"Knowing It Before Blocking It," the ABCD of the Peripheral Nerves: Part C (Prevention of Nerve Injuries).

"A clever person solves the problem. A wise person avoids it" (Albert Einstein). There is no convincing evidence that any modality 100% effectively prevents nerve injury. The risk of nerve injury remains the same even with the ultrasound due to limitations in the resolution of images and inter-operator and inter-patient differences. In a nutshell, caution is required when dealing with precious nerves in the perioperative period, either during peripheral nerve blocks (PNBs), patient positioning, or surgery. Identifying pre-existing nerve injury, either due to trauma or an existing neuropathy, and preventing further nerve injury should be an important goal in providing safe regional anesthesia (RA). Multimodal monitoring is key to avoiding multifactorial nerve injuries. The use of triple guidance (ultrasound + peripheral nerve stimulator + injection pressure monitor) during PNBs further improves the safety of RA. The ultrasound helps in real-time visualization of the nerve, needle, and drug spread; the peripheral nerve stimulator helps confirm the target nerves; and the injection pressure monitor helps avoid nerve injury. Such multimodalities can also give the confidence to administer PNB without risk of nerve injury. This article is part of the comprehensive overview of the essential understanding of peripheral nerves before blocking them. It describes various preventive measures to avoid peripheral nerve injuries while administering PNBs. It will help readers understand the importance of prevention in each step to avoid perioperative PNIs.

"Knowing It Before Blocking It," the ABCD of the Peripheral Nerves: Part D (Approach to the Patient With Nerve Injuries).

"Prevention is always better than cure." However, despite all precautions or preventive measures, sometimes patients develop neurodeficits due to suspected nerve injury in the perioperative period. Assessment and evaluation of the patient's symptoms can provide clues to the causative factors. Such causative factors can be corrected immediately to avoid further deterioration, or some may require further workup. The management plan for such a diagnosed nerve injury depends on the symptoms, the finding of the medical history, and the diagnostic imaging and tests. Simultaneous symptomatic relief in the form of pain medications, steroids, anti-inflammatory drugs, psychological counseling, and reassurance is essential to expedite treatment goals. Diagnosing and treating nerve injuries cannot be laid down as a straightforward part. It is a zigzag puzzle in its own right, playing with time and injury progression. Careful assessment to diagnose the extent of nerve damage plays an important role in treatment plans. It helps decide when to proceed and when to postpone, whether conservative strategies would suffice, or surgical repair would be required. Although most nerve injuries are self-limiting, some cases require surgical intervention that needs to be diagnosed early. The revolution was started by Sunderland in 1945 when he described neurosurgical techniques that drastically changed the entire scenario of nerve repairs. The ultimate effective treatment and full recovery may not be guaranteed, but attempts must be made to achieve the best results. With the patient's interests in mind, it is important to formulate a plan ensuring a good quality of life with minimal impact on their daily activities. Multifactorial nerve injury requires a multidisciplinary approach that primarily includes reassuring, psychological counseling, multimodal analgesia, and neurological and occupational consultations. This article describes the step-by-step approach known as the symptoms categorization-history taking-examination-diagnostic evaluations (SHED) approach to managing patients with peripheral nerve injuries. It also details the various modalities for diagnosing nerve injuries, sequential electrodiagnostic studies, and treatment plans depending on the type and extent of nerve injuries. It will help readers to design a treatment plan based on the patient's symptoms and evaluation results.

"Knowing It Before Blocking It," the ABCD of the Peripheral Nerves: Part A (Nerve Anatomy and Physiology).

Regional anesthesia (RA) is an interplay between the local anesthetic (LA) solution and the neural structures, resulting in nerve conduction blockade. For that, it is necessary to understand which hurdles the LA has to overcome and which components of the nerves are involved. Background knowledge of the neural and non-neural components of the nerve helps locate the safest area for LA deposition. In addition, knowledge of nerve physiology and the conduction process helps to understand the patterns of block onset, involved fibers, and block regression. Neural connective tissue protects the nerve on the one hand and influences the overall effect of the blockade and the occurrence of nerve injuries on the other. The arrangement of the nerve fibers explains the science behind the differential blockage after LA deposition. This article describes the important aspects of nerve anatomy (nerve formation and composition) and nerve physiology (impulse generation and propagation). It also provides insight into the physiological processes involved when a damaged neural structure leads to potential clinical symptoms. It will help readers sharpen their skills and knowledge to execute safe RA without damaging any vital structures in the nerve.

