What does "somatic dysfunction" mean?

[The following article was published in the San Diego Workers' Compensation Forum Newsletter. Osteopathic physicians frequently use the term "somatic dysfunction" to describe certain musculoskeletal diagnoses. This article was designed to explain this term to insurance adjusters and other Workers' Comp professionals.]
Patient A: 25 year-old male electrician presents with a stiff, sore neck of one day’s duration. Denies trauma. Spent previous day looking upward, pulling wires through ceiling. Started bothering him as he went to bed. Woke up not able to turn his neck.
Diagnosis: Neck sprain/strain (Somatic dysfunction: cervicothoracic junction)

Patient B: 20 year-old female visiting nurse slipped while descending staircase at a clients home. Managed to catch herself with the railing as she fell backwards, hence she did not actually strike the ground. No pain at the time, but within an hour or so, begins to feel sharp pain in the middle of the back associated with painful deep inspirations.

Diagnosis: Thoracic sprain/strain (Somatic dysfunctions: thoracolumbar junction and ribs)

Patient C: 35 year-old male construction worker bent forward to pick up a jackhammer that had been lying in a hole. Thought he felt a "tweak"/popping sensation as he stood up, but didn’t hurt. Next day, he begins experiencing aching in right side of his low back and finds he has some restricted movement in the region. No changes in his genitourinary or gastrointestinal systems, nor does he complain of radicular symptoms.

Diagnosis: Low back sprain/strain (Somatic dysfunction: lumbosacral region)

You know what a sprain/strain means – the patient did not sustain any bony injuries such as a fracture, i.e. a "soft-tissue" injury. But what about these "somatic dysfunction" diagnoses – is this doc trying to pad his bill?

No, in fact a Doctor of Osteopathic Medicine (D.O.) uses this term in an attempt to be more specific regarding their diagnoses. A sprain refers to a stretch-type injury of a ligament, whereas a strain refers to muscles and tendons. In the above mentioned examples, neither one of these mechanisms is responsible for the patients’ complaints. Rather, a mechanical restriction occurs first, which is usually followed by a reflex increase in muscle tone/spasm.

Allopathic physicians refer to this as "facet syndromes;" Chiropractors refer to them as subluxations. To osteopathic physicians, somatic dysfunction refers to impaired or altered function of related components of the somatic (body framework) system: skeletal, arthrodial, and myofascial structures, and related vascular, lymphatic and neural elements.

Recall the fact that humans are machines containing an internal skeletal supporting structure. The vertebral column contains 3 regional curves (cervical, thoracic, and lumbar), that can be easily visualized from the side. These curves are important because they help to cushion the discs and spinal cord from excessive or unexpected forces.

Sidebending a spine in its neutral posture (i.e. with curves intact) is generally well-tolerated and without ill-effects as the individual vertebral segments accommodate to the movement, as a group, and return back to their neutral postures once the movement is completed.

On the other hand, let’s say that there is a loss of normal curvature in a region when sidebending is attempted. The spinal mechanics are different. Rather than behaving as a group, a single vertebral segment must "give in" to allow for the segments above and below it to sidebend. [Try this simple experiment: fold an 8" x 11" piece of paper in half (so that it becomes 4" x 11"). Grasp the folded edge using the thumbs of both hands and attempt to bend the "spine" of the paper. You’ll observe that the paper must "kink" in order to promote bending.]

Incidentally, this "kink" doesn’t have to cause pain right away. In fact, the reflex mechanisms that kick in may not induce discomforts until 1-3 days later. Why the inspiratory rib discomforts seen with thoracic problems? This is because the rib heads articulate with the thoracic vertebral segments. If a particular segment is restricted in its motion, the adjacent rib will be affected, as well. Hence, a rib that is prevented from its normal inspiratory excursion causes pain (that often originates from the back and radiates anteriorly around the chest).

Finally, why bother using the term at all – isn’t sprain/strain still good enough for coding purposes? The reason has to do with a procedure called Osteopathic Manipulative Therapy (OMT). If a D.O. performs OMT as part of his/her overall treatment plan, a diagnosis of the appropriate regional somatic dysfunction needs to be included in order to support the need for this particular treatment modality (e.g. one wouldn’t code a laceration repair without a diagnosis of a laceration!).

Therefore, in summary, D.O.’s may list both the allopathic and osteopathic diagnoses as part of their assessments. The former to provide a sense of what is going on with the patient using conventional terminology, the latter to address billing documentation concerns.