Neuropharmacology & Neurotherapeutics
Interventional neuroradiology for neurologic disorders
Jul. 30, 2022
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Chiropractic healthcare is of interest to neurologists because it is used as a treatment for several neurologic conditions. More importantly, severe neurologic complications can result from chiropractic manipulation. No scientific basis can be found for the treatment of neurologic disorders by the technique of cervical manipulation by chiropractors. Although success has been claimed in the relief of backache, rigorously controlled studies have failed to prove the role of chiropractic manipulations in this benefit. Of concern are the serious neurologic complications resulting from cervical manipulation, of which the most important is stroke. Various recommendations are made to prevent these complications.
• Chiropractic, a nonscientific method of healthcare, is used for treatment of several neurologic disorders.
• Cervical spine manipulations are carried out for spinal problems and are claimed to benefit many other diseases as well.
• Neurologic complications can result from cervical spinal manipulation, such as compression or dissection injury of the vertebral artery, causing stroke.
"Chiropractic" is derived from the Greek word chiros, meaning "hand." It is a system of healthcare based on the relationship between the vertebral column and musculoskeletal system and on the function of various systems of the body, particularly the nervous system. The main therapeutic method is manipulation of the spine, which is not unique to chiropractic, but has been used since 400 BC and has been accepted and rejected several times over the centuries. Currently, chiropractors are the most prominent among practitioners of spinal manipulation, which include osteopaths, manual therapists, and even some physicians.
Chiropractic healthcare is of interest to neurologists because it is used as a treatment for several neurologic conditions. More importantly, severe neurologic complications can result from chiropractic manipulation.
Daniel David Palmer, a fish peddler and grocer who practiced magnetic healing, founded chiropractic in the United States in 1895. The establishment of chiropractic is related to Palmer's examination of a patient who had lost his hearing 17 years earlier when he exerted himself in a cramped and stooped position. Palmer located a painful prominent vertebra that appeared out of place. Using the reasoning that if he repositioned the vertebra the hearing might be restored, he applied a sharp thrust to the spinous process of the vertebra, and the patient's hearing improved (13). It was not explained how the acoustic nerve (contained within the cranial cavity with no connection to the spinal nerves) could be affected by spinal manipulation.
The original hypothesis of Palmer was that human disease is caused by misalignment or subluxations of bony vertebrae and adjacent structures, and that by "proper adjustment to release the pressure on the nerves caused thereby, the cause of disease is removed and the body rendered capable of natural restoration to good health." This hypothesis has remained unchanged over the past 125 years and forms the basis of modern chiropractic. Chiropractic differs from traditional medicine in that it avoids the use of pharmaceutical agents and surgery, instead relying on the body's ability to heal itself. As such, it is not a complete system of medicine but an alternative to western traditional medicine.
Neurologic complications of chiropractic manipulation have probably been occurring since the beginning of this technique, but the first report did not appear until 1925, when a patient suffered dislocation of the atlas (05). Cauda equina syndrome due to traumatic herniation of nucleus pulposus was described in 1943 (22). Stroke was first described in 1947 (66). Vascular complications were not well documented until stroke due to occlusion of the neck arteries was recognized and documented by angiography, which had become an established diagnostic procedure. Some of the cases cited in this article occurred more than 2 decades ago, but they are retained as the pattern of complications has not changed in more recent cases. This may be due to lack of any change in chiropractic technique.
Chiropractors undergo 4 years of schooling after graduation from secondary school. They learn the anatomy of the spine and detailed techniques of spinal manipulation.
Spinal examination and x-ray of the spine are frequently carried out during a patient’s initial investigation. Although imaging techniques such as CT scan and MRI can be ordered by chiropractors, they do not usually use these early in the course of management of spinal problems. In the case of backache, imaging studies are considered if the patient does not improve after a series of manipulations. Neurologic examination involves testing of cranial nerves, reflexes, and muscles, but the integration of information from this examination in the diagnosis of the patient is vague because of lack of any training in neurology.
There are about 60,000 practitioners of chiropractic healthcare in the United States but few in Europe. They are licensed as health practitioners. The United States government recognizes chiropractors as practitioners of medicine, and they can be commissioned in the United States Army. Insurance companies reimburse for some of the services performed by chiropractors. Chiropractic is now an established part of the American healthcare system, and some physicians work with chiropractors. A community-based study demonstrated a chiropractic visit rate of 41 per 100 persons and that 7.5% of the community used a chiropractor's service during a 3 to 5 year period (73). Approximately 12 million Americans undergo spinal manipulation therapy every year.
