Sciatica and Brachialgia
Barts and the London NHS Trust, The Wellington Hospital
- What are sciatica and brachialgia?
- What causes them?
- How can they be treated?
- What are the risks and outcomes of the various treatments?
The terms sciatica and brachialgia are used to describe nerve pain in the leg and in the arm respectively. Anyone who has ever had nerve pain will tell you that it is like no other pain they have ever had before. They tend to use very characteristic words to describe it, like “burning”, “gnawing”, “aching”, “shooting”, “electric shock.” Nerve pain does not respond very well to normal painkillers that you can get from a pharmacy, and even many doctors often find it hard to believe that it is painful as patients tell them it is. But it is usually excruciatingly painful, and patients can often find no respite from it even if they are taking large doses of very strong painkillers. Many patients can’t find a comfortable position during the day or night and they quickly get very tired.
Sciatica is pain caused as a result of pinching, pressure or damage to the sciatic nerve, which is the large nerve formed by a combination of smaller nervesBundles of fibres that carry information in the form of electrical impulses. which leave from the lumbarThe part of the back between the lowest ribs and the top of the pelvis. spine and the section of spine below that called the sacral spine. These smaller nerves join together outside the spine deep inside the pelvisThe bony basin formed by the hip bones and the lower vertebrae of the spine; also refers to the lower part of the abdomen. to form the sciatic nerve. The sciatic nerve runs deep in the buttock where it starts to give off branches as it travels down the back of the thigh. It controls all the muscles in the back of the thigh and all the muscles below the knee. It also carries all the sensory signals from these regions back to the spinal cord on their way to the brain.
The pain from sciatica is normally felt in a line starting as high as the low back, but more often in the buttock. It then travels either down the back of the thigh and calf and into the heel and sole of the foot, or it travels down the outside of the thigh and calf to the ankle and outside of the foot. The route it takes is important as that helps to determine which lumbar nerve roots have caused it.
Brachialgia is the exact analogy of sciatica but it is pain felt in the shoulder, arms, and hands. It can start as high as the neck and sometimes the head, and many patients have severe pain in the region of the shoulder blade. Brachialgia is due to problems affecting the cervicalRelating either to the cervix (the neck of the womb) or to the cervical vertebrae in the neck (cervical spine). nerve roots, and just as in the leg the course it takes, whether into the outer upper arm, or into the middle finger, or the inner forearm, is equally important in making the diagnosisThe process of determining which condition a patient may have. of the level of the problem.
In simple terms both sciatica and brachialgia are caused by damage to the spinal nerve roots generally inside the spine but occasionally just outside the spine. There are many potential causes of both conditions which are covered in some depth in another article (The ageing spine). The main causes are:
- Herniated intervertebral discOne of the tough pads of fibre and cartilage that separate the vertebrae and act as cushions to absorb forces on the spine.
- Degenerative disc disease
- Osteophyte formation
- Facet joint hypertrophyAn increase in the size of the tissue of an organ resulting from an increase in the size of its individual cells.
- Spinal stenosisNarrowing of a tubular structure or valve.
- Spinal cancerAbnormal, uncontrolled cell division resulting in a malignant tumour that may invade surrounding tissues or spread to distant parts of the body.
Before talking about treatment it is essential to find out what is causing the condition as this always guides treatment. The main causes of sciatica and brachialgia are are covered in depth in the accompanying article “The Ageing Spine”. Anyone who has been diagnosed with sciatica or brachialgia by their GP can be referred to a specialist consultant in spinal medicine or surgery. The consultant will take a full history to try to establish what may have caused the problem, and examine the patient to see how the problem has affected things like posture, flexibility, and nerve function. It is then important to get some imaging of the spine and nerves to visualise and characterise the problem. This will be an MRIAn abbreviation for magnetic resonance imaging, a technique for imaging the body that uses electromagnetic waves and a strong magnetic field. scan unless the patient has a contraindicationA condition which may make a medical treatment or procedure inadvisable. to MRI such as a pacemakerA small electrical device that functions to maintain a normal heart rate.. MRIs show extraordinary detail of bones, ligaments, nerves, and intervertebral discs. They are essential to identifying the nature of the problem and therefore guiding treatment.
