Tilemachos Paraskeuopoulos

Anatomy and clinical implications of the ultrasound-guided subsartorial saphenous nerve block.

Background: We evaluated the anatomic basis and the clinical results of an ultrasound-guided saphenous nerve block close to the level of the nerves exit from the inferior foramina of the adductor canal. Methods: The anatomic study was conducted in 11 knees of formalin-preserved cadavers in which the saphenous nerve was dissected from near its exit from the inferior foramina of the adductor canal. The clinical study was conducted in 23 volunteers. Using a linear probe, the femoral vessels and the sartorius muscle were depicted in short-axis view at the level where the saphenous nerve exits the inferior foramina of the adductor canal. Ten milliliters of 1.5% lidocaine was injected into the compartment structured by the sartorius muscle and the femoral artery. Results: The saphenous nerve was found to exit the adductor canal from its inferior foramina in 9 (81.8%) of 11 and at a more proximal level in 2 (18.2%) of 11 of the anatomic specimens. In a single specimen (9%), the saphenous nerve was formed by the anastomosis of 2 branches. In all the dissections, the saphenous nerve, after exiting the adductor canal, passed between the sartorius muscle and the femoral artery. Of the 23 volunteers, 22 responded with a complete sensory block, whereas a single volunteer demonstrated no sensory blockade. None of the volunteers experienced a motor block of the hip flexors and knee extensors. Conclusions: Ultrasound-guided injection directly caudally from the inferior foramina of the adductor canal, between the sartorius muscle and the femoral artery, seems to be an effective approach for saphenous nerve block.

Thoracic paravertebral spread using two different ultrasound‐guided intercostal injection techniques in human cadavers

The continuity between the intercostal and paravertebral space has been established by several studies. In this study, the paravertebral spread of a colored dye was attempted with two different ultrasound‐guided techniques. The posterior area of the trunk was scanned with a linear probe between the level of the fifth and the seventh thoracic vertebrae in eleven embalmed human cadavers. In the first technique, the probe was placed transversely below the inferior margin of the rib, and a needle was inserted between the internal intercostal membrane and the pleura. In the second technique, the probe was placed longitudinally at the intercostal space 5 cm lateral to the spinous processes, and the needle was inserted between the internal intercostal membrane and the pleura. In both techniques, 1 ml of methylene blue was injected, and both the intercostal and paravertebral spaces were prepared. In total, 33 injections were performed: 19 with the transverse technique and 14 with the longitudinal technique. Successful spread of the dye to the thoracic paravertebral space was recorded in 89.5% cases using the transverse technique and 92.8% cases using the longitudinal technique. No intrapleural spread of the dye was recorded in either technique. Ultrasound‐guided injection into the intercostal space may offer an alternative approach to the thoracic paravertebral space. Clin. Anat. 23:840–847, 2010.

Prospective randomized comparison between ultrasound-guided saphenous nerve block within and distal to the adductor canal with low volume of local anesthetic

Background and Aims: The anatomic site and the volume of local anesthetic needed for an ultrasound-guided saphenous nerve block differ in the literature. The purpose of this study was to examine the effect of two different ultrasound-guided low volume injections of local anesthetic on saphenous and vastus medialis nerves. Materials and Methods: Recruited patients (N = 48) scheduled for orthopedic surgery were randomized in two groups; Group distal adductor canal (DAC): Ultrasound-guided injection (5 ml of local anesthetic) distal to the inferior foramina of the adductor canal. Group adductor canal (AC): Ultrasound-guided injection (5 ml local anesthetic) within the adductor canal. Following the injection of local anesthetic, block progression was monitored in 5 min intervals for 15 min in the sartorial branches of the saphenous nerve and vastus medialis nerve. Results: Twenty two patients in each group completed the study. Complete block of the saphenous nerve was observed in 55% and 59% in Group AC and DAC, respectively (P = 0.88). The proportion of patients with vastus medialis weakness at 15 min in Group AC, 36%, was significantly higher than in Group DAC (0/22), (P = 0.021). Conclusions: Low volume of local anesthetic injected within the adductor canal or distally its inferior foramina leads to moderate success rate of the saphenous nerve block, while only the injection within the adductor canal may result in vastus medialis nerve motor block.

