There are estimated 20 million people in the United States suffering with peripheral neuropathy. The peripheral neuropathy is presented as sensory, motor and autonomic neuropathy. In few cases sensory neuropathy is simultaneously present with motor and autonomic neuropathy, such condition is known as mixed neuropathy. Most cases observed are sensory and motor neuropathy. Autonomic peripheral neuropathy is less common compared to sensory peripheral neuropathy.
Symptoms of Peripheral Sensory Neuropathy
Onset of symptoms of peripheral sensory neuropathy is often abrupt and sudden. Sensory peripheral nerve fibers carry information of pain, temperature changes, touch, pressure, vibration sensation and position of joint from peripheral tissue to spinal cord. Some diseases initiate irritation or microscopic injuries of peripheral sensory nerve fibers or receptors. Such physiological damaging effects of peripheral sensory nerve results in symptoms like pain, which is known as allodynia. The other abnormal sensory symptoms are tingling and numbness. The neuropathy involving motor nerve causes weakness and paralysis of muscles supplied by the affected nerve. Symptoms of peripheral sensory neuropathy like pain, numbness and weakness often becomes intolerable. Symptoms caused by peripheral sensory neuropathy often disappear for some period of time and may relapse with same severity or exaggerated symptoms. Peripheral sensory neuropathy often presents as a complication of disease like diabetes or side effects of the chemotherapy treatment.
Increased level of glucose in diabetes damages sensory nerve receptors and nerve fibers. Persistent increased of blood sugar in individual suffering with diabetes causes mild to severe damage of peripheral sensory nerve, which results in peripheral sensory neuropathy. Autoimmune disease like Guillain-Barre syndrome triggers immune system and makes it hyperactive. Hyperactive immune system prepares white blood cells to attack peripheral receptors and nerves. Guillain-Barre syndrome affects sensory and motor nerve fibers.
Causes of Peripheral Sensory Neuropathy
Common Causes of Peripheral Sensory Neuropathy
Peripheral Sensory Neuropathy Caused Due to Diabetes-
Persistent high blood sugar when inadequately treated causes diabetic neuropathy. Initial symptoms observed in diabetic peripheral sensory neuropathy is pain and tingling. The symptoms observed during advanced stage of untreated diabetic peripheral neuropathy involves abnormal motor as well as autonomic symptoms along with numbness. Abnormal motor symptoms are weakness and paralysis of affected muscles. Abnormal autonomic symptoms are urinary and bowel incontinence. The presence of symptoms like numbness, weakness, urinary and bowel incontinence along with pain in diabetic patient suggests advanced peripheral mix neuropathy. Pain and numbness symptoms are initially observed in feet, which gradually progresses to both the legs. The symptoms later spread to hand, forearm and upper arm. Diabetes during advanced stages affects all three peripheral nerves resulting in sensory, motor and autonomic neuropathy.
Peripheral Sensory Neuropathy Caused Due to Vitamin Deficiency-
Peripheral sensory neuropathy is often observed in patients who are on diet restriction. Diet restriction or decreased intake of vitamin may cause sensory peripheral neuropathy. Most often symptoms are observed following Vitamin B6 or B12 deficiency. Vitamin deficiency also causes abnormalities in skin, mucous membranes, and circulatory system.
Injury or Sudden Trauma to the Peripheral Nerve Causing Peripheral Sensory Neuropathy-
Peripheral nerve injury following direct impact of peripheral nerve during car accident, work injury and sports trauma causes symptoms like pain, tingling, numbness, muscle weakness and muscle paralysis because of sensory and motor nerve damage. The severity of symptoms depends on types of nerve injury. Sensory or motor nerve injury caused by pinch or laceration of nerve results in reversible damage and symptoms. While cut and incision of sensory and motor nerve after impact caused by penetrating sharp object results in irreversible nerve damage. Such injury is also observed when bony fragments penetrates or brushes the peripheral nerve following fracture or dislocation.
Peripheral Sensory Neuropathy Caused Due to Repetitive Nerve Stress-
The injured soft tissue following injury or surgery heals with scar tissue. If the scar tissue surrounds or attaches to the nerve then any movements involving scar tissue causes rubbing and repetitive stress of nerve leading to peripheral sensory neuropathy. The symptoms like pain and tingling indicates nerve has been irritated. If the pressure is removed by removing scar tissue without damaging nerve then patient is often symptomless and feels better. If treatment for peripheral sensory neuropathy caused due to repetitive nerve stress is not initiated then nerve may undergo permanent damage followed by symptoms like numbness in peripheral tissue and weakness in muscles supplied by the nerve.
Rare Causes of Peripheral Sensory Neuropathy
Charcot-Marie-Tooth Disease as a Cause for Peripheral Sensory Neuropathy-
Charcot-Marie-Tooth disease is one of the rare hereditary conditions associated with sensory and motor nerve abnormalities, also known as hereditary motor and peripheral sensory neuropathy. The symptoms are observed in upper and lower extremities. The disease affects mostly smaller and weaker muscles of hand, feet and extremities. The condition is diagnosed by genetic blood testing, nerve conduction studies and nerve biopsy.
