Health Questions and Answers

Peripheral Neuropathies

Which peripheral neuropathies are seen most commonly on the medical ward?
Peripheral neuropathies are probably the most frequent neurologic problems seen on a medical ward, unlike myopathies and neuromuscular junction diseases, which are rare. The most common peripheral neuropathies can be remembered by the mnemonic DANG THE RAPIST:
D- Diabetes
A- Alcohol
N- Nutritional (e.g., vitamin deficiencies)
G- Guillain-Barré syndrome
T- Trauma (e.g., carpal tunnel)
H- Hereditary
E- Environmental (toxins, drugs)
R- Remote effects of cancer
A- Amyloid
P- Porphyria
I- Inflammation (e.g., collagen vascular disease)
S- Syphilis
T- Tumors

The evaluation of a patient with a peripheral neuropathy usually begins with which study?
An electromyogram and nerve conduction velocity (EMG/NCV) study. This test applies electrical current directly over the nerves and uses an electrode to record the speed with which the nerves conduct the current. It thus documents the extent and degree of impairment of nerve conduction. The EMG uses a needle electrode within the muscles to record muscle contractions and thus show denervation of the muscles.

Describe the management of a patient with a neuropathy.
Once a neuropathy has been confirmed, work-up for the etiology, requiring evaluation for diabetes, alcoholism, vitamin B12 deficiency, metabolic abnormalities such as thyroid disease or uremia, familial illnesses, toxic exposure, and collagen vascular disease. A spinal tap is seldom needed to detect inflammatory neuropathies. Only rarely is a nerve biopsy required. Many neuropathies improve with treatment of the underlying etiology.

What is the most common entrapment neuropathy?
Carpal tunnel syndrome (CTS), caused by compression of the median nerve at the wrist.

Describe the presentation of CTS.
Most commonly the result of mechanical overuse, CTS usually presents with symptoms of pain and tingling in the hand (especially at night), weakness, and/or numbness. Pain in the hand at night is considered CTS until proved otherwise.

How is CTS diagnosed?
There may be no objective neurologic findings in CTS. As with other peripheral neuropathies, EMG/NCV studies are helpful in making the diagnosis.

How is CTS treated?
Treatment is usually surgical, involving open or endoscopic release at the wrist, although conservative measures (such as wrist splinting) may be sufficient for mild cases.

What is Guillain-Barré syndrome (GBS)?
GBS is an acute inflammatory polyradiculopathy with inflammation of the nerve roots and peripheral nerves. It is presumably autoimmune and often follows viral infections, surgery, pregnancies, and other immune-altering events. It runs a monophasic course, with weakness progressing for several days to weeks, reaching a plateau, and then recovering over a period of several weeks to months.

What are the symptoms of GBS?
GBS causes weakness, often but not always in an ascending pattern (from legs up the trunk to the arms and face). The weakness is hyporeflexive, but there is no significant sensory loss. Rapidly progressive weakness with absent reflexes and no sensory change is almost always GBS. The diagnosis is supported by high CSF protein and slowed nerve conduction velocities on EMG.

Treatment of GBS is based on which of its abnormalities?
Although GBS is presumably autoimmune, no specific antigen or well-defined immune abnormality has been confirmed. Nevertheless, treatment is directed toward an immunologic cause, employing IVIG or plasmapheresis. If done early in the disease, these treatments shorten the overall course. Because autonomic dysfunction frequently complicates the syndrome and because respiration is often impaired by the weakness, patients usually require management in the intensive care unit. Therapy thus focuses on the day-to-day concerns of respirators, vital signs, nutrition, and other aspects of critical care.

References
WEB SITES
www.neuroguide.com
www.aan.com (American Academy of Neurology)
www.medmatrix.org
www.internets.com/mednets/sneurolo.htm
www.medwebplus.com/subject/Neurology.html

BIBLIOGRAPHY

  • Zochodne DW: Diabetic neuropathies. Curr Treat Options Neurol 2: 23-29, 2000.
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