These are classified based on the location within the anatomy of the spine – vertebral column, spinal canal, intervertebral disc space and adjacent soft tissue.

Bacteria or fungal organisms can cause the infections occur after surgery, with postoperative infections typically occurring from three days to 3 months after surgery.

The most common form of vertebral infection is ‘vertebral osteomyelitis) which may develop from direct open spinal trauma, infections in surrounding areas and bacteria that spread to a vertebra.

Infections involving the space between adjacent vertebrae are called intervertebral disc space infections. These can be divided into three subcategories: adult hematogenous (spontaneous), childhood (discitis), and postoperative.

Spinal canal infections include spinal epidural abscess, which is an infection that develops around the dura (the tissue that surrounds the spinal cord and nerve root). Subdural abscess is more rare, affecting the potential space between the dura and arachnoid (the thin membrane of the spinal cord between dura mater and pia mater).

Infections within the spinal cord parenchyma (primary tissue) are known as intramedullary abscesses.

Adjacent soft-tissue infections include cervical and thoracic paraspinal lesions and lumbar psoas muscle abscesses. Soft-tissue infections tend to affect younger patients and are uncommon in older people.

Spinal infections can be caused by either a bacterial or a fungal infection in another part of the body that has been carried into the spine through the blood stream.

A bacterium called Staphylococcus aureus is the most common source of spinal infections. Escherichia coli is the next most common.

The lumbar region tends to be the most commonly affected part of the spine. Spinal infections may occur after a urological procedure because the veins in the lower spine are located in the pelvis. Due to the nature of their addiction, intravenous drug abusers tend to be more prone to infections affecting the cervical region.

Treatment
Spinal infections are managed on a case by case basis depending on the clinical presentation and the imaging findings. Treatment can range from bed rest and antibiotics with bracing to aspiration of pus to surgical stabilisation and decompression.

TARLOV CYST
These are fluid-filled nerve root cysts found most commonly at the sacral level of the spine – the vertebrae at the base of the spine. Tarlov cysts typically occur along the posterior nerve roots and can be valved or nonvalved. The key difference between Tarlov cysts and other spinal lesions is the presence of spinal nerve root fibers within the cyst wall or even within the cyst cavity.

Treatment
Many Tarlov cysts may be discovered incidentally on MRI but may not warrant any treatment other than observation. However, larger symptomatic cysts will benefit from microsurgical excision.

TETHERED SPINAL CORD SYNDROME
Tethered spinal cord syndrome is a neurological disorder caused by tissue attachments that limit the movement of the spinal cord within the column. The tissue attachments cause the spinal cord to stretch abnormally.

The lower tip of the spinal cord is normally located opposite the disc between the first and second lumbar vertebrae in the upper part of the lower back. In people with spina bifida, the spinal cord does not separate from the skin of the back in the developmental stage. This prevents the spinal cord from ‘ascending’ as is normally the case. Thus, it results in the spinal cord being low-lying or tethered.

In some cases, the spinal cord may have fat at its tip. This could connect to the fat which lies over the thecal sac (a sac filled with fluid within which the spinal cord floats). This is called a lipomyelomeningocele.

Tethered spinal cord syndrome is a condition which is closely associated with spina bifida. So closely in fact, that an estimated 20% to 50% of children with spina bifida defects repaired shortly after birth will require surgery at some point to untether the spinal cord.

Treatment
Tethered cord syndrome is a condition which almost always warrants surgery particularly in a growing child to prevent the detrimental effects of tethering and stretch of the spinal cord. Surgery is safe and simple and consists of microsurgical division of the tethering elements including the filum terminale.

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