This page has moved. Click here to view. Peripheral NeuropathyThe signs and symptoms of neuropathy consist of sensory and motor phenomena in a peripheral nervous system distribution. The neuropathy may involve a single nerve, such as the peroneal nerve after compression at the knee; multiple distal nerves symmetrically, such as with distal axonal polyneuropathy; or multiple individual nerves asymmetrically, such as with mononeuritis multiplex peripheral neuoropathy, numbness, tingling, nuropathy. Patients may complain of numbness, tingling, pain, burning, loss of sensation, a cold sensation, altered sensation ("sock around the foot," "walking on pebbles" or hypersensitivity) and muscle weakness in the distribution of If the hands are involved, the patient may be unable to button a shirt. In the lower extremities, early symptoms include an ill-defined unsteadiness. Physical examination reveals reduced positional sense; decreased pinprick, temperature and vibratory perception; muscle weakness, and atrophy with The most common type of polyneuropathy is a chronic predominantly sensory (large and small fiber) symmetric distal polyneuropathy. By the time sensory disturbances reach the upper shin, the fingers are usually involved. A typical stocking-and-glove pattern of sensory loss ensues. The first motor symptom is an inability to walk on the heels. Over time, an obvious footdrop may develop. This type of neuropathy has a large number of potential causes. However, in an estimated 30 percent of cases, no specific cause can be identified, and the diagnosis of a chronic idiopathic axonal neuropathy is made. In the United States, the most common causes of neuropathy are diabetes mellitus and alcohol abuse, but worldwide, leprosy is the most common cause of polyneuropathy. CAUSES OF POLYNEUROPATHIES Systemic Disorders. Polyneuropathy can complicate a variety of systemic disorders (Table 6). By far the disease most frequently associated with neuropathy is diabetes mellitus. There are an estimated 16 million persons with diabetes in the United States, 10 percent of whom experience symptomatic neuropathy. The most prevalent neuropathy in these patients is a symmetric distal Other common neuropathies in persons with diabetes include entrapment neuropathies. Truncal radiculopathy, isolated or multiple mononeuropathy and diabetic amyotrophy are much less common in this patient population. Diabetic amyotrophy is a highly painful, subacute, unilateral, proximal lumbosacral radiculoplexopathy that usually resolves spontaneously over a period of Rheumatologic Diseases. The most important neuropathy associated with rheumatologic disease is a mononeuritis multiplex caused by vasculitis of the nerves. Isolated peripheral nerve vasculitis, a mononeuropathy of subacute onset with severe burning dysesthetic pain, weakness and sensory loss, can occur in this setting. Multiple nerve involvement leads to patchy deficits in upper and lower extremities. This feature may be a presenting symptom of polyarteritis nodosa, or it may accompany other systemic vasculitic disorders, such as rheumatoid arthritis, Sjogren's disease or systemic lupus erythematosus. Sometimes, a confluent polyneuropathy with only mild asymmetry creates a confusing diagnostic picture. An electromyogram (EMG) and nerve and muscle biopsies are essential to establish the diagnosis and should be rapidly obtained if there is strong suspicion of mononeuritis multiplex. Aggressive treatment with corticosteroids and cyclophosphamide (Cytoxan, Neosar) can produce full recovery. Without treatment, severe disability or death from systemic complications can occur. Patients should be tested for anti-neutrophil cytoplasmic antibodies(ANCA), which are seen in Wegener's granulomatosis and occasionally in peripheral nerve vasculitis. In addition, patients may have an elevated sedimentation rate, positive ANA and anti-SS-A and anti-SS-B antibodies, as in systemic lupus erythe-matosus and Sjogren's syndrome. Nutritional Deficiency, Drugs and Toxins. Most neuropathies associated with nutritional deficiencies, drugs or toxins affect distal nerves, and the largest and longest fibers are the first affected. Alcohol abuse is a frequent cause of this type of neuropathy. Neuropathy typically progresses only minimally if the patient stops drinking. It is important to recognize vitamin B12 deficiency because this disorder can cause neuropathy as well as myelopathy. Selected drugs that can cause neuropathy are listed in Table 7. When evaluating a patient for polyneuropathy, the possibility of a drug-induced neuropathy should always be considered, and a thorough medication history should Chemotherapeutic agents are frequently neurotoxic, and severe dose-related polyneuropathy may limit their use. Chronic exposure to heavy metals or industrial toxins, such as lead, arsenic, gold, mercury, thallium and beryllium, can also result in Systemic and Nutritional Disorders Associated with Neuropathies Diabetes mellitus Thyroid disease Renal disease Hepatic disease Sarcoidosis Acromegaly Porphyria Vitamin