Lisa Udovic PGY3 Anesthesia Oct 30, 2013 Conus Medullaris Termina@on Study: A Closer Look
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Project Title and Ra@onale Introduc@on/Background Primary and Secondary Objec@ves Study Design •  Type •  Popula@on •  Inclusion/exclusion criteria •  Dura@on and Start Methodology •  Data Collec@on •  Sta@s@cal Analysis Limita@ons Conus Medullaris Termina7on Study: A Retrospec@ve Magne@c Resonance Imaging Study to Determine if Spinal Anesthesia is Safe in the L2-­‐L3 Interspace. 1 2 3 Miller says 10 % of Spinal C
ords End at L3 as b ased But this w
s tudy on a cadaver So How Many Spinal c ords d o end below L2? Is it safe to do spinal anesthesia at the L2-­‐L3 interspace? Inves@gat
Inves7gators ors Department of Radiology Dr. Nina Singh Dr. Luigi MaVeliano Department of Anesthesia Department of Clinical Dr. Paul James Epidemiology and Dr. Lisa A. Udovic Dr. Kathleen Oman Biosta@s@cs Dr. Lehana Thabane Dr. Wooheon T. Kim Dr. Leora Bernstein 1 Introduc7on: Background: Spinal Injury Landmarking Tuffier’s Line CMT Loca@on Introduc7on: Background: Spinal Injury •  The L2-­‐L3 interspace has generally been accepted as safe for neuraxial anesthesia and is common prac@ce today. •  Over the last two decades there have been mul@ple reports of spinal cord injury following spinal anesthesia 1-­‐12 •  It is possible that injury may be due to the fact that the (CMT) can extend as low as the upper third of the L3 vertebrae and may put the spinal cord at risk 14. Introduc7on: Background: Landmarking •  Many studies show that landmarking to a specific interspace is difficult and we are accurate only 29-­‐41% of the @me 15-­‐19 •  When landmarking using iliac crests it has been found that anesthesiologist’s are one interspace higher over half of the @me and can be up to four interspaces off 15 •  This is a problem in spinal anesthesia because spinal needles could poten@ally enter the L1-­‐L2 interspace or even higher uninten@onally into the spinal cord and cause spinal cord damage •  With the known difficul@es in landmarking, it is therefore important to find out the percentage of spinal cords that are termina@ng in the L2-­‐L3 interspace, and even the L1-­‐L2 interspace, since it has been shown that we can be uninten@onally higher than intended with spinal anesthesia Introduc7on: Background: Tuffier’s Line •  Tuffier’s Line is a horizontal line which intersects both iliac crests •  In a study by Kim et al Tuffier’s Line was found to be radiologically located between L4 and L5 •  Another study revealed that the palpated Tuffier’s Line falls at the L3-­‐4 interspace, one interspace higher than its radiological loca@on 20 •  This difference may lead to selec@on of a higher interspace for neuraxial technique and put the pa@ent’s spinal cord at risk of injury. •  As a result of this, it is important to assess exactly where Tuffier’s Line is located radiologically in both normal pa@ents and those with spinal pathology. Introduc7on: Background: CMT Loca@on •  Previous studies have reported the range of the CMT from T12 to L3, but it is widely accepted to terminate at the level of L1 21-­‐24 •  There are MRI and cadaver studies reported in the literature. However, the cadaver studies tend to show the CMT level at L2 25-­‐27, which is lower than most of the MRI studies at L1 14,21-­‐24,28-­‐32 •  However one study discusses the limita@ons of cadaveric studies since the spinal cord increases in mass aher the embalming process and this may affect results 33 Primary and Secondary Objec7ves The Goal is to Prevent SCI Primary: •  To determine the loca@on of the conus medullaris termina@on in an adult and pediatric popula@on and what percentage of individuals terminate below the L2 body •  This primary objec@ve was chosen in order to determine if spinal anesthesia is safe at the L2-­‐L3 interspace Primary and Secondary Objec7ves The Goal is to Prevent SCI Secondary: •  A secondary objec@ve is to determine the rela@onship of CMT to age, gender, BMI, and spine pathology. •  Spine pathology includes; disc degenera@on, bone degenera@on, compression fractures, osteoarthri@s, osteoporosis, tumor, spinal stenosis, scoliosis, spondylolisthesis, spina bifida or other congenital abnormality •  We are also looking at Tuffier’s Line and the percentage located above the L4 body, along with it’s rela@onship to age, gender, BMI or any spine pathology. •  With this informa@on we can es@mate what percentage of pa@ents are at increased risk of spinal cord injury during neuraxial technique as well as specific groups that may be at increased risk. Study Design Type: • 
Retrospec@ve case control study carried out at Hamilton Health Sciences, Hamilton, Ontario, Canada Popula7on: • 
