الفهرس 
Physiology of the neuromuscular junctionOnly 14 pages are availabe for public view
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Abstract
Myopathies are diseases of skeletal muscle( myopathic) which are not caused by nerve disorders ( not neurogenic) . These diseases cause the skeletal or voluntary muscles to become weak or wasted .
There are many different types of myopathies, some of which are inherited ( commonly Muscular dystrophies), some inflammatory, and some caused by endocrine problems. Myopathies are rare and not usually fatal. Typically, effects are mild, largely causing muscle weakness and movement problems, and many are transitory. Only rarely will patients become dependent on a wheelchair. However, muscular dystrophy (which is technically a form of myopathies) is far more severe. Some types of this disease are fatal in early adulthood.
Muscular dystrophies are a group of genetic disorders in which strength and muscle bulk gradually decline.
Duchenne’s muscular dystrophy is the most common and most severe form. Other major variants include Becker’s type, facioscapulohumeral, and limb-girdle dystrophies.
It is important for anesthesia, that these disorders show various symptoms and have a high risk during general anesthesia. Especially administration of succinylcholine and volatile anesthetics may cause problems. Also opioids, non-depolarizing muscle relaxants, and intravenous anesthetics can interfere with this kind of disorders.
Pre-operative examination should include the detection of associated cardiac and respiratory dysfunction, a neurological examination for scoring myopathic symptoms, electrocardiogram, chest X-ray, pulmonary function tests, arterial blood gas analysis, determination of serum Na+, K+, Cl-, Ca+2, Mg+2 and CK are important for anesthesia of these patients.
For pre-medication, substances leading to respiratory depression or decreased muscle tone are often not used in severely affected individuals. Regional or local anesthetic techniques can be employed in patients with cardiac and/or respiratory dysfunction.
The use of neuromuscular blocking agents (Even in healthy individuals) must be done under complete monitoring to prevent residual muscle paralysis after recovery from anesthesia. In patients with myopathies , the anesthesiologist must do a preoperative select of the appropriate anesthetic technique and muscle relaxant (if needed).
Patients suffering from muscular dystrophies have an elevated anesthetic risk to develop malignant hyperthermia or rhabdomyolysis. In addition serious cardio-pulmonary complications are imminent during anesthesia.
Several points to consider have been revealed regarding the anesthetic considerations of anesthesia in patients with Paramyotonia congenita (PC). In those patients, anesthesia is safely maintained using sevoflurane and nitrous oxide together with concomitant epidural anesthesia using mepivacaine. Efforts should be made to prevent perioperative attacks of muscle weakness when planning anesthesia for patients with this kind of disorder. Specifically, refraining from the use of muscle relaxants, care with regard to the composition of infusion fluids during operations, and the maintenance of body temperature are required for anesthesia .
Patients with Myotonia congenita and their response to muscle relaxants and anesthetic drugs were evaluated and the conclusion was:
(a) The response to non-depolarizing muscle relaxants is normal.
(b) The use of depolarizing muscle relaxants is hazardous because marked generalized contracture of skeletal muscle may develop preventing adequate airway maintenance and ventilation.
(c) Patients with myotonia congenita are more likely than normal patients to develop apnea after administration of sedative anesthetic drugs.
(d) Epidural anesthesia is reported to be safe in these patients .
Anesthetic considerations of patients with familial periodic paralysis is directed toward preventing attacks. Careful electrocardiographic monitoring is necessary to detect attacks and arrhythmias during anesthesia. In patients with familial periodic paralysis, the response to muscle relaxants is unpredictable. Increased sensitivity to non-depolarizing relaxants is encountered in those with hypokalemic periodic paralysis.
In cases of MH, The family history of death under general anesthesia, musculoskeletal abnormalities will be helpful to detect MH susceptibles, and giving a chance to the anesthesiologist to follow the MH protocol of preoperative preparation and intraoperative management, including equipments (e.g. capnogram), cooling aids, drugs (e.g. dantrolene sodium) with avoidance of triggering agents (e.g. succinylcholine), also postoperative observation of the patient is important to avoid postoperative complications.
Anesthetic complications frequently occur in patients with myopathies, although anesthetic procedures have become safer by the reduced administration of succinylcholine, and the use of total intravenous anesthesia (TIVA), new volatile anesthetics and non-depolarizing relaxants. Complications of anesthesia in patients with myopathies include rhabdomyolysis, cardiac complications, respiratory complications, myotonic reaction, masseter and generalized muscle spasm, autonomic dysregulation and malignant hyperthermia.