Decades ago, electrotherapists used a paraspinal sinusoidal current to apply spondylotherapy. In more recent years, pulsating ultrasound has been investigated. But not infrequently, the relief is relatively permanent. This has been attributed to breaking a self-perpetuating reflex arc. Vagal stimulation is usually applied to increase gastric activity, intestinal peristalsis, and nasal secretions.
Phrenic inhibition is helpful in chronic cough and hiccups.
The above is typical of most studies researched. Individuals' anatomy often refuse to follow textbook models. Ask any surgeon. It is also well to keep in mind that a midthoracic spinous process, say T7, is about one level below the T7 neuromere. See Figure 1.