Current opinion in neurology and neurosurgery
-
Curr Opin Neurol Neurosurg · Apr 1993
ReviewThe spinal pharmacology of facilitation of afferent processing evoked by high-threshold afferent input of the postinjury pain state.
Repetitive C afferent input evokes a facilitated state of processing that results in increased receptive fields and exaggerated responses to afferent input ("wind-up"). These phenomena underlie the behavioral phenomena of secondary hyperalgesia and this in turn is an important component of postoperative pain. The initiation of this facilitated component is not well blocked by even higher concentrations of volatile anesthetics, but it can be prevented by pretreatment with agents known to block afferent input (local anesthetics) or C-fiber transmitter release (opiates) or to act at one of several links to block a complex spinal cascade involving the N-methyl-D-aspartate receptor, nitric oxide synthase, and cyclooxygenase. These fundamental mechanisms promise to have an impact on the management of postoperative pain.
-
Neurogenic pain (encompassing all types of neuropathic and central pain) is discussed. Experimental work is presented in a model in which the rat sciatic nerve is loosely ligatured. In painful human neuropathies, tricyclic antidepressants have been found to be effective in proportion to the degree they facilitate monoaminergic activity. ⋯ In nociceptive pain, recent findings in humans emphasize the importance of both the retroinsular (SII) and the anterior cingulate cortices in the conscious appreciation of pain. Opioid studies have revealed individual differences in the metabolism of morphine to its 3- and 6-glucuronosides; patients with nociceptive pain who respond poorly to morphine or diamorphine probably have a high 3:6 ratio. It has been pointed out that methadone may be useful in such cases, as it is not broken down to glucuronosides.
-
Curr Opin Neurol Neurosurg · Feb 1993
ReviewSurgery, angioplasty, and interventional neuroradiology.
This article discusses recent advances in the treatment of three cerebrovascular conditions, namely carotid stenosis, cerebral aneurysm, and arteriovenous malformation. In all three the aim of treatment is to prevent stroke, and in all three, recent advances in interventional neuroradiology are supplementing traditional surgical techniques. ⋯ Recent advances in the management of cerebral aneurysm include new treatments for cerebral vasospasm and the use of endovascular occlusion to treat inoperable aneurysms. Endovascular embolization for arteriovenous malformations also looks promising, but more randomized trials are required to establish the benefit of these interventional procedures.
-
Usefulness of grading systems based on non-specific features (e.g. mitosis, necrosis) is unequivocal in only certain types of astrocytomas, and their efficiency remains to be seen in oligodendrogliomas and in mixed oligo-astrocytomas. The possibility of grading ependymomas is still uncertain. Accordingly, only a small proportion of gliomas which occur in children can be reliably graded. Lack of reproducibility is a severe impediment of both current conventional and kinetic methods in the prognosis of gliomas.
-
Several discussions of the neuroimaging of inflammatory diseases with emphasis on computerized tomography (CT) and magnetic resonance imaging (MRI) findings and on rare diseases, such as sparganosis, neuroborreliosis and various types of encephalitis, have been published during the past year. Infectious processes in immunosuppressed patients have been described by many authors, especially in the field of acquired immune deficiency syndrome (AIDS). The importance of gadolinium-diethylenetriamine-penta-acetic acid (Gd-DTPA) in MRI for delineation, and differential diagnosis of the inflammatory processes has been considered. Newly introduced techniques such as technetium-99m hexamethylpropyleneamine oxime (99mTc-HMPAO) single photon emission CT (SPECT) and proton spectroscopy have made the early detection of diseases possible.