My brother has developed back spinal stenosis. what is it exactly?

Ligament hypertrophy: The ligamentum flavum runs along the back of the spinal canal; with time and degenerative damage (felt to be relatively the same mechanism of disease as osteoarthritis), this ligament gets thicker and presses in on the spinal cord. Due to the nature of the disease, however, it is relatively slowly progressive, and often responds to physical therapy and pain medications as needed.

Stenosis: Narrowing of the sinal canal causing squeezing of the nerves usually causing legpain with standing and walking the canalis narrowedas joints inthe spine enlarge arthritis as dried disc settle thedisc bilge into the canal again robbing room for nerves inthe canal the camal size we start with varies individually and shrinks with age and degeneration.

Too small a canal: It is when the canal of the spine becomes too narrow for the contents-- compressing the neural/nerve tissue to a degree causing symptoms of pain/ numbness/tingling/weakness with standing/walking better sitting or bending over. This is due usually to degenerative changes occuring over time and can be related to the size canal he was born with- smoking can accelerate these degenerative changes.