Complications Arising from Spinal Manipulative Therapy in New Zealand

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RESEARCH REPORT

Complications Arising from Spinal Manipulative Therapy in New Zealand Darren A Rivett Peter Milburn Key Words Manipulative therapy, spine, complications, survey.

Summary Complications arising from spinal manipulative therapy applied by physiotherapists have received scant attention in the literature. Published investigations and case studies have predominantly reported adverse outcomes of chiropractic and medical manipulative intervention. The present study aimed to explore the extent and range of serious spinal manipulative complications in New Zealand caused by physiotherapists and other health professionals. A further aim was to determine whether a prospective study of this problem was warranted. A questionnaire was posted to all neurologists, neurosurgeons, orthopaedic, and vascular surgeons throughout the country (n = 230) asking them to describe any complications arising from spinal manipulative therapy witnessed in the previous five years. The response rate was 63% (n = 146) with 42 incidents reported. Cervical spine complications accounted for 62% of the total, including 14 cerebrovascular accidents of which at least two involved the carotid artery system. Physiotherapists were responsible for one-third (14) and chiropractors for more than half (23) of all complications. These findings indicate that serious complications arising from manipulative physiotherapy may constitute a hitherto unrecognised substantial proportion of all spinal manipulative complications. Further research seems justified using a prospective study design to ascertain the incidence rate of particular complications and identify hazardous techniques.

Introduction The health science literature is replete with case reports of complications resulting from the therapeutic application of passive joint manipulation of the spine, in particular after high velocity thrust procedures. Serious adverse responses including cerebrovascular accidents (CVA),disc rupture, radiculopathy, myelopathy, cauda equina syndrome, fracture and dislocation have been described, most frequently as a consequence of chiropractic intervention (Dvorak et al, 1993; Grieve, 1994; Hurwitz et al, 1996; Lee et al, 1995; Patijn, 1991; Terrett, 1987). Conversely, instances of serious complications following physiotherapeutic manipulation are relatively infrequently reported, implying that such unfavourable out-

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comes are quite rare in manipulative physiotherapy or are not reported. Furthermore, there are very few studies which have investigated the occurrence and nature of adverse responses related t o the application of manipulation t o the spine by physiotherapists. Michaeli (1993) surveyed 153 manipulative physiotherapists in South Africa in a retrospective study exploring complications following spinal mobilisation and manipulation (high velocity thrust). Respondents were asked to describe any such incidents experienced during their manual therapy career. There were 52 complications reported for approximately 228,050 manipulative procedures applied, with 92% involving cervical spine manipulation. In addition, a further 129 adverse responses following cervical spine mobilisation were described. Most notably one CVA and six cases of brachialgia with neurological deficit were attributed t o cervical spine mobilisation, with another case of brachialgia with neurological deficit resulting from cervical spine manipulation. One case of sciatica with neurological deficit followed lumbar spine manipulation and two cases of fractured ribs were reported following manipulation of the thoracic spine. However, if the retrospective nature of the study design (with associated recall bias) and other sources of bias are considered, it seems likely these findings under-report the situation (Rivett, 1995). A recent study (Rivett and Milburn, 1996) piloted a prospective study design for documenting adverse responses to cervical spine manipulation experienced by manipulative physiotherapists in New Zealand. Only one minor and no serious complications were described following nearly 500 manipulations. Thus, both this investigation and that of Michaeli (1993) further reinforced the impression that serious manipulative complications are rarely encountered in physiotherapy. The findings of these studies, however, are in contrast t o the results of an investigation of neurologic complications following chiropractic manipulation (Lee et al, 1995). In California, 127 neurologists responded to their survey in which they were asked to document neurologic complications witnessed in the preceding two years consequential to chiropractic spinal manipulation. For this period 56 strokes, 16 myelopathies and 30 radiculopathies were reported, with 76% of

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the non-vascular complications attributable t o cervical spine treatment. The number and nature of adverse responses uncovered in their study is alarming, especially since other types of serious complication, such as fracture or dislocation, were not sought. Thus, while it is clear that there is a distinct lack of research pertaining to the nature and extent of serious complications associated with spinal manipulative physiotherapy, evidence t o date suggests that such events are rare and may be of more concern t o other manipulative professions. Nevertheless, further investigation is needed before such a premise can be fully accepted. With mounting evidence supporting the benefit of manipulation in the alleviation of spinal pain (Hurwitz e t a l , 1996; Koes et al, 1996; Twomey and Taylor, 1995), it has become increasingly obvious further research is needed as to the possible consequences of this intervention. Specifically, a more complete understanding of the extent and nature of these incidents in physiotherapy practice is crucial with respect to issues of informed consent and collaborative clinical decision making (Delany, 1996). The aim of this study was therefore to explore the types of complication resulting from spinal manipulative therapy and to determine the extent that physiotherapy is responsible for such unfavourable outcomes in New Zealand. As no published studies of manipulative complications in New Zealand attributable t o other professions were found, it was decided to investigate adverse responses from all manipulative professions, as this would help place physiotherapy in perspective relative t o other disciplines. An additional aim was t o determine whether the size of the problem warrants further research using a prospective study design in order t o ascertain the incidence rate of specific complications in physiotherapy.

