Lateral C1-2 puncture for cervical myelography. Part III: Historical, anatomic, and technical considerations.

Three significantly different lateral approaches to the cervical subarachnoid space (anterior, midplane, and posterior needle positions) have been previously described for cordotomy and myelography. Experimental lateral C1-2 punctures were performed by each of these three methods in anatomic specimens, cadaver models with reconstituted cerebrospinal fluid pressures, a patient with cerebral death, and to a limited degree in patients undergoing routine cervical myelography. In the cervical region the dura is pushed ahead of the needle, forming a "tent" over the needle tip during C1-2 puncture; the needle projects several millimeters into the spinal canal before penetrating the dura, regardless of the method of entry or needle diameter. The extent of this tenting phenomenon and its relationship to the spinal cord are significantly affected by the needle diameter and position. A posterior technique for lateral C1-2 puncture is described.