Evidence-based guideline update: Determining brain death in adults
CalixtoMachado, Institute of Neurology and Neurosurgery
Published August 31, 2010
The Report of the AAN Subcommittee, [1] issued 15 years after the AAN hallmark publication on determining brain death (BD) in adults, [2] has touched on several key points.
Wijdicks et al. concluded that there are no published reports of recovery of neurologic function after BD diagnosis. This is an important clinical, social, and ethical finding related to diagnosing death on neurological grounds because irreversibility should be directly related to the determination of death. [3] Furthermore, the Subcommittee did not find consensus on a minimally acceptable observation period for assuring that neurologic functions have permanently stopped. [1] Ancillary tests may play an important role in shortening periods of observation, [3,4] but the panel of experts concluded that there are not enough data to show that newer tests confirm the termination of whole brain functioning. [1]
It is widely accepted that BD is a clinical diagnosis and that confirmatory laboratory tests are recommended when specific components of the clinical testing cannot be evaluated. [1,2,3] An ideal confirmatory test should be safe, accurate, and inexpensive. Ancillary tests either show absent cerebral blood flow and brain metabolism or demonstrate loss of bioelectrical activity. [3,4] The AAN Subcommittee examined two Class III studies in which somatosensory evoked potentials confirmed BD. [1] We used a test battery composed of multimodality evoked potentials (MEP) and electroretinography (ERG) to determine BD in a series of 72 patients. [4]
These tests are accessible in the intensive care unit (ICU) because they are portable machines. In addition, this test battery would permit the evaluation of several sensory pathways and the evaluation of brainstem and cerebral hemispheric functions. The period of observation is shortened and the examination of the primary brainstem lesions is also possible. [3,4]
Unfortunately, these techniques are not routinely used in ICU [3] because neuromonitoring systems need to be developed that would automatically record and process EEG and MEP. [5]
References
1. Wijdicks EF, Varelas PN, Gronseth GS et al. Evidence-based guideline update: determining brain death in adults: report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology 2010;74:1911-1918.
2. Practice parameters for determining brain death in adults (summary statement). The Quality Standards Subcommittee of the American Academy of Neurology. Neurology 1995;45:1012-1014.
3. Machado C. Brain death. A reappraisal. New York: Springer, 2007:1-223.
4. Machado-Curbelo C, Roman-Murga JM. Usefulness of multimodal evoked potentials and the electroretinogram in the early diagnosis of brain death. Rev Neurol 1998; 27:809-817.
5. Garcia-Larrea L, Bertrand O, Artru F et al. Brain-stem monitoring. II. Preterminal BAEP changes observed until brain death in deeply comatose patients. Electroencephalogr Clin Neurophysiol 1987; 68:446-457.
The Report of the AAN Subcommittee, [1] issued 15 years after the AAN hallmark publication on determining brain death (BD) in adults, [2] has touched on several key points.
Wijdicks et al. concluded that there are no published reports of recovery of neurologic function after BD diagnosis. This is an important clinical, social, and ethical finding related to diagnosing death on neurological grounds because irreversibility should be directly related to the determination of death. [3] Furthermore, the Subcommittee did not find consensus on a minimally acceptable observation period for assuring that neurologic functions have permanently stopped. [1] Ancillary tests may play an important role in shortening periods of observation, [3,4] but the panel of experts concluded that there are not enough data to show that newer tests confirm the termination of whole brain functioning. [1]
It is widely accepted that BD is a clinical diagnosis and that confirmatory laboratory tests are recommended when specific components of the clinical testing cannot be evaluated. [1,2,3] An ideal confirmatory test should be safe, accurate, and inexpensive. Ancillary tests either show absent cerebral blood flow and brain metabolism or demonstrate loss of bioelectrical activity. [3,4] The AAN Subcommittee examined two Class III studies in which somatosensory evoked potentials confirmed BD. [1] We used a test battery composed of multimodality evoked potentials (MEP) and electroretinography (ERG) to determine BD in a series of 72 patients. [4]
These tests are accessible in the intensive care unit (ICU) because they are portable machines. In addition, this test battery would permit the evaluation of several sensory pathways and the evaluation of brainstem and cerebral hemispheric functions. The period of observation is shortened and the examination of the primary brainstem lesions is also possible. [3,4]
Unfortunately, these techniques are not routinely used in ICU [3] because neuromonitoring systems need to be developed that would automatically record and process EEG and MEP. [5]
References
1. Wijdicks EF, Varelas PN, Gronseth GS et al. Evidence-based guideline update: determining brain death in adults: report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology 2010;74:1911-1918.
2. Practice parameters for determining brain death in adults (summary statement). The Quality Standards Subcommittee of the American Academy of Neurology. Neurology 1995;45:1012-1014.
3. Machado C. Brain death. A reappraisal. New York: Springer, 2007:1-223.
4. Machado-Curbelo C, Roman-Murga JM. Usefulness of multimodal evoked potentials and the electroretinogram in the early diagnosis of brain death. Rev Neurol 1998; 27:809-817.
5. Garcia-Larrea L, Bertrand O, Artru F et al. Brain-stem monitoring. II. Preterminal BAEP changes observed until brain death in deeply comatose patients. Electroencephalogr Clin Neurophysiol 1987; 68:446-457.
Disclosure: The authors report no disclosures.