Transcranial Motor Evoked Potential Alarm Criteria to Predict Foot Drop Injury During Lumbosacral Surgery.

STUDY DESIGN: A retrospective cohort analysis. OBJECTIVE: This study aims to investigate whether waveform alterations in transcranial motor evoked potentials (TCMEPs) can reliably predict postoperative foot drop. SUMMARY OF BACKGROUND DATA: Nerve injury leading to foot drop is a potential complication of lumbosacral surgery. Very limited data exist on the use of intraoperative TCMEPs to identify iatrogenic foot drop. METHODS: We retrospectively reviewed neuromonitoring data from 130 consecutive spine surgeries with instrumentation involving L4-S1. TCMEP waveform analysis included amplitude (A), area under the curve (AUC), latency (L), and duration (D). Patient outcomes were correlated with neuromonitoring results. Intraoperative alert criteria were established on the basis of observed intraoperative changes. RESULTS: Three patients developed severe foot drop with a muscle weakness functional grade ranging from 0/5 to 3/5. Two patients developed a mild foot drop with functional grade 4/5. Twenty-three patients had preoperative weakness in an L5 distribution. One-hundred two patients who had neither preoperative nor postoperative neurological complications served as a control group. Amplitude significantly decreased in patients with a severe postoperative deficit (P = 0.005) as did AUC and duration (P < 0.05). Intraoperative alert criteria defined as a >65% decrease in AUC resulted in a sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 100%, 91.4%, 12%, and 100%, respectively. When defining an alert criteria as a >50% decrease in amplitude, sensitivity, specificity, PPV, and NPV were 100%, 87.9%, 8.8%, and 100%, respectively. CONCLUSION: Reduction of TCMEP waveform associated with postoperative severe foot drop can be detected during lumbar surgery. Other waveform parameters such as AUC may predict foot drop better than the amplitude. Additional examinations in larger samples of foot drops are needed to validate these alert threshold findings. LEVEL OF EVIDENCE: 4.

Association between the use of gel pads under patients' knees and the incidence of peroneal neuropathy following liver transplantation.

INTRODUCTION: There have been intermittent reports of peroneal neuropathy (PN) occurring after liver transplantation. Although PN may not be viewed as a serious complication by liver transplant (LT) recipients who require the transplant for survival, PN can significantly reduce quality of life. The incidence of PN appears to have increased after the use of gel pads was introduced. These gel pads, which are placed under patients' knees during surgery, are used to reduce lower back strain and prevent contact between the peroneal nerve at the fibular head and the hard surface of the operating table. The aim of the present study was to investigate the association, if any, between the use of gel pads and the incidence of PN. METHODS: The medical records of 261 adult LT recipients were retrospectively reviewed. The recipients were divided into gel pad (n = 167) and non-gel pad (n = 94) groups. The incidence and possible risk factors of PN were compared between the two groups. RESULTS: The overall incidence of PN was 8.0% (21/261). The occurrence of PN was significantly higher in the gel pad group than in the non-gel pad group (10.8% vs. 3.2%; p < 0.05). Other possible risk factors were comparable between the two patient groups. CONCLUSION: As the use of gel pads may increase the incidence of PN, we recommend against the use of gel pads under the knees of LT recipients.

[Measurement of external pressure of peroneal nerve tract coming in contact with lithotomy leg holders using pressure distribution measurement system BIG-MAT®].

We investigated external pressure on peroneal nerve tract coming in contact with two kinds of leg holders using pressure distribution measurement system BIG- MAT® (Nitta Corp., Osaka) in the lithotomy position Peak contact (active) pressure at the left fibular head region coming in contact with knee-crutch-type leg holder M® (Takara Belmont Corp., Osaka), which supports the left popliteal fossa, was 78.0 ± 26.4 mmHg. On the other hand, peak contact pressure at the left lateral lower leg region coming in contact with boot-support-type leg holder Bel Flex® (Takara Belmont Corp., Osaka), which supports the left lower leg and foot was 26.3±7.9 mmHg. These results suggest that use of knee-crutch-type leg holder is more likely to induce common peroneal nerve palsy at the fibular head region, but use of boot-support-type leg holder dose not easily induce superficial peroneal nerve palsy at the lateral lower leg region, because capillary blood pressure is known to be 32 mmHg. Safer holders for positioning will be developed to prevent nerve palsy based on the analysis of chronological change in external pressure using BIG-MAT® system during anesthesia.

Complications of hysterectomy.

