By R. Chris. Lane College.
Myelin normally insulates the neuron from electrical activity and conducts electrical im- Spasticity pulses rapidly along nerve fibers cheap terramycin 250mg without prescription. When myelin is destroyed (a process called demyelination generic terramycin 250 mg amex, which probably results Spasticity involves increased muscle tone or contraction and from inflammation), fibrotic lesions are formed and nerve stiff, awkward movements. It occurs with neurologic disorders conduction is slowed or blocked around the lesions. It inhibits the release of calcium in skeletal muscle cells weakness and other symptoms vary according to the loca- and thereby decreases the strength of muscle contraction. In recent years, researchers have discovered that nerve cells can be repaired (remyelinated) if the process that dam- Indications for Use aged the myelin is stopped before the oligodendrocytes (the cells that form myelin) are destroyed. Other researchers are Skeletal muscle relaxants are used primarily as adjuncts to trying to develop methods for enhancing nerve conduction other treatment measures such as physical therapy. For example, exposure to sionally, parenteral agents are given to facilitate orthopedic cold by wearing a cooling vest or exercising in cool water procedures and examinations. In spastic disorders, skeletal temporarily increases the rate of nerve conduction and im- muscle relaxants are indicated when spasticity causes se- proves symptoms in some people. Avoiding environmental vere pain or inability to tolerate physical therapy, sit in a heat and conditions that cause fever may also help because wheelchair, or participate in self-care activities of daily liv- an elevated body temperature slows nerve conduction and ing (eg, eating, dressing). Dantrolene also is indicated for prevention and treatment Those with more extensive symptoms should try to avoid of malignant hyperthermia, a rare but life-threatening com- emotional stress, environmental temperature extremes, infec- plication of anesthesia characterized by hypercarbia, meta- tions, and excessive fatigue. Physical therapy may help main- bolic acidosis, skeletal muscle rigidity, fever, and cyanosis. For intraoperative malignant ications for different types and stages of the disease.
Positron emission tomographic imaging proves activated blood flow and facilitates rehabili- of serotonin activation effects on prefrontal cortex tation of poststroke aphasic patients buy terramycin 250mg cheap. Dysfunction in tromethorphan decreases the excitability of the hu- the neural circuitry of emotion regulation-a possible man motor cortex purchase terramycin 250mg without a prescription. Pfefferbaum A, Desmond J, Galloway C, Menon V, etine and fenozolone during hand sensorimotor tasks. Reorganization of frontal sys- J Cereb Blood Flow Metab 1999; 19:1365–1375. Brain Mapping: hanced after a single dose of serotonin reuptake in- The Methods. Pariente J, Loubinoux I, Carel C, Albucher J, Ras- in the frontal lobes. The role of the lateral frontal cortex in formance and cerebral activation of patients recov- mnemonic processing: The contribution of functional ering from stroke. Worsley K, Liao C, Aston J, Petre V, Duncan H, Horn J, Bigelow L, Weinberger D. A general statistical analysis amine enhances neural network-specific physio- for fMRI data. Mattay V, Callicott J, Bertolino A, Heaton I, Frank NeuroImage 2000; 12:1–13. Effects of dextroamphetamine on cognitive per- substrates for the effects of rehabilitative training on formance and cortical activation. Chapter 4 Neurostimulators and Neuroprostheses PERIPHERAL NERVOUS SYSTEM DEVICES with acquired deafness.
As a group discount 250mg terramycin with amex, the calcium channel blockers are well absorbed from the gastrointestinal tract following oral administration and are highly bound to protein discount terramycin 250 mg without prescription. SNS stimulation produces widespread effects in the body, the effects relevant to this discussion are the increases in heart rate, force of myocardial contraction, cardiac output, Diuretics and blood pressure that occur. When the nerve impulse is in- hibited or blocked at any location along its pathway, the re- Antihypertensive effects of diuretics are usually attributed to sult is decreased blood pressure (see Chap. In fact, diuretics usually produce Alpha1-adrenergic receptor blocking agents (eg, prazosin) the same effects as severe dietary sodium restriction. In many dilate blood vessels and decrease peripheral vascular resis- cases of hypertension, diuretic therapy alone may lower blood tance. One adverse effect, called the ﬁrst-dose phenomenon, cardiac output decrease. With long-term administration of a results in orthostatic hypotension with palpitations, dizziness, diuretic, cardiac output returns to normal, but there is a per- and perhaps syncope 1 to 3 hours after the ﬁrst dose or an in- sistent decrease in peripheral vascular resistance. To prevent this effect, ﬁrst doses and ﬁrst in- been attributed to a persistent small reduction in extracellular creased doses are taken at bedtime. Another effect, associated water and plasma volume, decreased receptor sensitivity to with long-term use or higher doses, leads to sodium and ﬂuid vasopressor substances such as angiotensin, direct arteriolar retention and a need for concurrent diuretic therapy. Cen- vasodilation, and arteriolar vasodilation secondary to elec- trally acting sympatholytics (eg, clonidine) stimulate pre- trolyte depletion in the vessel wall. When these drugs are taken, less to a diuretic alone, the diuretic may be continued and another norepinephrine is released and sympathetic outﬂow from the antihypertensive drug added, or monotherapy with a differ- vasomotor center is reduced. Stimulation of presynaptic ent type of antihypertensive drug may be tried. Reduced sympathetic activity commonly used in the management of hypertension. Loop CHAPTER 55 ANTIHYPERTENSIVE DRUGS 803 diuretics (eg, furosemide) or potassium-sparing diuretics • Oral contraceptives, corticosteroids, appetite sup- (eg, spironolactone) may be useful in some circumstances; pressants, nasal decongestants, non-steroidal anti- see Chapter 56 for discussion of diuretic drugs.