Method Consistent with the exploratory nature of the investigation a descriptive study design using a postal survey was employed.

Subjects Medical specialists likely to encounter the consequences of serious complications of spinal manipulative therapy were selected. The medical specialties chosen were neurology, neurosurgery, orthopaedic surgery and vascular surgery. The sample approached consisted of all specialists in these fields resident in New Zealand. This group was chosen as it serves as a catchment for such adverse responses. Furthermore, as the specialists were not responsible for the incidents, it was

considered that they would not be restricted o r inhibited in their reporting. Their expertise might also be of advantage in describing specific cases.

A total of 230 medical specialists were invited to participate in the study. Names and addresses of 143 orthopaedic surgeons, 37 vascular surgeons and 13 neurosurgeons were obtained from the Medical Council of New Zealand register. Details of 37 neurologists were provided by the Neurological Association of New Zealand.

Instrument and Procedure A questionnaire was designed based on a review of the literature pertaining to the nature and incidence of complications following spinal manipulative therapy. Introductory covering letters were included, explaining the rationale for the study and inviting the medical specialists t o participate by completing the enclosed questionnaires. There were two parts t o the survey documents. The first part asked the participants to nominate their field of medicine and t o indicate the number of cases of spinal manipulative complication personally encountered in the previous five years. It was considered that the iatrogenic nature and relative rarity of such cases would facilitate their recall. Manipulation was defined as any passive, manual therapy procedure applied to the spine, including both high velocity thrust and slower oscillatory techniques. If the participant had witnessed the outcome of a n unfavourable spinal manipulation in the designated period, then a copy of the second part of the questionnaire was to be completed for each case. The second section of the questionnaire asked for particular details of the case including type of complication, spinal region manipulated, health professional responsible, and final outcome of the complication. In addition, demographic data about the patient including age, sex and year of presentation were required. This information was used (in addition to case details) to minimise the possibility of data duplication by cross-checking all cases in an effort to ensure the same case was not included twice in the results. Closed-ended questions requiring a simple tick were used, although provision was made for further comment and other response options. This design was regarded as minimising the time needed t o complete the questionnaire and therefore possibly facilitate a satisfactory response rate. Four copies of the second part of the questionnaire were included with the instruction to make additional copies if required, or to contact the investigators for further copies. A self-addressed stamped envelope was provided t o encourage return of the survey. A numerical

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code was marked on the envelope for the purpose of enabling distribution of a follow-up questionnaire t o those specialists failing t o return the documents within four weeks. The anonymity of the patients involved in the reported cases was preserved, as was the participants' confidentiality. Approval for the study was granted by the Ethics Committee of the University of Otago. Responses were collated and descriptive analysis of the data undertaken.

Results Results of this survey will be reported in terms of the nature and number of complications arising from spinal manipulative therapy.

Response Following the original posting of questionnaires, 106 surveys were returned providing an initial response rate of 46.1%. Following distribution of a reminder letter t o non-respondents, a further 40 replies were received. Therefore, of the 230 medical specialists invited t o participate, 146 replied, giving an overall response rate of 63.5%. These respondents were distributed as follows: 25 neurologists, 8 neurosurgeons, 88 orthopaedic surgeons, 24 vascular surgeons and one unspecified. Twenty-three specialists (16%) reported cases that could be included in the analysis. A further eight practitioners (5%)described 23 cases which were excluded from the analysis as they either pre-dated the designated reporting period, were undated, or lacked sufficient data to preclude the possibility of duplication. Seventy-six participants (52%)indicated they had not encountered any manipulative complications in the five-year period. A further 16 respondents (11%) had either retired or worked overseas during the past five years, or practised in sub-specialties that were not relevant, such as paediatric neurology or hand surgery. The remaining 23 respondents (16%) indicated they could not gain access t o medical records or could not remember details of cases. Reported Cases Forty-two cases of complications resulting from spinal manipulative therapy were reported by 23 medical specialists. Twelve orthopaedic surgeons described 25 cases, with eight neurologists reporting a further 13 incidents and two neurosurgeons detailing two complications. The remaining two reports were provided by a vascular surgeon. The average age of the patients was 46 years (range 21 t o 79). Patients were equally distributed between male and female (20 and 21 respectively, with the sex of one patient unspecified).

