Skin sensitivity can be impaired by many different diseases and disorders. Although skin injuries (burns, incisions, etc.) and nerve lesions (from injury or restricted blood circulation) are the most commonly experienced causes of decreased sensitivity, several metabolic, toxic, and immunologic factors can influence haptic perception.
One of the most common complications of diabetes, known as diabetic neuropathy, results in damage to the nerves of the body that cause numbness, tingling, and pain. Diabetes can also slow the healing of cuts and cause rashes that alter the sensitivity of an area of skin.
Prolonged exposure to high blood sugar can damage delicate nerve fibers, causing diabetic neuropathy. Why this happens isn’t completely clear, but a combination of factors likely plays a role, including the complex interaction between nerves and blood vessels.
High blood sugar interferes with the ability of the nerves to transmit signals. It also weakens the walls of the small blood vessels (capillaries) that supply the nerves with oxygen and nutrients.
Chronic liver disease, thyroid dysfunction, hepatitis, liver cirrhosis, and alcohol abuse may also alter haptic perception and impair an individual’s ability to perceive tactile stimulation.
Although the exact location of a tactile impairment may be small, the consequences of the impairment may result in further damage to the skin (and further exacerbation of the impairment in perception). Since pain reception can be altered by a variety of skin conditions, the inability to perceive painful stimuli can prevent a person from avoiding or mitigating potentially harmful skin contact (such as touching a hot stove). Further loss of touch can impair motor skills. An inability to accurately perceive kinesthetic feedback from the legs can impair walking, whereas an impairment to haptic slip perception can impair a person’s ability to grasp and manipulate objects.