Computed tomographic-guided genitofemoral nerve block: a simple anterior approach.

Chronic groin pain, often as a consequence from surgery, is a challenge from both a diagnostic and treatment standpoint. Interventional therapy is often attempted.Genitofemoral nerve block can be used for the diagnosis and treatment of groin pain. Classically, this nerve is blocked blindly at the level of the pubic tubercle, or more recently, with ultrasound. We present a novel technique to blocking the genitofemoral nerve in males using an anterior approach with computed tomographic guidance.

A comparison of ultrasound-guided and landmark-based approaches to saphenous nerve blockade: a prospective, controlled, blinded, crossover trial.

BACKGROUND: Blockade of the saphenous nerve is often used for surgeries below the knee. Depending on the approach, success rates vary widely ranging from 33% to 88%. In this prospective volunteer study, we compared 2 ultrasound-guided techniques, the modified vastus medialis and perifemoral saphenous nerve block with a below the knee field block. METHODS: Twenty volunteer adults, in a single-blinded, crossover, prospective trial underwent 3 different saphenous nerve blocks. The primary end point of block success was loss of sensation in the distal two-thirds distribution of the saphenous nerve. Secondary variables included time to perform the block, time to sensory loss, pain during block, and motor weakness. RESULTS: Compared with the below the knee field block success rate (30%), both the modified vastus medialis and perifemoral techniques had significantly higher success rates (80%, difference 50% with confidence interval [CI], 23%-77%, P = 0.009, and 100%, difference 70% with CI, 41%-91%, P < 0.001, respectively). However, the difference when comparing the perifemoral ultrasound technique against the modified vastus medialis ultrasound technique did not show significance (difference 20% with CI, -7% to 49%, P = 0.125). Also, no statistical differences were found with the other variables measured, except the perifemoral technique showed faster block performance times than below the knee field block (P = 0.007). CONCLUSION: In our prospective study, we have demonstrated that ultrasound-guided above the knee saphenous nerve blocks have higher success rates than a below the knee field block and are easily performed in a short amount of time.

Profound pain reduction after induction of memantine treatment in two patients with severe phantom limb pain.

We present the cases of two patients who suffered severe lower extremity injuries and subsequently developed phantom limb pain (PLP) that was refractory to high dose opioids and adjunctive pain medications. Both patients were receiving large doses of oral methadone, IV hydromorphone via a patient-controlled analgesia delivery system, and adjunctive medications including tricyclic antidepressants, nonsteroidal anti-inflammatory medications, and anti-epileptics. Despite these treatments, the patients had severe PLP. Upon induction of the oral N-methyl-D-aspartate receptor antagonist memantine, both patients had a profound reduction in their PLP without any apparent side effects from the medication.

The Intraoperative Effect of Methadone on Somatosensory Evoked Potentials.

BACKGROUND: Evoked potentials (EP), both somatosensory evoked potentials (SSEP) and transcranial motor evoked potentials (TcMEP), are often used during complex spine surgery to monitor the integrity of spinal pathways during operations in or around the spine. Changes in these monitored EP signals (increased latency and decreased amplitude) may result from ischemia, direct surgical injury, changes in blood pressure, hypoxia, changes in CO2 tension, and anesthetic agents. Typically, a clinically significant change for SSEPs is defined as an increase in latency >10% or a decrease of amplitude >50%. A clinically significant change for TcMEPs is much more complex but is also described in terms of large signal loss or decrease. Opioids have been shown to both increase latency and decrease the amplitude of SSEPs, although this change is usually not clinically significant. There has been a renewed interest in methadone for use in spine and other complex surgeries. However, the effect of methadone on intraoperative monitoring of SSEPs and TcMEPs is unknown. We present the first study to directly look at the effects of methadone on SSEP and TcMEP monitoring during complex spine surgery. METHODS: The goal of this study was to observe the effect of methadone on an unrandomized set of patients. The primary endpoint was methadone's effect on SSEPs, and the secondary endpoint was methadone's effect on TcMEPs. Adult patients undergoing spine surgery requiring intraoperative neuromonitoring were induced with general anesthesia and had a baseline set of SSEPs and TcMEPs recorded. Next, methadone dosed 0.2 mg/kg/lean body weight was given. Repeat SSEPs and TcMEPs were recorded at 5, 10, and 15 minutes, with the timing based on distribution half-life of methadone between 6 and 8 minutes. Postoperatively, adverse events from methadone administration were collected. RESULTS: There was a statistically significant difference found in SSEPs for N20 latency (95% confidence interval [CI], 0.17-0.53; P=0.028), P37 latency (95% CI, 0.65-1.25; P=0.001), and N20 amplitude (95% CI, 0.09-0.32; P=<0.001), but not for P37 amplitude (95% CI, -0.19 to 0.00; P=0.634). There was no significant effect found for TcMEPs, the secondary endpoint of the study, and there were minimal adverse events recorded postoperatively. CONCLUSIONS: The data demonstrate that a single intravenous dose of methadone has a statistically significant difference on the amplitude and latency of SSEPs. However, this statistical difference does not translate into a clinical significance.

Retrospective analysis of quality improvement when using liposome bupivacaine for postoperative pain control.

BACKGROUND/OBJECTIVE: Liposome bupivacaine, a prolonged-release bupivacaine formulation, recently became available at the Naval Medical Center San Diego (NMCSD); before availability, postsurgical pain for large thoracic/abdominal procedures was primarily managed with opioids with/without continuous thoracic epidural (CTE) anesthesia. This retrospective chart review was part of a clinical quality initiative to determine whether postsurgical outcomes improved after liposome bupivacaine became available. METHODS: Data from patients who underwent laparotomy, sternotomy, or thoracotomy at NMCSD from May 2013 to May 2014 (after liposome bupivacaine treatment became available) were compared with data from patients who underwent these same procedures from December 2011 to May 2012 (before liposome bupivacaine treatment became available). Collected data included demographics, postoperative pain control methods, opioid consumption, perioperative pain scores, and lengths of intensive care unit and overall hospital stays. RESULTS: Data from 182 patients were collected: 88 pre-liposome bupivacaine (laparotomy, n=52; sternotomy, n=26; and thoracotomy, n=10) and 94 post-liposome bupivacaine (laparotomy, n=49; sternotomy, n=31; and thoracotomy, n=14) records. Mean hospital stay was 7.0 vs 5.8 days (P=0.009) in the pre- and post-liposome bupivacaine groups, respectively, and mean highest reported postoperative pain score was 7.1 vs 6.2 (P=0.007), respectively. No other significant between-group differences were observed for the overall population. In the laparotomy subgroup, there was a reduction in the proportion of patients who received CTE anesthesia post-liposome bupivacaine (22% [11/49] vs 35% [18/52] pre-liposome bupivacaine). CONCLUSION: Surgeons and anesthesiologists have changed the way they manage postoperative pain since the time point that liposome bupivacaine was introduced at NMCSD. Our findings suggest that utilization of liposome bupivacaine may be a useful alternative to epidural anesthesia.