Posted on Mon Dec 17, 2018
Back pain with or without radiation to the legs, the so-called sciatica, is amongst the top three reasons why patients seek medical attention.
The symptoms can become chronic and cause a great deal of pain and disability. It is also one of the commonest reasons for people not being able to go to work. In the vast majority of patients, the reason for back pain is so-called mechanical; meaning wear and tear of the spine. There is a degree of wear and tear of the spine in everybody over the age of 30, but of course lifestyle and genetic factors can determine the degree of wear and tear and its rate of progress. The commonest reason for patients to have sciatica is a disc bulge, itself secondary to wear and tear, in the lumbar spine (lower back), causing pressure on the nerves as they exit the spine to go to the legs.
Discs in reality are cushions between the vertebrae (back bones) which provide flexibility to the spine. Similar to the rest of the spine, with time, the discs can also start to wear out and changes like dehydration of the discs are an early sign that can be picked up on the MRI scan. Disc bulges can also be seen on MRI scans and many may be asymptomatic.
Symptoms, however, occur when the disc bulges (disc prolapse or disc slip) causes pressure on the nerve roots. Depending upon which disc is the problem and which nerve is being compressed, the symptoms can vary and clinical examination is very useful in working this out. MRI scanning of the spine, however, remains paramount in determining the exact location and extent of the disc slip and the compression of the nerve. Many patients presenting with sciatica will also have other symptoms such as numbness or tingling in the leg.
Weakness of the leg or the foot is seen less frequently, but clearly has a much bigger impact on the patient’s ability to carry out the activities of daily living. Any sign of leg or foot weakness in the context of sciatica therefore requires urgent medical attention and imaging of the spine to avoid long-term deficits. Rarely, the disc slip may be very severe, causing pressure on a range of nerves including those controlling bowel and bladder function. If this happens, patients may present with incontinence or numbness in their private parts. This would represent a neurosurgical emergency as urgent surgical attention is required to avoid long-term disability. Thankfully, this only happens in a very small number of patients.
When patients consult doctors for the management of their sciatica, a good clinical history is essential both to get a good understanding of the range of symptoms and also to determine any predisposing factors. Such factors could include heavy lifting, poor posture at work and sitting for long periods of time. All these can predispose to lower back and disc problems.
The doctor will also enquire about other symptoms, as very rarely back pain and sciatica may be due to non-wear and tear related problems of the spine, such as infection, inflammation or tumours. Clinical examination is also very helpful to assess any numbness or weakness of the legs that may be present. An MRI scan, however, is the key investigatory tool. Treatment options very much depend on the severity of the symptoms, their duration, the presence of any weakness in the legs or any problems with bowel and bladder function, the size and location of the disc slip and, of course, patients’ expectations and the impact of the symptoms on their quality of life.
Overall, in patients without any evidence of leg weakness or other deficits and a small-to-moderate disc prolapse, a conservative (non-surgical) approach is initially usually advised. This is because in the vast majority of patients, the disc prolapse and the nerve compression tend to settle over a six to eight-week window. During this time, oral analgesics and physiotherapy can prove very useful.
In terms of oral analgesics, usually relatively simple analgesics such as paracetamol can be considered. Non-steroidal anti-inflammatory drugs such as Brufen and diclofenac can also help settling the symptoms. A proportion of patients may require stronger drug therapy such as codeine-based medications or complex anti-neuropathic drugs such as pregabalin and gabapentin.
In terms of physical therapy, there is now a wide range of therapies available, including physiotherapy, osteopathy and chiropractic treatment. Different patients find different techniques more useful.
Once the initial six to eight weeks window has passed, if patients remain symptomatic, although clinical improvement over time may still occur, the timing then becomes less certain and predictable. In such a scenario, particularly in the presence of a large disc prolapse and significant nerve compression, surgery in the form of microdiscectomy has a real role to play to expedite symptom relief and recovery. As the term implies, microdiscectomy is an operation performed under a microscope to free up the nerve by removing the disc bulge which is compressing the nerve.
During the operation, the aim of the surgery is to free up the nerve rather than remove a fixed amount of disc material. Often the majority of the disc does not need to be removed. The risks of the operation are small and usually quoted as 1 in 500 for nerve damage, 1% for infection and 1% for leakage of spinal fluid which may prolong the hospital stay. Otherwise, usually most patients only stay in the hospital for one or two days for the operation. Following the operation, it is important that patients remain vigilant in terms of looking after their back.
Clearly, any lifestyle factors that would have predisposed to this problem in the first place should be managed. Physiotherapy is also often advised to build up the core muscles and strengthen the back. In a proportion of patients who are reluctant to take oral analgesics or consider surgical intervention, injection of local anaesthetic and steroids to dampen down the inflammation around the nerve root can be performed. This is usually very useful in providing pain relief but unfortunately the symptoms can recur.
Professor Keyoumars Ashkan
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