Intraneural Injection and Peripheral Nerve Injury

Assessment, management, and rehabilitation of traumatic peripheral nerve injuries for non-surgeons

Electrodiagnostic evaluation is often requested for persons with peripheral nerve injuries and plays an important role in their diagnosis, prognosis, and management. Peripheral nerve injuries are common and can have devastating effects on patients' physical, psychological, and socioeconomic well-being; alongside surgeons, electrodiagnostic medicine specialists serve a central function in ensuring patients receive optimal treatment for these injuries. Surgical intervention-nerve grafting, nerve transfers, and tendon transfers-often plays a critical role in the management of these injuries and the restoration of patients' function. Increasingly, nerve transfers are becoming the standard of care for some types of peripheral nerve injury due to two significant advantages: first, they shorten the time to reinnervation of denervated muscles; and second, they confer greater specificity in directing motor and sensory axons toward their respective targets. As the indications for, and use of, nerve transfers expand, so too does the role of the electrodiagnostic medicine specialist in establishing or confirming the diagnosis, determining the injury's prognosis, recommending treatment, aiding in surgical planning, and supporting rehabilitation. Having a working knowledge of nerve and/or tendon transfer options allows the electrodiagnostic medicine specialist to not only arrive at the diagnosis and prognosticate, but also to clarify which nerves and/or muscles might be suitable donors, such as confirming whether the branch to supinator could be a nerve transfer donor to restore distal posterior interosseous nerve function. Moreover, post-operative testing can determine if nerve transfer reinnervation is occurring and progress patients' rehabilitation and/or direct surgeons to consider tendon transfers.

Nerve Injury Following Regional Nerve Block: A Literature Review of Its Etiologies, Risk Factors, and Prevention

PURPOSE OF REVIEW

Postoperative nerve injury after nerve block is complex and multifactorial. The mechanisms, etiologies, and risk factors are explored. This review article conducts a literature search and summarizes current evidence and best practices in prevention of nerve injury.

RECENT FINDINGS

Emerging technology such as ultrasound, injection pressure monitors, and nerve stimulators for peripheral nerve block have been incorporated into regular practice to reduce the rate of nerve injury. Studies show avoidance of intrafascicular injection, limiting concentrations/volumes of local anesthetic, and appropriate patient selection are the most significant controllable factors in limiting the negative consequences of nerve block. Peripheral nerve injury is an uncommon occurrence after nerve block and is obscured by surgical manipulation, positioning, and underlying neural integrity. Underlying neural integrity is not always evident despite an adequate history and physical exam. Surgical stress, independently of nerve block, may exacerbate these neurologic disease processes and make diagnosing a postoperative nerve injury more challenging. Prevention of nerve injury by surgical teams, care with positioning, and avoidance of intrafascicular injection with nerve block are the most evidence-based practices.

Ketorolac Is Not More Effective Than Flunixin Meglumine or Phenylbutazone in Reducing Foot Pain in Horses

The objective was to compare the analgesic efficacy of ketorolac tromethamine (KT) and two other nonsteroidal anti-inflammatory drugs (NSAIDs), including flunixin meglumine (FM) and phenylbutazone (PB), using a heart bar shoe (HBS) model of reversible foot lameness in horses. Nine adult horses were used in a blinded, randomized, placebo-controlled crossover study. After induction of left front limb lameness using a modified HBS model, one of three NSAIDs (KT, 2.0 mg/kg IV; FM, 1.1 mg/kg IV; PB, 4.4 mg/kg IV) or saline (placebo) was administered IV as a single dose. Lameness was assessed every 30 minutes for 2 hours, then every hour up to 12 hours using both a lameness grading scale (lameness score; LS) and a body-mounted inertial sensor system (lameness locator; LL). High-performance liquid chromatography and mass spectrometry were used to measure plasma drug concentration at various time points. There was no difference in percent reduction of LS or LL value between KT and any other group, or between FM and placebo. The PB group showed a significantly higher percentage in LS reduction than the placebo and FM groups. The mean percent reduction in LL value was greater for the PB group than that for the placebo and FM groups. Plasma drug concentration was similar among horses for each drug at each time point, with drug concentrations decreasing over time. Thus, variation in plasma drug concentration did not influence lameness reduction for any drug. Ketorolac tromethamine was not superior to FM or PB in reducing lameness using a HBS model.

The effect of needle dimensions and infusion rates on injection pressures in regional anaesthesia needles: a bench-top study

Animal studies have shown that injection pressures > 75 kPa indicate probable intrafascicular needle tip position. This study describes the flow/pressure characteristics of seven common needle systems. A syringe pump delivered flow rates of 5, 6.67, 10, 13.3, 15 and 20 ml.min(-1) through these needle systems, while keeping the needle tips open to atmosphere. A pressure transducer connected between the syringe and needle provided a real-time graphical display for analysis. Mean plateau pressures increased linearly with flow and with decreasing needle diameter (2.7-92 kPa). Flow rates > 17 ml.min(-1) and needle sizes 22 G and smaller produced mean plateau pressures > 75 kPa. Pressure monitors upstream from the needle may produce false-positive alarms at high flow rates due to needle resistance, and unreliable readings due to non-laminar flow. We recommend injection rates ≤ 15 ml.min(-1) (0.25 ml.s(-1) ) to reduce the effect of factors upstream from the needle tip as a cause of high pressure readings.

Suprascapular nerve palsy following supraclavicular block for upper extremity surgery: report of 3 cases

Regional anesthesia has become the preferred method of anesthesia for many upper extremity operations and generally results in decreased hospital stays, postoperative opioid requirement, and postoperative nausea. Complications of regional anesthesia are rarely reported in the literature, possibly because of limited anesthesiologist-patient follow-up. Three cases of suprascapular nerve palsy after ultrasound-guided supraclavicular nerve block for routine outpatient upper extremity surgery are reported. All cases occurred in men who originally presented with shoulder pain, which resolved with time, followed by weakness in the supraspinatus and infraspinatus, which improved over time but did not resolve. One case resulted in ipsilateral phrenic nerve palsy as well. A review of the literature on the subject accompanies the report of these 3 cases.

Perioperative care for the older outpatient undergoing ambulatory surgery

As the number of ambulatory surgery procedures continues to grow in an aging global society, the implementation of evidence-based perioperative care programs for the elderly will assume increased importance. Given the recent advances in anesthesia, surgery, and monitoring technology, the ambulatory setting offers potential advantages for elderly patients undergoing elective surgery. In this review article we summarize the physiologic and pharmacologic effects of aging and their influence on anesthetic drugs, the important considerations in the preoperative evaluation of elderly outpatients with coexisting diseases, the advantages and disadvantages of different anesthetic techniques on a procedural-specific basis, and offer recommendations regarding the management of common postoperative side effects (including delirium and cognitive dysfunction, fatigue, dizziness, pain, and gastrointestinal dysfunction) after ambulatory surgery. We conclude with a discussion of future challenges related to the growth of ambulatory surgery practice in this segment of our surgical population. When information specifically for the elderly population was not available in the peer-reviewed literature, we drew from relevant information in other ambulatory surgery populations.