Fig. 2

Angle-free paramedian approach for lumbar puncture in a patient with severe scoliosis (Patient 1). (a-b) Cephalad angulation of the probe required to obtain a clear anterior complex image in the paramedian sagittal oblique view in the standard lateral decubitus position. (c) Modified position to eliminate the cephalad angulation of the probe required for the same image. (d-e) The probe was rotated 90 degrees to obtain the transverse median view, and then rocked clockwise (from caudal-to-cephalic view) to produce a normalized transverse interspinous view with the laminae at the same horizontal level. (f) Schematic image illustrates the degree of the rocking is the angle by which the trajectory of needle insertion must be modified to successfully direct the needle towards the spinal canal. (g-h) The probe was placed parallel to the floor, as verified by attaching a spirit level to obtain the image of the spinal canal. Once the spinal canal is centered in the middle of the screen, skin marks are made at the midpoint of the probe’s long and short edges. The intersection of these two marks is identified as the needle entry point. (i) Lumbar puncture’s triangle model. The hypotenuse (AB) is the midline approach; the base (AC) is the paramedian approach, and the height is the lateral offset from the midline approach