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Peripheral Neuropathy

Ref: University of Iowa Family Practice Handbook: Chapter 14: Neurology
          Masatomi H. Ikusaka, M.D.

I. CLASSIFICATION

  1. Polyneuropathy: a bilaterally symmetrical affection of the peripheral nerves, usually involving the legs more than the arms and the distal segments earlier and more severely than the proximal ones, i.e., the stocking-and-glove pattern
  2. Mononeuropathy: involvement of a single nerve
  3. Mononeuropathy multiplex: random involvement of multiple nerves
  4. Radiculopathy: involvement of the nerve roots
  5. Demyelination: commonly affects both proximal and distal segments of the nerve as in Guillain-Barre syndrome
  6. Axonal degeneration: commonly progresses from distal to proximal segments (i.e., dying-back neuropathy)

II. MANIFESTATIONS
Symptoms and signs include pain, paresthesias, weakness, muscle atrophy, reflex loss, anhidrosis, orthostatic hypotension

III. DIAGNOSIS

  1. Full neurologic examination is necessary with special attention to muscle weakness, reflex loss, autonomic dysfunction, and sensory deficits (touch, pain, temperature, position, and vibration)
  2. Nerve conduction study can confirm neuropathy and differentiate demyelination from axonal degeneration. The involvement of proximal nerves and roots can be determined by H and F responses
  3. Electromyography differentiates myogenic from neurogenic causes of weakness and confirms abnormality of neuromuscular junctions
  4. Nerve biopsy is undertaken only when the etiologic diagnosis remains in doubt after electrodiagnostic tests have been completed

IV. DIFFERENTIAL DIAGNOSIS

The most commonly acquired neuropathies are those associated with diabetes mellitus or alcoholism and the Guillain-Barre syndrome. Inherited peripheral neuropathies include Charcot-Marie-Tooth disease. Two questions must be answered to determine the etiology: polyneuropathy or mononeuropathy multiplex; acute, subacute, or chronic.

Ref:  ACP Library on Disk - © 1996 - American College of Physicians

Differential Diagnosis Neuropathy

The most common neuropathy encountered by general physicians is a distal symmetrical peripheral neuropathy, involving sensory and motor dysfunction with associated reflex loss. This disorder typically affects feet and legs before hands and arms.

To classify the neuropathy, the physician must assess the pattern of the deficit :
polyneuropathy, or mononeuropathy or mononeuropathy multiplex.

Predominant involvement of pain and temperature sensation suggests small fiber involvement, whereas prominent loss of vibration and position sense suggests large fiber involvement.

By assessing the clinical deficit, the physician can determine whether motor neurons, mixed nerves, or roots are involved.

Nerve conduction velocities may distinguish between demyelinating and axonal neuropathies, which usually show slow or normal conduction velocities, respectively. This approach allows a preliminary characterization of the disorder and generation of a differential diagnosis.

Sensory peripheral neuropathy, its associated conditions.

Motor neuropathies, its associated conditions:

Diabetes also causes sensory and sensorimotor neuropathies. The predominant pathology is axonal degeneration.

The most common neuropathies are
Sensory-motor neuropathies and are due to

Prescription drugs are a common and important cause of neuropathy. These agents typically produce distal axonal neuropathies. A listing of the common offenders is provided in Table 17.

Physicians commonly see patients with predominantly painful neuropathies.
When focal, the most common causes are diabetes mellitus, nerve root compression, and herpes zoster.

Painful polyneuropathies are found in

        

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