Abstract:The early recognition of comatose patients with a hopeless prognosis--regardless of how aggressively they are managed--is of utmost importance. Median somatosensory evoked potentials (SSEP) supplement and enhance neurological examination findings in anoxic-ischemic coma and are useful as an early guide in predicting outcome. The key finding is that bilateral absence of cortical evoked potentials reliably predicts unfavorable outcome in comatose patients after cardiac arrest. The author studied 50 comatose pati… Show more
“…1). Each of 7 patients with bilateral absence of cortical evoked response had generalized necrosis of the cerebral cortex leading to the conclusion that there were no viable neurons capable of responding to an afferent stimulus [1, 6]. Fig.…”
ObjectivesTo re-evaluate the role of median nerve somatosensory evoked potentials (SSEPs) and bilateral loss of the N20 cortical wave as a predictor of unfavorable outcome in comatose patients following cardiac arrest (CA) in the therapeutic hypothermia (TH) era.MethodsReview the results and conclusions drawn from isolated case reports and small series of comatose patients following CA in which the bilateral absence of N20 response has been associated with recovery, and evaluate the proposal that SSEP can no longer be considered a reliable and accurate predictor of unfavorable neurologic outcome.ResultsThere are many methodological limitations in those patients reported in the literature with severe post anoxic encephalopathy who recover despite having lost their N20 cortical potential. These limitations include lack of sufficient clinical and neurologic data, severe core body hypothermia, specifics of electrophysiologic testing, technical issues such as background noise artifacts, flawed interpretations sometimes related to interobserver inconsistency, and the extreme variability in interpretation and quality of SSEP analysis among different clinicians and hospitals.ConclusionsThe absence of the SSEP N20 cortical wave remains one of the most reliable early prognostic tools for identifying unfavorable neurologic outcome in the evaluation of patients with severe anoxic-ischemic encephalopathy whether or not they have been treated with TH. When confounding factors are eliminated the false positive rate (FPR) approaches zero.
“…1). Each of 7 patients with bilateral absence of cortical evoked response had generalized necrosis of the cerebral cortex leading to the conclusion that there were no viable neurons capable of responding to an afferent stimulus [1, 6]. Fig.…”
ObjectivesTo re-evaluate the role of median nerve somatosensory evoked potentials (SSEPs) and bilateral loss of the N20 cortical wave as a predictor of unfavorable outcome in comatose patients following cardiac arrest (CA) in the therapeutic hypothermia (TH) era.MethodsReview the results and conclusions drawn from isolated case reports and small series of comatose patients following CA in which the bilateral absence of N20 response has been associated with recovery, and evaluate the proposal that SSEP can no longer be considered a reliable and accurate predictor of unfavorable neurologic outcome.ResultsThere are many methodological limitations in those patients reported in the literature with severe post anoxic encephalopathy who recover despite having lost their N20 cortical potential. These limitations include lack of sufficient clinical and neurologic data, severe core body hypothermia, specifics of electrophysiologic testing, technical issues such as background noise artifacts, flawed interpretations sometimes related to interobserver inconsistency, and the extreme variability in interpretation and quality of SSEP analysis among different clinicians and hospitals.ConclusionsThe absence of the SSEP N20 cortical wave remains one of the most reliable early prognostic tools for identifying unfavorable neurologic outcome in the evaluation of patients with severe anoxic-ischemic encephalopathy whether or not they have been treated with TH. When confounding factors are eliminated the false positive rate (FPR) approaches zero.
“…Delay or loss of the N20 peak implies an interruption of the connecting pathways between the cervicomedullary junction and the sensory cortex. Therefore, caution in interpreting SEPs should be taken in patients with focal brain lesions [12]. A possible explanation of our observation might be an overrating of the motor score.…”
Bilateral absence of cortical N20 responses of median nerve somatosensory evoked potentials (SEP) predicts poor neurological outcome in postanoxic coma after cardiopulmonary resuscitation (CPR). Although SEP is easy to perform and available in most hospitals, it is worthwhile to know how neurological signs are associated with SEP results. The aim of this study was to investigate whether specific clinical neurological signs are associated with either an absent or a present median nerve SEP in patients after CPR. Data from the previously published multicenter prospective cohort study PROPAC (prognosis in postanoxic coma, 2000–2003) were used. Neurological examination, consisting of Glasgow Coma Score (GCS) and brain stem reflexes, and SEP were performed 24, 48, and 72 h after CPR. Positive predictive values for predicting absent and present SEP, as well as diagnostic accuracy were calculated. Data of 407 patients were included. Of the 781 SEPs performed, N20 s were present in 401, bilaterally absent in 299, and 81 SEPs were technically undeterminable. The highest positive predictive values (0.63–0.91) for an absent SEP were found for absent pupillary light responses. The highest positive predictive values (0.71–0.83) for a present SEP were found for motor scores of withdrawal to painful stimuli or better. Multivariate analyses showed a fair diagnostic accuracy (0.78) for neurological examination in predicting an absent or present SEP at 48 or 72 h after CPR. This study shows that neurological examination cannot reliably predict absent or present cortical N20 responses in median nerve SEPs in patients after CPR.
“…Absent N20 cortical response is predictive of death in comatose patients after cardiac arrest; delayed N20 responses are associated with either death or persistent vegetative state. 167 Clinicians are utilizing biochemical markers including neuron-specific enolase and the astrocyte/glial protein S100 more frequently in the evaluation of patients with disorders of consciousness. In diffuse axonal injury, elevations of neuron-specific enolase and S100 within the first 3 days after injury were associated with poor outcome, including severe disability, a vegetative state, and death.…”
Disorders of consciousness are due to failure of the arousal system. In this review, the authors introduce the spectrum of disorders of consciousness and describe the structures, projections, and neurotransmitters involved in the generation and maintenance of arousal. Next, they discuss the neurologic diseases frequently associated with arousal failure. Evaluation of patients with disorders of arousal is summarized, including the neurologic exam, electrophysiological studies, biochemical testing, and imaging modalities. Finally, they review treatment options, including therapeutic hypothermia, medications, and deep brain and spinal cord stimulation.
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