Once you have become a subscriber to one or more of these important resources it takes some time to become accustomed to search strategies and to optimize your use of these databases. One of the more important aspects of online literature searching is using the proper language or terms to ask for the information you want. On the surface this might appear simple, but in reality it can be quite complicated. For the purpose of this column, we can only superficially deal with search language. In subsequent articles, we will be able to explain this process thoroughly.
The most basic unit of search language is what the National Library of Medicine calls a Medical Subject Heading (MeSH). These MeSH terms define the vocabulary by which all information is indexed. Most health care databases (Exerpta Medica, Medline, Toxline, Nursing and Allied Health, etc.) use these headings. The chiropractic librarians' organization, CLIBCON; Canadian Memorial's Index, CRAC, and CHIROLARS use over 90 percent MeSH terms. The remaining 10 percent is a supplemental thesaurus of terms important to chiropractic.
Having a standardized language for indexing (and retrieving information) is important because authors use so many different words to express the same or similar concepts. Let's look at a few of the terms authors use for literature related to therapy for low back pain. (* = proper MeSH term)
| backache | therapy* |
| lumbalgia | care |
| low back pain* | management |
| lumbago | therapeutic intervention |
| back pain* | treatment |
By using the MeSH headings "low back pain" and "therapy," you can make a single search that will retrieve all of the articles related to the therapy of low back pain, regardless of the terms used by the author, because indexers convert all other terms to the proper MeSH term.
Most headings are very simple. Most anatomical structures are just as you might suspect; e.g., cervical vertebrae (not cervical spine), head, knee, intervertebral disc and hand. With subscriptions to online systems, a list of these headings are either provided free of charge or for a reasonable fee (as in the National Library of Medicine's MeSH heading book).
In view of the American Heart Association's recent claim that the danger of cervical manipulation was "small but significant" (Dynamic Chiropractic, March 11, 1994), let's look at articles related to the dangers of manipulation. This is a somewhat complex online query. Normally a single heading would be used to find information, however MeSH has a number of inconsistencies. If we are searching for articles about the adverse effects of adjustments or spinal manipulation, NLM uses the term "manipulation, orthopedic" if it involves manipulation by an osteopath, physical therapist or medical physician. The term can be coupled with the subheading "adverse effects." However, for chiropractic adjustment there is no MeSH term, and the NLM will usually call such chiropractic adjustments or manipulative procedures "chiropractic-methods." So, to find all articles related to the adverse effects of manipulation, one would look for "adverse effects" and "manipulation, orthopedic" or "chiropractic-methods." (Note that we use "adverse effects" and not complications." This is because NLM uses "adverse effects" in relation to treatment and "complications" in relation to diseases.) Fortunately, most searches are much more straightforward. When using this search strategy in CHIROLARS, we find approximately 2,500 articles dealing with manipulation, orthopedic and approximately 200 articles related to the adverse effects of manipulation, orthopedic.
One of the most interesting articles located was: Dvorak, T; Baumgartner, H; Burn, L; et al. Consensus and recommendations as to the side-effects and complications of manual therapy of the cervical spine. Journal of Manual Medicine 1991; 6: 117-8.
This article was a consensus process conducted by some of the leading medical advocates of spinal manipulation in Europe. They naturally began with a review of the literature, which cited previous morbidity studies where neurologic complications occurred once in every 400,000 high velocity manipulations of the cervical spine. The authors discuss contraindications of cervical manual procedures. They note: "Side effects and complications, especially the frequency, could be reduced by: proper diagnosis, helping to identify the absolute and relative contraindications for manual treatment; [and] recognition of index of suspicion." Other studies placed the risk of serious adverse effects from cervical adjustments at one in a million or less. Clearly spinal manipulation is relatively safe when compared to alternative drug and surgical interventions.
Ronald Rupert, MS, DC
Lake Dallas, Texas