Items in AFP with MESH term: Central Nervous System Diseases
Practical Selection of Antiemetics - Article
ABSTRACT: An understanding of the pathophysiology of nausea and the mechanisms of antiemetics can help family physicians improve the cost-effectiveness and efficacy of therapy. Nausea and vomiting are mediated primarily by visceral stimulation through dopamine and serotonin, by vestibular and central nervous system causes through histamine and acetylcholine, and by chemoreceptor trigger zone stimulation through dopamine and serotonin. Treatment is directed at these pathways. Antihistamines and anticholinergic agents are most effective in patients with nausea resulting from vestibular and central nervous system causes. Dopamine antagonists block dopamine in the intestines and chemoreceptor trigger zone; indications for these agents are similar to those for serotonin antagonists. Serotonin antagonists block serotonin in the intestines and chemoreceptor trigger zone, and are most effective for treating gastrointestinal irritation and postoperative nausea and vomiting. Complementary and alternative therapies, such as ginger, acupressure, and vitamin B6, have variable effectiveness in the treatment of pregnancy-induced nausea.
ABSTRACT: Opioid analgesics are useful agents for treating pain of various etiologies; however, adverse effects are potential limitations to their use. Strategies to minimize adverse effects of opioids include dose reduction, symptomatic management, opioid rotation, and changing the route of administration. Nausea occurs in approximately 25 percent of patients; prophylactic measures may not be required. Patients who do develop nausea will require antiemetic treatment with an antipsychotic, prokinetic agent, or serotonin antagonist. Understanding the mechanism for opioid-induced nausea will aid in the selection of appropriate agents. Constipation is considered an expected side effect with chronic opioid use. Physicians should minimize the development of constipation using prophylactic measures. Monotherapy with stool softeners often is not effective; a stool softener combined with a stimulant laxative is preferred. Sedation and cognitive changes occur with initiation of therapy or dose escalation. Underlying disease states or other centrally acting medications often will compound the opioid's adverse effects. Minimizing unnecessary medications and judicious use of stimulants and antipsychotics are used to manage the central nervous system side effects. Pruritus may develop, but it is generally not considered an allergic reaction. Antihistamines are the preferred management option should pharmacotherapy treatment be required.
Cerebrospinal Fluid Analysis - Article
ABSTRACT: Lumbar puncture is frequently performed in primary care. Properly interpreted tests can make cerebrospinal fluid (CSF) a key tool in the diagnosis of a variety of diseases. Proper evaluation of CSF depends on knowing which tests to order, normal ranges for the patient's age, and the test's limitations. Protein level, opening pressure, and CSF-to-serum glucose ratio vary with age. Xanthochromia is most often caused by the presence of blood, but several other conditions should be considered. The presence of blood can be a reliable predictor of subarachnoid hemorrhage but takes several hours to develop. The three-tube method, commonly used to rule out a central nervous system hemorrhage after a “traumatic tap,” is not completely reliable. Red blood cells in CSF caused by a traumatic tap or a subarachnoid hemorrhage artificially increase the white blood cell count and protein level, thereby confounding the diagnosis. Diagnostic uncertainty can be decreased by using accepted corrective formulas. White blood cell differential may be misleading early in the course of meningitis, because more than 10 percent of cases with bacterial infection will have an initial lymphocytic predominance and viral meningitis may initially be dominated by neutrophils. Culture is the gold standard for determining the causative organism in meningitis. However, polymerase chain reaction is much faster and more sensitive in some circumstances. Latex agglutination, with high sensitivity but low specificity, may have a role in managing partially treated meningitis. To prove herpetic, cryptococcal, or tubercular infection, special staining techniques or collection methods may be required.