Some young chiropractors in Canada want to dissociate themselves from their colleagues. These chiropractors want to oppose the claim that their colleagues can treat numerous medical conditions by spinal manipulation. This new generation of chiropractors wants to apply modern medical research methods to spinal manipulation, hoping that will improve their standing within the healthcare community.
According to an attempted overview of reviews to elucidate and quantify the risk of serious adverse events associated with spinal manipulative therapy, it is not possible to provide an overall conclusion about the safety of this procedure; however, the types of serious adverse events that are reported is significant, indicating the presence of some risk (55). High-quality research and consistent reporting of adverse events are needed.
• Most of the chiropractic spinal manipulations are done for treatment of backache and neck pain but several other disorders are treated as well.
• There are several contraindications for spinal manipulation including herniated intervertebral discs, cervical spondylosis, and spinal cord tumors.
• There is no evidence that chiropractic manipulation cures any neurologic disorder.
• Complications of chiropractic manipulations include injuries to neural structures in the spine and stroke.
The goal of chiropractic treatment is to promote the natural healing of various diseases without the use of medicines or surgery. It is presumed that by using spinal manipulation, harmful pressure on the nerves is released.
Chiropractors claim that by manipulating the spine, they can treat a wide variety of diseases, such as asthma, ulcers, rheumatoid arthritis, high blood pressure, liver trouble, and skin disorders. The following are among the neurologic disorders treated by chiropractors: migraine, tension headaches, peripheral neuritis, herniated intervertebral discs, sciatica, and postherpetic neuralgia. The only indication for spinal manipulation that is generally recognized is low backache. Symptoms of back pain account for most of chiropractic visits.
Contraindications to spinal manipulation are:
There is no evidence that chiropractic manipulation cures any neurologic disorder. Few controlled studies have evaluated the effectiveness of chiropractic manipulation, and those available studies often lack rigorous methodology.
Backache. There is evidence of some benefit in patients with backache. A randomized study comparing the effectiveness of chiropractic versus hospital outpatient management of low-back pain was carried out in the United Kingdom over a period of 3 years (48). The study concluded that:
• Back pain often remits spontaneously.
• Chiropractic treatment seems to be more effective than hospital management, possibly because more treatments are spread over longer time periods.
• Further studies to identify the effective components of chiropractic are needed.
Chiropractic management of back pain is supported by government healthcare providers in some countries because of cost effectiveness. A Cochrane Database Systematic Review suggests that there is no clinically relevant difference between chiropractic manipulation and other interventions for reducing pain and improving function in patients with chronic low-back pain (69). However, no study has proven the mechanism of benefit of chiropractic manipulation.
Cervicogenic headache. Headache-associated flexion-extension injury of the spine is also included in this category and is often treated with cervical manipulation by chiropractors. A randomized trial was carried out at a Danish chiropractic institute to determine whether the isolated intervention of high-velocity, low-amplitude spinal manipulation in the cervical spine had any effect on cervicogenic headache (56). The control group received low-level laser and deep friction massage, including trigger points in the upper cervical region. The results suggest a possible effect of manipulation on cervicogenic headache, but because of methodological problems, such an effect could not be unequivocally demonstrated.
Visual loss. Immediate resolution of monocular visual loss after closed head trauma has been reported following spinal manipulation under general anesthesia in a 9-year-old child (26). No neurologist or neurosurgeon was involved in the care of this patient, although the recovery of vision was claimed to have been verified by an ophthalmologist. This episode illustrates that nothing has changed in chiropractic concepts during the hundred years following the cure of deafness by spinal manipulation performed by the founder of chiropractic.
Hearing loss. A condition of "vertebrogenic hearing disorder" has been described in chiropractic literature, and the manifestations are tinnitus, a feeling of ear pressure, otalgia, and deafness as symptoms of a functional deficit of the upper cervical spine. Chiropractic manipulation of the upper cervical spine is recommended as the therapy of choice, but there is no scientific evidence of its effectiveness.
Although there is a public perception that chiropractic treatments are risk-free, several complications have been reported. Spinal manipulation is part of several healing arts and even some qualified physicians perform it. Most of the complications of manipulation reported in the literature are attributed to chiropractic manipulation. Chiropractors have raised objection to this, pointing out that some of the complications reported are due to manipulation by persons with no chiropractic qualification. Another argument offered by chiropractors in their defense is the extreme rarity of these complications. Statistics are irrelevant in those cases in which it is illogical to carry out forceful manipulation of the cervical spine, which carries the risk of precipitation of the rupture and protrusion of a degenerated disc or damage to the vertebral artery.