Manipulation can make sciatica and brachialgia worse and should not be considered until the patient has been seen and assessed by a spinal medical or surgical specialist. Although both sciatica and brachialgia can settle down spontaneously without any intervention, they are very different from simple mechanical back or neck pain, and the two should not be confused. While some people get twinges of sciatica or brachialgia for short periods of time from minor nerve root compromise, when there is significant nerve compression patients get no respite at all and find the pain all consuming, stopping them from standing or moving properly, and usually also stopping them from sleeping.
Physical therapy from special spinal physiotherapists can be helpful, but patients often find it very painful to be manipulated during the acuteHas a sudden onset. stage of the condition, so at this stage treatment is generally focussed on relieving associated muscle spasm, correcting postural abnormalities, and introducing some core stability exercises for sciatica.
Patients cannot be left like this hoping for the condition to settle down. Few people are able to work or lead anything approaching a normal life with the sort of pain they get with these conditions. Because of this anyone with either of these conditions should seek specialist help. They often need very strong painkillers such as Morphine or even stronger drugs like Fentanyl. Other specialist nerve pain drugs can also be used. Drugs in this category are Amitriptyline, Gabapentin, and Pregabalin. These drugs can be very effective in relieving nerve pain from smaller nerves but are unfortunately not very effective at relieving sciatica or brachialgia, which are caused by compromise of large nerves. Sometimes oral steroidsCompounds with a common basic structure, which occur naturally in the body. The term may also refer to man-made drugs administered because they act like hormones. are used, but these are also generally not very effective.
If the pain from sciatica or brachialgia cannot be quickly controlled by analgesicsAnother term for painkillers. the next step for most patients is for them to have some steroids injected around the affected nerve root. This has to be done very accurately, the injections being guided by continuous x-ray or by CTThe abbreviation for computed tomography, a scan that generates a series of cross-sectional x-ray images scanning. Steroid infiltration around nerves is usually very effective at controlling pain from sciatica or brachialgia. It may need to be repeated on up to two further occasions during the acute phase of the condition but most patients can avoid surgery by having these treatments.
If the pain cannot be controlled by analgesics, or by image guided spinal steroid injections then the next step is to consider surgery. The main indications for surgery to treat sciatica or brachialgia are the following:
- Inability to adequately control pain by analgesics and image guided percutaneousUsually related to medical procedures; entering the body through the skin. treatments
- Progressive muscle weakness due to nerve compromise
- Problems with bladderThe organ that stores urine. or bowelA common name for the large and/or small intestines. control in the presence of a known lumbar disc herniationAn abnormal protrusion (sticking out) of tissue.
Most patients get better in a few weeks with simple conservative management consisting of analgesia and physical therapy. These few weeks can seem like a lifetime for patients whose pain cannot be adequately controlled. The risks of conservative management are less than those of any interventional treatment, but there can be a risk attached to putting off these treatments too long.
If bladder or bowel weakness occur this is a surgical emergency called “Cauda Equina Syndrome.” If the spine is not surgically decompressed within hours the patient can be permanently paralysed.
With prolonged nerve compression and progressiveContinuously increasing in extent or severity. weakness in the arm or leg muscle strength may take many months to recover even after surgery and may not fully recover at all. Similarly if numbness develops the skin may not return to normal sensation.
It is vital therefore that if you develop sciatica or brachialgia you are evaluated and cared for by a spinal specialist who will know when to recommend that you have surgery.
What about the risks of surgery? While there are risks attached to surgery they should be weighed against the benefits, and against the risks of not operating. There are the general risks associated with all surgical procedures such as bleeding, infectionInvasion by organisms that may be harmful, for example bacteria or parasites., and general medical problems, but there are also risks associated with the nature of the surgery being undertaken. Obviously the spinal cord and nerve roots are very close to the site of surgery and these can, in rare circumstances, become damaged. Other structures nearby can also be damaged in rare instances. There is a small risk that the symptoms may be worse after surgery as the result of a complicationA condition that is linked to, or is a consequence of, another disease or procedure.. These risks are small though, with a serious surgical complication rate of typically less than 5% in the best centres.
The decision of whether to proceed to surgery, if so when, what sort of surgery to have, and by whom, should be made in close consultation with your spine specialist. It should be remembered though that the majority of patients with sciatica or brachialgia do not need surgery. These patients can be managed by a combination of analgesia, image guided percutaneous treatments, and carefully supervised physical therapy.