Introduction

Vertebrobasilar insufficiency (VBI) is a critical condition characterized by impaired blood flow to the posterior regions of the brain, including the brainstem, cerebellum, and occipital lobes. This condition arises from various causes such as atherosclerosis, arterial dissection, or external compression of the vertebral arteries, which can lead to a range of symptoms from dizziness and vertigo to severe neurological deficits and stroke-like episodes. Understanding the complex anatomy of the vertebrobasilar system and its susceptibility to various pathologies is essential for managing and treating VBI effectively.

In the realm of therapeutic interventions, cervical manipulation is often employed to address neck pain, headaches, and other musculoskeletal disorders. This technique involves applying specific forces to the cervical spine with the goal of improving joint function, relieving pain, and enhancing overall mobility. Despite its potential benefits, cervical manipulation has been scrutinized for its possible implications on the vertebrobasilar system, especially in individuals who may be predisposed to or already suffering from VBI.

The interplay between cervical manipulation and vertebrobasilar insufficiency raises important considerations about patient safety and treatment efficacy. On one hand, cervical manipulation can provide significant relief from musculoskeletal symptoms; on the other hand, it carries the risk of exacerbating or triggering adverse events in patients with compromised vertebrobasilar circulation. As such, it becomes crucial to understand the potential risks associated with cervical manipulation in this context, alongside implementing evidence-based guidelines to mitigate these risks.

This discussion aims to explore the intricate relationship between vertebrobasilar insufficiency and cervical manipulation. By examining the underlying mechanisms of VBI, the effects of cervical manipulation on the vertebrobasilar system, and the current safety protocols, we seek to provide a comprehensive overview that will aid healthcare practitioners in making informed decisions and enhancing patient safety.

Anatomy of Vertebrobasilar Insufficiency

Vertebrobasilar insufficiency (VBI) refers to a reduction in blood flow to the posterior part of the brain, primarily supplied by the vertebral and basilar arteries. These arteries are integral to cerebral circulation, delivering approximately 11% of the brain’s blood flow, while the remaining 89% is provided by the carotid system (Grant, 1994a). Understanding the anatomy and biomechanics of the vertebrobasilar system is crucial for comprehending how cervical movements can influence blood flow and potentially lead to insufficiency.

Anatomy of the Vertebral Arteries

An important distinguishing feature of the cervical region compared to other vertebral segments is the presence of the vertebral arteries. These arteries originate from the subclavian artery and ascend through the cervical spine, entering the transverse foramen of each cervical vertebra from C6 upward. This anatomical pathway is crucial because it exposes the vertebral arteries to potential mechanical stress during cervical movements.

As the vertebral arteries ascend, they traverse the transverse foramina of the cervical vertebrae. Upon reaching the atlas (C1), the arteries run almost horizontally. They then pass through the foramen magnum and join with their contralateral counterpart to form the basilar artery, which continues to supply the brainstem, cerebellum, and occipital lobes.

Biomechanics and Blood Flow Considerations

The cervical spine’s unique anatomy means that the vertebral arteries are closely associated with the bony structures of the cervical vertebrae, particularly at C1 and C2. This anatomical relationship is significant during head rotation and other cervical movements. Approximately 45-50 degrees of cervical rotation occurs primarily at the atlanto-axial joint, which is crucial for allowing a range of head and neck movements.

During rotational movements, the vertebral arteries, being attached to the transverse foramina at C1 and C2, are subjected to stretching, tension, compression, and twisting forces. These forces can significantly impact the blood flow through these arteries. The rotational movement of the head can cause the greatest decrease in blood flow to the vertebral arteries, as evidenced by several studies (deKleyn and Nieuwenhuyse, 1927; deKleyn and Versteegh, 1933; Tatlow and Bammer, 1957; Toole and Tucker, 1960; Brown and Tatlow, 1963; Andersson et al., 1970; Barton and Margolis, 1975; Grossman and Davies, 1982; Yang et al., 1985). These studies demonstrate that the mechanical stress applied during head rotation can lead to temporary or persistent reductions in blood flow, contributing to symptoms of vertebrobasilar insufficiency.

Clinical Implications

The anatomy and biomechanics of the vertebrobasilar system highlight the delicate balance required in cervical movements, particularly when considering interventions such as cervical manipulation. Given that the vertebral arteries are susceptible to mechanical stresses during cervical rotation, it is crucial to be aware of the potential risks associated with these movements, especially in individuals with compromised vertebrobasilar circulation.

