Peripheral Neuropathies – Polyneuropathies and Mononeuritis Multiplex – part 2

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Neuropathies Associated With Systemic & Metabolic Disorders

A. Diabetes Mellitus: In this disorder, involvement of the peripheral nervous system may lead to symmetric sensory or mixed polyneuropathy, asymmetric motor neuropathy (diabetic amyotrophy), thoracoabdominal radiculopathy, utonomic neuropathy, or isolated lesions of individual nerves. These may occur singly or in any combination.

Sensory polyneuropathy, the most common manifestation, may lead to no more than depressed tendon reflexes and impaired appreciation of vibration in the legs. When symptomatic, there may be pain, paresthesias, or numbness in the legs, but in severe cases distal sensory loss occurs in all limbs. Diabetic amyotrophy is characterized by asymmetric weakness and wasting involving predominantly the proximal muscles of the legs, accompanied by local pain.

Online Canada Drugs Thoracoabdominal radiculopathy leads to pain over the trunk. In patients with autonomic neuropathy, postural hypotension, impaired thermoregulatory sweating, postgustatory hyperhidrosis, constipation, flatulence, diarrhea, impotence, urinary retention, and incontinence may occur, and there may be abnormal pupillary responses. Isolated lesions of individual peripheral nerves are common and in the limbs tend to occur at sites of compression or entrapment. Treatment is symptomatic. Entrapment neuropathies may be helped by surgical decompression.

Treatment of neuropathic pain is discussed above.

B. Uremia: Uremia may lead to a symmetric sensorimotor polyneuropathy that tends to affect the lower limbs more than the upper limbs and is more marked distally than proximally. The diagnosis can be confirmed electrophysiologically, for motor and sensory conduction velocity is moderately reduced. The neuropathy improves both clinically and electrophysiologically with renal transplantation and to a lesser extent with chronic dialysis. Buy Online Generic Viagra

C. Alcoholism and Nutritional Deficiency: Many alcoholics have an axonal distal sensorimotor polyneuropathy that is frequently accompanied by painful cramps, muscle tenderness, and painful paresthesias and is often more marked in the legs than in the arms. Symptoms of autonomic dysfunction may also be conspicuous. Motor and sensory conduction velocity may be slightly reduced, even in subclinical cases, but gross slowing of conduction is uncommon. A similar distal sensorimotor polyneuropathy is a well-recognized feature of beriberi (thiamin deficiency). In vitamin B12 deficiency, distal sensory polyneuropathy may develop but is usually overshadowed by central nervous system manifestations (eg, myelopathy, optic neuropathy, or intellectual changes). Buy Online Cialis.

D. Paraproteinemias: A symmetric sensorimotor polyneuropathy that is gradual in onset, progressive in course, and often accompanied by pain and dysesthesias in the limbs may occur in patients (especially men) with multiple myeloma. The neuropathy is of the axonal type in classic lytic myeloma, but segmental demyelination (primary or secondary) and axonal loss may occur in sclerotic myeloma and lead to predominantly motor clinical manifestations.

Both demyelinating and axonal neuropathies are also observed in patients with paraproteinemias without myeloma. A small fraction will develop myeloma if serially followed. The demyelinating neuropathy in these patients may be due to the monoclonal protein’s reacting to a component of the nerve myelin. The neuropathy of classic multiple myeloma is poorly responsive to therapy. The polyneuropathy of benign monoclonal gammopathy may respond to immunosuppressant drugs and plasmapheresis.

Polyneuropathy may also occur in association with macroglobulinemia and cryoglobulinemia and sometimes responds to plasmapheresis. Entrapment neuropathy, such as carpal tunnel syndrome, is more common than polyneuropathy in patients with (nonhereditary) generalized amyloidosis. With polyneuropathy due to amyloidosis, sensory and autonomic symptoms are especially conspicuous, whereas distal wasting and weakness occur later; there is no specific treatment. Cheap Canadian Pharmacy

Neuropathies Associated With Infectious & Inflammatory Diseases

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A. Leprosy: Leprosy is an important cause of peripheral neuropathy in certain parts of the world. Sensory disturbances are mainly due to involvement of intracutaneous nerves. In tuberculoid leprosy, they develop at the same time and in the same distribution as the skin lesion but may be more extensive if nerve trunks lying beneath the lesion are also involved. In lepromatous leprosy, there is more extensive sensory loss, and this develops earlier and to a greater extent in the coolest regions of the body, such as the dorsal surfaces of the hands and feet, where the bacilli proliferate most actively. Motor deficits result from involvement of superficial nerves where their temperature is lowest, eg, the ulnar nerve in the region proximal to the olecranon groove, the median nerve as it emerges from beneath the forearm flexor muscle to run toward the carpal tunnel, the peroneal nerve at the head of the fibula, and the posterior tibial nerve in the lower part of the leg; patchy facial muscular weakness may also occur owing to involvement of the superficial branches of the seventh cranial nerve.

