Epidural ignalar ta'sirida asab shikastlanishining belgilari qanday?

Perioperative nerve injury is one of the complications of regional block anesthesia. Fortunately, serious disabling neurological complications are rare. Risk factors for neurological deficits include: nerve ischemia (eg, prolonged hypotension with vasoconstrictors), nerve trauma during puncture and catheterization, infection, and choice of local anesthetic solution. In addition, postoperative neurological injury can also be related to improper patient positioning, compression of surgical aids or tight surgical dressings, and surgical trauma. The study by Lynch et al. showed that the incidence of neurological complications after total shoulder arthroplasty was 4.3 percent , of which 75 percent were from nerve injury in the arm. Importantly, nerve injury in intersulcular nerve block occurs mostly in the upper and middle nerve trunks, making it difficult to determine the etiology of nerve injury (surgical injury or anesthesia injury). Patient-side factors include the patient's constitution and previous underlying neurological disease. For example, the incidence of peroneal nerve palsy increases after total knee arthroplasty in patients with foot valgus and previous neuropathy. Research on the safety of regional anesthesia involves a large sample survey of patients and case reports of postoperative neurological deficits. Therefore, prevention of complications and early diagnosis and treatment are very important in the risk management of regional anesthesia. incidence and etiology of neurological complications A French prospective study revealed the incidence and characteristics of serious complications related to regional block anesthesia. Auroy (1997) investigated 103,730 patients undergoing regional block anesthesia over a 5-month period, of which 21,278 received peripheral nerve blocks. They found that the rate of cardiac arrest and neurological complications after spinal anesthesia was significantly higher than other methods of anesthesia. Neurological complications occurred in 34 patients, of which 19 recovered completely within 3 months. All the injured patients with peripheral nerve block anesthesia had paraesthesia or pain during injection. All patients with postoperative neurological deficits were also associated with this paralysis. The authors believe that acupuncture injury and local anesthetic neurotoxicity are responsible for the vast majority of neurological complications. This study shows that the incidence of serious complications related to anesthesia is actually very low. However, sometimes even an experienced anesthesiologist can lead to serious complications, so vigilance should be exercised when performing regional block anesthesia. In a 2002 survey of 150,000 follow-up patients, the incidence of serious complications related to anesthesia was low. Cheney et al (1999) conducted a survey of the American Society of Anesthesiologists database to identify neurological damage caused by strict and inappropriate anesthesia procedures. Of the 4183 patients investigated, 670 (16 percent ) developed anesthesia-related neurological impairment. The most common sites were the ulnar nerve (190 cases), the subbranchial nerve (137 cases), the lumbosacral nerve root (105 cases) or the spinal cord (84 cases). Regional block anesthesia is the most likely to cause nerve injury; general anesthesia is the most likely to cause ulnar nerve injury. However, spinal cord and lumbosacral nerve root injuries have similar etiologies, both related to paraesthesia during acupuncture and catheter placement during regional block anesthesia or pain during drug injection. It should be noted that despite extensive investigations, the precise mechanism of nerve injury remains unclear. It is the ambiguity of the mechanism that leads patients or consulting physicians to believe that nerve damage is due to improper perioperative procedures. . Nerve Injury During Puncture and Catheterization Many anesthesiologists prefer to localize nerves by anaesthetizing the patient when performing peripheral regional blocks. Although the occurrence of paraesthesia indicates needle stick injury and increases the risk of long-term postoperative paresthesias, there are no clear data to confirm or disprove it. A study by Selander et al showed that compared with the method of perivascular puncture, patients with paraesthesia during axillary block had an increased incidence of postoperative nerve injury, but the difference was not significant. Importantly, 40 percent of patients who received transvascular peripheral nerve blocks also experienced paraesthesia, illustrating the difficulty of normalizing nerve localization and analyzing nerve damage. Postoperative neurological deficits are complex, such as mild hyperesthesia, with severe paresthesias, lasting 2 weeks to more than 1 year. Urban and Urquhart conducted a prospective study using a series of regional block anesthesia and found that paresthesias were fairly common on the day after