SMT-1 (Part 4) Flashcards
The importance of the Bronfort et.al (2005) study:
-SMT & low-intensity endurance training is effective for the treatment of CGH.
-SMT has similar effects as amitriptyline for treating migraines
Which patients will respond to SMT?
Predicting who will respond to SMT?
- Jull et al. (2002) study
- Jull & Stanton (2005) study:
- Niere (1998) study:
- 24% diagnosed with CGH did not respond to SMT and /or exercise
- Found age, high intensity and chronicity not suggestive of poor outcomes
- Low headache frequency, affective and autonomic pain descriptors, and dietary aggravators suggestive of poor outcome. High headache frequency suggestive of a good outcome
The results of the Cassidy et.al
(2008) study:
There were 818 VBA strokes hospitalized. %4.2% were vertebral occlusion, 41.2% were basilar, and 4.7% were both.
In that age, <45 years, the case was about X3 times more likely to see a chiropractor or a PCP before their stroke than controls.
There was no increased association between chiropractic visits and VBA stroke in those older than 45 years.
-But there was an association between VBA stroke in those >45 years and the use of primary care physician
The conclusion of the Cassidy et.al
(2008) study:
The associations between chiropractic visits & VBA stroke are not more significant than the association between PCP visits and VBA stroke.
*increased risks of VBA stroke associated with chiropractic and PCP visits are likely due to patients with headaches and neck pain from a VBA dissection that is already in process.
The results of the Murphy et al.
(2010) study:
-There is no strong Foundation for the claim that there is a causal relationship between cervical manipulation and Vertebral Artery Dissection S.yndrome VADS.
*The most plausible explanation for the association between cervical manipulation and VADS is that individuals who are experiencing a VA dissection seek care from a chiropractor or other practitioner for relief of the neck pain and headache that results from the pre-existing dissection. “The natural progression from dissection to stroke occurs independent of cs manipulation.”
VADS is NOT a complication to CS manipulation. There are NO benefits in “screening” for patients who are at risk because of the lack of reliability of screening tests.
The importance of differential diagnosis:
-The responsibility of the clinician is Not to attempt to ID the patient who is “at risk” of “post manipulative stroke” but to attempt to identify the patient who is having a dissection in progress so appropriate referral can be made.
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Risk of HVLAT?
The literature is very minimal. There is no documented case of a physiotherapist inducing a VBA stroke in the UK, USA, Canada, Australia, New Zealand, or South Africa.
Complications appear extremely rare: 1/50,000 to 1/4,000,000 and may not be cause and effect (Cassidy et.al 2008)
The results of the Thomas et. al 2011:
Should we ask about atherosclerotic risk factors for screening for VADS before CS manipulation?
General cardiovascular risk factors do NOT appear to be strongly represented in cervical artery dissection patients.
They may not be a helpful indicator of the risk of adverse neurovascular complications associated with manual therapy of the neck.
Screening for Cervical Arterial Dysfunction (CAD) in patients presenting with neck pain and headaches sx’s Based on Kerry & Taylor (2006)
- Cranial Nerve and Eye Exam
- Blood Pressure testing
- Sign of ICA and VA dissection (Non-ischemic & ischemic)
- PMH of factors related to atherosclerosis
- Hand help Doppler US (scratch)
- Functional CAD positional test
-Rotationa for VA
-Extension for ICA
Internal Forces Sustained by the vertebral artery during spinal manipulative therapy.
(Symons et al. 2002 Study Design)
Purpose: Quantify the strains & forces sustained by the vertebral artery in situ during SMT.
Participants: 6 VAs from 5 unembalmed postrigor cadavers
Methods:
1. US crystal place to cephalad/distal (C0-C1) & Caudad/proximal (C6-subclavian artery) loops of the VA.
- Strains recorded during:
-ROM testing
-Diagnostic testing
-Variety of HVLAT thrust manipulation
VA was strained until mechanical failure.
Internal Forces Sustained by the vertebral artery during spinal manipulative therapy.
(Symons et al. 2002 Study Results)
-SMT performed on the contralateral side of the CS resulted in an average strain of :
1. 6.2% to the distal (C0-C1) loop of the VA. (30%=50% of elongation required for maximal failure.
- 2.1% strain to the proximal (C6) loop
Values were similar to or lower than the strains recorded during diagnostic & ROM testing.
-Failure testing demonstrated that the VAs could be stretched to 139% to 162% of their testing length before mechanical failure occurred.
Internal Forces Sustained by the vertebral artery during spinal manipulative therapy.
(Symons et al. 2002 Study Conclusion)
The strain by the VA during (high-velocity low amplitude) SMT represents approximately 1/9 of the strain at mechanical failure.
A single HVLAT SMT thrust is unlikely to disrupt the Vertebral artery mechanically.
Microstructural damage in arterial tissue exposed to repeated tensile strains.
The Austin et.al 2010 study Design:
Purpose: Quantify microstructural damage in arterial tissue exposed to repeat train loading similar to the VA during CS HVLAT. Microstructural changes in the arteries are caused by a pathologist using qualitative histology.
