Changes in Vertebral Artery and Cerebral Hemodynamics Following Various Head Positions & Cervical Manipulation in Patients With Chronic/Recurrent Neck Pain
Phase: NA
Conditions: Vertebral Artery Dissection, Cerebrovascular Accident, Stroke
Sponsor: Canadian Memorial Chiropractic College

RE: “Changes in Vertebral Artery and Cerebral Hemodynamics Following Various 
Head Positions & Cervical Manipulation in Patients with Chronic/Recurrent Neck 
Pain.” 
 
Co-Investigators: 
Nicholas Moser, BSc DC 
John J. Triano, DC PhD 
Silvano Mior, DC PhD 
Pierre Coté, DC PhD 
Michael Noseworthy, PhD 
Greg Wells, PhD 
 
 
To whom it may concern, 
 
We thank you for you consideration of this work. Please find below 4 pages detailing the 
methods and procedures of the study. 
 
Sincerely, 
 
Nicholas Moser, BSc, DC 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Methods 
Participants  
Twenty patients were recruited from the campus-teaching clinic located at the Canadian 
Memorial Chiropractic College. Included were adults aged 18 years and older with 
chronic grade II31 mechanical neck pain that had been prescribed cervical manipulation 
for treatment of their condition. Patients with a history of neck pain with associated arm 
pain within the last 6 months; any current or history of neurologic symptoms including 
facial or extremity weakness, abnormal sensation to the face, body, or extremities, 
uncontrolled movements, abnormal gait, dizziness, unexplained nausea/vomiting, 
difficulty with speaking or swallowing; history of new or severe (Visual Analogue Scale 
>6) headaches in the last 3 months; any contraindications to MRI; or any history of using 
drugs that affect blood flow such as Warfarin, or anti-coagulants were excluded. All 
participants refrained from vigorous physical activity, alcohol, and caffeine one day 
before commencement of the study.   
The study was approved by the local ethics committees of St. Joseph's Healthcare 
Hamilton at McMaster University in Hamilton, Ontario, and Canadian Memorial 
Chiropractic College in Toronto, Ontario. Written informed consent was obtained from 
all participants before the study commenced. Data were collected at the Imaging 
Research Centre, Hamilton, Ontario. The study was registered with 
www.clinicaltrials.gov, NCT02667821.  
Test Protocols 
The study was conducted as a randomized controlled case-crossover trial. Prior to the 
MRI, baseline information on each participant was obtained and included age, gender, 
height, weight, hand dominance, NDI score neck pain intensity and headache intensity 
(see Table 1). On the day of the scan, prior to commencing, participants underwent a 
cervical spine examination, completed by the clinician performing the test maneuvers 
(SM), in order to identify the site of manipulation. Once participants provided verbal 
acknowledgement of being comfortable to proceed, they underwent three separate test 
maneuvers.  Each began with neutral (0 degree rotation) neck position (condition 1) as a 
standard natural control, followed by either maximum voluntary rotation (conditions 2), 
and one dynamic high-velocity-low-amplitude (HVLA) cervical rotary manipulation 
targeted at C1-C2 (condition 3). Each procedure was performed to the side of clinical 
findings elicited during cervical examination by the clinician. Tasks were selected based 
on their use in evaluation or treatment during clinical encounters.  
Neutral position of the head was defined by alignment in the Frankfort plane in a vertical 
orientation. For continuity of neutral alignment between protocols, the MRI laser land 
marking tool was used to cross triangulate three tape marks on the MRI head RF coil with 
three oil based markers (Vitamin E capsules) taped to the nasion (bridge of the nose) and 
immediately in front of the tragus of the ears, bilaterally. For each brain image obtained, 
the marker set provided quantitative orientation of the head position.  
Participants were randomly assigned to condition 2 or condition 3 using a randomized 
table generator (GraphPad Software Inc, La Jolla, CA). Each head condition was applied 
in the MRI scanner room adjacent to the MRI bore (Fig 1) and for condition 2 the 
position of the head was held for 1 minute and then returned to neutral for MRI 
sequencing. For the manipulation, the head was repositioned to neutral immediately after 

