Many medical conditions change the function, structure or blood flow in the brain. For example in a hemorrhagic stroke, a blood vessel in the brain leaks or ruptures, which deprives the brain tissue of oxygen and nutrients.
In another example, chronic pain leads to frequent, strong pain signals over a long period of time. This abnormal “nerve traffic” produces changes in the brain: causing the cortex to get “imprinted” with the pain signal. This results in the person experiencing pain even after the original cause of the pain has been repaired, and it also sensitizes them to pain in general.
Acupuncture can play an important role in helping the brain self-repair. Many hi-tech studies using ECG’s, EEG’s, and near-infrared spectroscopy have shown changes in the brain due to acupuncture needle manipulation. Furthermore it was discovered that acupuncture triggers the release of opiod pepetides (natural pain killers) in the central nervous system.
(“Effects of Acupuncuture on the Brain Hemodynamics”, auton. Nuerosci. 2010 Oct.28; 157(1-2):74-80). https://www.ncbi.nlm.nih.gov/pubmed/20605114.