In summary, the vertebral arteries’ unique anatomical course through the cervical spine and their susceptibility to mechanical forces during cervical rotation underscore the importance of careful evaluation and management of patients experiencing symptoms related to vertebrobasilar insufficiency. Understanding these anatomical and biomechanical principles helps clinicians make informed decisions regarding treatment options and strategies to minimize risks while optimizing patient care.

Incidence of vertebrobasilar stroke after manual spinal manipulation

Incidence of VBS Related to Cervical Manipulation

The reported incidence rates of VBS related to cervical manipulation vary widely due to differences in study methodologies and diagnostic criteria. Here’s a breakdown of the estimates:

  1. Maigne (1972): Suggests an extremely low incidence, indicating that such events are very rare compared to the number of manipulations performed.
  2. Cyriax (1978): Estimated a rate of 1 in 10 million manipulations, implying that VBS is an exceedingly rare complication.
  3. Hosek et al. (1981): Reported a similar low rate of 1 per million, reinforcing the rarity of this adverse event.
  4. Gutmann (1983) and Dvorak & Orelli (1985): Found slightly higher rates (2-3 per million), which still reflect a low overall risk.
  5. Rivet and Milburn: Provided a broader range, from 1 in 50,000 to 1 in 5 million manipulations. This variability may reflect differences in study populations and definitions of adverse events.
  6. Boyle et al.: Reported a higher rate of 6 per 100,000 manipulations. This figure is significantly higher compared to others and might be due to different criteria or reporting practices.
  7. Patijn: Estimated a rate of 1 per 518,886 manipulations, which aligns with the lower end of the spectrum found in other studies.

Factors Influencing Risk

  • Pre-existing Conditions: Patients with certain risk factors, such as pre-existing vascular conditions or anatomical variations, may be at a higher risk for adverse events.
  • Technique and Experience: The skill and experience of the practitioner, as well as the specific techniques used, can influence the risk of VBS.
  • Diagnostic Practices: The accuracy in diagnosing and reporting adverse events can vary, affecting the reported incidence rates.

Symptoms of vertebrobasilar insufficiency

Symptoms of vertebrobasilar insufficiency (VBI) are diverse and can significantly impact an individual’s quality of life. They arise from the reduced blood flow to the posterior regions of the brain, including the brainstem, cerebellum, and occipital lobes. One of the most common symptoms associated with VBI is dizziness, which may manifest as a sensation of lightheadedness or spinning (vertigo). This dizziness can be severe and debilitating, leading to a loss of balance and a heightened risk of falls. Patients may also experience a sense of unsteadiness, which can interfere with their ability to walk or perform daily activities.

Visual disturbances are another prominent symptom of VBI. Individuals may report blurred vision, double vision (diplopia), or transient loss of vision. These visual symptoms occur because the brainstem, which is critical for processing visual information, is affected by the reduced blood supply. Additionally, patients might experience difficulties with depth perception and coordination, making tasks that require precise movements, such as writing or buttoning a shirt, challenging.

Hearing-related symptoms can also be present in VBI. Tinnitus, or ringing in the ears, is a common complaint, and some individuals may experience hearing loss or changes in auditory perception. This can be particularly distressing and can compound the difficulties faced in daily life.

Neurological symptoms associated with VBI include problems with speech and cognitive functions. Patients may experience slurred speech, difficulty finding the right words, or problems with understanding spoken language. Cognitive impairments might include confusion, memory problems, or difficulty concentrating. These symptoms occur because the brainstem, which plays a crucial role in many of these functions, is compromised.

In addition to these symptoms, individuals with VBI may experience sudden onset of weakness or numbness, typically affecting one side of the body. This can be indicative of a transient ischemic attack (TIA) or a mini-stroke, which are related to the reduced blood flow in the vertebrobasilar system. In severe cases, VBI can lead to full-blown strokes, characterized by more profound weakness, paralysis, or loss of sensation on one side of the body, as well as difficulty with speech or comprehension.

Coordination problems are also prevalent, with patients often having trouble with fine motor skills or maintaining balance. This can result in a staggering gait or difficulty performing tasks that require hand-eye coordination. The sense of instability and lack of control over one’s movements can significantly affect the individual’s ability to perform daily activities and maintain independence.

