Polyneuropathy is a generalized disease of the peripheral nerves. Estimates on the prevalence in the general population range from 2% to 7%.[1]Italian General Practitioner Study Group (IGPSG). Chronic symmetric symptomatic polyneuropathy in the elderly: a field screening investigation in two Italian regions. I. Prevalence and general characteristics of the sample. Neurology. 1995;45:1832-1836.
http://www.ncbi.nlm.nih.gov/pubmed/7477977?tool=bestpractice.com
[2]Bharucha NE, Bharucha AE, Bharucha EP. Prevalence of peripheral neuropathy in the Parsi community of Bombay. Neurology. 1991;41:1315-1317.
http://www.ncbi.nlm.nih.gov/pubmed/1650932?tool=bestpractice.com
[3]Savettieri G, Rocca WA, Salemi G, Meneghini F, et al. Prevalence of diabetic neuropathy with somatic symptoms: a door-to-door survey in two Sicilian municipalities. Sicilian Neuro-Epidemiologic Study (SNES) Group. Neurology. 1993;43:1115-1120.
http://www.ncbi.nlm.nih.gov/pubmed/8170554?tool=bestpractice.com
Polyneuropathies are frequent neurological manifestations of systemic illnesses. For example, approximately 50% of diabetics and patients with advanced HIV develop a polyneuropathy.[4]Dyck PJ, Kratz KM, Karnes JL, et al. The prevalence by staged severity of various types of diabetic neuropathy, retinopathy, and nephropathy in a population-based cohort: the Rochester Diabetic Neuropathy Study. Neurology. 1993 Apr;43(4):817-24.
http://www.ncbi.nlm.nih.gov/pubmed/8469345?tool=bestpractice.com
[5]Simpson DM, Kitch D, Evans SR et al. HIV neuropathy natural history cohort study: assessment measures and risk factors. Neurology. 2006;66:1679-1687.
http://www.ncbi.nlm.nih.gov/pubmed/16769940?tool=bestpractice.com
Most neuropathies caused by toxins and metabolic factors are axonal. The etiologies of demyelinating polyneuropathy (e.g., Guillain-Barre syndrome, monoclonal gammopathies) are much more limited.
Clinical presentation
It most commonly presents as symmetric numbness, paresthesias, and dysesthesias in the feet and distal lower extremities (distal symmetrical polyneuropathy). In severe cases, sensory symptoms and signs fit a stocking-glove distribution. Balance and gait may be impaired. Early motor signs include atrophy of the intrinsic foot muscles and ankle weakness. The autonomic nervous system may be involved, resulting in symptoms such as early satiety, diarrhea or constipation, sexual performance problems, sweating disturbances, and orthostatic lightheadedness.
Asymmetric neuropathies or neuropathies presenting initially with upper extremity signs or symptoms should alert the practitioner to alternate neuropathy diagnoses, including entrapment neuropathies (focal neuropathies) or vasculitic neuropathies (multifocal neuropathies). The differential diagnosis of focal and multifocal neuropathies overlaps but is distinct from that of polyneuropathies.
