Comparative study between ultrasound determination and clinical assessment of the lumbar interspinous level for spinal anesthesia

Abstract

Background: Currently, Tuffier's line is considered the standard level for spinal anesthesia. Incorrect determination of this line may result in iatrogenic spinal cord injury1. The current study aims to compare the accuracy of the ultrasound versus clinical determination of the spinal level2,3, using X-ray as the standard for comparison. Methods: This prospective, randomized and controlled study included 200 adult patients of both genders and all classes of the American Society of Anesthesiologists (ASA). After approval of the Local Ethics Committee and securing informed consent, they were randomized into two equal groups. Patients in the Clinical Group (Group C) were examined by clinical landmarks to assess the Assumed Clinical Tuffier's Line (ACTL). Midpoint of ACTL was marked with a radio-opaque marker and then the True Clinical Tuffier's Line (TCTL) was determined using Fluoroscopy (Figure 1). Patients in the Ultrasound Group (Group U) were examined using ultrasound machine to determine the Ultrasound Tuffier's Line (USTL). The results of both groups were compared with the Radiological Tuffier's line (RTL) from plain X-rays done for both groups. Results: Results are presented in Table 1. In Group C, the ACTL accurately correlated with TCTL in only 12% of the patients. It correlated one space cephalad at L3-4 space (67%), at L3 spine (13%) and two spaces cephalad at L2-3 space (7%) and at L2 spine (1%). In Group U, the UTL accurately correlated in 78% of the patients. It corresponded cephalad to L3-4 space (16%) and to L3 spine (4%) and caudad to L5 spine (2%). Conclusion: Ultrasound examination of the spine is recommended in patients planned for spinal anesthesia, as it is superior to clinical assessment in determining the lumbar interspinous level which will minimize the possibility of iatrogenic spinal cord injury.