California neurologists were surveyed to obtain an estimate of the frequency of complications of chiropractic manipulation that occur within 24 hours of the procedure (41). One hundred seventy neurologists (36% of those contacted) who responded saw the following complications during a period of 2 years: 55 strokes, 16 myelopathies, and 30 radiculopathies. Considering the large number of spinal manipulations carried out, the frequency of these complications is low, but the socioeconomic impact is considerable. Most of the patients continued to have persistent neurologic deficits 3 months after the onset, and about one half had marked or severe deficits. A similar inquiry by the Association of British Neurologists revealed 35 cases of neurologic complications occurring within 24 hours of cervical spine manipulation over a 12-month period (75). These complications included stroke in brainstem territory (7 cases), stroke in carotid territory (2 cases), acute subdural hematoma (1 case), myelopathy (3 cases), and cervical radiculopathy (3 cases). A literature review identified 165 vertebrobasilar accidents, including 29 deaths (03). Incidence of vertebrobasilar accidents ranges from 1 in 20,000 to 1 in 1,000,000 patients who have cervical manipulations. The risk of manipulating the lumbar spine appears to be low, with fractures and cauda equina syndrome being the most serious reactions.
A survey in France approached 240 neurologists, neurosurgeons, rheumatologists, and physicians to determine the number of complications of spinal manipulation over a period of 2 years (15). Responses were obtained from 133 physicians, and 93 cases of complications were reported. Sixty-nine percent of these complications were radiculopathies, and approximatively 50% of these occurred at the cervical level less than 24 hours after spinal manipulation. The incidence of vertebrobasilar strokes was 30 times higher than reported in the published literature.
Not all complications due to manipulation are reported, and many are not linked to manipulation. Review of the medical literature for deaths following chiropractic procedures revealed 26 fatalities, and the alleged pathology usually was a vascular accident involving the dissection of a vertebral artery (21). It is unlikely that all such cases would be published, and there are likely more unreported deaths. Based on current evidence, it seems uncertain whether chiropractic treatment does more harm than good. An analysis of the reported cases reveals the following risk factors associated with complications:
A classification of neurologic complications of spinal manipulation is shown in Table 1, and some of these are described in the following text.
• Compression of neural structures within the spine due to displacement or collapse of vertebrae or disc protrusion
• Intracranial hypotension due to CSF leakage from dural tear
• Spinal extradural hemorrhage
• Complications related to missed diagnosis of a spinal cord tumor or other mass
- aggravation of neurologic deficit
• Brachial plexus injuries
• Peripheral nerve injuries
- vertebrobasilar ischemia
• Ocular complications of cervical manipulation
- loss of vision due to occlusion of the central retinal artery
• Traumatic aneurysm of the internal carotid artery
• Vertebral arteriovenous fistula
Radiculopathy. Isolated injuries to spinal nerves following chiropractic manipulation are reported infrequently and are often attributed to preexisting degenerative disease of the spine. A case of bilateral phrenic nerve palsy has been reported following chiropractic manipulation of the cervical spine (79). The patient became acutely dyspneic, and paralysis of the phrenic nerves was confirmed by fluoroscopy and electrophysiologic studies. In another case of phrenic nerve injury due to chiropractic manipulation, breathing difficulty persisted several months after the episode (71). In another case a healthy man developed bilateral paralysis of both diaphragms due to bilateral phrenic injury following chiropractic manipulation of cervical spine for neck pain (36).
Damage to neural structures within the spine. This may occur due to herniation of a degenerated nucleus pulposus, vascular compression, or hemorrhage or fracture of the vertebral column. The following case reports illustrate some of these complications.
A man who underwent spinal manipulation for recurrent sciatica 4 years after chemonucleolysis developed bilateral sciatica with urinary hesitancy. Myelography demonstrated a total block, and he underwent urgent discectomy with an excellent result 3 months after surgery (64).
Another man with a history of lumbar osteomyelitis underwent spinal manipulation for neck pain. Therapy continued for 3 weeks despite the development of severe quadriparesis. He underwent the removal of necrotic bone, the removal of an epidural abscess, and an urgent anterior cervical decompression with partial neurologic recovery (64).
Four patients were reported with cervical myelopathy or radiculopathy, or both, caused or aggravated by spinal manipulation (58). In 1 patient, magnetic resonance scans before and after chiropractic treatment strongly suggested that the disc prolapse syndrome experienced by the patient was provoked by the spinal manipulation.
