Polyneuropathy is a neurological disorder that occurs when many peripheral nerves throughout the body malfunction simultaneously. It may be acute and appear without warning, or chronic and develop gradually over a longer period of time. Many polyneuropathies have both motor and sensory involvement and some have autonomic dysfunction. These disorders are often symmetric and frequently involve distal extremities. There is a very large differential for polyneuropathy.
Evaluation and classification of polyneuropathies begins with a history and physical exam in order to document what the pattern of the disease process is (arms, legs, distal, proximal, symmetric), when they started, how long they've lasted, if they fluctuate, and what deficits and pain are involved. If pain is a factor, and it often is, determining where and how long the pain has been present is important. The patient must be interviewed, and physical testing is often necessary to further delineate and document the pain.
One also needs to know what disorders are already present within the family and what diseases the patient may currently have. This is vital in forming a differential diagnosis.
Although often diseases are suggested by the physical exam and history alone, testing is still a large part of the diagnosis. Tests which may be employed include: electrodiagnostic testing using electromyography, muscle biopsy, serum creatine kinase (CK), antibody testing, . Nerve biopsy is not used much, but is helpful in determing small fiber neuropathy. Other tests may be used, especially tests for specific disorders associated with polyneuropathies.
There is a large differential for polyneuropathies: vitamin deficiency, cancer, toxins, infections (ex. Guillain-Barré Syndrome), liver disease, endocrine disease (inc. diabetes with diabetic and pre-diabetic neuropathy), amyloidosis, genetic disorders, motor neuron disorders, motor neuropathies, kidney failure,paraneoplastic, polio, porphyria (some types), spinal muscular atrophy, catecholamine disorders, and many others. This is not a complete list.
- Merck Manual overview
- Diagram Diagnosis page
- Wash U. Neuro website, very complete
- Discussion of diabetic polyneuropathy with Spanish translation