Hysterectomy is the most common gynecologic procedure performed in the United States, with more than 600,000 procedures performed each year. Complications of hysterectomy vary based on route of surgery and surgical technique. The objective of this article is to review risk factors associated with specific types of complications associated with benign hysterectomy, methods to prevent and recognize complications, and appropriate management of complications. The most common complications of hysterectomy can be categorized as infectious, venous thromboembolic, genitourinary (GU) and gastrointestinal (GI) tract injury, bleeding, nerve injury, and vaginal cuff dehiscence. Infectious complications after hysterectomy are most common, ranging from 10.5% for abdominal hysterectomy to 13.0% for vaginal hysterectomy and 9.0% for laparoscopic hysterectomy. Venous thromboembolism is less common, ranging from a clinical diagnosis rate of 1% to events detected by more sensitive laboratory methods of up to 12%. Injury to the GU tract is estimated to occur at a rate of 1-2% for all major gynecologic surgeries, with 75% of these injuries occurring during hysterectomy. Injury to the GI tract after hysterectomy is less common, with a range of 0.1-1%. Bleeding complications after hysterectomy also are rare, with a median range of estimated blood loss of 238-660.5 mL for abdominal hysterectomy, 156-568 mL for laparoscopic hysterectomy, and 215-287 mL for vaginal hysterectomy, with transfusion only being more likely after laparoscopic compared to vaginal hysterectomy (odds ratio 2.07, confidence interval 1.12-3.81). Neuropathy after hysterectomy is a rare but significant event, with a rate of 0.2-2% after major pelvic surgery. Vaginal cuff dehiscence is estimated at a rate of 0.39%, and it is more common after total laparoscopic hysterectomy (1.35%) compared with laparoscopic-assisted vaginal hysterectomy (0.28%), total abdominal hysterectomy (0.15%), and total vaginal hysterectomy (0.08%). With an emphasis on optimizing surgical technique, recognition of surgical complications, and timely management, we aim to minimize risk for women undergoing hysterectomy.

[Risk management in brachial plexus block].

Peripheral nerve block has many advantages in surgical anesthesia with or without general anesthesia; postoperative analgesia, faster postoperative rehabilitation, and chronic pain management. However, serious adverse complications after peripheral nerve block can happen. Therefore, anesthetists should obtain full informed consent for possible complications, and require scrupulous attention to this procedure. This review focuses on complications of brachial plexus block because it is the most popular peripheral nerve block.

Inside-out medial meniscus suture: an analysis of the risk of injury to the popliteal neurovascular bundle.

PURPOSE: To assess the risk of damage to the popliteal neurovascular structures when inserting the needle through the posterior aspect of the knee during inside-out suture of the posterior horn of the medial meniscus. METHODS: The first stage of our study consisted of simulating a virtual meniscal suture during magnetic resonance imaging by tracing a line from 3 different points (located medially [MP], centrally [CP], and laterally [LP] to the patellar tendon) to the posterior horn of the medial meniscus. This procedure was undertaken both at rest and with valgus stress. The next phase involved the suture of the posterior horns of medial menisci taken from cadaveric specimens, the needle being inserted through 3 separate locations (again located medially [MP], centrally [CP], and laterally [LP] to the patellar tendon). Finally, the distance from each suture thread to the aforementioned neurovascular bundle was measured. RESULTS: During the magnetic resonance imaging study, the measured distances at rest were 26.4 mm for MP, 28.8 mm for CP, and 31 mm for LP, whereas those recorded with valgus stress were 21.7 mm for MP, 23.6 mm for CP, and 26 mm for LP. In the second phase of the study (cadaveric specimen suture), the distances obtained were 22.6 mm for MP, 27.6 mm for CP, and 33 mm for LP. CONCLUSIONS: Our results indicate that when the needle is inserted through the 3 points investigated into the posteromedial region of the knee (10 mm from the posterior horn of the internal meniscus) during inside-out suture, it is far enough from the popliteal neurovascular bundle for the maneuver to be performed with a reasonable safety margin. However, this margin can be increased further still if the needle is inserted into the joint through a point located laterally to the patellar tendon. CLINICAL RELEVANCE: Inside-out suture performed 10 mm from the posterior horn of the internal meniscus through the portals studied offers a sufficient margin of safety to avoid damage to the popliteal neurovascular bundle.

Anatomic variations of superficial peroneal nerve: clinical implications of a cadaver study.

