Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content ++ For further information, see CMDT Part 26-30: Polyneuropathies & Mononeuritis Multiplex +++ KEY FEATURES ++ Weakness, sensory disturbances, or both in the extremities Pain sometimes common +++ CLINICAL FINDINGS ++ Diabetes mellitus Peripheral nervous system involvement may lead to Symmetric sensory or mixed sensorimotor polyneuropathy Asymmetric motor radiculoneuropathy or plexopathy (diabetic amyotrophy) Thoracoabdominal radiculopathy Autonomic neuropathy Isolated lesions of individual nerves (mononeuritis multiplex) Uremia May lead to a symmetric sensorimotor polyneuropathy that tends to affect the lower limbs more than the upper limbs More marked distally than proximally Alcohol use disorder and nutritional deficiency Many patients with alcohol use disorder have an axonal distal sensorimotor polyneuropathy Frequently accompanied by painful cramps, muscle tenderness, and painful paresthesias Often more marked in the legs than in the arms Symptoms of autonomic dysfunction may also be conspicuous A similar distal sensorimotor polyneuropathy is a well-recognized feature of beriberi (thiamine deficiency) In vitamin B12 deficiency, distal sensory polyneuropathy may develop but is usually overshadowed by central nervous system manifestations (eg, myelopathy, optic neuropathy, or cognitive impairment and dementia) Paraproteinemias A symmetric sensorimotor polyneuropathy may occur in patients with plasma cell myeloma Onset is gradual Course is progressive Often accompanied by pain and dysesthesias in the limbs In classic lytic myeloma, neuropathy is axonal In sclerotic myeloma, segmental demyelination (primary or secondary) and axonal loss may occur and lead to predominantly motor clinical manifestations Both demyelinating and axonal neuropathies are also observed in patients with paraproteinemias without myeloma Polyneuropathy may also occur in association with macroglobulinemia and cryoglobulinemia With polyneuropathy due to amyloidosis, sensory and autonomic symptoms are especially conspicuous, whereas distal wasting and weakness occur later +++ DIAGNOSIS ++ Diabetes mellitus Motor and sensory nerve conduction velocities are significantly slower, and the ratio of motor nerve conduction velocity to F-wave conduction velocity ratio (M/F ratio) is significantly lower, than those of individuals without diabetes Uremia Motor and sensory conduction velocity is moderately reduced Alcohol use disorder and nutritional deficiency Motor and sensory conduction velocity may be slightly reduced, even in subclinical cases Gross slowing of conduction is uncommon Paraproteinemias Electrophysiologic studies show distal demyelinating changes, correlating with predominantly sensory losses +++ TREATMENT ++ Diabetes mellitus Control of hyperglycemia to reduce hemoglobin A1c to < 6.5% Diet, exercise, weight reduction Hypoglycemic medications, insulin, metformin Uremia Kidney transplantation Long-term dialysis Alcohol use disorder and nutritional deficiency Abstinence from alcohol Vitamin repletion Paraproteinemias Neuropathy of classic plasma cell myeloma: poorly responsive to therapy Polyneuropathy of benign monoclonal gammopathy: may respond to immunosuppressant drugs and plasmapheresis Polyneuropathy associated with macroglobulinemia and cryoglobulinemia: plasmapheresis Polyneuropathy due to amyloidosis: no specific treatment Your Access profile is currently affiliated with [InstitutionA] and is in the process of switching affiliations to [InstitutionB]. Please select how you would like to proceed. Keep the current affiliation with [InstitutionA] and continue with the Access profile sign in process Switch affiliation to [InstitutionB] and continue with the Access profile sign in process Get Free Access Through Your Institution Learn how to see if your library subscribes to McGraw Hill Medical products. Subscribe: Institutional or Individual Sign In Error: Incorrect UserName or Password Username Error: Please enter User Name Password Error: Please enter Password Sign in Forgot Password? Forgot Username? Download the Access App: iOS | Android Sign in via OpenAthens Sign in via Shibboleth You already have access! Please proceed to your institution's subscription. Create a free profile for additional features.