Balblanc and colleagues report a case of injury to the conus medullaris after lumbar vertebral manipulation (04). No extruded disc fragment was demonstrated. The neurologic manifestations in this patient were consistent with compression of the arterial supply of the conus medullaris by a small L4-L5 disc herniation.
A patient with a long history of low back pain, who was also on anticoagulant therapy, developed partial cauda equina syndrome with lower extremity paresis and urinary retention following chiropractic manipulation of the lower spine (74). CT and MRI scans showed an epidural hematoma at the L3 level, which was treated by laminectomy and evacuation of hematoma, but there was only partial recovery of the neurologic deficit.
A 45-year-old woman developed complete paraplegia following a chiropractic manipulation of the thoracic spine (45). CT showed a calcified disc herniation at the T8-T9 level without spinal cord compression, and MRI revealed a diffuse spinal cord ischemia from T6 to the conus medullaris. Vascular injury was the cause of neurologic deficit.
Cervical spinal cord injuries may occur in the absence of demonstrable vertebral or cervical disc lesions, likely due to compromised arterial blood supply during cervical manipulation. Neurologic symptoms occurring a few hours following manipulation of the cervical spine with high-velocity low-amplitude technique have been documented in a case report (08). MRI of the cervical spine revealed intramedullary high signal at the C2-C3 level of the right side of the cervical cord on the T2-weighted images.
A patient with neck pain and tingling in the hand but negative neurologic examination was referred by an internist to a chiropractor without an MRI study and became quadriplegic following manipulation of the neck (18). Despite undergoing an emergency C5-C6 anterior cervical diskectomy/fusion for a massive disc prolapse found on the MRI, the patient remained permanently quadriplegic and was awarded damages in a medicolegal case. All experts in the case on both sides agreed that the patient probably had a bulging cervical disc that acutely herniated due to chiropractic treatment.
Spinal extradural hemorrhage. There are several case reports of spinal extradural hemorrhage in the older literature. There is a case report of hemiplegia due to a spinal extradural hematoma following cervical spine manipulation performed for acute neck pain (44). Another case of thoracic spinal extradural hematoma followed spinal manipulative therapy in the absence of predisposing factors (42).
Intracranial hypotension. This is a well-recognized cause of orthostatic headache that arises due to CSF leak from meningeal diverticula or dural perforations. A patient developed intracranial hypotension following chiropractic cervical spine manipulation, and magnetic resonance imaging demonstrated dural leakage at cervical level (53). In another case, cervical spinal manipulation produced a remote lumbar dural tear leading to intracranial hypotension (65). In another case of subacute cervical cerebrospinal fluid leak resulting from chiropractic manipulation of the cervical spine, the patient presented with severe orthostatic headache, nausea, and vomiting (40). MRI revealed a new C5-C6 ventral CSF collection. A patient developed intracranial hypotension with severe postural headache, tinnitus, and nausea after chiropractic manipulation of the cervical spine because of cervical pain; cervical MRI revealed a large posterior dural tear at the level of C1-2, which was repaired with epidural blood patch followed by rapid recovery (77). Yet another case is reported of intracranial hypotension due to dural tear provoked by chiropractic manipulation of a calcified disc protrusion, which required surgical intervention as definitive treatment (84).
Complications of missed diagnosis of spinal cord tumor or other mass. An infant with congenital torticollis underwent chiropractic manipulation, and within a few hours had respiratory insufficiency, seizures, and quadriplegia. In surgery, a spinal cord astrocytoma (one that had undergone extensive necrosis due to manipulation) was found and resected with neurologic improvement (72).
One patient with backache due to undiagnosed paraspinal and epidural abscess developed complete paraplegia following chiropractic manipulation. Diagnosis was delayed but eventually established by MRI, and a laminectomy was performed with partial recovery of neurologic function (81).
Stroke. This is the most frequent complication and is nearly always associated with neck manipulation. It has been estimated that 1 in 20,000 cervical spinal manipulations cause a stroke (70).
Injuries and strokes related to the vertebrobasilar arterial system. It is estimated that vertebral artery dissection is the cause of at least 20% of ischemic strokes in younger persons (07). Cerebral and brainstem ischemia following rotational head movements is well known. It is mainly related to chiropractic manipulation but may also occur after a fall, hyperextension of head, or spontaneous head turning. Anatomically, 3 situations can produce extraluminal vertebral artery compression on head turning:
(1) Compression by skeletal muscles and fascial bands where the artery enters the transverse foramen at C6.
(2) Compression by osteophytes when the artery is within the transverse foramina.
