D. Wiessner

Misplacement of a psoas compartment catheter in the subarachnoid space

Background and Objectives: This case report describes an unusual cause of misplacement of an indwelling catheter in the subarachnoid space after primary psoas compartment block in a patient undergoing total knee arthroplasty. Case Report: A 67-year-old woman presenting for total knee joint replacement received a combination of continuous psoas compartment block and sciatic nerve block. Neurostimulation and additional ultrasound guidance were used for identification of the lumbar plexus. After elicitation of a quadriceps motor response, a negative aspiration test, and an uneventful test dose, 20 mL ropivacaine 0.375% and 20 mL mepivacaine 1% were injected. Despite difficult ultrasound conditions because of intestinal air, local anesthetic spread was observed paravertebrally at the medial border of the psoas muscle as usual. A catheter was then advanced 7 cm through the insulated directional puncture needle. An additional sciatic nerve block was performed by using Labats approach. Ten minutes after injection unilateral sensory block was noted and surgery was started. After uneventful surgery, bilateral sensory block to the T4 level and complete motor block in both lower limbs was detected. A second aspiration test was negative, and an epidural block was suspected. For verification of the catheter tip location, a computed tomography scan with contrast dye was performed revealing catheter placement in the subarachnoid space. The catheter was removed and showed a kink about 7 cm from the tip. After regression of the neuraxial block, lumbar plexus block persisted for another 2 hours. Conclusion: An additional test dose via the catheter is recommended if the indwelling catheter is inserted after injection of the local anesthetics through the puncture needle. If epidural anesthesia occurs, an x-ray of the catheter is advisable because negative aspiration via catheter does not rule out subarachnoid catheter location.

High-resolution ultrasound-guided high interscalene plexus block for carotid endarterectomy.

Background and Objectives High-resolution ultrasound imaging (HRUI) allows real-time visualization of peripheral nerves, needle insertion, and the spread of local-anesthetic (LA) solution. We evaluated the feasibility of performing a high interscalene brachial-plexus block for carotid endarterectomy by means of HRUI, thereby limiting the amount of LA to the dose required to sufficiently surround the relevant nerve structures. Methods The interscalene brachial plexus was localized in the interscalene groove at its most cephalad point in 14 patients undergoing carotid endarterectomy by use of an ultrasound device with a 17.5 MHz transducer. Up to 20 mL of ropivacaine 0.5% was injected. Results In all patients, HRUI allowed clear delineation of the upper part of the interscalene brachial plexus at the level of the 4th cervical vertebra appearing as 1 hypoechoic, roundish, hypodense node located in a distance of 1.5 ± 0.3 cm to the skin, 1.5 ± 0.2 cm lateral to the common carotid artery, and 0.6 ± 0.2 cm from the transverse process of the spine. Likewise HRUI allowed a clear delineation of minor blood vessels and adjacent anatomic structures, as well as accurate placement of the needle close to the nerves. Real-time observation of LA spread during injection was possible, even in increments of less than 1 mL. Conclusions High-resolution ultrasonic imaging allows clear depiction of the target tissues and facilitates accurate needle placement during high interscalene brachial-plexus blocks. This technique may minimize the risk of direct puncture-related complications, as well as accidental intravascular injection of LA. The observation of LA spread in all patients, even in small increments of less than 1 mL might enhance safety by limiting the injected LA to the actual demand. Well-placed LA spread could potentially avoid central nervous toxicity caused by intravascular injection or resorption of inadequately high dosages, in particular in nerve blocks of the highly vascularized neck region.

Precision of Traditional Approaches for Lumbar Plexus Block: Impact and Management of Interindividual Anatomic Variability

Background:Traditional methods for approaching the lumbar plexus from the posterior rely on finding the intersection of lines that are drawn based on surface landmarks. These methods may be inaccurate in many cases. The aim of this study was to determine the accuracy of these traditional approaches and determine if modifications could increase their accuracy. Methods:The lumbar plexus region of 48 cadavers (78 ± 7 yr; 167 ± 6 cm; 60 ± 13 kg; men/women: 29/19) was dissected, and relevant anatomic structures were marked. Needle proximity curves were obtained by triangulation for the five traditional approaches and for vectors from the posterior superior iliac spine directed towards the lumbar spinous processes of L3 and towards L4. Results:Proximity curves (mean ± SD) showed that except Pandin’s approach (13 ± 5 mm too medial), all others were too lateral: Winnie (17 ± 8 mm), Chayen (8 ± 5 mm), Capdevila (6 ± 4 mm), and Dekrey (17 ± 6 mm). Further, the curves had a narrow parabolic shape and thus a narrow margin of error. Both diagonal vectors had a significantly higher proximity to the lumbar plexus as compared with traditional approaches with a wide parabola, indicating more error tolerance. Using the vector posterior superior iliac spine-L3 with a length between 1/6–1/3 (= 16–22 mm) of the distance posterior superior iliac spine-L3, a proximity to the lumbar plexus < 5.0 ± 0.3 mm was reached. Conclusion:Improvement of both the proximity and the margin of error is possible by using diagonal landmark vectors. Relying on the position of the posterior superior iliac spine eliminates the sex and sided differences and individual body size, which can be problematic if firm metric distances are used in determining the entry point.

Bladder Tumor Recurrence after Primary Surgery for Transitional Cell Carcinoma of the Upper Urinary Tract

Objective: Primary transitional cell carcinoma (TCC) of the upper urinary tract represents 6–8% of all TCC cases. Nephroureterectomy with removal of a bladder cuff is the treatment of choice. The rates of TCC recurrence in the bladder after primary upper urinary tract surgery described in the literature range between 12.5 and 37.5%. In a retrospective analysis we examined the occurrence of TCC after nephroureterectomy for upper tract TCC in patients without a previous history of bladder TCC at the time of surgery. Methods: Between 1990 and 2002, 29 patients underwent primary nephroureterectomy for upper tract TCC. The mean age of the patients was 69.5 years. In 5 cases upper urinary tract tumors were multilocular, in the remaining cases unilocular in the renal pelvis (n = 12) or the ureter (n = 12). The follow-up was available for 29 patients with a mean follow-up of 3.37 (0.1–11.2) years. Results: 11/29 (37.9%) patients had TCC recurrence with 9/11 patients having bladder TCC diagnosed within 2.5 years (0.9–6.0) after nephroureterectomy. 13/29 patients are alive without TCC recurrence, 3/29 patients died due to systemic TCC progression and 5/29 died of unrelated causes without evidence of TCC recurrence. Conclusion: Our data indicate a high incidence of bladder TCC after nephroureterectomy for primary upper tract TCC of up to 6 years after primary surgery. Because of the high incidence of bladder TCC within the first 3 years of surgery, careful follow-up is needed over at least this period.