Anna Carrera

Intraneural Injection during Anterior Approach for Sciatic Nerve Block

To the Editor:—We read with interest the case report by Sala-Blanch et al. The authors describe an unorthodox but interesting treatment for patients undergoing continuous sciatic nerve block that raises several concerns. In short, using computed tomographic imaging without clear clinical indication, the authors documented that nerve stimulator–guided needle placement during sciatic nerve block through the anterior approach resulted in an intraneural needle placement. The authors then inserted the catheter and administered local anesthetics. Conventional wisdom suggests that intraneural needle placement and catheter insertion should be avoided because intraneural application of local anesthetics has been shown to result in neurologic injury in animal models. However, despite the documented intraneural needle and catheter placement—although it is not clear whether the stimulating needle lies between fascia and epineurium or between epineurium and perineurium—the patients did not have neurologic injury. Therefore, this case report suggests that not all intraneural injections lead to neurologic injury. It also suggests that nerve stimulators may not be reliable in avoiding intraneural needle or catheter placement. Finally, a better definition of what constitutes an intraneural versus an intraepineural sheath injection during blockade of peripheral nerves and plexuses is needed for more meaningful discussion of this matter. Some experts may view the patient treatment in report by Sala-Blanch et al. unusual or even potentially hazardous. However, their findings should be welcomed because they clearly pose some important questions. At the least, they suggest that future research should continue to focus on developing more reliable and objective tools of nerve localization and injection monitoring techniques to help avoid intraneural injection and reduce the risk of consequent neurologic injury. In any case, it is recommended to withdraw the needle or the catheter if one has any doubt that its position is too close to the nerve, for the safety of regional anesthesia.

Ultrasound-guided popliteal sciatic block with a single injection at the sciatic division results in faster block onset than the classical nerve stimulator technique.

BACKGROUND: For successful, fast-onset sciatic popliteal block (SPB), either a single injection above the division of the sciatic nerve, or 2 injections to block the tibial nerve (TN) and common peroneal nerve (CPN) separately have been recommended. In this study, we compared the traditional nerve stimulator (NS)-guided SPB above the division of the sciatic nerve with the ultrasound (US)-guided block with single injection of local anesthetic (LA) between the TN and CPN at the level of their division. We hypothesized that US-SPB with a single injection between TN and CPN would result in faster block onset than a single-injection NS-SPB. METHODS: Fifty-two patients were randomized to receive either an NS-SPB or a US-SPB. For both blocks, a single injection of 20 mL mepivacaine 1.5% was given using an automated injection pump while controlling for injection force. For NS-SPB, a TN response below 0.5 mA was sought 7 cm above the popliteal fossa crease (and proximal to the divergence of the TN and peroneal nerves). For US-SPB, the injection was made after a US-guided needle was inserted between the TN and CPN at the level of their separation. Motor response was not actively sought but registered if present. The location and spread of LA were evaluated by US in both groups. Onset of motor and sensory blocks was serially assessed in 5-minute intervals in the TN and CPN divisions and compared between the groups. RESULTS: All patients in both groups had successful block at 30 minutes after the injection, defined as sensory block to allow surgery without supplementation. A higher proportion of patients in the US-SPB group had a complete sensory (80% vs 4%, P < 0.001) and motor block (60% vs 8%, P < 0.001), defined as anesthesia and paralysis in all nerve territories, at 15 minutes after injection. US signs of intraepineural injection were present in 19 patients (73%) in the NS-SPB group and 25 patients (100%) in the US-SPB group (P < 0.001). CONCLUSIONS: A single injection of LA in US-SPB with needle insertion at the separation of the TN and CPN results in a similar success rate at 30 minutes; however, more patients in the US-SPB group than in the NS-SPB group had complete block at 15 minutes.

Macroscopic View of the Cervical Plexus and Brachial Plexus

The lateral anatomic region of the neck adjacent to the cervical spine contains, among its muscular elements, the cervical plexus and brachial plexus. Nerve plexuses are axon exchange networks that allow peripheral nerves to form from the fibers of two or more consecutive spinal nerves. In this sense, deep to the upper half of the sternocleidomastoid muscle, the spinal nerves from C1 to C4 exchange the axons of their anterior rami in the cervical plexus, giving rise to the peripheral nerves distributed in the anterolateral region of the neck.

