An 84-year-old man with coronary artery disease and atrial fibrillation had a ST-segment elevation myocardial infarction that was complicated by a ventricular fibrillation cardiac arrest with 45 minutes of pulselessness. His initial management included evaluation in the cardiac catheterization lab with placement of a bare metal stent into the right coronary artery. He underwent 24 hours of cooling post cardiac arrest, but following this he has had limited neurologic recovery. Post arrest day 6, neurology is consulted.
Which of the following is MOST correct?
Correct Answer: D
The extent of brain injury is the key factor for prognostication after cardiac arrest. Clinical examination has been the staple of prognosis— absent pupillary reflexes, absent corneal reflexes, motor response of extensor posturing, or no movement. These findings have come into question in the era of therapeutic cooling. Most importantly, absence of corneal reflexes does not necessarily portent a poor prognosis. Although electroencephalography is for the detection of seizures, the prognostication value has not been validated. Somatosensory evoked potentials (SSEPs) have been studied and the largest study evaluated 407 patients with cardiac arrest, and of the patients with bilaterally absent cortical sensory responses, all had poor neurologic outcome. Pertinent biomarkers include neuron-specific enolase, which was studied in the same SSEP study and levels higher than 33 µg/L predicting a poor outcome, but this study was performed before cooling. Hypothermia can attenuate release of neuron-specific enolase, and there are reports of good outcome with levels greater than 100 µg/L. Although there are limitations to imaging, many use MRI with most useful imaging coming 3 to 5 days post arrest. Common findings are diffuse cortical diffusion restriction and changes in the basal ganglia.
Consideration of Evaluation for Prognosis after Cardiac Arrest:
CT, computed tomography; EEG, electroencephalography; MRI, magnetic resonance imaging; NSE, neurospecific enolase; SSEP, somatosensory evoked potential.
References:
A 54-year-old woman is admitted to the intensive care unit (ICU) with a subarachnoid hemorrhage due to a left middle cerebral artery aneurysm rupture. Early external ventricular drain was placed because of a poor neurological examination. Over the course of 7 days, there have been ongoing issues with refractory elevated intracranial pressure and poor neurologic examination, progressing to no cranial nerve responses. Her examination is as follows: pupils 5 mm and nonreactive, absent oculocephalic reflexes, absent corneal reflexes, absence of facial grimace, absent gag, and absent cough. The only evoked motor response is minimal triple flexion in the bilateral legs. An apnea test was completed and there were no spontaneous respirations with an increase in pCO2 20 mm Hg more than baseline.
Which of the following is MOST true?
The clinical findings necessary to confirm irreversible cessation of all functions of the entire brain, including the brain stem: coma, absence of brain stem reflexes, and apnea. The above patient does demonstrate all three of these criteria consistent with brain death. There are multiple reported reflexive movements that can be seen in patients with the diagnosis of brain death. Patient’s apnea test is consistent with brain death criteria, which is based on increase pCO2 >60 mm Hg or 20 mm Hg more than baseline. Single apnea test is required. No ancillary tests are required if the full clinical examination is consistent with brain death. In some institutions, two assessments of brain stem reflexes are required before declaring brain death.
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?
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.
A 58-year-old woman with amyotrophic lateral sclerosis (ALS) presents to the emergency department complaining of increased weakness and difficulty with feeding herself. Her daughter inquires if there are any interventions which have been proven to increase life expectancy in ALS patients.
Which of these is the MOST appropriate answer?
Correct Answer: B
Patients with ALS have progressive degeneration of both upper and lower motor neurons causing weakness, difficulty swallowing, and respiratory insufficiency. Although many different approaches have been tried to manage these patients, there are only a few which have shown benefits in increasing life expectancy. Noninvasive ventilation, specifically with optimized bilevel positive airway pressure (BiPAP) protocols, helps to avoid hypercarbia, secondary to diaphragm and respiratory muscle weakness. Other interventions include riluzole, a medication that is thought to work on the neuronal level and shown to increase survival by few months and delay the onset of tracheostomy and ventilator dependence in selected ALS patients. Amantadine is used to promote alertness in patients with neurological injury; however, it has not been shown to be of benefit in ALS. Although patients with ALS often get gastrostomy tubes for safer feeding, colostomy and indwelling nasogastric tubes have not been shown to increase life expectancy. Prophylactic antibiotics are not recommended for ALS as there is no immune suppression.
A 74-year-old man with hypertension, coronary artery disease, and Parkinson disease is admitted to the ICU for management of pneumonia. He is intubated and started on broad-spectrum antibiotics. Six days after admission, he is found to have worsening fever, rigidity, and is no longer following commands.
What is the MOST likely etiology for his condition?
NMS is an uncommon but often life-threatening illness characterized by fever, rigidity, obtundation, and autonomic instability. Elevated serum creatine kinase levels can also be seen. Though the pathogenesis is not well understood, it is thought to be related to a sudden decrease in dopaminergic signaling, which may be caused by stopping dopaminergic drugs such as levodopa as well as the use of neuroleptics. It is commonly confused with serotonin syndrome, which is a much more rapidly developing condition caused by excess serotonin signaling. This patient is unlikely to have status epilepticus or stroke, as that is unlikely to cause worsening fevers with rigidity. Infective endocarditis would present with fevers and potentially with neurological deficits if it leads to septic emboli to the brain; however, rigidity, obtundation, and autonomic instability are not typical for infective endocarditis.
Click to expand