- This means damage to the nerve cells which lie outside the brain.
The symptoms of peripheral neuropathy include numbness, pins and needles, burning and funny sensations, usually starting in the feet and hands and extending in a "glove and stocking" distribution.
Peripheral neuropathy just means damage to nerves which go from the brain out to the body. With peripheral nerves, the body of the nerve lives in the brain or spinal cord and it sends out a long leg (dentrite) which goes all the way to its destination. If that destination is the big toe, then this makes it the longest cell in the body. Indeed if the body of the cell was the size of a football here on my desk, the tail would stretch to New York in America! The exception to this is the autonomic nervous system which has one junction box.
Such a long thin cell is difficult to nourish, and very susceptible to damage. So if there is a problem which damages peripheral nerves, then the longest cells will suffer first. Peripheral neuropathy therefore often starts off with symptoms in the feet, then the hands.
There are three types of nerves passing to the body:
- The sensory nerves which take information to the brain as a part of sight, hearing, taste, touch, smell, position of joints, balance, muscle tension, blood pressure etc
- The motor nerves which tell the muscles what to do and when.
- The autonomic nervous system - this is the bit of the body which does things automatically such as control of body temperature (sweating), heart rate, digestion, blood vessels (therefore blood pressure, flushing, fainting, feeling hot). These functions we have no conscious control over.
Because the body is very good at compensating for losses, the disease process may be advanced before symptoms are felt. I see this in farmers with organophosphate pesticide poisoning who may have no symptoms but tests are abnormal.
Causes of peripheral neuropathy
Local pressure symptoms
Carpal tunnel syndrome, from pressure on the median nerve at the wrist - typically results in pins and needles, pain and numbness in the hand including the thumb, index, middle and part of the ring finger. The little finger is spared. Cervical spondylosis - may result in nerve pressure sympotms in the hands and arms. Sciatica - pressure on sciatic neres in the back resulting in pain
Sometimes high dose B6 (200mgs daily) relieves symptoms.
High sugar in the blood - diabetes
This is perhaps the number one cause, Since diabetes is the end result of years of hypoglycaemia and carbohdrate intolerance, the first place to start is Hypoglycaemia - the full story.
These are universal in people eating Western diets who are not taking supplements. See Nutritional Supplements - what everybody should be taking all the time even if nothing is wrong. In particular deficiences of B vitamin, vitamin B12 are common together with poor antioxidant status. Anyone drinking more than one glass of wine a day will be deficient in thiamine - this is essential for normal nerve function.
Pesticides, especially organophosphates
Heavy metals - especially mercury and lead.
See Autoimmune diseases - the environmental approach to treating. Multiple sclerosis Guillam Barre syndrome
Leprosy is the commonest cause of peripheral neuropathy worldwide.
Symptoms of sensory peripheral neuropathy
- The commonest site is hands and feet. Often the first thing to fail is vibration sense (test for by placing a buzzing tuning fork on the big toe). Symptoms include numbness, altered sense of feeling, half dead feelings, tingling, crawling sensations, walking on cotton wool, coldness, possibly increased pain perception, inability to distinguish between hot and cold, difficulty picking up small objects and so on. Joint position sense may also be lost which may cause clumsiness, stumbling, poor co-ordination etc. Classically peripheral neuropathy causes a "glove and stocking" sensual loss.
- Failure of any of the sensory organs - inability to smell or taste food.
- Visual problems - such as slow processing of visual information - you can see things with your eyes, but not with your brain.
- Hearing problems - may cause tinnitus, hearing loss.
- Balance problems - may cause unsteadiness, vertigo, nausea.
These symptoms can indicate other disease processes, not just peripheral neuropathy.
Symptoms of motor peripheral neuropathy
The motor nerves drive muscles, so there will be muscle weakness. This may present with clumsiness or loss of fine control of muscles.
Symptoms of autonomic neuropathy
There may be a great many symptoms because the autonomic nervous system controls a great number of functions, eg
- blood pressure falls when you can't stand up
- too much or too little sweating
- poor temperature control, flushing
- inability to become sexually aroused
- heart rate too fast or too slow
- constipation or diarrhoea
- dry mouth
- dry eyes
Autonomic neuropathy is often blamed for POTs (postural orthostatic tachycardia syndrome). Actually I think it is the other way round. The autonomic nervous system is fine and the low blood pressure is a symptom of low cardiac output - see Low blood pressure and postural hypotension.
The autonomic nervous system has synapses outside the brain involving neurotransmitters. These can be "mimicked" by substances such as nicotine and caffeine. They may also be "mimicked" by proteins leaking from a leaky gut. This may cause a host of confusing symptoms for the sufferer, as can be inferred from the above list!
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