The Pathophysiology of the Osteoarthritis of the Thumb Joint Stability and Role of the Main Carpometacarpal Ligaments

Introduction: More than 16 ligaments around the joint have been described by Bettinger et al. (1999); four ligaments and the joint capsule are the main stabilizers of the trapeziometacarpal (TM) joint. These ligaments are the dorsoradial (DRL), intermetacarpal (IML), anterior oblique (AOL), and posterior oblique ligaments (POL). The importance of each of these ligaments in the stability of the TM joint is debatable. The purpose of the study was (1) to describe the anatomy and dimension of the thumb carpometacarpal (CMC) joint ligaments, (2) to assess the ligament lesions and the degree of subluxation of the CMC joint, and (3) to measure cartilage thickness in the trapezium and metacarpal and pattern of chondromalacia and osteoarthritis (OA). We investigated the role that these ligament ruptures play in the pathophysiology of the OA. Methods: Twenty-five fresh-frozen cadaver hands were dissected of all soft tissue to expose the joint capsule and ligaments of the TM joint. There were 14 male and 11 female with mean age of 67 years (range, 51-94 years). The dissection was performed under ×4.5 loupe magnification. We showed the main ligaments and also the ligament ruptures in IML, AOL or beak ligament, dorsal oblique ligament (DOL), and DRL. We described the location of the ligament tears and whether these ruptures were partial or total. The ligament ruptures and the metacarpal translation associated with these ruptures were measured (mm). Cartilage thickness in the trapezium and metacarpal of specimens was assessed. We described the degree of degenerative changes using the stanging protocol to describe visual degeneration by Koff et al. (2003). We investigated the relationship between the ligament ruptures and the area of chondromalacia and OA. Statistical analysis of data was performed with the chi-square test, and the level of significance was P < .05. Results: Seven principal ligaments of the thumb CMC joint were identified using Berger’s principles (200s1). Ligament lesions were found in all 25 specimens. Isolated rupture of the AOL was found in 7 (28%), isolated rupture of the DRL was found in 10 (40%), isolated rupture of the IML was found in 2 (8%). Combined rupture of the AOL and IML was found in 2 (8%) and combined rupture of the DRL and IML in 4 (16%) joints. The mean metacarpal displacement due to isolated rupture of the ligaments was DRL 17 mm (P = .006), AOL 11 mm, POL 0.5 mm, and IML 0.4 mm. We found 2 cases OA stage I, 7 cases OA stage II (1 IIa, 3 lib, and 3 IIc), 9 OA stage III, and 7 OA stage IV. There was a relationship between the presence of a tear in the DRL and the presence of OA in the radial quadrants (P = .032). Conclusion: These observations suggest a translation of metacarpal on trapezium in the production of arthritic lesions and support a hypothesis that pathologic joint instability could be a cause of CMC OA. This study suggests that repairing the DRL during ligament reconstruction of the CMC joint should be considered.

Macroscopic View of the Lumbar Plexus and Sacral Plexus

The motor and sensory innervation of the lower limb depends on the anterior branches of the lumbar and sacral spinal nerves. In the lumbar region, the combination of the anterior rami of spinal nerves L1 to L4 forms the lumbar plexus. Its collateral and terminal nerves are distributed through the lower region of the abdominal wall, external genitalia, anterior region of the thigh, and medial cutaneous territory of the leg and foot.

Spinal Dural Sac, Nerve Root Cuffs, Rootlets, and Nerve Roots

Nerve rootlets leave the spinal cord at the anterolateral and posterolateral sulci. Anterior rootlets contain predominantly efferent fibers from the anterior horn and carry motor signals to voluntary muscles. At thoracic and upper lumbar regions, they also carry preganglionic sympathetic fibers from the lateral horns. Posterior rootlets are prolongations of pseudounipolar nerve cells located at dorsal root ganglions (DRGs). Rootlets join to form the anterior roots (from 6 to 8 anterior rootlets) and posterior roots (from 8 to 10 posterior rootlets).

Principles of Major Nerve Blockade for the Perioperative Clinician: Indications, Common Side Effects, and Complications

The peripheral nerve blocks have become a commonplace in the clinical practice of anesthesiology. The perioperative physician is very likely to encounter patients who received peripheral nerve block for purpose of anesthesia or analgesia as well as their side effects or complications. In order to recognize expected neurologic and physiologic effects of nerve blockade from complications, the perioperative physician should be familiar with the principles of practice of peripheral nerve blocks and recent advances in the field. The purpose of this chapter is to highlight the essential aspects of nerve blocks, aiming primarily for practitioners whose training may not have included adequate information on this topic. We hope that this chapter and its didactic approach through numerous illustrations will be of assistance to neurologists or perioperative clinicians who encounter a patient with a side effect or neurologic complication after peripheral nerve blockade.