Seminars in neurology
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Tick paralysis results from inoculation of a toxin from tick salivary glands during a blood meal. It is a relatively uncommon neuromuscular disease with a higher prevalence among young girls, although older men who get exposed to ticks may also be affected. It typically presents as an acute ascending paralysis occurring a few days after tick attachment and may result in respiratory failure and death. ⋯ These appear to result from a failure of acetylcholine release at the motor nerve terminal level. There may be subtle abnormalities of motor nerve conduction velocity and sensory action potentials. Removal of the tick results in the very rapid reversal of clinical and physiologic deficits, quicker with North American ticks than with the Ixodes species seen in Australia.
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Congenital myasthenic syndromes are genetic disorders of neuromuscular transmission that should be considered in the differential diagnosis of seronegative myasthenia gravis and other neuromuscular disorders. They are present at birth but may not manifest until childhood or adult life. ⋯ Some types of congenital myasthenia (e.g., slow-channel and fast-channel syndrome, acetylcholinesterase deficiency, and choline acetyltransferase deficiency) can be identified by clinical features, response to cholinesterase inhibitors, and standard electrodiagnostic studies. The molecular genetics, pathogenesis, clinical features, differential diagnosis, natural history, and treatment of well-characterized congenital myasthenic syndromes are discussed.
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Seminars in neurology · Mar 2004
ReviewMyasthenia gravis: management of myasthenic crisis and perioperative care.
Myasthenic crisis may be defined as respiratory failure or delayed postoperative extubation for more than 24 hours resulting from myasthenic weakness. Myasthenic crisis results from weakness of upper airway muscles leading to obstruction and aspiration, weakness of respiratory muscles leading to reduced tidal volumes, or from weakness of both muscle groups. About one-fifth of patients with myasthenia gravis experience crisis, usually within the first year of illness. ⋯ Common precipitating factors for myasthenic crisis include respiratory infections, aspiration, sepsis, surgical procedures, rapid tapering of immune modulation, beginning treatment with corticosteroids, exposure to drugs that may increase myasthenic weakness, and pregnancy. Myasthenic crisis should not be fatal, as long as patients receive timely respiratory support and appropriate immunotherapy to reduce myasthenic weakness of the upper airway and respiratory muscles. Myasthenic patients with oropharyngeal or respiratory muscle weakness should receive preoperative plasma exchange or intravenous immunoglobulin therapy to a minimal level of weakness to prevent postoperative complications.
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Seminars in neurology · Mar 2004
ReviewAnesthesia issues in the perioperative management of myasthenia gravis.
Myasthenia gravis (MG) is an autoimmune disease of the neuromuscular junction. Current anesthetic practice may require the use of neuromuscular blocking (NMB) drugs that act at this junction to facilitate control of the airway and allow procedures to be performed on a motionless MG patient. This competes with the goals of rapid emergence and recapture of preoperative muscle strength following anesthesia. ⋯ If necessary, postoperative mechanical ventilation is accomplished with the use of specialized monitoring devices that help monitor awareness and depth of sedation. Currently used intravenous sedatives allow titrated depth of sedation and rapid emergence when extubation is appropriate. Communication to the patient, family, and other caregivers of the goals of the anesthetic plan and of the patient's evolving status are also very important duties of the anesthesiologist.
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Seminars in neurology · Sep 2003
Review Comparative StudyDiagnosis and management of stroke (brain attack).
Clinicians commonly encounter patients with cerebrovascular disorders in the hospital. Now, as never before, there are many effective diagnostic and therapeutic modalities. Several examples of typical cases of stroke and transient ischemic attack are presented in order to illustrate a rational approach to diagnosis and treatment. A redefinition of transient ischemic attack and stroke, salient elements of the neurological history and examination, localization techniques, stroke mimickers, mechanisms of infarction and hemorrhage, acute stroke teams, thrombolysis, and secondary prevention are highlighted.