Doctors in China have reported on a rare case of a woman who is missing her cerebellum, the part of her brain that is involved with motor control.

A 24-year-old woman was admitted to hospital and told doctors she had been dizzy and unable to walk steadily for more than 20 years. She went to the hospital after being nauseous for about a month.

She told doctors at a hospital in the Jinan Military Region in eastern China that her speech was not intelligible until she was six, and she did not go to school. Doctors noted she still had a "mild voice tremor with slurred pronunciation."

Most infants and children without a cerebellum have severe mental impairment, epilepsy, and water on the brain (called hydrocephalus).

Evidence of adults without a cerebellum is "lacking," the doctors said in a report in the August edition of the journal Brain. There are only eight other known living cases of a person missing their entire cerebellum and only one of those patients was "completely normal in neurological examinations."

In this case, however, the woman had just "mild mental retardation" and was able to learn to walk and talk, albeit at a slower pace than other children. She was married and had a daughter.

Doctors treated the woman with dehydration therapy and "non-surgical management," and she experienced "significant relief of symptoms" even at her four-year follow-up.

"If one part of the cerebellum is damaged, can another part take over?" the doctors asked in the study.

"This surprising phenomenon supports the concept of extracerebellar motor system plasticity," or the idea that other parts of the brain to take over when one area is functionally deficient.