You are working a resuscitation shift when EMS calls in a young comatose male, ETA 3min. Tryptophan! His mother probably gave him too many leftovers, he tried to decline but she insisted because Go-gurt does not make for a balanced diet. Case closed.
[spacer height=”20px”]Then EMS arrives, tells you they tried narcan with no response and intubated him in the field for a GCS of 5. His EKG is as seen above. You confirm his ET tube placement, put him on the monitor and send him straight for a CT head. CT shows a massive subarachnoid hemorrhage.
[spacer height=”20px”]So what about that EKG made you beeline for CT?
[spacer height=”20px”]EKG changes accompanying intracranial insults occur in situations when intracranial pressure (ICP) is elevated. Most commonly these are cases of massive intracranial hemorrhage – subarachnoid or intraparenchymal – or massive ischemic stroke with cerebral edema, traumatic brain injury, or cerebral metastases.
[spacer height=”20px”]The most characteristic EKG changes seen are:
1. Widespread giant T-wave inversions – referred to as “cerebral T-waves”
2. QT prolongation – QT longer than half of R-R
3. Bradycardia – Cushing reflex of bradycardia and hypertension indicative of impending brainstem herniation
[spacer height=”20px”]Additional changes include:
1. Diffuse ST segment elevation or depression similar to pericarditis pattern
2. U waves
3. Rhythm changes – a fib, junctional rhythms, PVCs, sinus tach
[spacer height=”20px”]Several animal models point to a massive sympathetic surge as the cause of these ischemic EKG changes. The idea is that edema and blood act as irritants to the hypothalamic nuclei of the brain, resulting in the release of norephinephrine from the adrenal medulla, causing hypertension and cardiac effects. Studies have shown signs of subendocardial ischemia, vasospasm and abnormal repolarization causing ventricular arrhythmias from norepinephrine surges. These cardiac changes are thought to be reversible as many post-mortem cases have demonstrated normal hearts. Additionally, as ICP is reduced, the EKG changes tend to resolve.
[spacer height=”20px”] Image from http://lifeinthefastlane.com/ecg-library/raised-intracranial-pressure/