Journal of neurosurgical anesthesiology
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J Neurosurg Anesthesiol · Jan 2005
Progressive suppression of motor evoked potentials during general anesthesia: the phenomenon of "anesthetic fade".
Transcranial motor evoked potentials (MEPs) are useful for assessing the integrity of spinal cord motor tracts during major spine surgery. Anesthetic agents depress the amplitude of MEPs in a dose-dependent fashion. Anecdotal reports suggest that MEP responses degrade or "fade" over the duration of a surgery, despite unchanged anesthetic levels or other physiologic variables. ⋯ Prolonged exposure to anesthetic agents necessitates higher stimulating thresholds to elicit MEP responses, separate from the dose-dependent depressant effect. This retrospective study is limited and cannot explain the mechanism for this observed fade in signals. Recognition of anesthetic fade is essential when interpreting changes to the MEP response to avoid false-positive findings.
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J Neurosurg Anesthesiol · Jan 2005
Trigemino-cardiac reflex during microvascular trigeminal decompression in cases of trigeminal neuralgia.
The trigemino-cardiac reflex (TCR) is a well-recognized phenomenon consisting of bradycardia, arterial hypotension, apnea, and gastric hypermotility during ocular surgery or other manipulations in and around the orbit. Thus far, it could bee shown that central stimulation of the trigeminal nerve during transsphenoidal surgery and surgery for tumors in the cerebellopontine angle can lead to TCR. In cases of microvascular trigeminal decompression for trigeminal neuralgia, no data of the possible occurrence of TCR are available. ⋯ After cessation of manipulation, HR and MABP returned (spontaneously) to levels before the stimulus. Risk factors of TCR were compared with results from the literature. In conclusion, the present results give evidence of TCR during manipulation of the central part of the trigeminal nerve during microvascular trigeminal decompression in cases of trigeminal neuralgia under a standardized anesthetic protocol.
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J Neurosurg Anesthesiol · Jan 2005
Letter Case ReportsDisplaced subclavian venous catheter leading to hydrothorax.
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Postoperative visual loss occurs more commonly in patients placed prone. The mechanism may be raised intraocular pressure (IOP) causing an ischemic oculopathy. ⋯ IOP increases when anesthetized patients are placed in the prone position.