I’m on the waiting list for spinal fusion surgery but read on the NHS website that one of the risks from the op is loss of vision. This has upset me more than the prospect of the surgery itself. Can you put my mind at rest?
Dawn Wickstead, Lancashire.
I understand your anxiety, but can reassure you this complication (known as perioperative vision loss) is a very rare risk of spinal surgery that’s performed when the patient is in a prone (or face down) position.
Lying in this position for a long period can restrict blood flow to the optic nerve, which transmits vision messages to the brain, and can affect sight permanently, leading to partial or complete loss of vision.
The risk factors include surgery that lasts more than six hours, major blood loss and having low blood pressure during the procedure.
People who have diabetes, high blood pressure, anaemia or who are obese are at increased risk – as, too, are men, suggests research, although exactly why this is the case is not clear. Learning how to minimise the risk of this happening is a major part of the training for anaesthetists involved in this type of surgery.
But I must emphasise how rare this complication is – affecting about 0.01 per cent of people undergoing spinal surgery; that’s roughly one in 10,000.
But please do inform your specialist of your concerns when you see him pre-operatively.
Lying prone for a long period can restrict blood flow to the optic nerve, which can lead to partial or complete loss of vision, writes Dr Martin Scurr
For some time I have experienced numbness in my toes. My GP prescribed vitamin B12, but this has not helped and nor have the electric foot massagers that I have tried. Can you suggest something that might work for this debilitating problem?
Mike Durand, Cornwall.
You have what is known medically as peripheral neuropathy, meaning that some of the nerves that supply your extremities have become damaged, causing numbness. It typically affects the hands and feet, and can cause numbness as well as pain, tingling and weakness. As in your case, the toes are most commonly affected.
Peripheral nerves are vulnerable as they are less protected than the major nerves, and can be damaged by a range of factors, from a minor injury to an underlying condition such as diabetes.
Other causes of nerve damage include having had chemotherapy, exposure to heavy metals such as mercury, or excess alcohol intake. In your case, it does not seem as if any of these factors are relevant.
Our bodies need vitamin B12 for healthy nerve function, and a shortfall can cause numbness, which is why your GP suggested trying a supplement.
But I’d suggest that having tried this, with no effect, you go back to your GP for referral for tests to determine the cause of the numbness – as only with a diagnosis can the correct treatment start.
Hopefully this will lead to a reduction in the symptoms and prevent whatever is affecting the nerves from worsening. First you need a test to check the electrical activity in your nerves – either with a nerve-conduction study, where tiny electric shocks are delivered via electrodes, or an electromyography (EMG), where a small needle is inserted into the skin.
While these can confirm neuropathy, they won’t identify the cause. So next you should have blood tests to check for diabetes, which is the most common cause of this set of symptoms.
Other investigations should include thyroid tests – as problems with the thyroid gland can lead to nerve damage, through several mechanisms including inflammation.
However, in over 40 per cent of cases of peripheral neuropathy, there is no clear cause despite investigations. My advice is that you must pursue this issue further with your doctor.