Superficial peroneal nerve and its branches are frequently at risk for iatrogenic damage. Although different studies on anatomical variations of superficial peroneal nerve are available in the medical literature, such reports are rare from India. Hence the present study was undertaken on Indian population. A total of 60 specimens of inferior extremities from 30 properly embalmed and formalin fixed cadavers were dissected and examined for the location and course of the superficial peroneal nerve including number, level, course and distributions of branches. The superficial peroneal nerve in 28.3% specimens was located in the anterior compartment of the leg. In 8.3% specimens the superficial peroneal nerve branched before piercing between the peroneus longus and extensor digitorum longus muscle whereas in 11.7% specimens it branched after piercing the aforementioned muscles and before piercing the deep fascia. In 41 out of 60 specimens the sensory division of superficial peroneal nerve branched into the medial dorsal cutaneous nerve and intermediate dorsal cutaneous nerve distal to its emergence from the deep fascia and proximal to its relation to the extensor retinaculum. In 20 out of 60 specimens the accessory deep peroneal nerve, an additional branch from the sensory division of superficial peroneal nerve, through its course in the anterior compartment of the leg passed deep to the extensor retinaculum and supplied the ankle and the dorsum of foot. Hopefully the present study will help in minimizing iatrogenic damage to the superficial peroneal nerve and its branches while performing arthroscopy, local anesthetic block, surgical approach to the fibula, open reduction and internal fixation of lateral malleolar fractures, application of external fixators, elevation of a fasciocutaneous or fibular flaps for grafting, surgical decompression of neurovascular structures, or miscellaneous surgery on leg, foot and ankle.

Compression-caused peroneal neuropathy: commentary from a biopsychologist.

Compression is the most common cause of damage to the fibular head, the site of most peroneal nerve injuries which cause foot drop. Compression injuries can be caused by prolonged immobility and habitual leg-crossing. A review of the literature does not reveal the existence of a nationwide study that investigates the prevalence of compression-caused foot drop, nor does the literature contain encouragement to arrange medical practices to prevent its occurrence (e.g., soft substrates for sitting, frequent reminders for the patient to uncross the legs). Treatments for foot drop do not appear to be strongly scientifically based and they do not incorporate the use of sensory integration, specifically use of the visual sense, during rehabilitation. Finally, compression-caused foot drop may be preventable, a conclusion that could ultimately have important implications in the context of Medicare and Medicaid reimbursement.

Sudden peroneal nerve palsy in a varus arthritic knee.

Peroneal nerve palsy has been reported in association with traumatic and nontraumatic causes. We encountered a 75-year-old man whose peroneal nerve palsy developed suddenly following varus deformity of the arthritic knee. A review of the literature found 1 other report describing a progressive peroneal nerve palsy associated with a varus deformity of the knee due to arthritis. Our patient had progressive intractable knee pain; 3-compartment, severe degenerative changes in the knees; varus knee malalignment and laxity; right peroneal nerve palsy; and decreased sensation to light touch and pinprick on the dorsum of the right foot. The preoperative WOMAC score was 36. Nerve conduction studies confirmed acute peroneal neuropathy with conduction block at the fibular neck and secondary axonal degeneration. Magnetic resonance imaging of the knee showed osteophytes and cysts surrounding the fibular neck. Although their compression could be responsible for the nerve palsy, the sudden process made this less possible. Thus, the patient underwent total knee arthroplasty of both knees without exploration of the nerve. At 5-month follow-up, the WOMAC score was 78. The patient walked with a cane with no varus thrust, and his right knee had no varus laxity in full extension. The peroneal nerve did not retain its function. Sensory examination and postoperative nerve conduction studies showed no improvement.

[A 17 year old adolescent with chronic neutropenia, recurrent infections, severe dysphagia and peroneus palsy]. / 17-jähriger Mann mit jahrelanger Neutropenie und Infektneigung, schwerer Dysphagie und Peroneuslähmung.

A 17-year-old German adolescent with a four year history of neutropenia and repeated infections presented with severe dysphagia and progressive right-sided peroneus palsy. In the past four years, extensive medical workup had been performed, and despite conspicuous findings, no diagnosis was made. Finally we diagnosed HIV related CMV esophagitis and HIV associated polyneuropathy. The CMV esophagitis was treated antivirally, and highly active antiretroviral HIV therapy was initiated. The mode of HIV transmission remained obscure until further research revealed a probable nosocomial infection during early childhood in Romania.

The relationship between the saphenopopliteal junction and the common peroneal nerve: a cada-veric study.