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Fig 1: Number of complications by health profession

The health professions held responsible for the manipulations resulting in complications are described in figure 1.More than half of the incidents (23 cases) resulted from chiropractic treatment with a further one-third (14 cases) due to physiotherapy. No cases were reported related to the intervention of a medical specialist. The types (and respective numbers) of complications encountered in each spinal region are indicated in the table. Well over half (62%) of the adverse responses related t o cervical spine treatment. One-third of cases were CVAs, with a similar proportion involving radiculopathies (including those in association with a disc prolapse).' Types and numbers of complications by spinal region Cervical

Thoracic

Lumbar

14 CVA Radiculopathy 7 Disc prolapse 3

Myelopathy Fracture Disc prolapse

Increased pain 2

Increased pain 1

Radiculopathy Disc prolapse Disc prolapse + radiculopathy Unknown

Total

Total

Total

26

3 1 1

6

3 3 3 1 10

Respondents sometimes volunteered additional information if they considered there was a lesson to be learnt from an incident. The importance of clinically recognising contra-indications to manipulative therapy was illustrated in several cases. In one instance cervical spine manipulation was applied in the clear clinical presence of vertebrobasilar insufficiency (VBI), in which a second manipulation was undertaken despite the provocation of hemiparaesthesia by the initial manipulation. Furthermore, in three cases complications arose from manipulative therapy applied t o the spine in the presence of undiagnosed malignancies o r unknown metastases. Manipulative treatment to the thoracic spine in two such cases (one instance of multiple myeloma and another of metastasis from prostate cancer) led to myelopathy.

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20

18 16 14

6 4 L

0

Spontaneous resolution

Resolution with intervention

Improving

Incomplete resolution

Permanently disabled

Fig 2: Reported outcomes of complications

The reported outcomes of all complications are described in figure 2. No deaths were reported, but the incident resulted in long-term adverse effects in 43%of cases. These ranged from sensory deficits and chronic pain to paraplegia and hemiparesis. Surgical intervention, most notably discectomy, was necessitated in some cases.

Cerebrovascular Accidents The cases of neurovascular complications form an interesting subgroup. Neurologists reported 11 incidents, vascular surgeons two cases and a neurosurgeon the remaining case. The average age of these patients was 41 years (range 26 t o 64 years) and there was a predominance of males (nine men compared with five women). Of the 14 cases reported, chiropractors were responsible for nine complications, osteopaths for two complications, and one case resulted from treatment applied by a general practitioner. Physiotherapists accounted for the other two CVAs. Two of the cases were identified as resulting from damage to a carotid artery and eight were in the vertebrobasilar distribution (in four cases, the traumatised artery was not indicated). In nine cases, resolution of the complication was incomplete with seven patients described as permanently disabled. In the other five instances, there were two cases of spontaneous resolution and two of resolution with intervention. One patient was still improving a t the time of the survey. Interestingly, in one case with angiographic evidence of vertebral artery dissection, the manipulative treatment had preceded the stroke by three weeks.

Physiotherapy Complications In addition t o the two CVAs reported, physiotherapists were responsible for six cases of radiculopathy, two cases of disc prolapse and one case of disc prolapse with radiculopathy. There were also three instances of significantly increased pain. Of the total of 14 physiotherapeutic complications, ten resulted from cervical spine manipulative therapy, with one related to thoracic treatment and three to lumbar spine procedures. Without knowledge of the number of patients treated or the number of manipulations applied, the incidence of complications arising from spinal manipulation could not be determined.

Discussion The findings of this study indicate that all manipulative health professionals are at risk of causing serious complications from spinal manipulative therapy. However, of particular concern was the sizeable portion attributable t o manipulative physiotherapy. This is surprising as there are very few cases reported in the literature describing such complications in which physiotherapy treatment was implicated (Fritz et a l , 1984; Grant, 1988; Michaeli, 1993; Parkin et al, 1978; Patijn, 1991; Rivett and Milburn, 1996). In a recent literature review of 118 cases of complication following manual therapy of the cervical spine, physiotherapy is not specifically described but probably accounted for some of the 19 ‘otherhnknown therapist’ cases cited (Hurwitz e t aZ, 1996). The present study alone has identified a further ten instances of complications of manipulative physiotherapy applied to the cervical spine. This suggests that

