By A. Olivier. Rust College.
Correct diagnosis of the neurologically compromised patient The questions in this chapter are prepared in two general not only requires integration of information contained in differ- styles proven 20 mg apcalis sx. First apcalis sx 20mg cheap, there are study or review questions that test gen- ent chapters but may also require inclusion of concepts gained in eral knowledge concerning the structure of the central ner- other basic science courses order 20mg apcalis sx amex. These ques- sampling that covers a wide variety of neuroanatomical and tions have been carefully reviewed for clinical accuracy and clinically relevant points. There is certainly a much larger va- relevance as used in these examples. At the end of each ex- riety of questions that could be developed from the topics cov- plained answer, page numbers appear in parentheses that ered in this atlas. It is hoped that this sample will give the user specify where the correct answer, be it in a figure or in the text, a good idea of how basic neuroscience information correlates may be found. In order to make this a fruitful learning exer- with a range of clinically relevant topics. In addition to the vestibulocochlear nerve, which of the following structures would most likely also be affected by the tumor in this Chapters 1 and 2 man? A 71-year-old man complains to his family physician that his face (B) Facial nerve “feels funny. MRI shows a lesion in the cerebral (D) Posterior inferior cerebellar artery cortex. This man’s lesion is most likely located in which of the fol- (E) Vagus nerve lowing cortical regions? A 67-year-old man complains to his family physician of severe (B) Lateral one-third of the postcentral headaches. The examination reveals visual deﬁcits in both eyes, (C) Lateral one-third of the precentral and MRI shows a lesion in the cerebral cortex. Which of the fol- (D) Middle one-third of the postcentral lowing cortical structures represents the most likely location of (E) Posterior paracentral this lesion? A 41-year-old woman complains to her family physician about re- (B) Cingulate gyrus curring episodes of sharp pain that seem to originate from around (C) Lingual gyrus her mouth and cheek. The pain is so intense that she is unable to (D) Parahippocampal gyrus eat, brush her teeth, or apply make-up. Which of the following (E) Precuneus cranial nerves is the most likely source of this pain? A sagittal MRI of a 23-year-old woman is located at, or immedi- (B) Glossopharyngeal (IX) ately adjacent to, the midline. Which of the following spaces or (C) Hypoglossal (XII) structures would be in the image and would indicate a midline (D) Trigeminal (V) plane? The labyrinthine artery is an important source of blood supply to (C) Interpeduncular fossa the inner ear. Which of the following arteries represents the ma- (D) Interventricular foramen jor vessel from which this branch usually arises? A 20-year-old man is brought to the emergency department from (C) Posterior inferior cerebellar the site of a motorcycle accident. He is unconscious and has a bro- (D) Superior cerebellar ken femur, humerus, and extensive facial injuries. Axial CT shows (E) Vertebral a white layer on the lateral aspect of the left hemisphere that is ap- proximately 5 mm thick and extends for 12 cm. The quadrigeminal artery in a 20-year-old man is occluded by a fat most likely represents: embolus originating from a compound fracture of the humerus. Which of the following portions of the ventricular system does not (E) Superior and inferior colliculi contain choroid plexus? MRI reveals a large tumor (3 cm in diameter) at the cere- (E) Third ventricle bellopontine angle, most likely a vestibular schwannoma (sometimes incorrectly called an acoustic neuroma). A 47-year-old man presents with an intense pain on his face aris- ing from stimulation at the corner of his mouth. MRI shows a vessel (A) Anosmia compressing the root of the trigeminal nerve.