(3) Compression or elongation of the artery by sliding structures of the atlantoaxial joints.
The population at risk cannot be identified in most of the cases, but some known risk factors for the development of stroke after neck manipulation are:
• Atlanto-occipital instability. Hemodynamic causes of vertebrobasilar ischemia after neck motion are well known in patients with such instability. A child with atlantoaxial instability was reported to have recurrent stroke when the vertebral artery was stretched and occluded at the atlantoaxial by neck rotation during chiropractic manipulation (25).
• Patients with a history of transient neurologic symptoms during previous manipulation.
• Patients with a history of vertebrobasilar insufficiency.
• Patients with atherosclerosis of the vertebrobasilar arterial system.
• Patients with atherosclerosis of the internal carotid artery. A case has been reported of cerebral embolism originating from extensively calcified internal carotid artery immediately following cervical spinal manipulation in the absence of dissection (11). It recommended that patients with extensively calcified carotid arteries not undergo spine manipulation therapy to avoid liberation of cerebral embolus.
• Patients with congenital anomalies (eg, kinking of vertebral artery, unilateral hypoplasia of the vertebral artery, or a vertebral artery terminating in posterior inferior cerebellar artery).
• Patients with laxity of ligaments of the cervical spine permitting excessive range of flexion and extension.
• Patients with cervical spondylosis. Osteophytes may impinge on the vertebral artery during neck movements.
In a series of 126 patients with cervical artery dissections, the most frequent cause was preceding chiropractic manipulation involving use of forceful neck rotation to both sides and was associated with a higher incidence of bilateral vertebral artery dissections than patients with carotid artery disease (16). In a retrospective review of 141 patients seen at a single institution between 2008 and 2012 who had a diagnosis of cervical artery dissection, 12 had documented chiropractic neck manipulation prior to the onset of symptoms of acute stroke; the patients had a total of 16 cervical artery dissections (39). All strokes were confirmed with MRI or CT, and follow-up information was available on 9 patients, 8 of whom had residual symptoms and 1 of whom died due to this injury. A retrospective review of 310 patients with vertebral artery dissections who presented at 1 institution between 2004 and 2018 showed that 34 of these suffered a chiropractor-associated injury (51). These patients tended to be younger, female, and had fewer comorbidities than patients with vertebral artery dissections due to other-causes.
In a review of 72 cases of stroke following abrupt head movements, 60 were reported to have occurred after chiropractic manipulation (23). Clinical syndromes consisted of occipital lobe (5%), cerebellar (8%), locked in (8%), Wallenberg (28%), other brainstem (49%), and unclassifiable (2%). The authors summarized the pathogenic mechanisms into the following steps:
• Damage to tunica media or tunica intima of 1 or both vertebral arteries. The damage may be subclinical or may evolve further.
• Vertebral artery dissection at the atlantoaxial joint with intimal tear and intramural bleeding may occur in cases where symptoms follow immediately after manipulation.
• Delayed symptoms are usually due to formation of a thrombus, pseudoaneurysm, or thromboembolism at the site of injury.
Chiropractic neck manipulation has been stated to be the most common cause of cerebellar infarction from traumatic vertebral artery occlusion. Vertebral artery occlusion occurs in about 50% of these cases, and posterior inferior cerebellar artery occlusion is found in 30%. Wallenberg syndrome develops in nearly one third of patients with cerebellar infarction.
Several cases have been reported of strokes in the territory of vertebrobasilar system following neck manipulation. A young woman died due to vertebrobasilar stroke following cervical manipulation for neck pain and headache (43). A 39-year-old man developed medial medullary infarction following chiropractic neck manipulation (82). He showed right hemiparesis sparing the face, right deep sensory impairment, and tongue deviation to the left 5 hours after neck manipulation. MRI revealed an ischemic lesion in the left medial portion of the medulla oblongata. Cerebral angiography demonstrated no apparent organic lesion of the right vertebral artery but showed hypoplasia of the left vertebral artery. Left medial medullary infarction may have occurred because of the reduced blood flow on the left following the contralateral vertebral artery compression.
Two patients with dissections of the vertebral arteries were diagnosed 2 days and 6 days after cervical manipulation (02). In the first case, a Wallenberg syndrome occurred due to a dissection of the right intracranial vertebral artery. The patient was treated with anticoagulant therapy, but little improvement of the disorder was noted. The second patient had transitory neurologic manifestations that led to the discovery of an intimal tear of the ostium of the right vertebral artery with a floating clot.
