Causes of Paralysis:

Paralysis occurs when communication between the brain and spinal cord fails.

Paralysis is caused by:

Injury to neurons in the brain (a stroke), or in the spinal cord. Trauma to the spinal cord affects only the areas  below the level of injury.
Poliomyelitis (a viral infection)
Lou Gehrig's disease (ALS, amyotrophic lateral sclerosis) can affect neurons in the entire spinal cord, resulting in  paralysis.
Botulism
Spina bifida
Multiple sclerosis
Guillain-Barré syndrome
Drugs that interfere with nerve function, such as curare, can also cause paralysis.

How do I know if there was Medical Malpractice?

Paralysis may be related to medical malpractice in any of a number of ways, including surgical errors, birth injuries, misdiagnosis, or other situations where a doctor, surgeon or other medical professional fails to timely and proper care or acts in a negligent manner.