Other systemic symptoms may include nausea, vomiting, and a general feeling of unwellness. These symptoms are often associated with the dizziness and vertigo that occur in VBI. In some cases, patients may also experience a sensation of pressure in the head or a headache, although these are less specific to VBI and can overlap with other conditions.

Overall, the symptoms of vertebrobasilar insufficiency are multifaceted and can vary in severity. The combination of dizziness, visual and auditory disturbances, neurological deficits, and coordination problems can significantly affect an individual’s functional ability and quality of life. Early recognition and management of these symptoms are essential to prevent progression and reduce the risk of more serious outcomes, such as stroke. Accurate diagnosis and targeted treatment strategies are crucial for effectively managing VBI and improving patient outcomes.

  • Dizziness (the most common symptom)
  • Dizziness/syncope: Sixty percent of TBI patients experience at least one episode of dizziness.
  • The patient suddenly feels weak in the knees and falls.
  • Diplopia/loss of vision
  • Paresthesia
  • Confusion
  • Dysphagia/dysarthria
  • Headache
  • Altered consciousness
  • Ataxia
  • Contralateral motor weakness
  • Loss of temperature and pain
  • Incontinence

Dissection of the vertebral artery

The vertebral artery, a crucial vessel supplying blood to the posterior regions of the brain, is particularly vulnerable to injury during certain manipulative procedures. This vulnerability is notably significant when the artery transitions from the transverse foramen of the second cervical vertebra (C2, also known as the axis) to that of the first cervical vertebra (C1, the atlas). The vertebral artery, as it exits the transverse foramen of C2, must undergo a sharp directional change to enter the transverse foramen of C1. This abrupt shift in direction places the artery at considerable risk, particularly during cervical manipulation.

Cervical manipulation, which often involves rotational movements of the head and neck, places substantial strain on the vertebral artery, especially at the C2 level. During these procedures, the vertebral artery can be stretched, compressed, or twisted, which may potentially lead to dissection—a serious condition where the artery’s inner lining tears. When the vertebral artery is already compromised or insufficient, its susceptibility to injury increases significantly. The risk of such an injury can be heightened by the mechanical forces applied during cervical manipulation.

Dissection of the vertebral artery is a critical concern in the context of cervical manipulation. Research has demonstrated that cervical manipulation can independently increase the risk of vertebral artery dissection (VAD) and subsequent stroke. Smith et al. suggested that the risk of VAD with stroke following cervical manipulation may be increased by approximately six-fold. This heightened risk underscores the need for careful assessment and consideration before performing manipulative procedures on patients with potential vertebrobasilar insufficiency.

The clinical presentation of vertebral artery dissection often includes symptoms such as dizziness, lightheadedness, and other signs of reduced cerebral blood flow. These symptoms can be distressing and may prompt urgent medical evaluation. While vertebral artery dissection can occur in younger individuals, it is more commonly observed in older populations, reflecting a greater overall risk with age.

Statistical data on the incidence of VAD following cervical manipulation indicates a variable risk range. Reports suggest that the occurrence of VAD after cervical manipulation ranges from as infrequent as 1 in 10,000 to as rare as 1 in 2 million procedures (references 3-4). Despite these low incidence rates, the potential severity of VAD necessitates a cautious approach.

As a therapist or healthcare provider, recognizing the potential for vertebral artery dissection is crucial. Even though the likelihood of such an adverse event is minimal, it remains essential to assess the integrity of the vertebral artery before undertaking any cervical manipulation. This pre-manipulative evaluation helps ensure patient safety and mitigate the risk of potentially severe complications.

In summary, the vertebral artery’s anatomical course and susceptibility to mechanical stress highlight the importance of careful consideration and assessment during cervical manipulation. Understanding the risks associated with vertebral artery dissection and implementing appropriate safety measures can significantly reduce the likelihood of adverse outcomes and enhance patient safety in clinical practice.

Trauma to the vertebral artery following cervical manipulation occurs primarily in its atlantoaxial component, which is stretched forward during rotation.

Symptoms of Vertebral Artery Dissection

  • Headaches 87%
  • Neck pain 67%
  • Vertigo 52 %
  • Visual disturbances 33%
  • Paresthesia
    • Face 30%
    • Arm 33%
    • Leg 15 %

Risk factor

A number of risk factors are reported to be associated with an increased risk of cervical artery dissection and should be carefully assessed during the history.

