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Porphyria Educational Services


The diagnosis of peripheral neuropathies can be frustrating, and even
painful. Diagnosis also is very time consuming not to mention that it is
very expensive.

To obtain a correct PN diagnosis, a porphyric must first have careful
clinical and electrodiagnostic assessment. This assessment must be carried out with
attention to the pattern of involvement and the types of nerve fibers most

The reason for this is that it both narrows the differential diagnosis and
helps to focus the laboratory evaluation. An algorithmic approach to the evaluation and
differential diagnosis of a patient with peripheral neuropathy is
presented.based on several important elements.

These elements include use of the clinical history and physical
examination, the use of electromyography and nerve conduction studies,
and autonomic testing.

In addition there are cerebrospinal fluid analysis and nerve biopsy

The underlying cause of axonal neuropathies can frequently be treated;
demyelinating neuropathies are generally managed with the assistance of a
neurologist, however a neurologist can be a consulting physician to one's
primary physician after a PN diagnosis has been established by the neuro.

The incidence of peripheral neuropathy is not known, but it is a common
feature of many systemic diseases. Diabetes and alcoholism are the most
common etiologies of peripheral neuropathy in adults living in developed

The primary worldwide cause of treatable neuropathy is leprosy.

Neuropathies associated with human immunodeficiency virus (HIV) infection
account for an increasing number of cases.

Peripheral neuropathy has numerous other causes, including hereditary,
toxic, metabolic, infectious, inflammatory, ischemic and paraneoplastic
disorders. The number of peripheral neuropathies for which an etiology
cannot be found despite extensive evaluation ranges from 13 to 22 percent.

Many undiagnosed patients (up to 42 percent) are found, after a careful
family history and examination of kin, to have a familial neuropathy. This is
where the acute hepatic porphyrias come in.

The evaluation of a peripheral neuropathy can be time-consuming and costly
but is less so if established after documented porphyria has been
A systematic approach based on a careful clinical and electrodiagnostic
assessment can help narrow the possibilities and tailor the laboratory
evaluation to a specific differential diagnosis.

Diabetes and alcoholism are the most common causes of peripheral
neuropathy in the United States, but since 1991 a large number of PN cases have been
documented stemming from one of the acute hepatic porphyrias.

The most common presentation of peripheral neuropathy is distal symmetric
sensorimotor dysfunction.

It most often begins to appear at the onset of an acute attack and based
on the occurrence of such attacks and their severity, PN may las from a few days
to a few weeks. It can sometimes end in respiratory paralysis and death.

Adams, R.A., MD, Peripheral Neuropathy, 1994, Journal of Neuromedicine.
No. 8. pp. 34-39.

ANN NOELLE PONCELET, M.D.,University of California, San Francisco, San
Francisco, 1997.