What Is Peripheral Neuropathy? Peripheral neuropathy refers to diseases affecting the peripheral nervous system, which consists of motor or sensory neurons, nerve roots, plexuses and peripheral nerves. Motor nerves control movements of all muscles under conscious control. Sensory inputs (e.g. heat, cold and touch) from skin receptors are conveyed to the brain via the sensory nerves. Autonomic nerves are found in vital organs (e.g. heart, lungs) and helps to regulate body functions such as heart rate and breathing. Clinical classification of peripheral neuropathy is based on: Part of the peripheral nervous system involved: the peripheral nerve (mono- or poly- neuropathy depending on number of nerves affected), plexus (plexopathy), nerve root (radiculopathy) or motor/sensory neurons (neuronopathy). Types of nerve fibers involved, e.g. sensory polyneuropathy when only sensory fibers are affected. Underlying mechanism of nerve damage, e.g. demyelinating versus axonal neuropathy. Axonal lesions are due to irreversible damage to the neurons (e.g. diabetic polyneuropathy) whereas demyelinating lesions are due to involvement of the myelin sheath (e.g. chronic inflammatory demyelinating polyneuropathy or CIDP for short).   Symptoms And Signs The clinical presentation will depend on the type of nerve fibers affected. Motor nerve damage causes weakness and sometimes painful cramps and muscle twitching. Sensory nerve damage causes a decrease in the appreciation of pinprick, light touch or vibration sensations on the hands and feet. It may also cause unsteadiness when walking. Pain receptors can become over sensitised resulting in spontaneous burning pain, discomfort to light touch (allodynia) and hypersensitivity to pain (hyperalgesia). Involvement of autonomic nerves results in a variety of symptoms, e.g. abnormal sweating, postural giddiness, irregular heart rate, urinary incontinence and erectile dysfunction in men.   Causes And Risk Factors There are many causes of peripheral neuropathy, both inherited and acquired. Inherited neuropathies are due to inborn defects in the genetic code and are collectively known as Charcot-Marie-Tooth (CMT) disease. Causes of acquired peripheral neuropathy include the following: Physical injury to the nerve. This can be from trauma such as fractures or from acute compression such as "Saturday night" palsy. Peripheral nerves are also prone to compression at certain anatomic sites. This is known as entrapment neuropathy. A common example is Carpal Tunnel Syndrome (CTS). In this condition, the median nerve gets compressed as it passes through a narrow passageway in the wrist (carpal tunnel). Metabolic Neuropathy, e.g. Diabetes mellitus and renal failure. Nutritional Neuropathy, e.g. Vitamin B12 deficiency and chronic alcohol abuse. Autoimmune disorders, e.g. Rheumatoid arthritis. Infections, e.g. Human Immunodeficiency Virus (HIV) and leprosy. Immune mediated neuropathy. This is due to nerve inflammation from a defective immune system, such as in CIDP. Toxins and Drugs, e.g. heavy metals like lead and drugs like Cisplatin.   Diagnosis And Screening Your doctor will perform a thorough clinical evaluation to determine the part of the peripheral nervous system that is affected, the likely cause and then order the appropriate investigations as listed below. Electromyography (EMG). This is an important investigation that will help to localize, characterize the nature and severity of the peripheral neuropathy. The first part of EMG involves stimulating the peripheral nerves and recording its electrical signals. The second part involves inserting a very fine needle into the limb or back muscles and recording their motor activities. Blood investigations. To screen for an underlying cause, e.g. diabetes, vitamin deficiencies, abnormal proteins in blood and antibodies. In certain types of hereditary neuropathy, blood samples may be sent for genetic confirmation. Lumbar puncture. This is a bedside procedure where a small amount of cerebrospinal fluid (from lower back) is withdrawn for analysis under sterile condition and local anaesthesia. Skin biopsy. This is a simple, bedside procedure to confirm neuropathy affecting small nerve endings in the skin. Punch skin biopsies (about 3mm in diameter) are performed under local anaesthesia in the leg and thigh. Autonomic function test. This is a non-invasive test that evaluates the autonomic nervous system. Nerve biopsy. This is occasionally performed to confirm the presence of nerve inflammation, e.g. in vasculitic neuropathy.   Treatment Treatment will depend on underlying cause and the type of the neuropathy. For example, in diabetic neuropathy, treatment will be directed at achieving a normal blood sugar control as this will prevent further nerve damage. Symptomatic relief for neuropathic pain can usually be achieved by medication, such as amitriptyline and gabapentin. Immune-mediated neuropathies (e.g. CIDP), are treated with either intravenous immune globulin (IVIG), or steroids. IVIG is pooled donor plasma which contains normal antibodies that can temporarily counteract the abnormal ones in the body. Steroids will help to suppress an abnormal immune response that attacks the nerve. Surgical decompression may benefit those with entrapment neuropathy, e.g. CTS.   Living With The Condition In most patients, symptoms and functional impairment can be managed and normal life expectancy is expected unless there is a co-existent systemic disease. One should adopt a healthy lifestyle so as to encourage nerve regeneration. Active and passive forms of exercise can improve muscle strength and prevent muscle wasting in paralysed limbs. Meticulous foot care is also important, especially in diabetic polyneuropathy. Mechanical aids can help to reduce pain and improve function. Hand or foot braces can compensate for muscle weakness or alleviate nerve compression. Disclaimer: This brochure is meant to be a guide only.