Infections of the Spine
Infections of the Spine
Extensive infection (abscess) of the spine causing swallowing difficulties and compression of the spinal cord
surgical fixation for infection
Extreme late deformity after contracting TB
Condition
Infections of the spine are uncommon but can lead to serious complications like paralysis or instability of the spine if untreated. They are more common in patients with other health problems like diabetes, HIV AIDS, alcoholism, drug abuse or other disease which compromise the immune system (kidney failure). Tuberculosis of the spine is a special type of infection which is increasing in numbers in the UK. Spinal infections can also be caused by any spinal operation or injection. Thankfully, the risks in routine operations is low (2-4%). These usually occur within the first 2-3 weeks after surgery.
In patients with a spinal infection three important questions need to be answered:
Which organism is causing the infection?
In principle, any bacterial infection can be treated with antibiotics. Therefore, it is essential to identify the organism, which is causing it as soon as possible. At the same time, the microbiology lab will be able to test antibiotics and say whether the organism is sensitive or resistant.
Where exactly is the infection?
It is important to know where in the spine the infection has started and has spread to. This has an influence on how long antibiotics are given.
Discitis is an infection of the intervertebral disc. It usually starts at the junction of the vertebral body and disc (so-called endplates) and spreads into the disc. The intervertebral disc has a very poor blood supply. This means that blood cells which form part of the body’s defence system, cannot fight the infection.
An epidural abscess forms if the infection is in the space between the bony parts of the vertebral column and dural sac (see ‘The Spine&Spinal conditions’ -Normal Structure of the Spine’). This is a continuous space from the head to the sacrum (base of the spine). Infections can spread quickly along a number of levels if left untreated.
Osteomyelitis means an infection of the bone. In the spine this occurs in the vertebral body. This can lead to the collapse of the vertebral body.
The infection can destroy the bones or ligaments. This can have an effect on the stability of the spine. It can also cause pressure on the nerves or spinal cord leading to numbness or paralysis. This information will have an important influence on the decision whether surgery is indicated or not.
Symptoms
Patients with spinal infections typically have severe pain in a localised area of the spine, which develops over a short time (days). The pain may radiate down the arm or leg if it effects nerve roots (radiculopathy). Most patients will also have fever and may feels generally unwell. If untreated, the infection will spread and cause pressure on nerves or the spinal cord. This can lead to myelopathy or cauda equina syndrome.
In tuberculosis (TB) of the spine, symptoms often develop slower over weeks and sometimes months. Because of the slower progression, some patients are misdiagnosed by their doctors with musculoskeletal neck or back pain. However, many patients will show other typical signs of tuberculosis like night sweats and unexplained weight loss.
Complications
If untreated spinal infections can lead to permanent paralysis and spinal instability or collapse of the vertebral body. A systemic infection, which may have caused the spinal infection or can be the result of it (uncommon) can affect other organs and is life threatening in extreme cases.
Investigations and Diagnosis
A clear history of symptoms, risk factors and other health problems is essential. Clinical examination will establish signs of systemic infections or possible sources. It is important to assess the neurological function and pick up signs of myelopathy. Checking the blood pressure, pulse and temperature are very basic but essential tests.
Blood tests include full blood count, blood cultures (in which organisms will grow over 48hours) and so-called inflammatory parameters like ESR and CRP. The latter will also help to monitor the effect of antibiotic treatment.
An urgent MRI scan will help to establish the diagnosis and show the extent of the infection. Plain x-rays, flexion and extension views and CT-scans also may be indicated.
If no organism has been grown from blood cultures a biopsy of the infection may be indicated. This, however, is negative in many cases and treatment should not be delayed as this might take a few days to organise in most hospitals.
Treatment and Outlook
Pyogenic infections (infections by pus producing organisms like Staphylococcus aureus, groups of Streptococcus, E.coli and others) can be treated successfully in most cases but will progress rapidly if left alone! Therefore antibiotics form the basis of any treatment and should be given as soon as possible but after blood cultures have been taken. The initial treatment is usually with broad spectrum antibiotics until the blood cultures or direct samples identify the organism and sensitivities to specific antibiotics. The treatment might then be changed according to the results. In cases where no organisms can be identified, these broad spectrum antibiotics are continued. The duration of the treatment depends on the severity and extent of the initial infection, improvement of inflammatory parameters (see above) and clinical response to the treatment. Initially, antibiotics are given intravenously but may be switched to tablets at a later stage. The antibiotic treatment of patients should be supervised by an infectious disease team or microbiologist.
Any patient with TB needs to be under the care of a specialist team (often infectious disease team or chest physicians) and attend a TB-clinic. Most patients need to take a combination of four drugs for a duration of one year. Because of the slower clinical progress, the need for immediate treatment (i.e. within a day or two) is not as important as in pyogenic infection. This is why in patients who are clinically well and stable and where the diagnosis could not be established otherwise a biopsy might be done before the start of the treatment.
Overall, the prognosis of spinal infections is good if treatment is started early. Osteomyelitis (spread of the infection into the vertebral body) is a complication which often requires antibiotic treatment for three months. Surgery is not necessary in the majority of cases and is usually only indicated if there is any significant compression of the spinal cord (in cases of mild compression non-surgical treatment is often sufficient), instability or progressive deformity of the spine. This is in particular true for TB. Sometimes a brace is necessary to stabilise the spine until the infection has healed. In many cases of discitis and TB the affected segment of the spine will fuse.
Infections of the spine are very painful and strong painkillers are often necessary in the beginning.