A healthy, 39-year-old woman was reported to develop sudden left peripheral visual field loss after chiropractic neck manipulation (14). Visual field testing disclosed a left superior homonymous hemianopsia. MRI scan performed on the day of the event disclosed an acute infarction of the ventromedial aspect of the inferior right occipital lobe. The findings are compatible with an infarction in the territory of the right posterior cerebral branch of the basilar artery. One case of right-side superior homonymous quadrantanopia was reported after chiropractic neck manipulation, and MRI confirmed an infarct in the left inferior extrastriate cortex (38). Neuro-ophthalmologic findings, such as isolated homonymous hemianopsia due to occipital lobe infarction, are a common feature of cervical manipulation-induced stroke (12).
An analysis has been reported of clinical course and neuroradiologic findings of 10 patients who developed ischemic strokes secondary to vertebral artery dissection or internal carotid artery dissection following chiropractic manipulation of the cervical spine (30). The important conclusions of this study were that none of the patients had any preexisting risk factors for stroke and that the dissection was located close to the atlantoaxial joint in all the patients with vertebral artery involvement. Neurologic deficits were severe, disabling, and potentially life threatening in these patients. A population-based case control study of chiropractic manipulation and vertebral artery occlusion concluded that the analysis is consistent with a positive association in young adults, but potential sources of bias are also to be taken into consideration (68). The rarity of vertebral artery occlusion makes this association difficult to study despite high volumes of chiropractic treatment. A population-based analysis suggests that vertebrobasilar artery stroke patients who consulted a chiropractor the year before their stroke are older than previously documented in clinical case series and that most patients had at least 1 cardio- or cerebrovascular comorbidity (09). These findings suggest that case reports or surveys of healthcare professionals may not provide a reliable assessment of predisposition to development of vertebrobasilar artery stroke.
A young patient suffered from incomplete Wallenberg syndrome a few hours after a single session of cervical chiropractic manipulation; vertebral artery dissection and cerebral lesions were demonstrated by magnetic resonance angiography (49).
In a young woman who developed headache, vomiting, diplopia, dizziness, and ataxia following neck manipulation by her chiropractor, CT revealed an infarct in the inferior half of the left cerebellar hemisphere and compression of the fourth ventricle causing moderate acute obstructive hydrocephalus (37). Magnetic resonance angiography revealed severe narrowing and low flow in the intracranial segment of the left distal vertebral artery. The patient was treated with mannitol and a ventriculostomy and made an excellent functional recovery.
A 39-year-old man who presented with a 6-hour history of vertigo and imbalance and signs of cerebellar dysfunction 2 weeks following cervical manipulation by a chiropractor for intermittent neck pain was diagnosed as posterior inferior cerebellar artery infarction due to dissection of the extracranial vertebral artery (34). He was treated with antiplatelet therapy and recovered without any sequelae.
A 32-year-old woman underwent chiropractic manipulation resulting in vertebral artery dissection with occlusion by thrombus, which was not amenable to endovascular treatment, and developed brainstem infarct with hemorrhagic transformation, cerebral edema, and cerebellar herniation leading to death shortly after arrival at the hospital (80). The authors of this case report suggested that medical clearance for risk factors prior to cervical manipulation in patients at risk of vertebral artery dissection would drastically reduce morbidity and mortality. Another problem is that chiropractors are not trained in detecting early signs and symptoms of this complication. Further research is needed to modify high velocity thrust manipulation of the cervical spine, which places the carotid and vertebral arteries at risk of dissection.
Strokes related to dissection of the carotid arteries. Carotid artery dissections are 3 to 5 times more common than vertebral artery dissections. Dissection of carotid arteries following cervical manipulation has been described (62; 32; 35; 85). A case has been reported of Horner syndrome and dissection of the internal carotid artery after chiropractic manipulation of the neck (61). Cerebral infarction in the territory of the middle cerebral artery has been reported following chiropractic manipulation of the neck (06).
One case has been described of an asymptomatic carotid artery dissection combined with a stroke in the territory of vertebral basilar artery (59). Asymptomatic carotid artery dissection (detected by MRI) may occur more frequently, but may not come to a physician's attention unless the patient develops a complication, such as an aneurysm formation.
A study investigating stroke following cervical manipulation found evidence that in some cases the dissection was present prior to the manipulation as a cause of neck pain, and stroke after manipulative therapy was due to embolization of thrombotic material from the dissected artery (47). This points out another risk of chiropractic approach as the practitioners are not qualified to investigate and detect carotid or vertebral arterial dissection prior to applying manipulation therapy.