  • Unilateral neck pain of acute onset
  • Occipital, frontal, supraorbital or temporal headache of acute onset
  • Family history of migraine (especially without aura)
  • History of trauma to the cervical spine (including minor or “trivial” trauma)
  • Appearance of pain related to a sudden movement of the cervical spine
  • Tinnitus (especially “pulsative tinnitus”)
  • History of hypertension and risk factors for cardiovascular disease
  • Recent upper and/or lower respiratory tract infection (within the last week)
  • Neurological symptoms and ataxia of the upper and/or lower limbs
  • Smoking
  • Hyperlipidemia.

Vertebrobasilar insufficiency tests

Vertebrobasilar insufficiency (VBI) tests are used for prevention purposes before performing cervical manipulations or mobilization.

These tests are provocative and performed to test the collateral and vertebrobasilar blood supply to the brain. They are performed to test the collateral and vertebrobasilar blood supply to the brain for signs and symptoms of vertebral artery pathology, which may present a risk prior to manipulation.

1. Passive test for verification of vertebral artery integrity

  • Place the patient supine and perform passive extension and lateral flexion of the head and neck.
  • Passively rotate the neck to the same side and hold for approximately 30 seconds.
  • Repeat the test with a movement of the head to the opposite side.
  • The test is considered positive if there is a fall in the arms, loss of balance or pronation of the hands; a positive result indicates a decrease in the blood supply to the brain.
  • Other positive symptoms:
    • Dizziness
    • Tinnitus
    • Dizziness
    • Nystagmus
    • Paresthesia
    • Dysarthria
    • Diplopia
    • Dysphagia

2. Test actif de l’artère vertébrale (Dekleyn’s)

  • Patient in supine position, head off the table.
  • Ask the patient to hyperextend and rotate the head.
  • Hold this position for 15 to 30 seconds.
  • Repeat the reverse operation.

Positive test: Vertigo, dizziness, visual blurring, nausea, fainting and nystagmus. –

Structures affected: Stenosis or compression of the vertebral, basilar or carotid artery.

If the presence of BVI is evident in a patient, the practitioner should immediately discontinue provocation testing and return the patient’s neck to a neutral position (Rivett et al., 2005). Manipulation procedures should be discontinued and the patient referred to a specialist for further medical examination.

Quizz

Quizz 1

What is Vertebrobasilar Insufficiency (VBI)?

a) A condition affecting the carotid arteries
b) A reduction in blood flow to the anterior brain regions
c) A reduction in blood flow to the posterior brain regions
d) An increase in blood flow to the spinal cord
e) A condition related to upper limb circulation

2. How do the vertebral arteries enter the cervical spine?

a) Through the foramen magnum
b) Through the transverse foramen of each cervical vertebra from C1
c) Through the transverse foramen of each cervical vertebra from C6
d) Directly from the subclavian artery to the brainstem
e) Through the sacral foramina

3. What is a significant mechanical stress placed on the vertebral arteries during cervical movements?

a) Compression and stretching
b) Increased blood flow
c) Reduced arterial tension
d) Enhanced artery elasticity
e) None of the above

4. What does cervical manipulation often involve?

a) Applying specific forces to the lumbar spine
b) Applying specific forces to the cervical spine
c) Applying general pressure to the entire spine
d) Massaging the sacral area
e) Performing passive leg movements

5. Which of the following is NOT a reported incidence rate of vertebrobasilar stroke (VBS) related to cervical manipulation?

a) 1 in 10 million manipulations
b) 1 in 100,000 manipulations
c) 1 in 1 million manipulations
d) 1 in 5 million manipulations
e) 6 in 100,000 manipulations

6. Which test involves placing the patient supine and performing passive extension and lateral flexion of the head?

a) Dekleyn’s Test
b) Schober’s Test
c) Passive Test for Vertebral Artery Integrity
d) Active Test for Vertebral Artery Integrity
e) Tinel’s Sign

7. What symptoms are commonly associated with vertebrobasilar insufficiency (VBI)?

a) Tingling in the toes
b) Headaches, dizziness, and visual disturbances
c) Sudden muscle spasms in the back
d) Lower back pain and stiffness
e) Cold extremities and reduced grip strength