and the patient was retracted into the MRI bore. Condition 2 was independently measured 
by inclinometer.  
After each condition, MRI of the cerebrum and upper neck for blood flow ensued. The 
total time elapsed for each participant testing protocol was 60 minutes. The total time 
elapsed for each condition was approximately 20 minutes. This included applying the 
condition (1 minute), replacing the participant back into the MRI bore (approximately 1 
minute), and routine image sequencing (approximately 18 minutes). Estimates of 
repeatability of flow measures were made in preliminary work by quantifying VA flow in 
a single healthy participant twice over a 2-month interval. 
A practitioner with more than 30 years of practice experience conducted the upper 
cervical manipulation.32-34 The manipulation procedure required no transfer of the 
participant; rather, it was performed on the adjustable and pivotal MRI bed in the MRI 
room with the participant in the supine position (Fig 1). The procedure was a high 
velocity, low amplitude (HVLA) impulse, designed to initially position the participants’ 
heads in an axial rotation, flexion as well as lateral flexion postures. Variations of head 
positions between operators have been demonstrated to be relatively small.35,36 The 
clinician performed the procedures in representative manner, first establishing the end 
range of motion to determine appropriate preload position for the manipulation before 
applying a typical clinical force impulse in the coronal plane with minimal traction 
component. Before the delivery of each maneuver, the participants were queried on their 
comfort, condition, and willingness to continue.  
A brief 5-item analogue scale was administered to each of the participants and clinician 
immediately after the test maneuvers. This scale provides quantitative estimates of the 
patient's and operator's judgment of the descriptive characteristics of the CSM procedure 
on a continuous scale of 0 to 10. The words “fast,” “force,” “comfort,” “confidence,” and 
“precise” were used as descriptors as validated and used in several other studies.37-39 
The scale provided a means of contrasting the procedure characteristics within the 
context of the range of typical performance, as represented within the literature.  
Magnetic Resonance Imaging Protocols  
Four MRI series were performed on each participant (3-Telsa GE Signa Excite HD MRI 
scanner and 20 channel neurovascular array RF coil; GE Healthcare, Milwaukee WI), 
including anatomical images, arterial spin labeling (ASL), blood oxygen level dependent 
(rsMRI BOLD) and phase contract MRI. Following head positioning, immobilization 
with sponges and a localizer scan, anatomical images were collected using a 3D IR-
prepped fast SPGR T1-weighted scan (TR/TE=11.4/4.3 ms, T1 = 450 ms, flip angle = 12 
degrees, 512 x 256 matrix, 140 slices, 24 cm FOV, reconstructed to 1mm3 isotropic 
voxels). Microvasculature was assessed using a 3D spiral-based fast spin echo pseudo-
continuous arterial spin labeling (pCASL). pCASL sequence was used to assess 
cerebrovascular perfusion (TE/TR/TI=10.5/4629/1525ms, FOV=24cm, 512x8spiral 
interleaves, 3NEX, reconstructed to 128x128matrix with 4mm thick slices, scan time 
=30s). The ASL sequence was immediately followed with the phase contrast MRI. At the 
level of C1-2, the contralateral and ipsilateral vertebral arteries (to the direction of head 
motion) were assessed and anatomical images were established to localize the VA 
circulation. As previously published by Ho et al the method for obtaining flow 
quantification of the VA was a 2-dimensional phase-contrast pulse sequence. To capture 
accurate VA flow, the imaging plane is ideally perpendicular to the central axis of the 

