Paresthesia in the median nerve distribution within 2 minutes is considered positive.Diagnostic performance characteristics such as sensitivity and specificity are reported, but difficult to interpret because of the lack of a consensus reference standard for CTS or IMNCT. Causes
Idiopathic Median Neuropathy at the Carpal Tunnel
Genetic factors are believed to be the most important determinants of who develops carpal tunnel syndrome due to IMNCT. In other words, your wrist structure seems programmed at birth to develop IMNCT later in life. A genome-wide association study (GWAS) of carpal tunnel syndrome identified 16 genomic loci significantly associated with the disease, including several loci previously known to be associated with human height.Factors that may contribute to symptoms, but have not been experimentally associated with neuropathy include obesity, and Diabetes mellitus . One case-control study noted that individuals classified as obese (BMI > 29) are 2.5 times more likely than slender individuals (BMI < 20) to be diagnosed with CTS. Its not clear whether this association is due to an alteration of pathophysiology, a variation in symptoms, or a variation in care-seeking. Discrete Pathophysiology and Carpal Tunnel Syndrome
Hereditary neuropathy with susceptibility to pressure palsies is a genetic condition that appears to increase the probability of developing MNCT. Heterozygous mutations in the gene SH3TC2, associated with Charcot-Marie-Tooth, may confer susceptibility to neuropathy, including CTS.Association between common benign tumors such as lipomas, ganglion, and vascular malformation should be handled with care. Such tumors are very common and overlap with IMNCT is more likely than pressure on the median nerve.
African histoplasmosis is a fungal infection caused by Histoplasma capsulatum var. duboisii, or Histoplama duboisii (Hcd). : 316  Disease has been most often reported in Uganda, Nigeria, Zaire (Democratic Republic of the Congo) and Senegal, as Hcd is exclusive to Africa. In human disease it manifests differently than histoplasmosis (caused by Histoplasma capsulatum, or Hcc), most often involving the skin and bones and rarely involving the lungs. Also unlike Hcc, Hcd has been reported to rarely present in those with HIV, likely due to underreporting. However, this along with the differences in Hcc and Hcd have been disputed.The favored locations of African histoplasmosis are "osteoarticular, ganglionic and pulmonary". Genitourinary skin damage is rare, occurring in only 4-11% patients and typically as a secondary skin invasion in those with disseminated infection.It presents as "localized with isolated skin, bone, or lymph node infections or disseminated with multiple cutaneous lesions present all over the body, subcutaneous abscesses, enlarged lymph nodes, liver and spleen, and visceral organ enlargement" Cutaneous manifestations can be isolated or present with nodules, papules, or ulcers. They may present with subcutaneous swelling, cold abscesses progressing to spontaneous fistulization, or ulcers that may bud. If left alone, lesions may turn into a large ulcer. See also
Histoplasmosis

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== Further reading ==