On 2016 Nov 27, Michael Gorn commented:

Thank you for creating this great video tutorial of our lumbar puncture (LP) technique. Video 1 is the most accurate representation of the way we performed the sonography for the study. You have captured the pertinent landmarks, especially the vascular supply of the anterior spinal space that we postulated was the main reason behind a bloody LP. This is how the concept of the Maximum Safe Depth (MSD) was developed. As you clearly demonstrated, the MSD measurements are very close in both transverse and longitudinal views, thus we used longitudinal views for convenience. Once the MSD measurement is obtained, it is marked on the needle as a safe entry depth while performing the LP. The MSD may be exceeded with caution if the needle entry level is shallow as justified by the Pythagorean equation demonstrated in the paper. However, if the entry angle is close to 90 degrees, we recommend redirecting the needle or reattempting the LP. Thank you again for your contribution.

On 2016 Nov 26, James Tsung commented:

Link to Video: http://bit.ly/2gK9osv

On 2016 Nov 26, James Tsung commented:

Link to Video: http://bit.ly/2gK9osv

On 2016 Nov 27, Michael Gorn commented:

Thank you for creating this great video tutorial of our lumbar puncture (LP) technique. Video 1 is the most accurate representation of the way we performed the sonography for the study. You have captured the pertinent landmarks, especially the vascular supply of the anterior spinal space that we postulated was the main reason behind a bloody LP. This is how the concept of the Maximum Safe Depth (MSD) was developed. As you clearly demonstrated, the MSD measurements are very close in both transverse and longitudinal views, thus we used longitudinal views for convenience. Once the MSD measurement is obtained, it is marked on the needle as a safe entry depth while performing the LP. The MSD may be exceeded with caution if the needle entry level is shallow as justified by the Pythagorean equation demonstrated in the paper. However, if the entry angle is close to 90 degrees, we recommend redirecting the needle or reattempting the LP. Thank you again for your contribution.