Neurophysiologie clinique = Clinical neurophysiology
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The contribution of clinical neurophysiology in the neurological prognosis of hypoxic-ischemic coma has been well established in adults: the bilateral absence of cortical somatosensory evoked potentials (SEP) is considered the single best indicator of adverse outcome, while the presence of the auditory mismatch negativity (MMN) is thought to herald arousal. ⋯ This case illustrates the particular significance of SEP and MMN together with EEG in gaining prognostic information, even in sedated and hypothermic patients, and encourages systematic study of these prognostic tools in paediatric postanoxic coma.
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In the nineties, epidural cortical stimulation (ECS) of precentral region has been performed to treat drug-resistant neuropathic pain and repetitive transcranial magnetic stimulation (rTMS) of prefrontal region has shown antidepressant effects in episodes of major depression. These were among the first attempts to treat neurological or psychiatric disorders with cortical stimulation. Actually, a variety of invasive and noninvasive techniques of cortical stimulation could serve therapeutic purpose, including ECS, rTMS, but also transcranial electrical stimulation using pulsed currents (TCES) or direct currents (tDCS). ⋯ The existence of after-effects relates to processes of synaptic plasticity induced by the stimulation. Cortical stimulation may also have neuroprotective effects against disease-related excitotoxic phenomena. Considering the multiple techniques and the various potential clinical indications, it is a challenge to determine the place of cortical stimulation in the treatment of neurological and psychiatric diseases, in particular by the side of deep brain stimulation.
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It is presumed that idiopathic overactive bladder syndrome (OBS) is due to visceral hypersensitivity. Sacral-root stimulation can restore the bladder function, but its mechanism remains uncertain. It is well-known that long-term peripheral stimulation can induce brain plasticity. Hence, we investigated whether brain reorganization occurred along with clinical improvement after sacral-root stimulation. ⋯ Our results showed that cerebral activities changed after sacral-root stimulation. The improvement in urinary urgency and urgency perception was probably due in part to brain reorganization.
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Transcranial electrical stimulated motor evoked potential monitoring (TES-MEP) has proven to be a successful and reliable neuromonitoring technique during spinal correction surgery. However, three criteria for TES-MEP monitoring have been described in the literature. This study aims at discussing and comparing the following criteria: (1) the "threshold level criterion" introduced by Calancie et al. (J Neurosurg 88 (1998) 457-70): a more than 100V over more than 1h increase of threshold level to get useful TES-MEP responses indicated neurological impairment; (2) the "amplitude criterion": for TES-MEP monitoring in corrective surgery of the spine, a more than 80% decrease of one or more response amplitudes was considered a valuable criterion for impending neurological deficits by Langeloo et al. (Spine 28 (2003) 1043-50); (3) "the morphology criterion": introduced in 2005 by Quinones et al. (Neurosurgery 56 (2005) 982-93), it is based on the morphology of the MEP-compound muscle action potentials (CMAP). ⋯ Although all methods have been reported to be successful during spinal surgery, the threshold criterion and the morphology change criterion carry several drawbacks. We consider the amplitude reduction method to be most useful during corrective spinal surgery. The sequences of observations and decisions during a TES-MEP monitoring that is based on this criterion are schematized in a flowchart.
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During resection of intramedullary spinal-cord tumors intraoperative neurophysiological monitoring has become a true surgical technology. Motor evoked potentials are the most important modality for this purpose. Its use requires neurophysiological expertise from the surgeon, and a monitoring team in place able to handle the necessary equipment. ⋯ Such adaptation comprises simply waiting for the recordings to spontaneously improve again, irrigating with warm saline solution to wash out blocking potassium. Other measures include the elevation of mean arterial pressure to improve local perfusion. Even staged resection can be considered if intraoperative measures do not sufficiently improve the recordings.