
Loss of bowel or bladder control, or loss of sensation in the private parts is a serious symptom and can indicate that severe pressure is being placed on the lower nerves in the spinal canal (cauda equina syndrome). If this occurs medical attention should be sought immediately.
The majority of patients presenting with sciatic symptoms find their symptoms resolving spontaneously within 10 weeks of onset. Initially, the doctor may recommend some bed rest, cold therapy, and medications. Bed rest takes the pressure off nerves in the low back. During the first 24 to 48 hours cold therapy helps to reduce swelling, muscle spasm, and pain by reducing blood flow. Never apply cold or ice directly to skin; instead wrap the ice pack or cold product in a towel and apply for no longer than 15 minutes.
Medications may include an anti-inflammatory to reduce swelling, a muscle relaxant to calm spasm, and a pain-killer (narcotic) to alleviate intense but short-lived pain (acute pain). Mild to moderate pain may be treated with non-steroidal anti-inflammatory drugs (NSAIDs). These work by relieving both swelling and pain. Discuss NSAID use with your doctor first.
The doctor may recommend physical therapy. Physical therapy includes a combination of non-surgical treatments to decrease pain and increase flexibility. Ice and heat therapy, gentle massage, stretching, and pelvic traction are some examples.
If leg pain is severe, or leg weakness is developing, the doctor may prescribe a spinal injection. This is undertaken as a day case. This may be an interlaminar or transforaminal epidural steroid injection. An interlaminar epidural (ILE) is similar to the epidural injection that women receive in labour and is often administered without radiological guidance. It involves the injection of a larger volume of local anaesthetic and steroid into the spinal canal by passing the needle into the canal. A transforaminal steroid injection (TFSI) is undertaken under radiological guidance and involves placing the needle in close proximity to the nerve, which is being pressed on by the bulging disc. A smaller volume of local anaesthetic and steroid is delivered closer the nerve.
The patient may experience loss of sensation and / or power in the leg after the injection due to the action of the injected local anaesthetic, though this typically resolves within a 12-hour period. These procedures may be undertaken under light sedation and if this is the case you will need to fast prior to the injection and arrange for transport home from hospital.
In four to six weeks, the majority of patients find their symptoms have significantly improved without surgery.
Spine surgery is considered if non-surgical treatment does not relieve symptoms. Constant pain, leg weakness, or loss of function requires further evaluation. Rarely, does a lumbar herniated disc cause bowel/bladder incontinence or groin/genital numbness, which requires immediate medical attention.
To relieve nerve pressure and leg pain, surgery usually involves a partial disc removal or microdiscectomy. The surgeon accesses the herniated disc by removing a portion of the bone covering the nerve. This procedure is called a laminotomy. Fortunately, these procedures can often be done utilizing minimally invasive techniques. Minimally invasive surgery does not require large incisions, but instead uses small cuts and tiny specialized instruments and devices such as a microscope and endoscope during the operation.
Maintaining an active lifestyle is the single best protection in avoiding lumbar disc disease. The main thrust of any exercise programme is to maintain the strength of the core trunk muscle groups (abdominal and paraspinal muscles). These muscles may be weakened as we get older and adopt a more sedentary lifestyle, or by other life events including pregnancy.
Strengthening the truncal muscles can be undertaken under the direction of a physiotherapist who may also recommend a Pilates or yoga programme. In terms of aerobic exercise, swimming provides the most return in terms of time. However care should be taken to avoid repetitive spinal extensions that can result from the breaststroke in particular.
IMPORTANT NOTICE: Please note you will need a referral letter from your GP to use any of
the services of UPMC Beacon Centre for Orthopaedics, except for the Physiotherapy department.