On this blog, we have repeatedly discussed the serious adverse effects of Spinal Manipulative Therapies (SMT) as frequently administered by chiropractors, osteopaths and physiotherapists. These events mostly relate to vascular accidents involving vertebral or carotid arterial dissections after SMT of the upper spine. Lower down, the spine is anatomically far less vulnerable which, however, does not mean that injuries in this region after SMT are impossible. They have been reported repeatedly but, to the best of my knowledge, there is no up-to-date review of such events – that is until recently.
Australian researchers have just filled this gap by publishing a systematic review aimed at systematically reviewing all reports of serious adverse events following lumbo-pelvic SMT. They conducted electronic searches in MEDLINE, EMBASE, CINAHL, and The Cochrane Library up to January 12, 2012. Article-selection was performed by two independent reviewers using predefined criteria. Cases were included involving individuals 18 years or older who experienced a serious adverse event following SMT applied to the lumbar spine or pelvis by any type of provider (chiropractic, medical, physical therapy, osteopathic, layperson). A serious adverse event was defined as an untoward occurrence that resulted in death or was life threatening, required hospital admission, or resulted in significant or permanent disability. Reports published in English, German, Dutch, and Swedish were included.
The searches identified a total of 2046 papers, and 41 articles reporting a total of 77 cases were included in the review. Important case details were frequently missing in these reports, such as descriptions of SMT technique, the pre-SMT presentation of the patient, the specific details of the adverse event, time from SMT to the adverse event, factors contributing to the adverse event, and clinical outcome.
The 77 adverse events consisted of cauda equina syndrome (29 cases); lumbar disk herniation (23 cases); fracture (7 cases); haematoma or haemorrhagic cyst (6 cases); and12 cases of neurologic or vascular compromise, soft tissue trauma, muscle abscess formation, disrupted fracture healing, and oesophageal rupture.
The authors’ conclusion was that this systematic review describes case details from published articles that describe serious adverse events that have been reported to occur following SMT of the lumbo-pelvic region. The anecdotal nature of these cases does not allow for causal inferences between SMT and the events identified in this review.
This review is timely and sound. Yet several factors need consideration:
1) The search strategy was thorough but it is unlikely that all relevant articles were retrieved because these papers are often well-hidden in obscure and not electronically listed journals.
2) It is laudable that the authors included languages other than English but it would have been preferable to impose no language restrictions at all.
3) Under-reporting of adverse events is a huge problem, and it is anyone’s guess how large it really is [we have shown that, in our research it was precisely 100%]
4) This means that the 77 cases, which seem like a minute number, could in reality be 770 or 7700 or 77000; nobody can tell.
Cauda equina (horse tail) syndrome was the most frequent and most serious adverse event reported. This condition is caused by nerve injury at the lower end of the spinal canal. Symptoms can include leg pain along the sciatic nerve, severe back pain, altered or loss of sensation over the area around the genitals, anus and inner thighs as well as urine retention or incontinence and faecal incontinence. The condition must be treated as an emergency and usually requires surgical decompression of the injured nerves.
Disk herniation, the second most frequent adverse event, is an interesting complication of SMT. Most therapists using SMT would probably claim (no, I have no reference for that speculation!) that they can effectively treat herniated disks with SMT. The evidence for this claim is, as far as I know, non-existent. In view of the fact that SMT can actually cause a disk to herniate, I wonder whether SMT should not be contra-indicated for this condition. I am sure there will be some discussion about this question following this post.
The authors make a strong point about the fact that case reports never allow causal inference. One can only agree with this notion. However, the precautionary principle in medicine also means that, if case reports provide reasonable suspicion that an intervention might led to adverse-effects, we need to be careful and should warn patients of this possibility. It also means that it is up to the users of SMT to demonstrate beyond reasonable doubt that SMT is safe.