Overview
Peripheral neuropathy is an umbrella term for disorders affecting nerves of the peripheral nervous system (i.e. the part of the nervous system that lies outside the brain and spinal cord).
Differentiating peripheral neuropathy from other disorders
As a general rule of thumb, since most peripheral neuropathies do not involve the brain or spinal cord, upper motor neurones (UMNs, such as the corticospinal tract) are not involved, so UMN signs are not present. However, some disorders can cause both UMN and peripheral nerve damage. Lower motor neurone signs (LMNs) are present in peripheral neuropathy if they affect motor neurones.
Classification
It can be classified based on the number and distribution of nerves:
- Mononeuropathy – neuropathy affecting a single peripheral nerve
- (Symmetrical) polyneuropathy – neuropathy affecting nerves bilaterally
- Mononeuritis multiplex – 2 or more nerves affected in different discrete areas of the body
It can also be classified based on its clinical presentation:
- Predominantly motor:
- Charcot-Marie-Tooth disease
- Guillain-Barré syndrome
- Diabetic neuropathy
- Porphyria
- Lead poisoning
- Diphtheria
- Predominantly sensory:
- Diabetic neuropathy
- B12, folate, and/or thiamine deficiency
- Chronic kidney disease and uraemia
- Chronic excess alcohol consumption
- Amyloidosis
- Autonomic neuropathy – may be characterised by:
- Urinary or bowel retention/incontinence
- Dysphagia
- Gastroparesis
- Reduced awareness of hypoglycaemia
- Arrhythmia
- Postural hypotension
- Apnoea