A case has been presented of cerebellar infarction with proximal subclavian artery thrombosis causing subclavian steal syndrome in an individual who had received a shoulder massage comprised of chiropractic manipulation a day prior to admission (60). The authors failed to link the subclavian thrombosis to stroke because of the absence of vertebral artery dissection, but no other cause, such as coagulopathy, was discovered. However, the finding of a narrow interscalene triangle on the left side on neck CT in this case suggests an unfavorable anatomical structure as a risk factor where forceful manipulation may induce thrombus formation. The thrombus resolved on anticoagulation therapy.
Management of craniocervical arterial dissections. A prospective study has reviewed various methods used for the management of craniocervical arterial dissections including medical management with antiplatelet or anticoagulant therapy (01). Neurosurgical procedures included endovascular stenting, thrombectomy with arterial repair, and cerebellar decompression to prevent impending herniation. Although several patients made complete recovery, 31% of patients were left permanently disabled or died due to their arterial injuries. In a series of 116 cases of cervical arterial dissection due to spontaneous, traumatic, or iatrogenic causes treated by endovascular procedures, 6 of 67 (9%) patients with spontaneous dissection (4 cases involving the carotid and 2 cases involving the vertebral arteries) reported recent chiropractic manipulation (52). Endovascular treatment of carotid artery dissection and vertebral artery dissection including stent placement and coil occlusion has low procedural morbidity and is associated with a low incidence of future stroke.
Ocular complications with visual impairment. A 49-year-old man developed sudden visual loss in his right eye due to central retinal artery occlusion after chiropractic neck manipulation (33). Stenosis of the right internal carotid artery with diffuse atherosclerotic plaques in the right common carotid artery was detected by ultrasound examination. Ophthalmic artery occlusion due to carotid arterial dissection secondary to chiropractic manipulation was diagnosed in a 46‐year‐old healthy male with only a past medical history of chronic musculoskeletal neck pain treated with chiropractic neck manipulation, and despite treatment, he remained nearly blind in the right eye (67).
A patient with cystoid macular edema treated by intravitreal injection of triamcinolone earlier in the day presented with severely impaired vision in the right eye due to hemorrhagic choroidal detachment following chiropractic manipulation of the neck later the same day (17).
Brachial plexus injuries. Acute brachial plexus upper trunk palsy involving C5 and C6 nerve roots has been reported following cervical spine manipulative therapy (10). Upper trunk brachial plexus palsy usually results from high-energy trauma and has not been previously reported following spinal manipulation.
Peripheral nerve injuries. Peripheral nerve injuries due to chiropractic manipulation include the following:
• Palsy of the long thoracic nerve of Bell with scapular winging
• Phrenic nerve damage resulting in unilateral diaphragmatic paralysis following chiropractic manipulation of the neck
Posttraumatic aneurysm formation. In some cases, the patient may not present with dissection of the vertebrobasilar arterial system, but an aneurysm may develop later. An intracranial vertebral aneurysm has been reported at the site of an isolated dissection of the vertebral artery associated with chiropractic neck manipulation (46). A case of an internal carotid artery aneurysm presented acutely following chiropractic neck manipulation with hypoglossal and glossopharyngeal nerve palsy (83).
Vertebral arteriovenous fistula. A case report of a patient documented the development of a fistula between the vertebral artery and the epidural veins, manifesting as radiculopathy of the arm (87). This patient had a history of chiropractic-induced vertebrobasilar infarction, and the arteriovenous fistula was a complication of chiropractic manipulation. The patient's arm pain was relieved after surgical repair of the fistula.
Conclusions regarding adverse effects of spinal manipulation. An exhaustive review of the literature up to 1993 revealed 367 case reports of vertebrobasilar dissection associated with spinal manipulation, but the nature of precipitating trauma was poorly defined, and it was not possible to identify a specific neck movement that would be considered the offending factor in most of the cases (28). A systematic review of papers published from 2001 and 2006 revealed that more than 200 patients had serious complications following manipulation of the cervical spine, of which the most common were due to vertebral artery dissections (19). Because these complications are rarely reported in the literature, the exact incidence is difficult to determine. A review of published adverse events of chiropractic manipulations between 1966 and 2007 revealed that the frequency of all adverse events, serious as well as nonserious, varied between 33% and 60.9% (27). The frequency of serious adverse events in this survey varied between 5 strokes per 100,000 manipulations to 1.46 serious adverse events per 10,000,000 manipulations and 2.68 deaths per 10,000,000 manipulations. It was concluded that there are no robust data regarding the incidence or prevalence of complications of chiropractic manipulation and that properly designed prospective controlled trials are needed.