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serious complications of spinal manipulative physiotherapy may be significantly more frequent than the literature indicates. As contended by Rivett (1995), reliance on published case studies alone is likely to lead to a marked underestimation of the extent of the problem. Is the occurrence of manipulative physiotherapy complications therefore of greater concern in New Zealand than elsewhere? Unfortunately, as only data pertaining t o South Africa are available (Michaeli, 19931, this question cannot be answered with any degree of certainty. Physiotherapy education in New Zealand has traditionally had a strong emphasis in manipulative therapy and postgraduate courses in this field have been available for nearly thirty years, including more recent university programmes in manipulative physiotherapy. As a result it may be that physiotherapists in this country use spinal manipulative therapy procedures t o a greater extent than do other physiotherapists with different educational backgrounds, and are therefore more likely t o experience related complications. Indeed, in 1994 approximately 20% of registered physiotherapists in New Zealand worked in the field of manual o r manipulative physiotherapy (NZHIS, 1996). However, the number and type of serious physiotherapeutic complications reported in the present study are somewhat similar t o those found in South Africa by Michaeli (1993). The response rate for the present study compares favourably with the 61.2% response rate attained by Michaeli (1993) in his survey of physiotherapists in South Africa. It is substantially higher than the 36% response rate achieved by Lee et a1 (1995) in their survey of Californian neurologists. High response rates in surveys of medical practitioners are notoriously difficult to achieve and the 63.5% in the present study represents a very good return (Dvorak et a l , 1993). This may partially reflect the concern of some of the medical specialists about the size of the problem. It should also be considered that the non-respondents may differ in some way from those who did reply. For example, they may not have encountered as many manipulative complications and might therefore consider the issue was not of importance. However, it is noteworthy that specialists from all four medical fields surveyed reported cases. The range of medical specialists witnessing these cases indicates that the study by Lee et al (1995) reflected a marked underestimation of the extent of the problem, as it was limited t o neurologists and neurological complications. In fact, orthopaedic surgeons reported over half of the adverse responses described in the present study, while by contrast neurologists contributed fewer than a third.

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Consistent with other investigations, the bulk of the reported complications were related to manipulative therapy of the cervical spine (Lee et a l , 1995; Michaeli, 1993; Patijn, 1991). It appears that this region of the spine is particularly liable t o complications resulting from manipulative therapy, most notably WAS. The risk of neurovascular complications has recently been highlighted in the physiotherapy literature (Delany, 1996; Grant, 1996; Rivett, 1995,1997), as well as in the medical literature (Hurwitz et al, 1996; Lee et al, 1995; Patijn, 1991) and chiropractic literature (Carey, 1993; Dabbs and Lauretti, 1995; Klougart et al, 1996). In the present study more than half of cervical spine complications were neurovascular. In addition, considering the findings of the present study, the risk of intervertebral disc trauma and radiculopathy in both the cervical and lumbar spine regions appears to be of greater consequence than is reflected in the physiotherapy literature. The three cases of myelopathy and ensuing permanent disability resulting from chiropractic thoracic spine manipulation also suggest that procedures applied to this region warrant careful scrutiny. In several cases there was underlying pathology that predisposed the patient to a n adverse response t o manipulative therapy. Instances of undiagnosed malignancies, VBI and osteomyelitis emphasise the need for a systematic and thorough clinical examination t o determine such contraindications prior to the application of treatment. However, it is uncertain whether the contra-indications in all these cases could have been detected clinically and complications averted. It should be acknowledged that with certain manipulative procedures there will always be a slight risk, although it can be reduced with careful clinical screening. The results of this survey cannot be used to determine accurately the incidence rate for any particular type of complication nor for any one profession. However, considering that New Zealand has a relatively small population (3.5 million), the number of serious complications reported in the last five years could suggest the incidence rate of some manipulative complications may well be higher than previously proposed (Hurwitz et al, 1996; Klougart et a l , 1996; Rivett, 1995). Furthermore, the findings of this study are likely to represent an underestimation of the true number of incidents as only about two-thirds of medical specialists approached actually participated, and of those responding, 12 commented that they regularly encountered such cases but could not provide enough detail for inclusion in the present study.

