Peripheral neuropathy is one of the prime causes of numbness in the toes and feet
There are several different types and causes of peripheral neuropathy. Many of them lead to numbness, tingling and pain in the legs feet or toes. This can sometimes be confusing as these are also common symptoms of sciatica. The clue lies in the history and presentation which is different for this problem.
Peripheral nerves are the nerves that run from your spinal cord out into your limbs (as distinct from the central nervous system which is made up of your spinal cord and brain). The term explains itself if you break it down i.e. peripheral = edges, neuro= nerve, pathy= illness or pathology.
Peripheral nerves are made up of different type of nerve cells and fibres and they carry information to and from the brain via the spinal cord.
The three main types of fibre are:
Peripheral neuropathy can affect all these nerve fibres in different ways but the most common initial symptom is numbness and tingling or pain. This is because the sensory nerve fibres are affected and come to your notice first. The numbness and tingling often follows a pattern with this problem.
Numbness from an irritated sciatic nerve commonly follows the line of the nerve root called a dermatome. Peripheral neuropathy tends to be less defined or follows a sort of sock distribution. Imagine you have pulled on a pair of short socks. Sometimes the sock is just pulled on a little giving you a numb toe or toes, but sometimes the socks are pulled up more causing numb feet and legs all the way up to your knees.
|Sock and glove distribution numbness seen with peripheral neuropathy - this is different to the lines of numbness seen with sciatica.|
Sometimes the motor fibres are also affected leading to loss of power and control, like a drop foot for example.
Anything that affects the nerve can lead to this type of problem. However it is helpful to split the causes of peripheral neuropathy into two broad categories
1. Diabetic neuropathy
2. Idiopathic and non-diabetic peripheral neuropathy
This is one of the most common causes of peripheral neuropathy. It can affect all three different types of nerve in the limb and is caused by a variety of interlinked factors including metabolic, circulation and hormonal. Put very simply the nerves degenerate and they cannot repair themselves due to poor circulation as diabetes affects the blood supply.
Up to 20% of newly diagnosed diabetics will have these diabetic neuropathy symptoms rising to 50% in older diabetic people (Sherman 2009).
If the nerve is affected by trauma or entrapment anywhere along its length you can get symptoms of numbness and tingling. An example is meralgia paresthetica affecting the lateral cutaneous nerve in the thigh caused by entrapment at the groin.
There are a variety of other causes of peripheral neuropathy including alcoholism and vitamin B12 deficiency. Finally there is a large group of people where the cause of this problem is not clear. This is called idiopathic which means cause unknown.
Advertisement - Article Continues Below
Sherman, A.L., 2009. Diabetic Neuropathy: eMedicine Physical Medicine and Rehabilitation. Available at: http://emedicine.medscape.com/article/315434-overview
Patient.co.uk - good reliable patient centred information.
Other Causes of Numbness