In 1990, Macdonald et al.defined the criteria for evaluating response to treatment and disease progression. They suggested that variations in the tumor-enhancing area, neurological function, and steroid dosage should be considered in the assessment of tumor response 1). Although these criteria have since been the cornerstone in response evaluation in many phase II clinical trials, some doubts have been expressed regarding the evaluation of disease progression in patients treated with TMZ concomitant with radiotherapy.
In 1990, Parviz Kambin described a triangular safe zone bordered by the exiting root anteriorly, the traversing root medially, and the superior endplate of the lower lumbar vertebra inferiorly 2). The anatomical description of this safe zone allowed the field of endoscopic spine surgery to outgrow the technique of percutaneous nucleotomy, which was limited by the use of small needlelike instruments. Kambin's triangle was a working corridor that allowed larger instruments and working channels to be introduced in even closer proximity to foraminal pathology without injuring the exiting nerve.