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Strokes CVAs constituted the largest sub-group of compli-

cations and are worthy of further discussion. This sub-group accounted for half of the total cases where resolution of the complication was incomplete. In fact, half the patients suffering CVAs were left permanently disabled. The average age of these patients was 41 years, which is consistent with the findings of Terrett (19871, and the average age of 37 years reported by Grant (1988). The predominance of males in the sample has not been reported elsewhere. Of some interest are the two cases of neurological ischaemia in the distribution of the carotid system. While undoubtedly the vast majority of neurovascular complications are due to vertebral artery trauma, there is some evidence which suggests the internal carotid artery is also a t risk (Refshauge, 1994; Rivett, 1997). Furthermore Lee et al (1995) determined t h a t the carotid system was implicated in approximately 5% of cases of stroke following chiropractic manipulation. Following a survey of the Stroke Council of the American Heart Association, it was reported that one-third of 360 previously unreported cases of extracranial arterial trauma involved carotid artery injury (Robertson, 1982). There are also case reports in the literature of iatrogenic CVAs in the carotid distribution (Beatty, 1977; Jumper and Horton, 1996; Peters et a l , 1995). Therefore, the risk of neurological deficit following manipulative trauma t o the internal carotid artery appears to merit further investigation. The two instances of CVAs consequent t o manipulative physiotherapy are of concern, as premanipulative testing for VBI (APA, 1988) has been a n accepted part of clinical practice and education in New Zealand throughout the fiveyear reporting period. Furthermore, these two cases were in addition to another CVA in New Zealand resulting from the application of cervical spine manipulation by a physiotherapist during the designated reporting period for the present study (Rivett and Milburn, 1996). Three such instances of manipulative stroke in a five-year timespan in a relatively small physiotherapy community raise doubts as t o the sensitivity of the pre-manipulative testing protocol (APA, 1988) in detecting patients at risk.

Limitations There are some limitations of the study. First, the results probably represent an underestimate of the true number of complications due t o the response rate and the retrospective nature of the study design (with associated recall problems). Indeed, some practitioners indicated they had witnessed manipulative complications but were not able to provide enough detail due to difficulty

in accessing patient records. If this was likely to be a tedious process it would probably also act as a disincentive t o reporting. In addition, minor complications (such as fleeting dizziness or minor exacerbations) are unlikely to be brought t o the attention of medical specialists. Therefore the data cannot be used to calculate precise incidence rates. Secondly, determination of the cause and effect relationship was left to the expert judgement of the medical specialists, which is normal clinical practice with such cases. However, it is possible that some outcomes (eg disc prolapse, radiculopathy) may have manifested as part of the progression of the patient’s disorder or were due t o spontaneous onset and were not caused by manipulative therapy. Finally, the term ‘disabled’ was not defined and was open to individual interpretation by the clinicians. Despite these limitations, the present study addresses several deficiencies in our knowledge of manipulative complications. So far as the authors are aware, it is the first study of its kind in which independent witnesses (ie not responsible for the onset of the adverse reaction) have reported complications attributable to physiotherapists. Furthermore, it is the only investigation in the manipulative literature in which specialists in all four pertinent fields of medicine (neurology, neurosurgery, orthopaedic surgery and vascular surgery) have been surveyed, therefore providing a more complete and accurate picture of the extent and range of such complications. In addition, this is the first published survey of adverse responses t o manipulative therapy conducted in New Zealand, a country with well established postgraduate education in manipulative physiotherapy.

Conclusion The results of this survey of medical specialists have demonstrated that spinal manipulative therapy may have a wide range of serious complications, some with permanent outcomes. The greatest risk appears to be related to procedures involving the cervical spine, most notably for stroke and radiculopathy. Chiropractic and physiotherapy accounted for the bulk of adverse responses. The relative risk for each profession cannot be determined from the findings of this study. Nevertheless, the number of serious complications reported in a sparsely populated country such as New Zealand is alarming. Several cases described in the present sample illustrate the importance of a thorough clinical examination in detecting contra-indications to spinal manipulative therapy. On the other hand, some doubt is

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cast over the validity of current premanipulative tests for VBI in the prevention of neurovascular incidents. I n addition t o the vertebral artery, attention is drawn t o the risk of trauma t o the internal carotid artery. This study h a s provided enough evidence of serious complications consequent to spinal manipulative physiotherapy t o indicate further investigation of this problem is warranted. A prospective study is urgently needed in order t o calculate the rate of incidence of specific complications and t o identify the techniques which are associated with unacceptable risk, particularly involving the cervical spine. Acknowledgments The authors wish to acknowledge the help of Sara Drum, Dorothy Jamieson and Blair Martin in the distribution of the questionnaire.

Authors Darren A Rivett MAppSc(ManipPhty) GradDipManTher BAppSc(Phty) and Peter Milburn PhD are senior lecturers in the School of Physiotherapy, University of Otago. This article was received on February 20,1997, and accepted on July 7, 1997. It reports work by Darren Rivett towards his PhD for which Peter Milburn is a supervisor.

Address for Correspondence Mr D A Rivett, School of Physiotherapy, University of Otago, PO Box 56, Dunedin, New Zealand.

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