Pediatric and adults pa@ents, no age restric@ons, male and female Study Design Inclusion Criteria: •  Pediatric and adult pa@ents no age restric@ons •  Male and female •  With a lumbo-­‐sacral MRI completed and reported by radiologist •  We plan to include abnormal MRI scans and will categorize them according to the type of abnormality Study Design Exclusion Criteria: •  Any pa@ents who did not have an axial lumbar MRI will be excluded due to difficul@es with defini@vely iden@fying the conus medullaris termina@on •  Any pa@ents who are iden@fied as having sacraliza@on or lumbariza@on will also be excluded due to difficul@es with coun@ng vertebra and hence assigning a CMT level. Study Design Dura7on and Start: •  The start date for data collec@on will begin in Nov 2013 for Lumbar MRI’s completed between September 2012 to September 2013 •  Lumbar or abdominal x-­‐rays obtained within 5 years of the MRI will also be collected •  The research protocol has been submiVed to the Research Ethics Board (REB) in October 2013 and awai@ng approval Methodology Data Collec7on/Management: • 
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Lumbar MRI’s, lumbar x-­‐rays, abdominal x-­‐rays and spinal history from Meditech will be collected Data will be collected by Dr.’s Lisa Udovic, Kathleen Oman, Thomas Kim, and Leora Bernstein It will be collected by a sequen@al series on scans done between September 2012 to September 2013 to prevent selec@on bias Redcap, an online data collec@on tool will be used for the collec@on and storage of data and saved on a password protected computer Methodology Data Collec7on/Management: • 
The MRI scans will be assessed by two reviewers from the radiology department, Dr. Nina Singh and Dr. Luigi MaVeliano • 
They will determine the level of the CMT and Tuffier’s line and any discrepancies will be resolved by consensus • 
The vertebral bodies will be divided into thirds, upper, middle and lower third. The CMT level will either be assigned to the appropriate 1/3 of the vertebral body or the interspace between. Methodology Data Collec7on/
Management: • 
We will also be reviewing Tuffier’s line on the MRI and lumbar x-­‐ray if available and determine if it corresponds to L4 /L5. This will include the body of both L4 and L5 vertebrae and the space in between. We want to determine the percentage occurring above the L4 body. Methodology Proposed Data Collec7on Fields: MRN Ini@als Gender Age Ethnicity Height Weight BMI Spine History Indica@on for Lumbar MRI Lumbar MRI Normal Type of Pathology on Lumbar MRI Level of CMT Is CMT level at or below L2 Tuffier’s Line level on MRI Lumbar x-­‐ray done ? Indica@on for lumbar x-­‐ray? Lumbar x-­‐ray normal? Pathology on Lumbar x-­‐ray? Tuffier’s Line level on Lumbar x-­‐ray Abdominal x-­‐ray done? Indica@on for abdominal x-­‐ray ?clop Abdominal x-­‐ray normal? Pathology on Abdominal x-­‐ray? Tuffier’s Line level on Abdominal x-­‐ray? Is Tuffier’s Line between L4 and L5 ? Is Tuffier’s Line above L4 ? Ethics REB Approval: •  We have applied for approval by the local Research Ethics Board (REB) in October 2013. •  The informa@on collected will be kept confiden@al and anonymous •  Data will be stored in Redcap on password protected computers in the research department at McMaster University and any data on USB key will be encrypted Sta7s7cal Analysis •  We calculated a sample size of 1000 subjects based on an es@mated incidence of 2.5% for a CMT occurring below L2 and a margin of error of 1%. •  We will describe the number of pa@ents whose conus terminates below the body of L2 with a percentage and 95% confidence interval •  We also plan to look at what percentage of the popula@on’s iliac crest corresponds to L4-­‐L5 interspace •  The CMT will be reported as a mean/median with differences between age groups and sex with an analysis of variance. •  The impact of demographics (age, gender, ethnicity and BMI) and clinical (spine diagnosis type) will be evaluated using logis@c regression analysis. Significance will be assumed at p=0.05 or less. Sample Size Spreadsheet Initial'Estimate'(P) 0.01
0.012
455.460096
0.02
752.9536
0.025
936.39
0.045
1650.9276
0.1
3457.44
Margin'of'Error'ME'
0.02
0.05
0.06
113.865024 18.2184038 12.6516693
188.2384 30.118144 20.9153778
234.0975
37.4556 26.0108333
412.7319 66.037104
45.8591
864.36
138.2976
96.04
Limita7ons: The first limita@on is that the study is retrospec@ve in nature The pa@ents also have an indica@on for an MRI and therefore the results may not be applicable to the general popula@on. Another concern is that according to radiology it may be difficult to accurately use the MRI to es@mate Tuffier’s Line if the MRI doesn’t contain the en@re iliac crest. Other studies have addressed this problem by performing secondary studies looking at x-­‐ray correspondence to MRI derived Tuffier’s Line Questions, Comments or
Suggestions ?
What’s Your Message?
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