Motor disturbances in leprosy are suggestive of multiple mononeuropathy, whereas sensory changes resemble those of distal polyneuropathy. Examination, however, relates the distribution of sensory deficits to the temperature of the tissues; in the legs, for example, sparing frequently occurs between the toes and in the popliteal fossae, where the temperature is higher.

Treatment is with antileprotic agents.

B. AIDS: A variety of neuropathies occur in HIV-infected patients. Patients with AIDS may develop a chronic symmetric sensorimotor axonal polyneuropathy associated usually with no abnormal cerebrospinal fluid findings.

Treatment is symptomatic. AIDS patients may also develop progressive polyradiculopathy or radiculomyelopathy that leads to leg weakness and urinary retention; sensory loss is less conspicuous than in polyneuropathy. The cerebrospinal fluid may show mononuclear pleocytosis and increased protein and low glucose concentrations.

Cytomegalovirus is responsible in at least some cases. The prognosis is generally poor, but some patients respond to intravenous ganciclovir (2.5 mg/kg every 8 hours for 10 days, then 7.5 mg/kg daily 5 days per week).

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An inflammatory demyelinating polyradiculoneuropathy sometimes occurs in HIV-seropositive patients without AIDS and may follow an acute, subacute, or chronic course. Weakness is usually more conspicuous distally than proximally and tends to overshadow sensory symptoms. Tendon reflexes are depressed or absent. The cerebrospinal fluid shows an increased cell count and protein concentration. Treatment with plasmapheresis has helped some patients. Spontaneous improvement may also occur. Seropositive patients without AIDS may also develop a mononeuropathy multiplex that sometimes responds to treatment with plasmapheresis.

C. Lyme Borreliosis: The neurologic Buy Online Brand Viagra manifestations of Lyme disease include meningitis, meningoencephalitis, polyradiculoneuropathy, mononeuropathy multiplex, and cranial neuropathy. Serologic tests establish the underlying disorder.

D. Sarcoidosis: Cranial nerve palsies (especially facial palsy), multiple mononeuropathy, and, less commonly, symmetric polyneuropathy may all occur, the latter sometimes preferentially affecting either motor or sensory fibers.

Improvement may occur with use of corticosteroids.

E. Polyarteritis: Involvement of the vasa nervorum by the vasculitic process may result in infarction of the nerve.
Clinically, one encounters an asymmetric sensorimotor polyneuropathy (mononeuritis multiplex) that pursues a waxing and waning course. Steroids and cytotoxic agents—especially cyclophosphamide—may be of benefit in severe cases. canadian drug pharmacy

F. Rheumatoid Arthritis: Compressive or entrapment neuropathies, ischemic neuropathies, mild distal sensory polyneuropathy, and severe progressive sensorimotor polyneuropathy can occur in rheumatoid arthritis.

Neuropathy Associated With Critical Illness

Patients in intensive care units with sepsis and multiorgan failure sometimes develop polyneuropathies. This may be manifested initially by unexpected difficulty in weaning patients from a mechanical ventilator and in more advanced cases by wasting and weakness of the extremities and loss of tendon reflexes. Sensory abnormalities are relatively inconspicuous. The neuropathy is axonal in type. Its pathogenesis is obscure, and treatment is supportive. The prognosis is good provided patients recover from the underlying critical illness. Generic Zithromax is a macrolide antibiotic used to treat bacterial infections.

Toxic Neuropathies

Axonal polyneuropathy may follow exposure to industrial agents or pesticides such as acrylamide, organophosphorus compounds, hexacarbon solvents, methyl bromide, and carbon disulfide; metals such as arsenic, thallium, mercury, and lead; and drugs such as phenytoin, perhexiline, isoniazid, nitrofurantoin, vincristine, and pyridoxine in high doses. Detailed occupational, environmental, and medical histories and recognition of clusters of cases are important in suggesting the diagnosis. Treatment is by preventing further exposure to the causal agent.

Isoniazid neuropathy is prevented by pyridoxine supplementation.

Diphtheritic neuropathy results from a neurotoxin released by the causative organism and is common in many areas.
Palatal weakness may develop 2–4 weeks after infection of the throat, and infection of the skin may similarly be followed by focal weakness of neighboring muscles. Disturbances of accommodation may occur about 4–5 weeks after infection and distal sensorimotor demyelinating polyneuropathy after 1–3 months.

Neuropathies Associated With Malignant Diseases

Both a sensorimotor and a purely sensory polyneuropathy may occur as a nonmetastatic complication of malignant diseases. The sensorimotor polyneuropathy may be mild and occur in the course of known malignant disease; or it may have an acute or subacute onset, lead to severe disability, and occur before there is any clinical evidence of the cancer, occasionally following a remitting course.