blood vessel. This imaging plane was selected on the vessel of interest at the C1-2 
intervertebral level based on arterial visualization on a maximum intensity projection of a 
2-dimensional time-of flight MRI angiogram. Magnetic resonance acquisition parameters 
were as follows: fast gradient recalled echo; echo time/repeat time, 3.9/8.9 milliseconds; 
flip angle, 20o’ 20 cm field of view; 512* 512 matrix; 244-Hz/pixel receiver bandwidth; 
1 average; 4 mm thick; and velocity encoding of 50 cm/s encoded for 30 phases per 
cardiac cycle. Owing to anatomical variations, occasional slices could only approximate 
orthogonality. All image measurements were obtained by manually selecting the optimal 
anatomical site between the base of the odontoid process and approximately 1 cm above 
the tip of the dens. According to Lotz et al vessel obliquity is tolerable to above or equal 
to 15 degrees, above which will cause a deviation from the true flow.41  Data capture 
was triggered by prospective gating using a peripheral pulse (MRI scanner–pulsed 
oximeter). The image acquisition time for each flow measurement was approximately 1 
minute 30 seconds depending on heart rate. 40 Flow analysis was performed using 
Segment v1.9 software 47 (Medviso, Lund, Sweden). Dynamic regions of interest were 
drawn on the left and right vertebral arteries to quantify mean, as well as peak velocities, 
and flows. Data in the trigger window portion of the cardiac cycle were derived by spline 
interpolation using Matlab (Mathworks, Natick, MA). The final data set for a complete 
cardiac cycle, therefore, contained measurements from all the cardiac cycles that elapsed 
during the scan time. A typical phase-contrast image is presented in Figure 2, with 
regions of interest (ie, vascular cross sections) labeled. Subsequently, rsMRI BOLD was 
performed. This was acquired using a gradient echo, echo planar imaging (GE-EPI) 
sequence (64x64 matrix, 28 axial slices (5mm thick, no skip), 24cm FOV, TE/TR/flip 
angle = 35ms/2000ms/90o, 180 temporal points, total scan time=6 minutes). During the 
rsMRI BOLD scan, subjects were asked to keep their eyes open, stay awake, and not 
think of anything in particular.  
Following the 3D anatomical, rsMRI BOLD, ASL and phase contrast MRI the subject 
was removed from the MRI and condition 2 and 3 were applied separately in a 
randomized order. Each condition was immediately followed by realignment of the head, 
return to the MRI bore, scan of a 3-plane localizer and then ASL, phase contrast, rsMRI 
BOLD and 3D anatomical scans. The latter three were always performed with the 3D 
anatomical last seeing as microvascular changes (i.e. blood flow) were more likely to be 
detected early after the manipulation while structural changes (i.e. 3D scan) wouldn’t be 
expected to occur. 
Data Analysis 
Data quantification was performed by an experienced analyst who remained blinded to 
the test maneuvers. ASL blood flow and rsMRI BOLD data were analyzed using analysis 
of functional neuroimaging (AFNI). Functional rsMRI BOLD data preparation first 
involved slice timing correction and 3D rigid body motion correction. For each subject all 
ASL and rsMRI BOLD data were spatially registered to the initial (neutral condition) 
position. Anatomical, blood flow and functional data were transformed automatically to 
the Colin27 atlas, using the AFNI command @auto_tlrc, with functional data resampled 
to a 2mm isometric grid.42 Temporal band-pass filtering with cutoffs of 0.009Hz < f < 
0.08Hz was performed in order to suppress unwanted physiological signals and some 
hardware noise.43 Functional connectivity within the default mode network (DMN) was 
assessed using the AFNI plugin InstaCorr, a seed-based approach, which uses the Pearson 

method of correlation to compare time signals.44 The DMN is the most dominant 
temporally correlated resting network in the awake brain, defined as regions positively 
correlated in time with the posterior cingulate cortex (PCC) seed voxel. The PCC was 
defined automatically using the AFNI Talairach method ‘Talairach to’ and selecting a 
single voxel from each the left and right PCC for one analysis (ColinN27 coordinates: 10, 
54, 14, and -10, 54, 14). These were both subsequently fused in the post-processing. A 
5mm FWHM Gaussian spatial smoothing filter was applied for maximize likelihood of 
overlap with inter-subject group analysis. Also, temporal outliers determined with the 
AFNI function 3dToutcount were censored out. The ASL cerebral blood flow data was 
analyzed similar to rsMRI BOLD in that following spatial co-registration to the neutral 
condition and spatial blurring with a 5mm FWHM Gaussian convolution kernel, ASL 
data was warped to the N27 atlas. Group analysis was accomplished using a 1-way within 
subject 3D-ANOVA, with the one factor being neck position. Post hoc testing included 
contrasts between neutral, maximum voluntary rotation and CSM, and also a contrast 
between maximum voluntary rotation and CSM. Statistical significance was defined as 
anything lower than an alpha value of 0.05. 
Mean and SDs were calculated for VA blood velocity, flow, peak velocity, and peak flow 
for each of the head conditions and VA side. Differences between task maneuvers and 
VA flow and velocity were evaluated using a repeated-measures analysis of variance with 
factors of head position and VA side, and a level of significance was set at .05, using R-
project version 2.12.1 (R Development Core Team, 2010. R: A language and 
environment for statistical computing. R Foundation for Statistical Computing, Vienna, 
Austria. ISBN 3-900051-07-0, URL http://www.R-project.org/). 
Ratings for the perception of performance of the HVLA cervical manipulation procedure 
were expressed quantitatively as the distance along the VAS line of intensity for each 
descriptive term as a percent of the total length. In this form, the results were expected to 
represent the typical experience at midpoint (e.g. 5 of 10). A composite rating was 
developed as the average across all descriptive terms, assuming equal weighting, as an 
index of the overall experience. As secondary variables, descriptive statistics were 
calculated and Student-tests were performed between the raters using Bonferroni 
correction for significance of p less than or equal to 0.01. ICCs were also calculated 
examining for correspondence between raters.