Results of a randomized clinical trial suggest that adverse reactions to chiropractic manipulation for neck pain are common and that despite somewhat imprecise estimation, adverse reactions appear more likely to follow cervical spine manipulation than mobilization (31).
In response to this criticism of cervical manipulation, some chiropractors have come up with the interesting explanation that the stroke is incidental as these patients went to see them because of the premonitory symptoms of stroke, such as nonspecific dizziness and headache, and that the stroke would have occurred regardless of the manipulation (54). As it is unrealistic to expect that practice of chiropractic manipulation will stop, the following preventive measures are recommended:
• Manipulation of the cervical spine should be avoided as much as possible.
• Patients undergoing spinal manipulative therapy need to consent to the possible risks of stroke or vascular injury from the procedure after these have been explained (57).
• Manipulation should be performed only if the risk factors for neurologic complications are excluded.
• A premanipulative vertebrobasilar insufficiency test can be used to identify patients at risk for developing vertebrobasilar insufficiency following cervical manipulation (50). In this test, transcranial Doppler is used to measure intracranial vertebral artery blood flow following measured neck rotation. Use of a velocimeter may provide a more objective assessment of vertebral artery blood flow than the provocative tests, but the reliability and clinical utility has not yet been properly documented (78).
• Manipulation should be performed only by properly trained persons with a thorough knowledge of anatomy and of the complications that can result from this procedure.
• In patients with neurologic disorders, a neurologic consultation should be mandatory to determine if manipulation can be performed safely.
• Manipulation should be stopped at the earliest symptoms or suspicion of neurologic complication, and the patient should be promptly referred to a neurologist.
• Chiropractors should be trained to detect strokes in early stages of evolution in patients who present to them for spinal manipulation. In the case of 1 patient with severe neck pain and visual field defect, the chiropractor suspected vertebral artery disease and deferred manipulation (24). MR angiography revealed an early thrombus formation in the left vertebral artery, which resolved after antiplatelet therapy.
A study was carried out to test the claim that the addition of chiropractic care, including craniosacral therapy, to a regimen of standard obstetric pregnancy care results in fewer obstetric interventions during labor and delivery (63). Due to the limitations in the design of the project, it is this author’s opinion that this study provides no evidence that the addition of chiropractic care and craniosacral therapy during pregnancy results in any observable benefit or detriment concerning obstetric interventions used during labor and delivery or that chiropractic care for pregnancy-related neuromusculoskeletal disorders should not complicate labor or delivery. Reports of complications of chiropractic manipulations during pregnancy are rare, as they are usually avoided. Review of literature from 1978 to 2009 reveals adverse effects from spinal manipulation in 5 pregnant patients and 2 postpartum patients with severity of injury ranging from minor to more severe including fracture, stroke, and epidural hematoma (76).
Yokota and colleagues described the case of a 38-year-old man who suddenly developed nausea, vomiting, and vertigo during chiropractic neck manipulation (86). This was followed by right hemiplegia, right deep sensory disturbance, and left hypoglossal nerve palsy consistent with a medial medullary infarction (Dejerine syndrome). The MRI revealed infarction at the left medial part of the medulla. In this case, injury occurred to the left vertebral artery with an intimal tearing during neck manipulation, which caused infarction of the brainstem. This type of stroke following chiropractic manipulation is rare; cases of lateral medullary infarction are more common.
• Chiropractic has no scientific basis.
Chiropractic has no scientific basis. The department of complementary medicine at the University of Exeter in the United Kingdom concluded that chiropractic concepts are not based on solid science, and its therapeutic value has not been demonstrated beyond reasonable doubt (20). No scientific study has disproved these conclusions since then.
• Medicolegal review provides an insight into the neurologic complications of chiropractic manipulation.
A study has investigated the relationship between chiropractic spinal manipulation and malpractice by querying the legal database VerdictSearch of “Medical Malpractice” by using the terms “chiropractor” or “spinal manipulation” (29). Between 1998 and 2018, 48 cases involving chiropractic management were reported in the United States, of which 45 (93.8%) involved spinal manipulation. Plaintiffs primarily alleged overaggressive treatment. Most of the cases involved neurologic injury that required surgery. Although the defense (chiropractitioner) was victorious in 70.8% of cases, with a plaintiff (patient) victory only in 20.8%, medicolegal review provides an insight into the neurologic complications of chiropractic manipulation.
K K Jain MD†
Dr. Jain was a consultant in neurology and had no relevant financial relationships to disclose.See Profile
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