This article is intended to provide general information and awareness. It should not be used as a substitute for individual medical advice, diagnosis or treatment.
Why Are Spinal Cord Tumours So Rare – and Why Can They Take So Long to Diagnose?
Spinal cord tumours are rare. For many people diagnosed with one, this can be both reassuring and frustrating.
The chances of developing a spinal cord tumour are very small. But their rarity can also create a problem. Spinal cord tumours may not initially be suspected when someone begins developing symptoms. This is particularly important with intradural spinal tumours – tumours growing within the protective covering of the spinal cord, which include both intramedullary and extramedullary tumours.
The symptoms can begin gradually, sometimes months or even years before diagnosis, and can initially resemble much more common conditions affecting the neck, back, joints or peripheral nerves.
What do intramedullary and extramedullary mean?
The terminology can sound complicated, but the basic distinction is relatively straightforward.
Intramedullary spinal cord tumours grow within the spinal cord itself. Common examples include:
- Ependymomas
- Astrocytomas
- Haemangioblastomas
Intradural extramedullary tumours grow inside the dura – the membrane surroundingthespinal cord, but outside the spinal cord itself.
Examples include:
- Meningiomas
- Schwannomas
- Other nerve sheath tumours
Both can affect spinal cord function.
An intramedullary tumour can disrupt or damage the nerve pathways running through the spinal cord as it enlarges.
An extramedullary tumour can increasingly compress the spinal cord or spinal nerves from the outside.
The eventual symptoms therefore depend heavily upon where the tumour is located, its size, its type and how quickly it is growing.
Just how rare are spinal cord tumours?
They are considerably less common than brain tumours and many other neurological conditions.
Published estimates vary depending upon exactly which types of tumour are included, but one recent medical review estimated the overall incidence of spinal tumours at approximately 0.74 to 1.6 cases per 100,000 people each year.
Intramedullary tumours are rarer still. They represent only a minority of spinal tumours, with ependymomas and astrocytomas accounting for most primary intramedullary tumours. This rarity has an important consequence.
A Medical Practioner seeing someone with neck pain, back pain, numbness, tingling or leg discomfort is statistically far more likely to be dealing with a common condition than a spinal cord tumour. That is entirely understandable.
The difficulty arises when symptoms persist, progress or begin appearing in combinations which suggest that something is affecting the spinal cord.
Why are spinal cord tumours so rare?
There is no single simple explanation. Tumours develop when cells acquire changes that allow them to grow and divide abnormally. Different tissues contain different cell populations and have different biological environments.
Intramedullary tumours arise from cells within the spinal cord itself. Around 80% of intramedullary tumours are derived from glial cells, which support the nervous system. The most common examples are ependymomas and astrocytomas.
Unlike cancers where well-established environmental or lifestyle risk factors exist, there are currently no specific identifiable risk factors for most intramedullary spinal cord tumours. A small proportion are associated with genetic conditions such as neurofibromatosis or von Hippel-Lindau syndrome, but most occur without an obvious explanation. For many patients, therefore, there is no satisfactory answer to the understandable question: “Why did this happen to me?”
Usually, there was nothing that person knowingly did to cause it and nothing obvious they could have done to prevent it.
Why can diagnosis take so long?
One of the biggest problems is that spinal cord tumours do not necessarily announce themselves dramatically. Symptoms can develop slowly and insidiously.
Research into intramedullary tumours describes their early symptoms as frequently nonspecific. Back or neck pain, altered sensation and weakness are among the common presentations. But these symptoms can also occur in countless other conditions.
- Someone experiencing neck pain may initially be thought to have a muscular or cervical spine problem.
- Back pain may be attributed to a disc problem, posture or general mechanical back pain.
- Tingling or numbness might initially suggest a trapped nerve.
- Weakness or walking difficulties can have many neurological, orthopaedic and muscular causes.
For a rare disease, this creates a diagnostic challenge.
The symptoms may appear one at a time
Another difficulty is that the classic neurological picture may not be present at the beginning. A person might initially experience:
Pain
Then, months later:
Tingling or altered sensation
Later still:
Weakness, stiffness or problems walking
And eventually:
Bladder or bowel changes
Looking backwards after diagnosis, the connection between those symptoms can appear obvious.
At the time they occurred, however, they may have seemed like separate and relatively ordinary problems. This is one reason why a detailed history of how symptoms have changed over time can be extremely important.
Slow-growing tumours can be particularly deceptive
Some spinal cord tumours grow relatively slowly. That sounds preferable to an aggressive tumour, and in many respects it is, but slow growth can make diagnosis more difficult. The nervous system can sometimes compensate for gradual changes remarkably well.
