Spine Infections - Part I: Osteomyelitis and Discitis
Spine infections can be considered a serious and life-threatening problem. These can vary from mild pain- causing infections to completely paralytic infections that may even cause death. Most commonly a spine infection is acquired through the bloodstream and is present with an infection somewhere else in the patient's body. Rarely an infection can be due to procedures such as injections or surgery. In these cases, the infection is limited largely to the spine itself. As soon as the thought of a spine infection is entertained, an infectious disease specialist as well as a spine surgeon should be involved and consulted.
The most common spine infection is known as vertebral osteomyelitis, which basically means that the infection in the spine is limited to the bones themselves. It does not involve the spinal canal, the spinal nerves, or the discs. This is usually acquired from the bloodstream through a process called hematogenous seeding in a large majority of cases. This is so often the case that whenever I see a patient with vertebral osteomyelitis my first thought is to look for infection elsewhere in the body.
The most common symptom of a spine infection is isolated back pain. The most classical complaint is that the patient cannot find relief from his/her back pain in any position. Most people who have back pain from a fracture or from a herniated disc can find comfort while laying down. However, in the case of a patient with a spine infection, he/she seems to never be able to get a comfortable position no matter how hard he/she seems to try. One should consider the possible diagnosis of a spine infection - however rare it might be - whenever thinking about the cause of a patient's back pain. If if the possibility exists of a spine infection, more testing maybe required, usually in the form of an MRI and blood tests. The MRI provides the most specific information regarding the nature of the infection and the location of the infection. It is very important to diagnose and treat a spine infection as early as possible to prevent its progression and to prevent any possible damage to the spinal nerves / spinal cord.
While vertebral osteomyelitis can be a severe and painful condition, surgical treatment can be largely avoided with early treatment with intravenous antibiotics and occasional bracing to make the patient comfortable while the antibiotics help remove the infection. I only consider surgery if the infection spreads and begins to compress the nerves and/or the patient fails a prolonged course of non-operative treatment (>3 months).
Given the fact that the vertebra are next to the discs in the spine, very commonly the infection in the vertebra can spread or also involve the adjacent discs. This condition is known as discitis and collectively this condition is known as osteomyelitis/osteodiscitis. Usually discitis present sin a very similar way to osteomyelitis in that the patient's main complaint is usually isolated low back pain without the ability to find a comfortable position. Discitis is also most often caused by the process of hematogenous seeding. The ability to detect changes in the disc on xrays may be limited and thus an MRI is again used with blood tests to confirm the diagnosis of discitis. Very similar to osteomyelitis, discitis rarely require surgerys and can be usually treated with a course of intravenous antibiotics and bracing for comfort. The treatment course for these infections can be complicated and must thus be managed in a team oriented approach by an infectious disease specialist and an orthopedic spine surgeon.
Spine Infections - Part II: Epidural Abscess
While spine infections are rare, they can be dangerous and must be treated early and appropriately.
On rare occasions, infection in the spine can cause an epidural abscess to form. The term epidural abscess suggests that this infection has started to spread around the nerves and spinal cord, making it more difficult to treat with antibiotics and non- operative treatment. Moreover, the mass that is formed may cause pressure on the nerves and/or spinal cord, causing these structures to stop functioning normally. This can cause a variety of symptoms, ranging from simple numbness all the way to complete paralysis. Thus, it is important that every patient with a spine infection be assessed for possible epidural abscess prior to embarking on a treatment plan before neurological problems develop.
An epidural abscess is best visualized via a cervical or lumbar MRI with intravenous contrast depending on the area of the infection. If an epidural abscess is found, surgical treatment must be considered more seriously. If an epidural abscess is not found, then non-operative treatment with a course of intravenous antibiotics and bracing is strongly recommended for the treatment of osteomyelitis/discitis. In these cases surgical treatment is only used if the initial treatment fails.
The outcome of surgical treatment for epidural abscess is directly related to how early the infection is diagnosed and treated. If the infection is treated surgically and the spinal elements are decompressed prior to developing significant neurological problems, then the outcome is quite good. However, if surgical treatment is delayed and/or the diagnosis missed and then treatment is initiated after the patient begins to have significant neurological problems, then the outcome is poor. Thus, again this information highlights the importance of early detection and appropriate decision-making amongst members of the treatment team and the patient.
The diagnosis of epidural abscess in the spine can be difficult and complex. The decision about whether an epidural abscess is present or not is made by the orthopedic spine surgeon in conjunction with a neuroradiologist, who is well trained in reviewing these types of MRIs. An infectious disease specialist is also consulted to help determine the need for initial antibiotics, antibiotics after surgery while the culture results are pending, and once the infecting organism is definitively isolated/identified.
Spine infections are very rare and epidural spine infections make up a very small minority of the spine infections. Nonetheless, it should be kept foremost in our minds because of the importance in early diagnosis/treatment and its prognosis. Please discuss any further questions with a board-certified orthopedic spine surgeon.