I blacked out for about 30 seconds while on a fishing trip. I feel fine now, but I'd like to know what caused it. I'm 84.
Your blackout, a brief loss of consciousness caused by a sudden lack of blood flow to the brain, may have been brief - but it could be a sign of an underlying problem and so you are absolutely right to want to know more.
The most likely explanation is a cardiovascular problem. My thinking is that an abnormality in the rhythm of your heart caused a sudden drop in your blood pressure, which made it more difficult for blood to get to your brain.
This can be diagnosed with an electrocardiogram (ECG), which checks the electrical activity of the heart: if the initial ECG comes back clear, you may be given a portable ECG to wear for up to a week. (Another type of ECG looks at the heart's rhythm when exercising but, in your longer letter, you explain that your episode did not occur during exertion.)
Please be reassured that I am not suggesting you had a heart attack. Nevertheless, an abnormal heart rhythm can in some cases be serious, including raising the risk of stroke.
The other possibility is that you had a transient ischaemic attack (TIA) or 'mini-stroke'.
These typically occur when one of the carotid arteries - the blood vessels in the neck that supply the brain with oxygen-rich blood - becomes blocked.
A TIA is generally fleeting and does not do any lasting damage. However, it can be a precursor to an actual stroke, so if the heart tests come back clear, it's vital you have an ultrasound scan of your neck arteries.
This will check for a build-up of cholesterol deposits that can be the source of small, artery-blocking clots. You should also undergo an MRI of your brain to check the arteries there.
The key is to be proactive. Don't wait to see if you faint again before contacting your GP - make that appointment now.
Two months ago after going to my doctor with tingly hands and feet, I was diagnosed with vitamin B12 deficiency and given B12 injections. My hands and feet are still tingly, and also very cold and white. Is this normal?
What you have is pernicious anaemia - the most common cause of vitamin B12 deficiency, caused by an autoimmune reaction.
Vitamin B12 is found in eggs, meat and fish - and is absorbed in the small intestine, with the help of a protein called intrinsic factor. This is secreted by the cells in the stomach lining.
But this process can break down if the cells become damaged, for instance as a result of chronic gastritis (inflammation of the stomach lining) from long-term use of non-steroidal anti-inflammatory drugs or a long-term stomach infection.
But the main cause of this damage is the immune system mistakenly attacking the cells.
The subsequent lack of intrinsic factor reduces your body's ability to absorb B12. This vitamin is important for normal brain, nerve and bone marrow function (and red blood cells) so a lack of it leads to symptoms such as the tingly hands and toes you describe, as well as tiredness and brain fog.
The condition is treated with vitamin B12 injections, given four times a year for life.
The symptoms should improve, though the rate of recovery depends on the severity and duration of the symptoms before the diagnosis was made.
Some patients experience significant improvement within the first three months, and recovery will take up to 12 months, although studies have found that symptoms can continue to improve for up to 18 months.
But there's a window for this: if the nerve damage first occurred 12 months or longer before the condition was diagnosed, full recovery might not be possible.
The tingly, cold sensation and white appearance you describe are due to the effects of nerve damage reducing blood flow in your fingers and toes, but there's every reason to expect that this aspect of the condition will improve over time.