Someone may unconsciously change:
- How they walk
- How they climb stairs
- How they use one arm or hand
- How far they walk
- How they balance
- How they position their body
A small deterioration can become the person’s new normal. Only when several changes accumulate does it become clear that something significant is happening. This can make the history of spinal cord tumour symptoms very different from something such as a stroke, where neurological impairment can appear suddenly.
Pain alone doesn’t necessarily point towards the spinal cord
Back and neck pain are extremely common. Most people experiencing them do not need an MRI scan looking for a spinal cord tumour. This creates an unavoidable balancing act for healthcare professionals. Scanning everyone experiencing ordinary back pain would uncover very few spinal cord tumours while placing enormous demands upon imaging services. However, persistent pain accompanied by progressive neurological changes deserves greater attention.
Potential neurological symptoms can include:
- Increasing weakness in an arm or leg
- Changes in walking
- Increasing balance problems
- Persistent numbness or altered sensation
- Unusual burning, tingling or electric sensations
- Loss of dexterity in the hands
- Increasing stiffness or spasms
- Changes affecting both sides of the body
- New bladder or bowel dysfunction
None of these symptoms automatically means someone has a spinal cord tumour. There are numerous other possible causes. But a progressive combination of neurological symptoms may warrant further neurological assessment.
MRI transformed the diagnosis of spinal cord tumours
Modern MRI scanning has dramatically improved our ability to see the spinal cord. MRI can show the spinal cord itself, surrounding structures and abnormalities within or around it.
For suspected intramedullary tumours, an MRI, often including imaging before and after contrast is the principal diagnostic imaging technique. The problem is therefore not necessarily that the tumour cannot be seen. It may be that nobody initially has sufficient reason to image the spinal cord. A person can consequently undergo treatment or investigations for more common explanations before an MRI identifies the actual cause.
Research has demonstrated significant diagnostic delays
Delayed diagnosis is not simply anecdotal. One study examining 101 people with primary intradural spinal cord tumours reported a median time to diagnosis of 12 months.
The researchers found diagnostic delay in more than 80% of cases, with common reasons including symptoms initially being attributed to the wrong diagnosis and delays in obtaining appropriate imaging. Earlier studies have also reported diagnostic journeys lasting many months and, in unusual cases, years.
That does not mean every person with a spinal cord tumour experiences a lengthy delay. Some tumours are identified quickly. But the evidence supports what many patients have experienced. These tumours can be genuinely difficult to recognise during their earlier stages.
Why earlier diagnosis matters
The spinal cord is extraordinarily important but also extremely vulnerable. Unlike many peripheral nerves, significant damage to the spinal cord may not fully recover. This means neurological function before treatment can be an important factor in someone’s eventual outcome.
The aim should therefore not be to encourage everyone with back pain to worry that they have a tumour. It should be to improve awareness of persistent and progressive neurological symptoms, particularly when the original explanation no longer adequately accounts for what is happening.
When should someone go back to their doctor?
If you have already sought medical advice but your symptoms continue to change, it is reasonable to return. Rather than simply saying:
“My back still hurts.”
it may be useful to explain specifically what has changed. For example:
“The pain hasn’t gone away and during the last three months I’ve also developed numbness in my right leg and I’ve started catching my foot when I walk.”
That additional information can significantly alter the clinical picture. Keeping a simple record of symptoms can also help identify progression that is difficult to recognise from day to day. Important information includes:
- When the symptom began
- Whether it is worsening
- Which part of the body is affected
- Whether strength has changed
- Whether walking or balance has changed
- Whether sensation has changed
- Whether bladder or bowel function has changed
- Whether symptoms are now affecting everyday activities
Rare does not mean impossible
There is an important balance to strike when discussing spinal cord tumours. The overwhelming majority of people experiencing back pain, neck pain, tingling or similar symptoms will not have a spinal cord tumour. We should not create unnecessary fear.
At the same time, rarity should not prevent further investigation when neurological symptoms are unexplained and progressively worsening. For people eventually diagnosed with a spinal cord tumour, one of the most common questions is “Why did nobody find this earlier?”
Sometimes there may have been missed opportunities. But in other cases the answer lies partly in the nature of the disease itself.
- Spinal cord tumours are rare
- Their initial symptoms can be vague
- Many grow slowly
- Their symptoms overlap with much more common conditions
- And the full neurological pattern may only become apparent over time
- Greater awareness among patients as well as healthcare professionals can help shorten that journey
The message is therefore not that every unexplained pain requires an MRI. It is much simpler:
When neurological symptoms persist, accumulate or progressively worsen, they deserve to be taken seriously.