Ultrasound anatomy of the cervical paravertebral space: a preliminary study

PurposeThe aim of the study was to examine the ultrasound anatomy of the cervical paravertebral space in order to facilitate the implementation of sonographically guided regional anesthesia techniques for this region.MethodsTwenty volunteers were recruited, and the anatomic components of the cervical paravertebral space were sonographically examined. The transducer was positioned in the axial and coronal plane at the posterior cervical triangle. The cervical transverse processes with their respective nerve roots, the deep cervical fascia and the paravertebral muscles were identified.ResultsThere was excellent visualization of the C-3, C-4, C-5, C-6 and C-7 transverse processes in all cases. Excellent visualization of the scalene muscles, vertebral artery and deep cervical fascia was also achieved in all cases. Visualization of the levator of scapula muscle was difficult in 9 and excellent in 11 out of the 20 cases. In all cases, visualization of the C-1, C-2 and C-3 nerve roots was unfeasible. The identification of the C-4 nerve root was excellent in 3, difficult in 6 and unfeasible in 11 out of the 20 cases. The C-5, C-6 and C-7 nerve roots were excellently identified in all cases. The C-8 nerve root was identified only in 8 of the 20 cases. The cervical nerve roots also showed high variation, dividing into more than one branch as they exited the cervical transverse processes.ConclusionCervical paravertebral anatomy can be depicted with ultrasound imaging techniques. This could be highly clinically significant for the implementation of regional anesthesia techniques.

Cutaneous perforators of the peroneal artery: Cadaveric study with implications in the design of the osteocutaneous free fibular flap.

Bilateral dissection of 15 formalin embalmed cadaver legs was performed in order to study the anatomic pattern of the peroneal artery (PA) and its cutaneous perforating vessels (CB). The total number of CB from the PA was 125 or an average of 4.17 branches per leg. CB were distributed in the superoinferior axis between 18.25 and 84.25% of the length of the fibula and their average length was 5 ± 1.8 cm. 86/125 (68.8%) of the CB were classified as myocutaneous branches (MC) that penetrated muscle before reaching the skin, whereas 39/125 (31.2%) were septocutaneous branches (SC) that passed through the intermuscular septum. The mean distance between the posterior border of the fibula and the site where the perforators emerged was 1.88 ± 0.79 cm for the SC and 1.21 ± 0.87 cm for the MC. These anatomic findings should encourage the surgeon to design the skin paddle in the boundary between the middle and the distal third of the fibular length about 2 cm behind the posterior fibular border on the posterolateral leg, where the number of CB is maximal. Clin. Anat. 22:826–833, 2009.

Imaging in anesthesia: the role of 4 MHz to 7 MHz sector array ultrasound probe in the identification of the sciatic nerve at different anatomic locations.

o the Editor: Few studies have examined the use of ultrasound for ciatic nerve identification or blockade and thus the clincal utility of such is still being determined.1-4 Additionlly, linear probes are used to identify the sciatic nerve at he popliteal1 and the posterior part of the upper thigh,2 hile a curved probe (2 MHz-5 MHz) is used for the glueal, infragluteal,3 and upper anterior thigh approaches.4 ur experience has shown that a 4 MHz to 7 MHz sector rray probe can provide significant advantages in the dentification and blockade of the sciatic nerve at the opliteal fossa, the lateral thigh (upper and midfemoral evel) and the infragluteal region. Additionally, the sciatic erve can be clearly identified at the anterior thigh in ormally weighted individuals (Fig 1).

Ultrasound and transcutaneous neurostimulator combined technique as a training method for nerve identification in anesthesia residents.

To the Editor: We thank the editor for a chance to respond to the astute comments made by Drs. Michalek and Gabrhelik concerning our article.1 We have chosen the stellate ganglion as a target of our therapy because it is more comfortable to the patient, technically easy, and less time consuming. The optimal ganglion to be treated might vary, depending on the pain condition, and should be studied separately by comparing the treatment of different sites. The report published by Spacek et al.,2 which does not show a statistical relation between saline and buprenorphine when applied to the superior cervical ganglion, could be interpreted as a lack of any pathophysiologic role for this particular ganglion in trigeminal neuralgia. Knowing what results GLOA would have upon application to the gasserian ganglion, which is the more prominent culprit in trigeminal neuralgia, would be interesting. We have not tried this treatment on patients other than those reported in our article. However, we do plan to evaluate this treatment option in other painful conditions of the head and neck. As we clearly mentioned in our article, the placebo effect of GLOA cannot be completely ruled out. The true therapeutic effect of GLOA can be accurately evaluated only by conducting a well-designed double-blinded, placebo-controlled study at different ganglia.