"Knowing It Before Blocking It," the ABCD of the Peripheral Nerves: Part B (Nerve Injury Types, Mechanisms, and Pathogenesis).

Selander emphatically said, "Handle these nerves with care," and those words still echo, conveying a loud and clear message that, however rare, peripheral nerve injury (PNI) remains a perturbing possibility that cannot be ignored. The unprecedented nerve injuries associated with peripheral nerve blocks (PNBs) can be most tormenting for the unfortunate patient and a nightmare for the anesthetist. Possible justifications for the seemingly infrequent occurrences of PNB-related PNIs include a lack of documentation/reporting, improper aftercare, or associated legal implications. Although they make up only a small portion of medicolegal claims, they are sometimes difficult to defend. The most common allegations are attributed to insufficient informed consent; preventable damage to a nerve(s); delay in diagnosis, referral, or treatment; misdiagnosis, and inappropriate treatment and follow-up care. Also, sufficient prospective studies or randomized trials have not been conducted, as exploring such nerve injuries (PNB-related) in living patients or volunteers may be impractical or unethical. Understanding the pathophysiology of various types of nerve injury is vital to dealing with them further. Processes like degeneration, regeneration, remyelination, and reinnervation can influence the findings of electrophysiological studies. Events occurring in such a process and their impact during the assessment determine the prognosis and the need for further interventions. This educational review describes various types of PNB-related nerve injuries and their associated pathophysiology.

Coping With the Fear of Compartment Syndrome Without Compromising Analgesia: A Narrative Review.

Pain management in trauma or surgery with a high risk of developing compartment syndrome (CS) is always challenging due to fears of masking symptoms that could delay diagnosis and treatment. Regional anesthesia/analgesia (RA) can facilitate enhanced postoperative recovery and improve patient satisfaction by providing excellent postoperative analgesia. However, its consideration in surgeries with a high risk of developing CS remains controversial and contentious. Studies suggest focusing more on early diagnosis through regular vigilant monitoring with a high index of suspicion rather than discontinuing the analgesic method alone. The most consistent features in all reported cases of CS were altered sensation in the affected limb, disproportionate pain in the presence of a functional nerve block, and an escalating need for analgesics. Several extrinsic or intrinsic factors are responsible for the progressive increase in compartment pressure that can lead to vascular compromise and subsequent ischemic changes in muscles, tissues, and nerves. Measurement of intracompartmental pressure (ICP) has always been considered the gold standard for diagnosing CS. An ICP of 30 mm Hg is considered the cut-off point for fasciotomy that helps restore muscle perfusion and avoid irreversible tissue damage. The chronology of symptoms can sometimes provide clues to the severity of CS, the pathophysiology involved, and the management required. Therefore, it is necessary to look for warning signs, further investigate the causes, and make quick decisions to diagnose and treat CS and its complications on time. Any delay in the diagnosis and treatment of CS can result in high morbidity and poor outcomes. A well-integrated interprofessional team of health professionals can deliver the required complexity of care through a holistic and multidisciplinary approach. This review article highlights the symptoms, risk factors, and pathophysiology involved in CS. It can guide readers in choosing various options to diagnose, prevent, and treat CS. It also discusses the role of RA in patients or surgeries prone to developing CS.

Anatomical and Technical Considerations of the Hi-PAC (Hi-Volume Proximal Adductor Canal) Block: A Novel Motor-Sparing Regional Analgesia Technique for Below-Knee Surgeries.

Below-knee surgeries are among the most commonly performed orthopedic or plastic and reconstructive procedures. They are associated with significant postoperative pain despite the use of systemic analgesics. The regional analgesia (RA) technique has been proven beneficial for better patient outcomes when used as an adjunct to multimodal analgesia in the early postoperative period. However, apprehension of an acute compartment syndrome (ACS) can limit the administration of appropriate RA techniques in such surgeries, leading to more opioid consumption to meet the increasing analgesic demands. Many modifications in the RA related to techniques and the local anesthetic type, concentration, and volume have been described to tackle such situations. The ideal RA technique should provide procedure-specific analgesia below the knee joint without affecting motor power and/or causing any delay in diagnosing or treating ACS. The high-volume proximal adductor canal (Hi-PAC) block is a novel RA technique described as motor-sparing and procedure-specific for the below-knee surgeries. The Hi-PAC block, a single-injection technique, is administered in the proximal adductor canal targeting the saphenous nerve and depositing local anesthetics (LA) adjacent to the femoral artery below the vasoadductor membrane (VAM). By directly blocking the saphenous nerve and indirectly the sciatic nerve, it covers the entire innervation of the pain-generating components involved in the below-knee surgeries. This article describes the anatomical and technical considerations of the Hi-PAC block and provides background knowledge of the relevant anatomy and sonoanatomy for a better understanding of its intricacies.