8. What is a critical concern related to cervical manipulation and vertebral artery dissection?

a) Decreased blood flow in the carotid arteries
b) Increased risk of vertebral artery dissection
c) Improved circulation to the spinal cord
d) Enhanced flexibility of the lumbar spine
e) None of the above

9. How does the mechanical stress applied during cervical rotation affect the vertebral arteries?

a) It improves blood flow through the arteries
b) It causes temporary or persistent reductions in blood flow
c) It has no significant impact on blood flow
d) It increases arterial elasticity
e) It enhances vertebral artery strength

10. What should be done if vertebrobasilar insufficiency is evident during testing?

a) Continue with cervical manipulation
b) Apply more pressure during the test
c) Discontinue manipulation and refer the patient to a specialist
d) Perform additional manual therapy
e) Ignore the symptoms as they are non-critical

Answers

  1. c) A reduction in blood flow to the posterior brain regions
  2. c) Through the transverse foramen of each cervical vertebra from C6
  3. a) Compression and stretching
  4. b) Applying specific forces to the cervical spine
  5. b) 1 in 100,000 manipulations
  6. c) Passive Test for Vertebral Artery Integrity
  7. b) Headaches, dizziness, and visual disturbances
  8. b) Increased risk of vertebral artery dissection
  9. b) It causes temporary or persistent reductions in blood flow
  10. c) Discontinue manipulation and refer the patient to a specialist
Quizz 2

Which anatomical feature is particularly notable about the vertebral arteries in the cervical region?

a) They enter the vertebrae directly from the heart
b) They ascend through the transverse foramina of the cervical vertebrae
c) They are found only in the lumbar spine
d) They pass through the sacral foramina
e) They originate from the internal carotid artery

2. What is the primary risk factor for vertebral artery dissection during cervical manipulation?

a) Reduced vertebral artery elasticity
b) Sharp directional change of the artery
c) Increased blood flow through the artery
d) High levels of physical fitness
e) Decreased mechanical stress

3. What type of symptoms might indicate vertebral artery dissection?

a) Lower back pain and stiffness
b) Unilateral neck pain and sudden headache
c) Pain in the extremities
d) Cold hands and feet
e) Abdominal cramping

4. What is the purpose of the passive test for vertebral artery integrity?

a) To assess overall spinal flexibility
b) To evaluate the integrity of the vertebral artery during passive head movements
c) To measure leg strength
d) To test respiratory function
e) To determine overall cardiovascular health

5. How is the risk of vertebrobasilar stroke (VBS) reported to vary according to the studies?

a) Consistently high across all studies
b) Ranges from extremely rare to relatively frequent
c) Identical in all studies
d) Only reported as common in older studies
e) Not reported in recent studies

6. What does the Dekleyn’s Test involve?

a) Assessing the integrity of the lumbar spine
b) Hyperextending and rotating the head while supine
c) Applying pressure to the thoracic spine
d) Measuring spinal range of motion
e) Performing passive leg extensions

7. Which of the following is NOT a symptom of vertebrobasilar insufficiency (VBI)?

a) Tinnitus
b) Blurred vision
c) Dizziness
d) Chest pain
e) Slurred speech

8. According to the text, which of the following conditions is a risk factor for vertebral artery dissection?

a) Recent upper respiratory infection
b) Regular physical exercise
c) Low blood pressure
d) Balanced diet
e) Frequent hydration

9. What should be done if a positive result is obtained from vertebrobasilar insufficiency testing?

a) Continue with the planned cervical manipulation
b) Adjust the manipulation technique
c) Discontinue the manipulation and refer the patient for further evaluation
d) Perform additional manipulative procedures
e) Ignore the result as it is not significant

10. How is cervical manipulation related to the risk of vertebral artery dissection?

a) It is unrelated to the risk
b) It decreases the risk significantly
c) It can independently increase the risk of vertebral artery dissection
d) It has no impact on vertebral artery dissection
e) It improves arterial integrity

Answers

  1. b) They ascend through the transverse foramina of the cervical vertebrae
  2. b) Sharp directional change of the artery
  3. b) Unilateral neck pain and sudden headache
  4. b) To evaluate the integrity of the vertebral artery during passive head movements
  5. b) Ranges from extremely rare to relatively frequent
  6. b) Hyperextending and rotating the head while supine
  7. d) Chest pain
  8. a) Recent upper respiratory infection
  9. c) Discontinue the manipulation and refer the patient for further evaluation
  10. c) It can independently increase the risk of vertebral artery dissection
Quizz 3