surgery, with 9 percent for intermuscular sulcus blocks and 19 percent for axillary blocks, and 2 weeks later The incidence was significantly reduced and almost disappeared after 4 weeks. Stan et al (1995) reported a 0.2 percent incidence of neurological deficits with transarterial axillary block, whereas vascular complications such as transient arterial spasm, intravascular infusion and hematoma occurred in 1.4 percent . percent . Theoretically, the use of neurostimulators for anesthesia through neuropositioning has a high success rate and a low risk of neurological complications, but it has yet to be formally proven. Fanelli et al prospectively evaluated 3996 patients with sciatic-femoral, axillary and intermuscular sulcus blocks using multipoint injection/nerve stimulation and found that within the first month after surgery, 69 patients (1.7 percent ) had neurological dysfunction, and all but 1 recovered completely after 4-12 weeks. This is similar to the complication rate associated with the use of anesthesia via paraesthesia. Nerve damage can occur when the tourniquet inflation pressure exceeds 400mmHg. The use of neurostimulators does not prevent intraneural injections. It has been reported that the use of neurostimulators to block the arm from the nerve, may cause serious nerve damage (Benumot, 2000; Passanante, 1996). Currently, there is no convincing evidence of which method of anesthesia has a high success rate or a low complication rate. Needle type, type (length) and bevel shape can also affect the degree of nerve damage, but there is a lack of clear research. Indwelling catheters in the peripheral nerve sheath can result in direct damage to the nerve. The risk of complications from brachial and peripheral nerve conduits has not been clearly reported (Motamed, 1997; Sada, 1983). Difficulty in catheter placement can lead to laceration of blood vessels, tissue damage, and bleeding. Serious complications and long-term unhealed conditions are rare. Bergman looked at 405 patients who underwent serial arm denervation blocks with a 2.2 percent complication rate, including local infection (withdrawable catheter, antibiotics), axillary hematoma, and catheter residue requiring surgical removal. In addition, 2 had local anesthetic toxicity (eg, convulsions), 4 had postoperative neurological deficits, and 2 had complications unrelated to anesthesia. Nervous system ischemia Peripheral nerves have a dual blood supply, including internal intraneural vessels and external adventitial vessels. Decreased and interrupted nerve blood supply will result in nerve ischemia. When the volume of intraneural injection fluid exceeds 50-100 ml, the intraneural pressure can exceed the capillary filtration pressure for 10 minutes and lead to nerve ischemia (Selander, 1978). Intraneural injections can also cause intraneural hematomas. Epineural blood flow is sensitive to adrenergic stimulation (Neal, 2003). The use of epinephrine-containing local anesthetic solutions could theoretically lead to peripheral nerve ischemia, especially in patients with microvascular disease. Hematoma compression can also cause nerve ischemia. In a survey of 1000 patients who underwent transvascular axillary block, Stan et al. found that 1.4 percent of patients had vascular complications (eg, transient arterial spasm, intravascular misinjection, and hematoma). Radial nerve injury and hematoma have also been reported in axillary nerve blocks. There are few studies on the risk of complications such as bleeding after peripheral nerve block in patients with coagulation disorders. The consequences of an intrathecal hemorrhage, although not as severe as an intraspinal hemorrhage, can cause nerve damage. For cardiac catheterization, a thick catheter is implanted and anticoagulated from the femoral and brachial vessels. However, the resulting neurological dysfunction is relatively rare. In fact, anticoagulated patients can be anesthetized with single-dose and continuous peripheral nerve blocks in addition to axial anesthesia. Clinicians often communicate and discuss the perioperative management of patients on anticoagulation for thromboprophylaxis, which is beneficial in reducing the risk of serious hemorrhagic complications. Patients should be closely monitored for early detection of nerve compression symptoms such as pain, paraesthesia, or weakness. Untimely diagnosis or treatment can lead to irreversible neurological ischemia. Infectious complications Any regional block anesthesia can lead to infection, and single neurological sequelae are rare. The source of infection may be exogenous, such as a contaminated medical device or disposal, or endogenous, such as secondary to a foci of infection near the site of puncture or catheter placement. Although infection at the puncture site is an absolute contraindication to regional block anesthesia, regional block anesthesia is also often used for infiltrative cellulitis, lymphangitis, and erythema. Indwelling catheters could theoretically increase the risk of infection, but although colonization may occur, infections are relatively rare. With local infection, the catheter can be withdrawn and antibiotics administered. Residual catheter stumps can be a source of infection. The authors have encountered cases of axillary abscesses requiring surgical resection without neurological sequelae. 