Participants: 24 test specimens from cadaveric rabit ascending aortas divided into three groups:
-Group 1: Specimens exposed to
1000 strains cycle at 0.06 strains (6% elongation).
-Group 2: Specimen exposed to 1000 strains cycle at 0.3 strain (30% elongation)
-Group 3: No stress/strain
Microstructural damage in arterial tissue exposed to repeated tensile strains.
The Austin et.al 2010 study Methods:
The average peak forces applied externally to the neck region of the subject during SMT range from 100-150N & are achieved within 80-150 ms.
0.06= normal strain of VA during SMT or at 6% elongation
0.3= 50% of ultimate failure or 30% elongation
Microstructural damage in arterial tissue exposed to repeated tensile strains.
The Austin et.al 2010 study Results:
-Control (no strain) and 0.06 strain tissue were statistically the same
-0.3 strain group had microstructural damage> control group
“1,000 repeat cycles mimicking SMT did not cause microdamage in arterial tissue.”
One thousand repeat strain cycles corresponding to approximately 50% of ultimate failure strain (0.30) cause significant microdamage in arterial tissue.
Microstructural damage in arterial tissue exposed to repeated tensile strains.
The Austin et.al 2010 study conclusion:
Cadaveric arterial tissues similar to human vertebral arteries did NOT exhibit histologically identifiable microdamage when exposed to repeated mechanical loading equivalent to strains observed in the human vertebral artery during chiropractic cervical spine manipulative therapy.
Biomechanics of vertebral artery segments C1-C6 during CS manipulation based on Wuest et al 2010 study design:
Purpose: Measure strain in the human vertebral artery within the transverse foramina during CS SMT
Participant: 1 Cadaver
Method: US crystal and machine
Tested:
1. ROM all CS PROM
2. VBI testing (Houle VBA testing full extension + Rotation)
3. Cervical HVLAT performed at C2-3 & C4-5 levels.
- Lateral flexion & rotation maneuver
- Pure lateral flexion maneuver (lateral break)
Biomechanics of vertebral artery segments C1-C6 during CS manipulation based on Wuest et al 2010 results:
PROM of the CS caused greater strain on the VA than CS SMT:
*1.5 mm lengthening of the VA during repetitive rotational ROM testing.
*0.2mm lengthening during the manipulation
Biomechanics of vertebral artery segments C1-C6 during CS manipulation based on Wuest et al 2010 conclusion:
The vertebral artery VA strains experienced during CS SMT are substantially less (1/5th the size) than the:
-Strain in the VA C1-C6 segments experienced during regular neck rotation & VBI diagnostic testing.
-CS manipulation DOES NOT appear to put any tensile stress beyond normal on VA segments C1-C6.
Biomechanical characterization of CS manipulation in living subjects and cadavers.
Based on Symons et al. 2012 Methods:
Purpose: Determine if the findings of Wuest et al. (2010) on cadavers apply to strain rates in living subjects.
-14 subjects w/ neck pain
-14 subjects w/o neck pain
- 5 Cadavers
Dependent Variables:
* Preload of Cervical HVLAT
*Peak Force of Cervical HVLAT
*Duration of Cervical HVLAT
Biomechanical characterization of CS manipulation in living subjects and cadavers.
Based on Symons et al. 2012 Conclusion:
When performed in cadavers, CS manipulation tends to be more AGGRESSIVE in terms of all biomechanical indices used to describe cadaver HVLAT.
*There were NO statistical differences in terms of preload, peak force & duration of HVLAT in living subjects with versus w/o neck pain
Biomechanical characterization of CS manipulation in living subjects and cadavers.
Based on Symons et al. 2012 Results:
*Both PRELOAD & PEAK FORCES were significantly higher for cadaveric HVLAT than in living subjects
-Living subjects: 190..3 N
-Cadaver: 283.9 N
-The THRUST DURATION: Was faster for cadaveric HVLAT than in living subjects
-Living subjects: 175 ms
-Cadaver: 120 ms
Effect of selected manual therapy interventions for mechanical neck pain on vertebral and intervertebral carotid arterial blood flow and cerebral inflow
Based on Thomas et al. 2013 Purpose:
Examine the effects of selected manual therapeutic interventions on blood flow in the craniocervical arteries and blood supply to the brain using Magnetic resonance angiography (MRA)
Effect of selected manual therapy interventions for mechanical neck pain on vertebral and intervertebral carotid arterial blood flow and cerebral inflow
Based on Thomas et al. 2013 methods:
Participants: 20 healthy adults average age 33 y/o
Imaged using 3T MRA in the following neck positions:
1. neutral
2, Rotation
3. Rotation/distraction (like cryriax manipulation)
4. C1-c2 rotation (like Maitland/osteopathic manipulation)
5. Distraction
Effect of selected manual therapy interventions for mechanical neck pain on vertebral and intervertebral carotid arterial blood flow and cerebral inflow
Based on Thomas et al. 2013 Results:
*Average inflow to the brain= 6.98 mL/s
*No significant changes in flow in any of the 4 arteries in any position
