A 28-year-old previously healthy male is admitted to the ICU with altered mental status and hypoxic respiratory failure following a traumatic brain injury. There is limited history of his actual injury, but the night before his admission, he was intoxicated with friends when he got in an altercation and was hit on left side of his head and did have a brief loss of consciousness. His friends took him home, and at that time he was confused, complaining of a headache but was still talking and walking. He went to bed and he was checked on 10 hours later and was unresponsive. Emergency medical services (EMS) was called, and on arrival he was unresponsive with fixed, dilated pupils and no movements to painful stimulation and was intubated without sedation or paralytic.
A head computed tomography (CT) was completed on arrival to the emergency department and demonstrated a 1.4 cm left-sided holocephalic subdural with 1.2 cm of left-to-right midline shift including uncal herniation and midbrain compression. His examination demonstrates lack of brain stem responses, no spontaneous breathing, and no movement to painful stimulation. An apnea test was attempted to evaluate for brain death but was unable to be completed because of hemodynamic instability. A whole brain positron emission tomography (PET) scan was completed and showed no activity in the brain stem and cortex.
What is the MOST correct statement regarding the patient?
A. The patient does not meet brain death criteria because the ancillary study does not support the diagnosis of brain deathCorrect Answer: D
The diagnosis of brain death is primarily clinical. However, ancillary tests are performed when the clinical criteria cannot be applied reliably. Irreversible coma that is explained by neuroimaging, lack of other etiology that could explain brain death (CNS-depressant drugs, paralytics, electrolyte abnormalities, profound hypothermia, hypotension), and clinical examination are all criteria required to make the diagnosis. The diagnosis of brain death can be challenging in cases when there is unreliable clinical examination or it is not possible to perform apnea test, for which ancillary tests should be performed. In this patient’s case, apnea test was not completed because of hemodynamic instability for which ancillary test is required. There are several ancillary tests including EEG, cerebral angiography, nuclear scan, transcranial Dopplers, CT angiography, and magnetic resonance angiography (MRA). The ideal ancillary test is one with no confounding effects from sedatives or metabolic disturbances and preferable with no false positives. Evaluating cerebral perfusion with fourvessel cerebral angiography and nuclear scan of blood flow is commonly utilized. However, CT angiography and MRA may soon be found to be equally suitable.
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