1. What is the primary consequence of vertebrobasilar insufficiency (VBI)?

a) Increased blood flow to the brainstem
b) Impaired blood flow to the posterior regions of the brain
c) Enhanced coordination and balance
d) Decreased sensitivity to pain
e) Improved cognitive function

2. In which part of the cervical spine does the vertebral artery undergo a significant directional change?

a) C3-C4
b) C5-C6
c) C1-C2
d) C7-T1
e) C2-C3

3. What does the incidence rate of vertebrobasilar stroke (VBS) related to cervical manipulation typically reflect?

a) A high frequency of complications
b) A consistent risk across different studies
c) A low overall risk with considerable variability
d) No reported cases in recent studies
e) A risk that increases with each manipulation

4. What are common symptoms of vertebrobasilar insufficiency (VBI) that affect visual perception?

a) Double vision and blurred vision
b) Deafness and tinnitus
c) Sensory loss in the extremities
d) Seizures and tremors
e) Chronic cough and sore throat

5. Which of the following is NOT a common symptom of vertebral artery dissection?

a) Headaches
b) Neck pain
c) Visual disturbances
d) Difficulty swallowing
e) Joint pain in the knees

6. What is the primary goal of performing vertebrobasilar insufficiency tests before cervical manipulation?

a) To determine the overall spinal health
b) To assess the integrity of vertebral and basilar blood supply
c) To measure the patient’s pain tolerance
d) To evaluate muscle strength in the neck
e) To check for signs of infection

7. How does cervical manipulation potentially affect the vertebral arteries?

a) It increases blood flow through the arteries
b) It can place mechanical stress on the arteries
c) It has no effect on the arteries
d) It decreases the risk of arterial dissection
e) It improves arterial elasticity

8. Which study reported the highest incidence rate of vertebrobasilar stroke (VBS) related to cervical manipulation?

a) Maigne (1972)
b) Cyriax (1978)
c) Boyle et al.
d) Hosek et al. (1981)
e) Rivet and Milburn

9. Which risk factor is associated with an increased risk of cervical artery dissection?

a) A family history of migraine
b) Regular aerobic exercise
c) Adequate hydration
d) Low cholesterol levels
e) Balanced dietary habits

10. When a positive result is obtained from a vertebrobasilar insufficiency test, what is the recommended course of action?

a) Continue with cervical manipulation as planned
b) Repeat the test to confirm results
c) Stop manipulation and refer the patient for further medical evaluation
d) Apply a different treatment approach immediately
e) Monitor the patient without further action

Answers

  1. b) Impaired blood flow to the posterior regions of the brain
  2. c) C1-C2
  3. c) A low overall risk with considerable variability
  4. a) Double vision and blurred vision
  5. e) Joint pain in the knees
  6. b) To assess the integrity of vertebral and basilar blood supply
  7. b) It can place mechanical stress on the arteries
  8. c) Boyle et al.
  9. a) A family history of migraine
  10. c) Stop manipulation and refer the patient for further medical evaluation

References

  • W‐L Chen, C‐H Chern, Y‐L Wu, and C‐H Lee, Emerg Med J. 2006 Jan; 23(1)Vertebral artery dissection and cerebellar infarction following chiropractic manipulation
  • Assendelft W J J, Bouter L M, Knipschild P G. Complications of spinal manipulations: a comprehensive review of the literature. J Fam Pract 199642475–480. [PubMed] []
  • Rothwell D M, Bondy S J, Williams J I. Chiropractic manipulation and stroke. A population‐based case‐control study. Stroke 2001321054–1060. [PubMed] []
  • Meeker W C, Haldeman S. Chiropractic: a profession at the crossroads of mainstream and alternative medicine. Ann Intern Med 2002136216–227. [PubMed] []
  • Rivett DA, Milburn PA. A prospective study of cervical spine manipulation. J Man Med 1996;4:166–70.
  • Boyle E, Cote P, Grier AR, et al. Examining vertebrobasilar artery stroke in two Canadian provinces. Spine 2008;33(4S):S170–
  • Patijn J. Complications in manual medicine: A review of the literature. J Man Med 1991;6: 89–92.

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