Is Neuropathy Always Caused By Diabetes?
Diabetes is the most common cause of polyneuropathy, but it is not the only cause of neuropathy. Peripheral neuropathies (polyneuropathy) are the most common type of disorder of the peripheral nervous system in adults and are prevalent in about 5-8% people. Alcohol-related polyneuropathy is seen in about 22-66% of cases of people with chronic alcoholism. Chemotherapy-induced neuropathy is also increasing in number due to the increase in the number of malignant diseases, which is prevalent in about 30-40% of the patients depending on the type of medication and treatment regimen. Polyneuropathy is also seen in genetic aberrations or due to vitamin deficiency or overdose, immunological processes and exposure to various toxic substances and drugs. Neuropathic pain is present in about half of all cases of polyneuropathy. It is important to diagnose the cause of polyneuropathy in order to treat the patient.(1)
Peripheral neuropathy affects the sensory, motor or autonomic nervous system. Sensory neuropathy leads to numbness, tingling, and burning, cold paresthesia, burning pain, stinging, electric shocks like pain, gait instability, and falls. Motor neuropathy leads to weakness, muscle cramps, fasciculations (muscle twitches) and muscle loss.
Autonomic neuropathy presents as dry skin, body hair loss, skin changes, glare sensation, diarrhea, bladder dysfunction, rapid heartbeat, gastrointestinal symptoms, and urogenital symptoms (such as impaired micturition and erectile dysfunction).(1)
Alcohol-induced polyneuropathy is associated with the duration of alcohol abuse and quantity of alcohol consumption in the lifetime. Delta alcoholics (people who cannot abstain from alcohol) are more commonly affected than the people who drink alcohol occasionally. Furthermore, women are more commonly affected than men. Intake of alcohol >100 g/day over a chronic period increases the chances of peripheral neuropathy. Sensational dysfunction is seen that may be present with or without neuropathic pain. Mostly, sensorimotor neuropathy is observed affecting the thin nerve fibers. It is managed by abstaining from alcohol and dietary changes.(1)
Chemotherapy-induced neuropathy is mostly seen with cancer therapy and drugs such as platinum derivatives, antibody-based therapies, vinca alkaloids, taxanes and proteasome inhibitors that mostly affected sensory nerves. The damage increases with the increase in the duration of the treatment; however, once therapy is discontinued, recovery is seen. In therapies with platinum and on rare occasions vincristine derivatives can cause an initial worsening of symptoms after discontinuation of therapy.(1)
Various drugs and environmental toxins can lead to peripheral neuropathy. These include anti-infective agents (dapsone, isoniazid, chloroquine, metronidazole, quinolones, nitrofurantoin, and thalidomide), anti-rheumatic drugs and immunosuppressive drugs (chloroquine, colchicines, gold, tacrolimus), cardiovascular drugs (amiodarone, hydralazine, propafenone, dronedarone), psychiatric medications and sedatives (lithium, disulfiram) and other medications (pyridoxine, phenytoin). The environmental toxins causing peripheral neuropathy include lead, mercury, arsenic, thallium, acrylamide, solvents, carbon disulfide, and triorthocresyl phosphate. Treatment includes avoiding the exposure of these toxins and rapid removal of the toxins from the body.(1)
Vitamin B12 deficiency can lead to paresthesia and tingling of feet, sensory ataxia, and hypesthesia (reduced physical sensation). Vitamin B6 deficiency, as well as overdose, can lead to subacute sensorimotor peripheral neuropathy.(1)
Immune-mediated neuropathy is seen in conditions such as Guillain Barre syndrome, chronic inflammatory polyradiculoneuropathy, paraproteinemic neuropathies, paranodopathies, multifocal motor neuropathy, and vasculitic neuropathies.(1)
Most of the neuropathic pain is due to an abnormality in the peripheral nervous systems, such as painful peripheral neuropathy, radiculopathy, complex regional pain syndrome, and postherpetic neuralgia. However, occasionally, neuropathic pain can be due to central neuropathy as observed in neurological complications of the central nervous system too. The central neuropathic pain can arise from diseases of the brain, brainstem, and spinal cord. The various insults of the central nervous system can be vascular (ischemic or hemorrhagic), infectious (abscess, myelitis, encephalitis), traumatic (brain or spinal cord), demyelinating, or neoplastic disorders). The most common causes of central neuropathic pain include stroke, multiple sclerosis, and spinal cord injury. There is dysfunction of spinal-thalamic-cortical pathways that can be manifested as abnormal pain and temperature sensations.(2)
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