Neurologic/neuromuscular Flashcards
what are the risk factors for postoperative prolonged intubation for patients with myasthenia graves?
The Leventhal scoring system is a weighted score that is applied to patients with myasthenia gravis in order to predict their need for extended postoperative mechanical ventilation. The score was developed in a cohort of patients undergoing transsternal thymectomy and is presented as follows: Duration of myasthenia gravis for more than 6 years: 12 points History of chronic respiratory disease other than myasthenia gravis: 10 points A dose of pyridostigmine greater than 750 mg daily: 8 points Preoperative vital capacity less than 2.9 liters: 4 points duration of myasthenia graves fro more than 6 years carries the greatest risk
what is the anatomy of the circle of willis?
causes of nicotinic achr upregulation?
Succinylcholine should also be avoided in those with myotonic dystrophy, but this is not secondary to AChR upregulation. Patients with myotonic dystrophy can have severe myotonic contractions induced by the use of succinylcholine. Other things that can lead to perioperative myotonia in these patients are the use of neuromuscular blocker reversal agents and hypothermia.
how much does potassium increase in the normal healthy patient when succinylcholine is given?
Potassium release after administration will be the same as with healthy patients, increasing serum levels roughly 0.5 - 1 mmol/L (0.5 - 1 mEq/L).
what cranial nerves have parasympathetic activity? what area of the brainstem do they originate from?
what type of channel defect leads to hypokalemic periodic paralysis?
what type of channel defect leads to hyperkalemic periodic paralysis?
calcium channel defect
HypoK PP paralysis usually affects the limbs and trunk…diaphragm is spared
hyperK PP is a sodium channel defect…tx K restriction and thiazide diuretics…symptoms may be limited to tongue and eyelids…during an attack hyperk may be associated with dysrrhythmias and respiratory failure
- what are muscular dystrophies a disease of?
- what type of weakness associated with limb-girdle muscular dystrophy? anything else?
- should sux or volatile agents be used?
- a disease of muscle membrane and cause a progressive loss of skeletal muscle function. cardiac and smooth muscle may also be affected
- Limb-girdle muscular dystrophy is associated with proximal weakness in the shoulder and pelvic girdles and multiple gene defects causing an array of clinical pictures. Cardiomyopathy and atrioventricular conduction defects may lead to the short life-span seen in some of these patients.
- Succinylcholine should be avoided due to hyperkalemia risk and volatile anesthetics should be avoided due to rhabdomyolysis risk.
- what is produced in the anterior portion of the pituitary gland?
- what produced in the posterior pituitary gland?
- GH, prolactin, acth, B-lipoprotein, thyrotropin, gonadotropins, FSH, LH
- ADH, oxytoxcin
what is the treatment for prolactin-secreting microadenoma?
Dopamine agonists: bromocriptine and cabergoline
symptoms in women from prolacting : amenorrhea and galactorrhea
men: impotence
what is considered an elevated ICP?
what is a volatile agent that increases ICP?
normal 5-15mmhg
elevated ICP @ 20mmhg
- Nitrous oxide causes an increase in cerebral metabolic rate, cerebral blood flow, and ICP.
what is transient neonatal myasthenia gravis?
maternal antibodies to acetylcholine receptos freely cross the placenta and may cause transient neonatal myasthenia gravis with respiratory distress, poor feeding, and generalzied hypotonia.
Treatment with nutritional or respiratory support and acetylcholinesterase inhibitors, and neonates recover in weeks to months as maternal abs decrease.
what is the path of somatosensory evoked potentials?
peripheral nerve, ipsilateral dorsal root gangila, ipsilateral posterior and later spinal cord, decussation of nerve fibers at the cervicomedullary junction, contralateral medial lemniscus (within the brainstem), contralateral ventroposterolateral nucleus of the thalamus, contralateral thalamocortical radiation, and associated contralater sensorimotor cortex.
what are the goals of anesthetic management during cerebral aneurysm clipping?
should you do spinal in a patient with amyotrophic lateral sclerosis?
no shoud be avoided. Risk of exacerbating disease
what can i do to eliminate the risk of posoperative myagias when sux given?
nothing elimates the risk of myalgias
pretreatemtn with a nondepolarizing neuromuscular muscle relaxant, administration of lidocaine, and NSAIDs have all been should to decrease the incidence of myalgias
when should anti-seizure med be given?
whats the treatment choice?
has a seizure lasting longer than 5 minutes, or two seizures within 5 minute period
difference bw myasthenia gravis vs myasthenic syndrome?
what do our volatile anesthetics do to cmro2, cbf, and icp?
IV ?
CMRO2 generally decreases with hypothermia and sleep. Anesthetics also change CMRO2. All volatile anesthetics (isoflurane, desflurane, and sevoflurane) decrease CMRO2, thereby causing some decrease in CBF in response. However, the volatiles also has a direct cerebral vasodilating effect, therefore increasing CBF. With low levels of volatiles (typically less than 1 MAC), these two effects balance out, and the CBF remains essentially the same. However, with higher amounts of inhaled anesthetics, the CBF has a dose-dependent increase, and the overall effect is increased CBF. This phenomenon is referred to as “uncoupling” because the CMRO2 decreases while the CBF increase. This term is a misnomer as the CBF does decrease with a decrease in CMRO2; however, it also increases due to the vasodilatory effect of the volatiles. So the volatile anesthetics essentially have two different and distinct effects on the brain, which at higher concentrations leads to an overall increase in CBF and decrease in CMRO2. The combination leads to an increase in overall ICP.