【Patients with previous neurological disorders】 Anesthesiologists should attach great importance to such patients. Postoperative neurological deficit assessment is difficult because nerve damage may be due to surgical injury, tourniquet compression, improper positioning, or anesthesia. Regardless of the type of anesthesia used, preexisting neurological progression may worsen in the perioperative period. The protocol for regional anesthesia in such patients should be individualized. It is necessary to understand not only the pathophysiology of neurological disorders, but also the mechanism of nerve injury associated with regional block anesthesia and the incidence of neurological complications after anesthesia. When regional block anesthesia is selected, a formal examination of the patient's neurological disorder should be performed preoperatively and the patient should be informed about the likelihood of continued progression of the disorder. In patients with pre-existing neurological deficits, especially chronic neurological injury, there is a theoretically increased risk of other neurological injury following anesthesia. Clinically, it is difficult to determine the risk of neurological complications in such patients receiving regional block anesthesia. So far there are no relevant controlled studies, only some case reports. In a study on the effect of local anesthetics on nerve conduction block in diabetic rats, Kalichman and Calcutt et al. found that the amount of local anesthetics was reduced and the risk of local anesthetic-induced nerve damage was increased. These results suggest that patients with diabetes have a reduced need for local anesthetics. Dose reductions may reduce the risk of neurological damage. But anthropological research in this area is still lacking. Hebl et al (2001) found no difference in neurological function after ulnar nerve dissection under general or axillary nerve block anesthesia, but all patients with reduced neurological function after axillary nerve block anesthesia had ulnar nerve abnormalities during anesthesia. Sensation or poor response to neurostimulators. Those with preoperative neurological deficits are more prone to neurological injury, such as puncture or catheterization injury, systemic toxicity to local anesthetics, and vasoconstrictor-induced neurological ischemia. Diluted or low-potency local anesthetics should be selected for patients who are prone to local anesthetic poisoning. Controversy exists regarding the use of epinephrine during regional block anesthesia in patients with previous neurological deficits. Because epinephrine and phenylephrine can prolong block time, the advantages (eg, improved quality of anesthesia and prolonged anesthesia time) are compared with disadvantages (eg, nerve ischemia caused by vasoconstrictors); and there is also interaction between nerve tissue and local anesthetics Therefore, the concentration and dose of local anesthetic should be fully considered. Regional block anesthesia in already anesthetized patients Theoretically, such patients are at increased risk of perioperative neurological complications when regional block anesthesia is administered, because they cannot respond to acupuncture and catheter-induced paraesthesia or Pain produced by intraneural injection is a clear response. However, there is no clear data to confirm. At present, most of them are case reports, and there are no randomized studies or large sample surveys. In addition, there are provisions in medical theory. The actual risk of complications after regional block anesthesia has not been formally assessed in patients already anesthetized or deeply sedated. A paediatric study showed that regional block anesthesia under general anesthesia is safe, but this needs to be carefully explored. As mentioned earlier, direct trauma from anesthesia and local anesthetic toxicity are responsible for nerve injury, and pain when acupuncture is placed or injected is the most important risk factor for nerve injury. Compared with neuraxial anesthesia, peripheral nerve block or nerve block is relatively risky for anesthetized patients. During general anesthesia or deep sedation, larger single doses or shorter intervals increase the risk of local anesthetic toxicity, because patients fail to respond to early symptoms of elevated blood local anesthetic concentrations. In addition, although peripheral nerve blocks are sometimes an option, most regional block anesthesia requires localization of the nerve trunk or sheath by eliciting patient paraesthesia or using a neurostimulator, or by adjacent blood vessels. However, the use of neurostimulators cannot replace the current clinically commonly used methods such as