Another purported cause for piriformis syndrome is stiffness, or hypomobility, of the sacroiliac joints.

These causes are of two types: obstructed defecation and colonic slow transit (or hypomobility).

Hypomobility of this kind can also occur with an inflammatory disease such as ankylosing spondylitis, rheumatoid arthritis, or an infection.

Of the 22 neuromusculoskeletal dysfunction terms used in the search strategies, 6 were never used by authors or indexers (apophyseal, blockage, hypomobility, manipulable lesion, motion unit, and quality of motion.)

For example, spinal vertebral joint motion palpation tests, which aim to detect the presence of hypomobility, have face validity because they seem to be reasonable measures of the concept they are intended to measure [ 33 ] .

While palatopharyngeal incompetence and palatopharyngeal insufficiency contribute to similar symptomatology as they relate to speech and swallowing, the former results from a hypomobility or paralysis of intact anatomy that is normally responsible for effecting palatopharyngeal closure while the latter results from a congenital or acquired absence of that anatomy.