Electrophysiological stimulation (Tsui test) is feasible for epidural catheter positioning in adults with chronic back pain: a cohort study

Abstract

Purpose Determining epidural catheter placement and accurately depositing corticosteroids at the site of the pathology in adults with chronic back pain can be challenging. Fluoroscopy is considered the standard of care for guiding epidural catheter positioning and subsequent injection in patients receiving epidural corticosteroids, but the technique has some limitations. We hypothesized that electrophysiological stimulation using the Tsui test is feasible for determining the appropriate epidural catheter position in adults with chronic back pain receiving epidural corticosteroids. Methods We conducted a prospective cohort study of 12 patients receiving epidural corticosteroid injections for chronic back pain. Anatomical landmarks and epidural needle positions were initially confirmed by fluoroscopy. Epidural catheter position was assessed according to sensory and motor responses, as described by Tsui et al. (Can J Anaesth 45: 640-644, 1998). The current was increased slowly from zero until muscle activity was visible or the current reached 10 mA. The catheter was then advanced until muscle responses occurred in the desired myotome. The test was deemed positive or negative according to the Tsui criteria. The anatomical level was confirmed by fluoroscopy prior to injection. Results Electrophysiological stimulation effectively established the appropriate epidural catheter position in 11 patients (92%). Epidural stimulation occurred at a mean (SD) threshold of 3.95 (3.35) mA. The kappa statistic between interventions was 0.65, indicating a substantial level of agreement. Conclusion This study demonstrated that electrophysiological stimulation using the Tsui technique is feasible for epidural catheter positioning in adults with chronic back pain. It may optimize epidural steroid injection in this population. RésuméObjectif Il peut être difficile de déterminer le positionnement du cathéter péridural et de placer de façon précise les corticostéroïdes au site de la lésion chez les adultes souffrant de maux de dos chroniques. La fluoroscopie est considérée comme la norme de soins pour guider le positionnement du cathéter péridural et l'injection subséquente chez les patients recevant des corticostéroïdes par voie péridurale, mais la technique comporte certaines limites. Nous avons émis l'hypothèse que la stimulation électrophysiologique réalisée à l'aide du test de Tsui était faisable pour déterminer le positionnement adéquat du cathéter péridural chez les adultes souffrant de maux de dos Author contributions Niamh McAuliffe made substantial contributions to conception and design, acquisition of data, analysis and interpretation of data; drafted the article and revised the manuscript; and approved the final version to be published. Sharon Pickworth made substantial contributions to conception and design, acquisition of data; revised the manuscript; and approved the final version to be published. Tania DiRenna made substantial contributions to conception and design, acquisition of data; and revised the manuscript;...

Low-dose intrathecal local anesthetic does not increase the threshold current for the epidural stimulation test: a prospective observational trial of neuraxial analgesia in labouring women

“…[8][9][10][11][12][13][14][15][16][17][18] The motor threshold current (MTC) achieved when using the EST can distinguish whether the catheter tip is positioned epidurally (medium MTC: 2-15 mA), subcutaneously (high MTC: [ 15 mA), or intrathecally (low MTC: \ 2 mA), although a low MTC might also conceivably be due to the catheter abutting a nerve root. It should be emphasized that these MTC ranges are somewhat arbitrary depending on the individual interpreting the EST results.…”

Epidural electrical stimulation test versus local anesthetic test dose for thoracic epidural catheter placement: a prospective observational study

“…With the EEST, low-amplitude electrical current is applied to the epidural catheter following its insertion and evoked muscle contraction is sought. While this technique has been studied in various patient populations with excellent results, [13][14][15][16][17] it remains relatively unfamiliar to most anesthesia health care providers. Moreover, none of the previous studies compared EEST with the LA test dose to assess the correct thoracic epidural catheter position.…”