Acute Idiopathic Polyneuropathy (Guillain-Barre Guillain-Barré Syndrome)

This acute or subacute polyradiculoneuropathy sometimes follows infective illness, inoculations, or surgical procedures. There is an association with preceding Campylobacter jejuni enteritis. The disorder probably has an immunologic basis, but the precise mechanism is unclear. The main complaint is of weakness that varies widely in severity in different patients and often has a proximal emphasis and symmetric distribution. It usually begins in the legs, spreading to a variable extent but frequently involving the arms and often one or both sides of the face. The muscles of respiration or deglutition may also be affected. Sensory symptoms are usually less conspicuous than motor ones, but distal paresthesias and dysesthesias are common, and neuropathic or radicular pain is present in many patients. Autonomic disturbances are also common, may be severe, and are sometimes life-threatening; they include tachycardia, cardiac irregularities, hypotension or hypertension (high blood pressure), facial flushing, abnormalities of sweating, pulmonary dysfunction, and impaired sphincter control.

The cerebrospinal fluid characteristically contains a high protein concentration with a normal cell content, but these changes may take 2 or 3 weeks to develop. Electrophysiologic studies may reveal marked abnormalities, which do not necessarily parallel the clinical disorder in their temporal course. Pathologic examination has shown that primary demyelination occurs in regions infiltrated with inflammatory cells, and it seems probable that myelin disruption has an autoimmune basis.

When the diagnosis is made, the history and appropriate laboratory studies should exclude the possibility of porphyric, diphtheritic, or toxic (heavy metal, hexacarbon, organophosphate) neuropathies. Poliomyelitis, botulism, and tick paralysis must also be considered. The presence of pyramidal signs, a markedly asymmetric motor deficit, a sharp sensory level, or early sphincter involvement should suggest a focal cord lesion.

Most patients eventually make a good recovery, but this may take many months, and 10–20% of patients of are left with persisting disability. Treatment with prednisone is ineffective and may actually affect the outcome adversely by prolonging recovery time. Plasmapheresis is of value; it is best performed within the first few days of illness and is best reserved for clinically severe or rapidly progressive cases or those with ventilatory impairment. Intravenous immunoglobulin (400 mg/kg/d for 5 days) is also helpful and imposes less stress on the cardiovascular system than plasmapheresis. Patients should be admitted to intensive care units if their forced vital capacity is declining, and intubation is considered if the forced vital capacity reaches 15 mL/kg, dyspnea becomes evident, or the oxygen saturation declines. Respiratory toilet and chest physical therapy help prevent atelectasis. Marked hypotension may respond to volume replacement or pressor agents. Low-dose heparin to prevent pulmonary embolism should be considered.

Approximately 3% of patients with acute idiopathic polyneuropathy have one or more clinically similar relapses, sometimes several years after the initial illness. Plasma exchange therapy may produce improvement in chronic and relapsing inflammatory polyneuropathy. canadian prescription drug

Chronic Inflammatory Polyneuropathy

Chronic inflammatory demyelinating polyneuropathy, an acquired immunologically mediated disorder, is clinically similar to Guillain-Barre Guillain-Barré syndrome except that it has a relapsing or steadily progressive course over months or years. In the relapsing form, partial recovery may occur after some relapses, but in other instances there is no recovery between exacerbations. Although remission may occur spontaneously with time, the disorder frequently follows a progressive downhill course leading to severe functional disability. Imuran (AZATHIOPRINE) is an immunosuppressive agent.

Electrodiagnostic studies show marked slowing of motor and sensory conduction, and focal conduction block.
Signs of partial denervation may also be present owing to secondary axonal degeneration. Nerve biopsy may show chronic perivascular inflammatory infiltrates in the endoneurium and epineurium, without accompanying evidence of vasculitis. However, a normal nerve biopsy result or the presence of nonspecific abnormalities does not exclude the diagnosis.

Corticosteroids may be effective in arresting or reversing the downhill course. Treatment is usually begun with prednisone, 60 mg daily, continued for 2–3 months or until a definite response has occurred. If no response has occurred despite 3 months of treatment, a higher dose may be tried. In responsive cases, the dose is gradually tapered, but most patients become corticosteroid-dependent, often requiring prednisone, 20 mg daily on alternate days, on a long-term basis. Patients unresponsive to corticosteroids may benefit instead from treatment with a cytotoxic drug such as azathioprine. There are increasing anecdotal reports of short-term benefit with plasmapheresis; high-dose intravenous immunoglobulin treatment (eg, 400 mg/kg/d) may produce clinical improvement lasting for weeks to months.

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