Spinal Epidural Abscess: Delays In Diagnosis, Neurological Injury And The Medicolegal Issues

Spinal Epidural Abscess: a rare diagnosis with serious consequences

Spinal epidural abscess (SEA) is an uncommon but potentially catastrophic infection.

It occurs when a collection of pus accumulates in the space around the spinal cord (the epidural space), where progressive inflammation, compression of the spinal cord and impaired blood supply can cause permanent neurological injury. The consequences may include paralysis, loss of bladder or bowel function, chronic pain, sepsis and even death. Timely intervention is therefore critical to avoid serious long-term injury.

SEA is rare. Evidence of incidence varies, but the incidence is probably around 1 in 100,000. Many clinicians will not see a single case throughout their careers.

SEA presents a particularly challenging combination of factors. Early symptoms may be non-specific, the classic clinical presentation is frequently absent, and definitive diagnosis usually requires urgent magnetic resonance imaging (MRI). Yet the window during which intervention may prevent irreversible neurological injury can be short.

Development of a Spinal Abscess

SEA may develop in multiple ways, and the usual presentation comprises of spinal pain, fever and neurological deficit.

However, the initial presentation can vary enormously, and many patients do not exhibit all three features.

MRI is the principal diagnostic investigation. However, not every presentation of back pain requires an emergency MRI and so identifying those patients that may have a serious underlying pathology, can be challenging. Diagnostic delay, therefore, remains common.

Delays in Diagnosis

The initial assessment frequently provides the most important opportunity to prevent avoidable injury.

Patients may present to general practice, urgent care, emergency departments or secondary care with symptoms that initially resemble musculoskeletal back pain, sciatica or another relatively common condition.

It is therefore important to consider whether there was a proper exploration of issues such as:

• The onset, severity and progression of spinal pain.
• Recent infection, or systemic illness.
• Recent spinal procedures, injections or surgery.
• Relevant comorbidities and immunosuppression.
• New limb weakness, altered sensation or gait disturbance.
• Bladder or bowel dysfunction and other features suggesting neural compression.

It is not uncommon to find that a neurological examination was not done, or if it was done, it was incomplete.

It is also not uncommon to find that a patient may attend on several occasions with persistent or worsening pain before developing neurological deficits.

Once there is suspicion of a serious underlying spinal problem, often the next steps would be to arrange urgent review, often with blood tests and imaging.

Inflammatory markers may be raised. The white blood cell count may be elevated, although a normal count does not reliably exclude infection.

MRI is the key investigation for identifying SEA, defining its extent and assessing associated neural compression. In a patient with severe spinal pain and new or progressive neurological deficits, or a combination of pain, infection and relevant risk factors, urgent imaging and specialist assessment may be essential.

 The precise urgency depends on the clinical presentation. For example, a patient with evolving motor weakness or signs of cord or cauda equina compression would present a significant degree of urgency and any delays should be examined carefully.

Treatment

SEA requires urgent spinal specialist involvement. Management commonly includes intravenous antimicrobial therapy, microbiological investigation and surgical decompression and washout is often necessary. In some cases, patients without neurological deficits may be managed non-operatively with antibiotics and close monitoring.

A patient may continue to deteriorate while waiting for definitive treatment. Unfortunately, where there has been a period of delay, a patient may suffer injuries which become permanent.

The timing of neurological deterioration is therefore particularly important. A patient who was neurologically intact when the opportunity for diagnosis arose may have a different prognosis from one who already had established, severe neurological impairment.

However, the distinction should not be oversimplified. The duration, severity and progression of compression, the extent of infection and other patient-specific factors may all influence the outcome.

Conventional wisdom suggests that once a neurological injury has been suffered, surgery (for example) will not reverse that but instead, prevent further deterioration.

However, there are studies in the medical literature which suggest that with early intervention even quite serious neurological deterioration may be reversed.

I have recently acted for a client who, by the time he underwent surgery, had lost function in his legs. Despite delayed surgery, he made a good recovery in terms of leg function and he is now ambulant.

Injuries associated with Spinal Abscess

The consequences of neurological injury from SEA include not only the obvious problems of paralysis, but include the full range of problems that can arise from spinal cord injury.

It is often the “hidden” injuries that are most troubling and which cause the greatest impact on a patient’s life, independence and wellbeing.

Chronic unremitting neurological pain day after day can lead to a patient being unable to work, go about their routine daily activities or have any enjoyment in leisure activities.

Neurological injury from SEA can also lead to problems with bladder, bowel and sexual function. These are often not visible injuries, but these “below the belt” problems can be devastating. Patients may not even venture out to the shops for fear if unexpected incontinence for example.

Over the years I have acted for numerous clients where there have been delays in diagnosis and management of SEAs. Those range from cases where a diagnosis should have been made sufficiently early that treatment with antibiotics alone would have brought about a full recovery, to cases where initial suspicions were raised but access to MRI scanning was delayed to a particularly troubling case where the diagnosis was made, but nothing was done and the patient deteriorated.