Saphenous and Infrapatellar Nerves at the Adductor Canal: Anatomy and Implications in Regional Anesthesia

Conflicting data exist regarding the anatomical relationship of the saphenous and infrapatellar nerves at the adductor canal and the location of the superior foramen of the canal. Therefore, the authors performed a cadaveric study to detail the relationship and course of the saphenous and infrapatellar nerves and the level of the superior foramen of the canal. The adductor canal and subsartorial compartment were dissected in 17 human cadavers. The distance between the superior foramen of the canal and the mid-distance (MD) between the base of the patella and the anterior superior iliac crest were measured; the course of the saphenous and infrapatellar nerves and the level of origin of the infrapatellar branch were detailed. In 13 of 17 specimens, the superior foramen of the adductor canal was distal to the MD (mean, 6.5 cm); in the remaining specimens, it was proximal to the MD. In 12 of 17 specimens, the infrapatellar branch exited the canal separately from the saphenous nerve; in the remaining specimens, it originated caudally to the canal. In all dissections, the infrapatellar branch had a constant course in close proximity to the saphenous nerve within the canal and between the sartorious muscle and femoral artery caudally to the canal. Most commonly, the superior foramen of the adductor canal is located caudally to the MD; the infrapatellar branch originates from the saphenous nerve within the canal and has a constant course in close proximity to the saphenous nerve. These observations should be considered for regional anesthesia techniques at the adductor canal.

Ultrasound-guided obturator nerve block: the importance of the medial circumflex femoral vessels.

To the Editor: W e read with interest the excellent work of Manassero et al concerning a new approach of ultrasound-guided interfascial obturator nerve block. Although injections of local anesthetic between the planes of the adductor muscles is a very successful technique for blocking the obturator nerve, it is of great importance for the operator to clearly describe the intrafascial course of the vessels at this anatomic region. This possibility of vascular puncture occurring could have also been discussed. In the inguinal-femoral region, vascular structures must be recognized during ultrasound scanning, in particular, the medial circumflex femoral artery and vein. These vessels arise from the medial and posterior aspect of the profunda femoris vessels or sometimes directly from the femoral vessels and run intrafascially between the pectineus and iliopsoas muscles and then between the obturator externusYadductor magnus and the adductor brevis muscles. Because of the close relationship of the medial circumflex femoral artery and vein with the obturator nerve divisions and subdivisions, it is important to detect sonographically the vascular components of the region before needle advancement. Manipulation of the ultrasound transducer may visualize the exact anatomic course of these vessels and thus avoid puncture or intravascular local anesthetic injection (Fig. 1). In conclusion, the inguinal-femoral anatomic region is a highly vascularized area, and it is crucial for the anesthesiologist to identify major vascular components before the implementation of any obturator nerve block.

Anatomical basis of the various spread patterns around the femoral nerve in the inguinal region.

References 1 Ilies C, Grudev G, Hedderich J, et al. Comparison of a continuous noninvasive arterial pressure device with invasive measurements in cardiovascular postsurgical intensive care patients: a prospective observational study. Eur J Anaesthesiol 2015; 32:20–28. 2 Cecconi M, Rhodes A, Poloniecki J, et al. Bench-to-bedside review: the importance of the precision of the reference technique in method comparison studies – with specific reference to the measurement of cardiac output. Crit Care 2009; 13:201. 3 Columb MO. Clinical measurement and assessing agreement. Curr Anaesth Crit Care 2008; 19:328–329. 4 Chemla D, Teboul JL, Richard C. Noninvasive assessment of arterial pressure. Curr Opin Crit Care 2008; 14:317–321. 5 Kim SH, Lilot M, Sidhu KS, et al. Accuracy and precision of continuous noninvasive arterial pressure monitoring compared with invasive arterial pressure: a systematic review and meta-analysis. Anesthesiology 2014; 120:1080–1097. 6 Alpert BS, Quinn DE, Friedman BA. A review of the latest guidelines for NIBP device validation. Blood Press Monit 2013; 18:297–302. 7 O’Brien E, Atkins N, Stergiou G, et al. European society of hypertension international protocol revision 2010 for the validation of blood pressure measuring devices in adults. Blood Press Monit 2010; 15:23–38.