(See also Overview of the Peripheral Nervous System Overview of the Peripheral Nervous System The peripheral nervous system refers to the parts of the nervous system that are outside the central nervous system, that is, those outside the brain and spinal cord. Thus, the peripheral nervous... read more .)
Hereditary neuropathies may affect only
Motor nerves control muscle movement, and sensory nerves carry sensory information—about such things as pain, temperature, and vibration—to the brain. Autonomic nerves Autonomic nervous system The peripheral nervous system consists of more than 100 billion nerve cells (neurons) that run throughout the body like strings, making connections with the brain, other parts of the body, and... read more regulate involuntary body process.
Some hereditary neuropathies are relatively common but often are not recognized.
The genes responsible for many hereditary neuropathies have been identified. These neuropathies include
Hereditary neuropathy with liability to pressure palsies Hereditary Neuropathy With Liability to Pressure Palsies (HNPP) Hereditary neuropathy with liability to pressure palsies is a hereditary disorder in which nerves become increasingly sensitive to pressure, injury, and use. In this disorder, nerves are easily... read more
When the sensory nerves are affected, the ability to feel pain and changes in temperature may be impaired more than the ability to sense vibration and position (knowing where the arms and legs are). The hands and feet are affected most. Because people cannot feel pain, they may injure their feet and not know it. Such injuries increase the risk of infections, including bone infections, and risk of joint damage (called neurogenic arthropathy Neurogenic Arthropathy Neurogenic arthropathy is caused by progressive joint destruction, often very rapid, that develops because people cannot sense pain, continually injure joints, and thus are not aware of the... read more , or Charcot joints). If the ability to sense vibration and position is affected, people have problems with balance and walking.
When motor nerves are affected, muscles weaken, waste away (atrophy), and can become completely paralyzed.
When autonomic nerves are affected, body processes do not function normally. For example, blood pressure may decrease when a person stands (called orthostatic hypotension Dizziness or Light-Headedness When Standing Up In some people, particularly older people, blood pressure drops excessively when they sit or stand up (a condition called orthostatic or postural hypotension). Symptoms of faintness, light-headedness... read more ), making the person feel dizzy or light-headed. Men may have difficulty initiating and maintaining an erection (erectile dysfunction). People may involuntarily pass urine (urinary incontinence Urinary Incontinence in Adults Urinary incontinence is involuntary loss of urine. Incontinence can occur in both men and women at any age, but it is more common among women and older people, affecting about 30% of older women... read more ) or have difficulty emptying the bladder (urine retention Urinary Retention Urinary retention is inability to urinate or incomplete emptying of the bladder. People who have incomplete emptying of the bladder may have urinary frequency or urinary incontinence. If the... read more ). Some people are severely constipated.