No. Braces do not change the narrowing. In the neck (cervical spine), a brace can reduce symptoms of stenosis (myelopathy) in mild cases and in those who are not candidates for surgery. In theory, a brace that flexes (bends the spine forward) the low back could reduce lumbar stenosis symptoms, but it would probably be uncomfortable to wear.
No. Spinal stenosis arises from arthritic changes in the spine, leading to spinal canal narrowing and symptomatic nerve compression. Bracing is not a widely prescribed treatment for spinal stenosis. Common options for spinal stenosis include medications, therapy services, spinal injections, and surgery.