Peripheral Sensory Neuropathy Caused Due to Thyroid Hormone Deficiency (Hypothyroidism)-
Hypothyroidism is a disease caused by lower production of thyroid hormone by thyroid gland. Lower thyroid hormone causes retention of fluid and swelling of tissue around the peripheral nerve. Hypothyroidism also reduces the peripheral tissue metabolism. The continuous pressure over the nerve by swollen tissue and decrease metabolism of peripheral nerve causes sensory nerve damage, which results in peripheral sensory neuropathy symptoms like pain, tingling and numbness.
Acromegaly and Gigantism-
Acromegaly and gigantism is caused by increased production of growth hormone. The disease causes increased growth of bones, ligaments and joint capsules. The sensory peripheral nerve often gets trapped within hypertrophied tissue. The trapped causes pinched or irritation of peripheral sensory nerve resulting in sensory nerve damage.
Bacterial infection causes bacterial infiltration of peripheral nerve and spinal cord. The bacteria infection and toxins secreted by bacteria in few cases attacks the peripheral sensory and motor nerves resulting in partial or total nerve damage. The bacterial infection that causes sensory peripheral neuropathies are diphtheria, lime disease, leprosy and tick borne infection. Viral infection such as Epstein-Barr virus damages the peripheral nerve and the nerve receptors as well as spinal cord. The initial symptoms observed are severe shooting or lightening pain known as post herpetic neuralgia or shingles. The viral infection like HIV virus causes immunodeficiency and results in AIDS. The AIDS results in severe pain and tingling because of irritation and damage of peripheral sensory nerve.
Peripheral Sensory Neuropathy Caused Due to Autoimmune Disease-
Autoimmune disease is often triggered by viral infection or genetic abnormalities. Once the autoimmune sequence is triggered the white blood cells attacks the body’s own tissues including the nerve. Sensory peripheral neuropathy is observed in patients suffering with systemic autoimmune disease such as Sjogren’s syndrome, lupus and rheumatoid arthritis. The white blood cell nibbles soft tissue like mucosa, joint capsule, ligaments and tendons. The attack of soft tissue causes tissue inflammation, which spreads to peripheral nerve resulting in inflammatory peripheral neuropathy. When the tissue surrounding nerves becomes inflamed, the inflammation can spread directly into sensory and motor nerve fibers.
Kidney disorder results in impaired kidney function. Severe and chronic impaired kidney function is also known as uremia. Uremia results in accumulation of fluid and waste product in peripheral tissues as well as organs. The fluid and waste product irritates as well as damages predominantly peripheral sensory nerve resulting in peripheral sensory neuropathy.
Benign cancer mass irritates or compresses the surrounding peripheral nerve receptors and nerve fibers. The irritation or squeeze of sensory and motor nerve fibers causes peripheral sensory neuropathy symptoms like pain, tingling, numbness and weakness. Similarly malignant cancer mass compresses, irritates or infiltrate cancer cells in peripheral sensory as well as motor nerve fibers. The penetration or compression of peripheral nerve causes permanent nerve damage. The destruction or damage of sensory nerve receptors, sensory and motor nerve fibers result in peripheral mix neuropathy. Few patients suffering with malignant cancer also triggers abnormal immune response. The abnormal immune response triggers widespread degenerative changes in sensory and motor nerve fibers resulting in mix neuropathy. The condition is known as Paraneoplastic Syndromes.
Chemotherapy- Most benign and malignant cancers are treated by medications and surgery. The medication treatment is known as chemotherapy. Pharmacological drugs used for chemotherapy destroys cancer cells as well as some of the normal tissue, which includes peripheral nerves. The effects on normal tissue are often insignificant when compare to its effect on benign or malignant cancer tissue. Most of the cases of peripheral sensory neuropathy caused by chemotherapy are reversible once the chemotherapy course is completed. Rarely in few cases chemotherapy is discontinued when symptoms of peripheral neuropathy become widespread and predominant.
Environmental or industrial toxins- Heavy metal toxicity is often caused by consumption or exposure to lead, mercury, and arsenic metals. Such metal toxicity results in peripheral neuropathy. Industrial solvents are used as insecticides. Regular exposure to insecticides follows toxic effects of solvents over peripheral nerves. The physiological side effect causes degenerative changes of sensory and motor nerves. Peripheral sensory neuropath symptoms like tingling, numbness, itching and burning pain are warning signs of toxicity. Removal of exposure to such toxins improves symptoms if permanent damage is not already occurred.
Heavy Alcohol Consumption- Regular high intake of alcohol causes vitamin deficiency as well as direct effects on peripheral nerve. The long term drinking alcohol results in peripheral sensory neuropathy. The nerve damage is often irreversible in patients who is been alcoholics for long period of time. The regular alcohol consumption causes vitamin B12, thiamine, and folate deficiency followed peripheral neuropathy.
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