Polyneuropathy, the condition that led to the death of Cincinnati Reds legend Joe Morgan, is a common form of a group of disorders known as peripheral neuropathy.
The group of disorders causes damage to nerves beyond the brain and spinal cord. Peripheral nerves travel from the spinal cord to muscles, skin, internal organs, and glands. In polyneuropathy, multiple peripheral nerves throughout the body malfunction at the same time.
That’s a problem because peripheral nerves send many types of sensory information to the central nervous system, such as a message that the feet are cold, according to the National Institute of Neurological Disorders and Stroke.
The peripheral nerves also carry signals from the central nervous system to the rest of the body. Best known are the signals to the muscles that tell them to contract, which is how we move, but there are different types of signals that help control everything from our heart and blood vessels, digestion, urination and sexual function, to our bones and immune system.
“The peripheral nerves are like the cables that connect the different parts of a computer or connect the internet,” the institute writes in a fact sheet. “When they malfunction, complex functions can grind to a halt.”
There are three different causes for polyneuropathy: acquired, hereditary and no known cause, called ideopathic. What happened in Morgan’s case isn’t clear from his medical history. Morgan had a bone marrow transplant for leukemia and complications after a knee replacement in the last decade, according to media reports.
According to the Merck Manual, polyneuropathy can affect:
- Motor nerves (which control muscle movement).
- Sensory nerves (which transmit sensory information).
- Cranial nerves (which connect the head, face, eyes, nose, muscles, and ears to the brain).
- A combination of the above.
Treatment typically involves focusing on easing the symptoms and focusing on the underlying cause (diabetes in the case of diabetic neuropathy, one of the most common forms of polyneuropathy).
Although there are different causes of polyneuropathy, a web posting by Virginia Mason Hospital says the symptoms remain relatively constant and can include:
- Tingling or burning.
- Weakness in the arms or legs.
Some neuropathies may involve muscles used in swallowing, breathing or eye movement.
A serious but rare form of acquired polyneuropathy is Guillain-Barré syndrome, caused by the body’s immune system mistakenly attacking the peripheral nerves and damaging their myelin insulation. The late actor Andy Griffith suffered from the syndrome.