Spinal column infection is not common and 30 per cent of cases have a
significant delay in diagnosis, the average being 3 months. The common
presenting symptoms are fever and unremitting pain especially at night. The
distribution is bimodal, occurring in the very young and the very old. In
children the infection is frequently sterile and may simply be a discitis. Very
young children may present simply with malaise and inability to walk. There may
be a scoliosis. The infection is usually centred on the disc, and in the early
stages there may be no X-ray changes although MRI will show the typical changes
of oedema in the end plates and disc, with changes in the surrounding soft
tissues. After 2 weeks narrowing of the disc space usually occurs. Needle
biopsy of the disc only grows bacteria in about 40 per cent of cases. Unless the
child is septicaemic, expectant treatment can be tried. Established infection or
failure to improve requires treatment with broad-spectrum antibiotics. A plaster
jacket may be helpful in controlling pain and accelerating resolution of
symptoms. In the long term the disc may reconstitute, or occasionally
spontaneous fusion of the disc may occur.
Infection
of the spinal column is usually more serious in adults. As in children it is
usually centred on the disc, and by the time of presentation X-ray changes are
usually present in the form of disc space narrowing with destruction of the end
plates. The patient may be generally unwell and septicaemic. Many patients have
reduced immunity to infection due to conditions such as diabetes or carcinoma,
and recent urinary catheterisation or surgery is not uncommon. It is important
to establish the bacterium causing the infection if possible before starting
treatment. The most common bacterium is Staphylococcus aureus, but almost
any bacterium can cause the infection and tuberculosis must always be
considered as a possibility (see below). Blood cultures should always be carried
out and in many cases this will establish the type of bacteria. Needle biopsy of
the disc space is an alternative method of diagnosis. This is done under local
anaesthetic with X-ray control, and will confirm the diagnosis in about 60 per
cent of cases. Surgery tends to be used for patients where there is considerable
bone destruction or deformity,. neurological compromise due to compression on
the spinal cord or failure to eradicate the infection with antibiotics. Simple
stabilisation of the infected area combined with antibiotics may be adequate in
older individuals, but otherwise débridement of the disc space, bone grafting
and stabilisation are most likely to result in cure. Surprisingly internal
fixation in these patients rarely seems to cause problems of persistent
infection, although it may be advisable to remove the fixation once the bone has
healed. Antibiotic treatment is usually continued for some months.
Some
cases of disc space infection will progress to epidural abscess. This will
present with neurological symptoms and signs and should be drained as a surgical
emergency (see below).
Tuberculosis
Tuberculosis is more frequently seen in the Third World than in the
developed world but it is becoming more common, and should always be considered
as a possible diagnosis in those with spinal infection.
Treatment
with multiple antibiotics over long periods has proven very effective in
treating spinal tuberculosis, and has been shown to be effective in managing
some patients with paraplegia. Eventual fusion of the infected area can be
expected in around 80 per cent of patients without surgery. Surgery combined
with antibiotics is used where there is a large abscess which requires draining
or considerable deformity of the spine. Failure of antibiotic treatment may also
be a surgical indication. In general the best surgical results are with anterior
débridement and bone grafting of the infected area.
Spinal
epidural abscess
Infection within the epidural space is a rare but potentially disastrous
condition. Usually due to haematogenous spread from remote sites or associated
with intravenous drug usage, pus can collect and spread within the epidural
space and cause compression of the spinal cord or cauda equina. Infection may
spread from local sites (discitis/vertebral osteomyelitis or paravertebral
infection) (see Fig. 33.33) and may present as a postoperative complication.
Staphylococcus
aureus represents the commonest
causative organism. A variety of other organisms including bacteroides, aerobic
and anaerobic streptococci may be found. Consider unusual organisms in
association with immune compromise, including fungal infections.
Presentation
Presentation includes:
• severe local pain;
• systemic signs of infection;
• radicular signs;
• onset of symptoms and signs of cord and cauda equina compression.
Progression
of symptoms can be very rapid and therefore early recognition is vital to allow
a good outcome. A high index of suspicion to achieve diagnosis before the onset
of complete paralysis is very important. If the diagnosis is delayed to this
point, vascular thrombosis may result in irreversible paralysis.
Diagnosis
Diagnosis includes:
• clinical awareness of the condition;
• general tests: haemoglobin, white cell count, ESR, CRP, blood
cultures, midstream urine;
• plain spinal X-rays, chest X-ray;
• MRI scan.
Plain
X-rays may show evidence of osteomyelitis and should be performed, but MRI is
the investigation of choice (see Fig. 33.34). The precise location of the
abscess and its extent and position in relation to the cord can all be
In
the absence of MRI, myelography and CT myelography would enable the diagnosis of
an epidural mass, but it is harder to define the full extent of the lesion. Care
must be taken to avoid carrying infection into the intradural compartment at
the time of lumbar puncture. If a cervical abscess is suspected, a lumbar spinal
puncture can be used, the contrast being run up to the cervical region. However,
if the abscess is thought to be in the thoracolumhar region, a cervical puncture
must be made. CT rnyelography will help to define the extent of the lesion and
will also provide important anatomical information about adjacent vertebral
bodies.
Management
Management of this condition
includes:
• surgical drainage of the abscess;
• antibiotic therapy;
• treatment of source of infection/paravertebral infection;
• management of neurological disability.
Dorsally placed collections can be drained via a laminectomy.
If available, the
advice of a hone infection unit should be taken. Certainly, advice from a
medical microbiologist will help in the choice of antibiotic and the duration of
treatment. In principle, intravenous therapy via a long intravenous line, and
modified according to culture results, should be continued for at least 2
weeks. Be prepared to repeat the MRI scans to ensure that the abscess has been
fully drained.
Any residual neurological deficit will require input
from physiotherapists and occupational therapists, directed by a rehabilitation
facility. Recovery, however, may he slow and protracted over many months.