nerve localization through patient paraesthesia. Urmey et al used insulated and non-insulated puncture for intermuscular sulcus block in unanesthetized patients. Turn on the neurostimulator when the patient is anaesthetized and adjust the current to 1.0 amps. Only 30 percent of patients showed limb motor response. Allopathic sites were not associated with associated motor responses. The results show that the neurostimulator only interacts with sensory nerves and does not elicit motor responses, so the use of neurostimulators in already anesthetized patients does not protect against nerve damage. Passannante (1996) reported a case of neuropathy in the arm following a neurostimulator for intermuscular sulcus block in an anesthetized patient. The motor response in this case was 0.2 mA, and no blood or cerebrospinal fluid was withdrawn at the time of administration. After analysis, it is believed that the needle tip may be located in the dural sleeve or subarachnoid space, so part of the local anesthetic enters the spinal cord during administration, and the patient does not respond to pain, so a large dose of local anesthetic is mistakenly injected into the nerve, which increases nerve damage severity. Benumof (2000) reported 4 cases of cervical spinal cord injury after general anesthesia or sedation in patients with intermuscular sulcus block, 3 of which were treated with neurostimulators. Diagnosis and Management of Nervous System Complications Neurological deficits that develop within 24 hours after surgery suggest intraneural hematoma, intraneural edema, or involvement of a sufficient number of nerve fibers, which can often be diagnosed quickly. However, many paraesthesias that persist after regional block anesthesia do not appear immediately after nerve injury, but often appear after days or weeks. A study evaluating nerve conduction after cubital nerve block found that although the ulnar nerve action potential had returned to normal after 24 hours, 3 of 28 patients had decreased action potential amplitude on examination 1 week later, and only 1 had a neurological deficit. The system is not functioning properly. The use of percutaneous nerve stimulation technology (fiber neurometer) can observe the development of nerve function

Delayed disorder. This late-onset neurological disorder indicates tissue reaction or scarring. Although it has not been determined whether this response is related to mechanical and/or chemical damage. Although the vast majority of neurological complications resolve completely within days or weeks, severe neurological injury necessitates a neurological consultation to determine the extent of the injury and to cooperate in treatment. Neurophysiological tests, such as nerve conduction studies, evoked potentials and electromyography, play an important role in diagnosis and prognostic assessment. Decreased evoked potential amplitudes indicate fewer axons, and prolonged latencies indicate demyelination. Potential fluctuations indicate axonal degeneration. These all appear 2-3 weeks after injury and peak at 1-3 months. Current research on nerve conduction has many limitations and can only assess larger motor sensations and fibers. Demyelination of small nerve fibers remains undetectable. In addition, there is no EMG response after nerve injury, often taking several weeks to become apparent. Although neurophysiological testing is usually performed only after neurological symptoms develop, basic work-up, including functional assessment of the contralateral limb, can be very helpful in detecting the underlying and previous neurological status of the patient. All in all, serious complications after regional block anesthesia are rare but devastating for the patient or the anesthesiologist. Therefore, when seeing a patient before surgery, the patient's past medical history should be carefully investigated, risk discussions should be appropriately conducted, and an appropriate anesthesia method should be selected for prevention and treatment. Other anesthesia methods, such as peripheral nerve block or general anesthesia, should be selected for high-risk patients who undergo anesthesia with nerve axis block. For anesthetized patients who want to perform regional block anesthesia, caution should be exercised because the patient cannot clearly respond to the pain that occurs during acupuncture cannulation and local anesthetic injection. During the operation, the patient should be properly adjusted to avoid nerve damage. Postoperatively, patients should be closely monitored for early detection of potential nerve damage, such as hematoma or abscess, tight surgical dressings, improper use of surgical aids, and compression of vulnerable nerve sites. Newly occurring neurological deficits should be evaluated by a neurologist or neurosurgeon, and the patient's neurological status should be stated in writing, next examinations or medical treatment should be arranged, and regular follow-up visits should be made

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