Most spinal problems are not serious and most of my patients never need an operation. These three situations are the exceptions, and each one needs prompt assessment.
A point I make often is that most causes of back pain, and indeed most spinal problems, are not particularly serious. The majority of patients I see in clinic do not need an operation.
But there are three presentations I do worry about. I am not setting these out to alarm anyone. I am setting them out because they need prompt assessment and investigation, and because recognising them early genuinely changes the outcome.
1. Weakness in a limb
The first is a patient who develops weakness, usually in one leg and often around the ankle.
Typically this comes on during or after a period of sciatica, pain shooting down the leg from a nerve compressed in the lumbar spine, usually a single nerve pinched by a herniated disc.
Most of the time sciatica can be managed without surgery, and most of the time it settles. What concerns me is when weakness appears.
Patients sometimes notice their foot beginning to slap the ground as they walk. We call this a foot drop: you literally cannot lift the foot. Depending on which nerve is compressed, a different muscle group in the leg may be affected instead.
The same thing happens in the arm when a nerve is compressed in the neck, essentially the sciatica of the arm, known as cervical radiculopathy. Pain radiates down the arm and part of it becomes weak.
Why this matters. My job as a surgeon is to preserve your neurological function. If weakness is developing, whether alongside the pain or even as the pain settles, that nerve is losing function and becoming damaged. The window in which we can restore it by taking the pressure off is limited.
The sooner the pressure comes off, the more likely function is to recover.
2. Cauda equina syndrome
The second is cauda equina syndrome, and this one is a genuine emergency.
It is characterised by pain shooting down both legs, often with saddle numbness: numbness and tingling in the genital region, frequently first noticed when wiping after using the toilet.
As it progresses, patients develop urinary retention. You lose the sensation of needing to pass urine and the bladder does not empty. At later stages comes overflow incontinence, wetting yourself without realising. In the final stages there is faecal incontinence too.
If these symptoms set in, this is a clinical emergency and decompression is required immediately. Do not wait to see whether it settles.
The commonest cause is a very large disc herniation compressing all the nerves travelling to the legs and to the bladder and bowel sphincters.
3. Myelopathy
The third is myelopathy, meaning dysfunction of the spinal cord itself, the central structure transmitting messages between the brain and the body.
It is usually caused by compression of the cord. The higher up the spine the compression sits, the more limbs are affected. In the neck, a herniated disc compressing the cord can cause weakness in both the arms and the legs.
The early signs are subtler than people expect:
- Hands becoming clumsy, noticed when buttoning shirts or writing
- Walking becoming unsteady or wobbly
Other causes include certain spinal tumours, such as an intradural extramedullary tumour, which sits within the lining of the spine, outside the cord but pressing on it. Lower down, in the thoracic region, the arms function normally while the legs slowly weaken.
Again, the sooner this is diagnosed and treated, the more function we can preserve.
Why these three are different
Thankfully, all three scenarios are uncommon.
With the majority of patients, we are treating pain. In these three, we are trying to preserve and restore function. That is a fundamentally different task.
I treat these cases with urgency because function, once lost, is difficult to recover. I do often see functional recovery after surgery, but far more reliably when surgery happens early and less has been lost.
The key takeaway
Timing of assessment, investigation and treatment is what matters most in these three situations.
If you develop weakness in a limb, changes in bladder or bowel control with numbness in the saddle region, or clumsiness in the hands with unsteady walking, seek assessment promptly. Cauda equina syndrome in particular warrants immediate emergency attention rather than a routine appointment.