OBJECTIVES: The variable anatomy of the short saphenous vein (SSV) and the potential failure to identify the saphenopopliteal junction (SPJ) contribute to an increased risk of damage to the common peroneal nerve (CPN) during surgical exploration. The aim of the present study was to determine the variation of the SPJ, its relationship to the CPN, and the relationship of both SPJ and CPN to defined anatomical landmarks. METHODS: Measurements of the distance between the SPJ and CPN, and the defined anatomical landmarks (fibula head, lateral joint space, lateral femoral epicondyle), were undertaken on 30 cadaveric limbs following careful dissection of the popliteal fossa. RESULTS: The level of SPJ termination was classified as low (below), normal (within 100 mm above) and high (more than 100 mm above), the lateral femoral epicondyle. Of the 30 limbs dissected, 70% of SPJs were normal, 23% low and 7% high. Direct measurement from the SPJ to anatomical landmarks showed a higher interquartile range (IQR) in low compared with normal terminations; however, the vertical distance from the SPJ to the fibula head showed an increase in IQR from low to normal terminations (7.1-14.2). The mean distances between the SPJ and CPN in low and normal terminations were 23.3 and 16.7 mm, respectively. Comparison of the IQR showed values very similar to low terminations having a slightly higher IQR compared with normal terminations (7.15-6.0). CONCLUSION: Significant anatomic variation was observed in the termination of the SSV, with 67% located within 66 mm above the lateral femoral epicondyle. The risk of damaging the CPN during saphenopopliteal ligation may be higher for SPJs located above the lateral femoral epicondyle because of the proximity of the two structures and variability of SPJ.

Peroneal neuropathy following liver transplantation: possible predisposing factors and outcome.

INTRODUCTION: Perioperative peroneal neuropathy is an uncommon complication following operations remote from the leg or in supine position including liver transplant. MATERIALS AND METHODS: We retrospectively reviewed the medical records of 132 living-donor liver transplant recipients done at our center between September 2006 and December 2008. Various potential preoperative, intraoperative, and postoperative factors were studied in the cases that developed perioperative peroneal neuropathy. RESULTS: Peroneal neuropathy was reported in 7 recipients (5.3%) following liver transplant. Apart from intraoperative positioning, other identifiable predisposing factors appear to be poor nutritional status, tall and slender body shape, alcoholic liver disease, and higher pretransplant model for endstage liver disease score. All patients were treated conservatively, including nutritionally balanced diet and vitamin supplements combined with physical rehabilitation therapy. The motor power returned to normal within 6 months in all 7 patients. CONCLUSIONS: Perioperative peroneal neuropathy may be contributed by various preoperative factors apart from intraoperative nerve compression. It can be effectively prevented by being aware of the predisposing factors and implicating adequate precautions perioperatively.

[Peroneal nerve palsy after total knee arthroplasty under continuous epidural anaesthesia]. / Peronäusläsionen nach KTEP-Implantation unter Verwendung einer postoperativ fortgeführten periduralen Analgesie.

BACKGROUND: Peroneal nerve palsy is a rare but distressing complication of total knee arthroplasty (TKA). After introducing a standardised intraoperative and postoperative epidural anaesthesia protocol under otherwise unchanged perioperative management, we noted a sudden cumulation of peroneal nerve palsies after TKA. PATIENTS AND METHODS: In this retrospective study we checked the patients' histories for well-known risk factors for nerve lesions after TKA as well as for those risk factors controversially discussed in the literature. RESULTS: We found an additive harmful impact of epidural anaesthesia leading to unrecognised pressure on the peroneal nerve, which caused, in combination with a pressure lesion of the pneumatic tourniquet, an axonal lesion in terms of a double-crush syndrome. By lowering the pneumatic tourniquet pressure and carefully positioning the operated leg, we found a clearly reduced risk of nerve lesion while preserving the advantages of epidural anaesthesia for the patient. CONCLUSION: To prevent a peroneal lesion after TKA while using continuous epidural anaesthesia, we strongly recommend limiting the pneumatic tourniquet pressure to 320 mmHg while ensuring pressure-free positioning of the operated leg.

Foot drop as a complication of weight loss after bariatric surgery: is it preventable?

BACKGROUND: Although rare, the relationship between peroneal nerve palsy and weight loss has been well documented over the last decades. Of the 160 patients operated for persisting foot drop in our institution, weight loss was considered to be the major contributing factor for 78 patients (43.5%). METHODS: We compared patients who developed a foot drop after bariatric surgery with a control group of patients who underwent bariatric surgery (gastric banding) but did not develop peroneal neuropathy. RESULTS: 9 patients developed foot drop after bariatric surgery. The mean weight loss for these patients was 45 kg. Weight reduction took place during a mean period of 8.6 months. Our control group consists of 10 patients. The mean weight loss of these patients was 43.8 kg, and the weight reduction took place during a mean period of 21.7 months. CONCLUSION: In contrast to earlier studies, we demonstrated that significant weight loss is correlated with a higher risk to develop foot drop and that the time period in which the weight loss is achieved is important. A rapid reduction of body weight is correlated with a higher risk to develop foot drop.