It is used in cases of overdose cheap 20mg apcalis sx fast delivery, usually to reverse the respiratory depression but with the cost of also reversing the analgesia order apcalis sx 20 mg otc. INTERACTIONS WITH OTHER NEUROTRANSMITTERS Some opioids cheap 20mg apcalis sx, such as methadone and ketobemidone, have been reported to bind additionally to NMDA receptors and so may be different in their pharmacological profile. However, it is very unclear that this has any bearing on their effects in patients, especially in cases where morphine effectiveness is reduced, such as in neuropathic pain. In terms of changes in opioid systems relevant to the control of pain after nerve injury, nerve damage can lead to a loss of opioid receptors such as the marked reduction in spinal opioid receptor number seen after nerve section. Although this may be an explanation of the poor effectiveness of opioids in post-amputation pains, less severe nerve damage, where opioids can also lack effectiveness, only slightly alters opioid receptor number. However, the levels of the non-opioid peptide, cholecystokinin (CCK), can determine the potency of morphine and the peptide may, in turn, be upregulated after nerve damage. Activation of the CCKB receptor mobilises internal calcium whereas opioid receptors hyperpolarise Ð these actions of CCK thereby physiologically antagonise those of opioids. Antagonists at the CCKB receptor have been predicted to enhance or restore morphine analgesia after nerve injury but none have been tested in patients as yet. As discussed earlier, the changes that occur in the periphery and spinal cord after nerve damage can result in overexcitability of spinal neurons so that a hypersensitive state is induced. The N-methyl-D-aspartate (NMDA) receptor is a major candidate in the generation of hyperalgesic states in neuropathic and tissue damage pain states. Quite simply, if neuronal excitability is dramatically increased then opioid controls may be insufficiently efficacious unless doses are increased sufficiently to increase the degree of inhibition required to balance the level of excitation. Here, the combination of a low dose of opioid, increasing inhibition, with a drug that blocks excitation such as ketamine may result in synergistic or additive effects that result in the desired degree of analgesia without adverse side-effects. Other combinations could include the use of anti-convulsants with opioids. In common with neuropathy, NMDA receptor activation occurs after inflammation but here opioid actions are enhanced since CCK levels decrease. Thus, this augmented opioid actions may counter the increased excitability without the need for large increase in doses of opioid. BEHAVIOUR AND PAIN Finally, as outlined above, descending monoamine systems, originating in the midbrain and brainstem that act through the spinal release of noradrenaline and 5-HT, modulate the spinal transmission of pain. Alpha2 adrenoceptors appear to be important in this role but it is unlikely that behavioural effects such as sedation can be separated from the analgesia. Since both noradrenaline and 5-HT are key transmitters in the control of mood and anxiety and yet also participate in the control of sensory events that lead to 474 NEUROTRANSMITTERS, DRUGS AND BRAIN FUNCTION pain we can start to see links between state of mind and the level of pain experienced. This may be just one early step in the understanding of some of the chemistry of the psychological aspects of pain. Independently of their effects on mood, antidepressants increase activity in these descending control systems and are used as analgesics in neuropathic pain states. Individual differences in levels of pain, in the transition from acute to chronic pain, in susceptibility to neuropathic pain after nerve damage and in analgesic effectiveness may have a genetic basis. There is marked variability in animal genetic strains in terms of the sequelae of tissue and nerve damage and even in their responses to morphine. Given the huge range of human phenotypes, this may indicate important individual differences in susceptibility to pain and analgesia but we have no way of monitoring this possibility. Dray, A, Urban, L and Dickenson, AH (1994) Pharmacology of chronic pain. McMahon, SB, Lewin, GR and Wall, PD (1993) Central excitability triggered by noxious inputs. Edited by Roy Webster Copyright & 2001 John Wiley & Sons Ltd ISBN: Hardback 0-471-97819-1 Paperback 0-471-98586-4 Electronic 0-470-84657-7 Section N SM IT S A IO Neurotransmitters, Drugs and Brain Function. Edited by Roy Webster Copyright & 2001 John Wiley & Sons Ltd ISBN:Hardback 0-471-97819-1 Paperback 0-471-98586-4 Electronic 0-470-84657-7 22 Sleep and aking R. STANFORD INTRODUCTION There have been many references in this book to the role of neurotransmitters in the control of CNS excitability. It is therefore appropriate, but possibly foolhardy, to see if the two natural extremes of that excitability, namely sleep and waking, can be explained in terms of neurotransmitter activity. Of course, these states are not constant:our sleep can be deep or light and, even when we are awake, our attention and vigilance fluctuate, as the reading of these pages will no doubt demonstrate.
10 of 10 - Review by A. Olivier
Votes: 296 votes
Total customer reviews: 296