Comparing Analgesic Efficacy of a Novel Dual Subsartorial Block Using Two Different Volumes in Patients Undergoing Total Knee Arthroplasty: A Prospective, Double-Blind, Monocentric, Randomised Trial.

INTRODUCTION: Total knee arthroplasty (TKA) is a life-changing joint surgery that improves health-related quality of life and functional status. Patients in need of this surgery mostly belong to the geriatric age group with limited functional reserves and multiple co-morbidities requiring utmost perioperative care with the most suitable analgesic modalities. Regional analgesia (RA) should provide effective analgesia while allowing early mobility, reduced opioid consumption, and early discharge. Dual subsartorial block (DSB) is a novel procedure-specific, motor-sparing, and opioid-sparing RA technique for TKA surgeries. Our study compared the analgesic efficacy of the two different combinations of volumes used in DSB. METHODS: This prospective randomized comparative study included patients between 25-75 years of age of American Society of Anesthesiology (ASA) I-II grades who underwent an elective cemented unilateral total knee replacement performed via medial approaches under neuraxial anesthesia. A total of 104 patients were divided into two equal groups based on the local anesthetic (LA) volumes (Group A 10/20 ml and Group B 20/10 ml) used in the DSB. Postoperative pain scores (using a visual analog scale) and quadriceps strengths (using neurological exam), and opioid consumption were measured at regular intervals till discharge. RESULTS: Most patients (71.2%) remained pain-free and comfortable until discharge, while 28.8% complained of pain within 12 hours of DSB. Mean quadriceps strength remained almost normal (4-5/5) until the discharge with no incidences of buckling or fall in either group. Over time, the postoperative trend between the groups showed a significant difference for dynamic pain (p = 0.002) and quadriceps strength (p = <0.001). There was an insignificant difference (p = 0.161) between the groups regarding opioid consumption, with the median oral morphine equivalent of zero in both groups.  Discussion: The effective analgesic coverage of DSB is based on the involvement of all innervations of the procedure-specific pain generators of TKR surgeries. The specific focus on selective sensory innervations and the type/volume of the LA used makes DSB a motor-sparing RA alternative that facilitates early mobility and discharge. It can provide effective postoperative analgesia without compromising the motor strength of the quadriceps muscle when administered in either 10/20 or 20/10 volumes.

Regional anesthesia for scapular fracture surgery: an educational review of anatomy and techniques.

Scapular fractures are very rare, and those requiring surgical interventions are even rarer. Most scapula surgeries are done under general anesthesia with or without the regional anesthesia (RA) technique as an adjunct. Since scapular innervation is complicated, a thorough review of the relevant anatomy is warranted. In this RAPM educational article, we aimed to summarize the target nerves and blocks needed to optimize analgesia or even to provide surgical anesthesia for scapula surgeries. In this review, we are describing an algorithmic "identify-select-combine" approach, which enables the anesthesiologist to understand detailed innervation of the scapula and to obtain a procedure-specific RA technique. Procedure-specific RA would probably be the way forward for defining future RA practices.

Scapular Block: An Innovative Procedure-Specific Regional Anesthesia Technique for Scapula Surgery-A Case Report.

A 40-year-old healthy male patient underwent open reduction and internal fixation with screws and plate for a comminuted fracture of the right scapula under ultrasound-guided "scapular block" with optimal sedation. We coined the term "scapular block" for an innovative combination of previously described regional anesthesia techniques to cover all dermatomes, myotomes, and osteotomes involved in scapula surgery. It is a combination of 5 target blocks (selective superior trunk block, selective supraclavicular nerve block, subclavian perivascular block, suprascapular nerve block, and erector spinae plane block) via 3 approaches (interscalene, supraclavicular, and paraspinal).