B1 (thiamine deficiency) Vitamin B12 (cyanocobalamin deficiency) Vitamin B6 (pyridoxine deficiency) Vitamin E (tocopherol deficiency) Postgastroplasty neuropathy Critical illness neuropathy Paraproteinemias. Monoclonal gammopathy affects approximately 10 percent of patients with idiopathic polyneuropathy. Underlying hematologic disorders, such as myeloma, amyloidosis, Waldenstrom's disease, lymphoma or 1ymphoproliferative disease, are sometimes found. In more than two-thirds of patients, hematologic evaluation fails to reveal a primary cause, and a diagnosis of a polyneuropathy with a monoclonal gammopathy of undetermined significance (MGUS) is made. Most polyneuropathies associated with MGUS are insidious sensorimotor distal neuropathies with onset usually during the sixth decade. Some cases have features of a chronic inflammatory demyelihating polyneuropathy. In 50 percent of patients, IgM antibodies are directed against myelin-associated glycoprotein. Treatment may include intravenous immunoglobulin, plasmapheresis, corticosteroids and cyclophosphamide. All patients with Malignancies. Patients with cancer commonly have a nonspecific, mild, sensorimotor, distal polyneuropathy. However, because serious neurologic complications, such as spinal cord compression and leptomeningeal disease, are Immune-Mediated Polyneuropathies. 1. Acute inflammatory polyradiculoneuropathy (Guillain-Barre syndrome). Guillain-Barre syndrome is an acute, severe, demyelinating polyneuropathy that affects individuals of all ages. The incidence of Guillain-Barre syndrome is Clinical signs and symptoms of the syndrome include acute symmetric weakness and areflexia. The weakness component may range from relatively mild leg weakness to complete paralysis of all facial, bulbar (swallowing), respiratory, trunk and Drugs that Can Cause Neuropathies Chloroquine (Aralen) Cisplatin (PlatinoI-AQ) Colchicine Dapsone Disulfiram (Antabuse) Paclitaxel (Taxol) Ethanol Isoniazid (Laniazid, Nydrazid) Metronidazole (Flagyl, Metizol, Protostat) Nitrofurantoin (Macrobid, Macrodantin) Phenytoin (Dilantin) Pyridoxine (vitamin B6; Beesix, Nestrex) Simvastatin (Zocor) Suramin (Metaret) Tacrolimus (Prograt) Thalidomide (Synovir, Thalomid) Vinca alkaloids (e.g., vincristine sulfate [Oncovin, Vincasar]) Zalcitabine (Hivid) Pain is common at the onset of Guillain-Barre syndrome. Severe back or neck pain may be present and often leads to a work-up that includes MRI of the spine to search for more localized disease. Guillain-Barre syndrome has been observed in HIV-positive patients at Treatment for Guillain-Barre syndrome involves admission to an extensively monitored hospital bed or an intensive care unit. Treatment with intravenous immunoglobulin or plasmapheresis is effective in shortening the duration of the disease. In 2. Chronic inflammatory demyelinating polyradiculoneuropathy. Chronic inflammatory demyelinating polyradiculoneuropathy is a chronic immune-mediated neuropathy with pathologic features similar to those of Guillain-Barre syndrome. Chronic inflammatory demyelinating polyradiculoneuropathy has an insidious onset and occurs Infections. Polyneuropathies associated with infections include Lyme disease, leprosy and HIV disease. The neurologic complications of Lyme disease most commonly consist of chronic basilar meningitis with a facial nerve palsy. However, cervical radiculitis and a neuropathic picture resembling mononeuritis multiplex may HIV-infected patients may have a variety of neuropathic disorders, including a painful distal neuropathy that occurs in the late stages of infection, neuropathy caused by malnutrition or antiretroviral drugs, Guillain-Barre syndrome, chronic inflammatory demyelinating polyradiculoneuropathy, multiple mononeuropathies and acute lumbosacral polyradiculopathy. The latter two Hereditary Polyneuropathies. Most hereditary polyneuropathies are classified as Charcot-Marie-Tooth (CMT) disease, which has a prevalence of about 1 in 2,500 persons. Clinical features include pes cavus, hammertoe, distal atrophy and Specific gene defects that cause some forms of CMT disease have been identified, and commercial tests for these genetic abnormalities are available.26 CMT1 is a demyelinating hereditary neuropathy characterized by PAIN CONTROL Adequate pain control can be difficult to achieve, especially in the presence of prominent small sensory fiber involvement. A low-dose tricyclic (nortriptyline [Aventyl, Pamelor], amitriptyline [Elavil]) is often the initial choice. Other agents that may be effective for this indication include gabapentin, tramadol /Ultram), other anticonvulsants (e.g., phenytoin, carbamazepine) and Medications Used for Neuropathic Pain Nortriptyline (Aventyl, Pamelor), 25 to 75 mg each evening Amitriptyline (Elavil), 25 to 100 mg each evening Gabapentin (Neurontin), 300 to 600 mg three times per day Tramadol (Ultram), 50 to 100 mg two times per day Phenytoin (Dilantin), 100 mg three times per day Carbamazepine (e.g., Tegretol), 200 mg three times per day
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