Evidence of Raised Intracranial Pressure on ECG – A Resident Clinical Pearl

Robert Dunfield, PGY2 FMEM program,  Dalhousie University Saint John

Reviewed & Edited by Dr. Mandy Peach

Case

A 44 year old male presents to your trauma bay with progressive confusion and altered level of consciousness for the past three days. Collateral history reveals possible recent recreational methamphetamine use. No specific abnormal neurological features or findings on history and physical. A full workup is performed and investigations reveal a left frontal intracerebral hematoma with the following CT head (Figure 1) and ECG (Figure 2):

 

1. What clinical (history and physical) features suggest an elevated intracranial pressure? [4, 5]

On history, suspect an elevated intracranial pressure with:

• headaches
• vomiting
• altered mental status (ranging and alternating from drowsiness to coma)
• visual changes (blurred, diplopia, photophobia)
• history of malignancy, trauma

On examination, suspect an elevated intracranial pressure with:

• Cushing triad: hypertension, bradycardia and irregular respiration. This is a sign of impending brain herniation
• pupils unequal, unreactive
• disc edema
• optic atrophy
• bulging anterior fontanelle (in infants)
• evidence of trauma

 

2. What features on ECG are in keeping with an elevated intracranial pressure? [1, 2, 6]

Elevations in ICP or brain injuries are commonly associated with the following ECG changes:

• “Cerebral” T waves: widespread giant T wave inversion
• Flat T waves
• ST elevation/depression
• QTc prolongation
• Sinus bradycardia (if seen assess for other features of Cushing triad)
• Increased U wave amplitude
• Osborn (J) waves
• Other dysrhythmias: sinus tachycardia, junctional rhythms, premature ventricular contractions, atrial fibrillation, AV blocks

ECG changes are common with elevated ICP and intracranial hemorrhage. Approximately 56% of patients with intracranial hemorrhage have associated ECG changes.

Most importantly, recognize that these ECG changes can mimic acute coronary syndromes. This is potentially dangerous as a misdiagnosis of STEMI in a patient with an intracranial bleed could lead to unnecessary thrombolytics or PCI. For this reason, keep an elevated ICP in mind when identifying the above ECG changes.

 

3. What is a cerebral T wave? [1, 5]

Cerebral T waves are deep, symmetric, inverted T-waves seen on an ECG in patients with large intracranial bleeds. They are typically widespread

 

4. What other causes, other than elevated ICP, result in inverted T waves and should be kept on your differential? [2]

When analyzing an ECG it is important to recognize other causes of inverted T waves. The differential for inverted T waves includes:

• Myocardial ischemia and infarction
• Bundle branch block
• Ventricular hypertrophy
• Pulmonary embolism
• Hypertrophic cardiomyopathy

 

5. What is the pathophysiological cause for the ECG changes associated with an elevated ICP? [3, 4]

The full pathophysiology of ECG changes related to an elevated ICP is not fully understood.

ECG changes related to an elevation in ICP are thought to be related to neurogenic cardiac injury. This is mostly due to a surge of systemic catecholamines as a result of significant sympathetic activation from the central neuroendocrine axis and activation of the adrenal glands. Additionally, any injury to the hypothalamus or insula can cause dysfunction of the autonomic nervous system and a systemic inflammatory response.

Systemic catecholamine levels can be elevated for as long as 10 days. This prolonged exposure to catecholamines as well as the systemic inflammatory response can result in cardiac injury and dysfunction.

It is also possible for the heart to suffer from “neurogenic stunned myocardium syndrome” (NSM). This is reversible myocyte damage that results in ECG changes, in addition to other cardiac effects, due an excessive release of norepinephrine. The amount of cardiac damage caused by NSM correlates with the degree of brain injury. NSM can develop within four hours of brain injury. Other causes of NSM include pheochromocytoma, near drowning, and severe emotional experiences.

 

6. What are the most common intracranial findings associated with ECG changes related to an increased ICP? [1, 3]

The most common causes of ECG changes related to an elevation in ICP involve massive intracranial hemorrhage, including subarachnoid hemorrhage (49 to 100% of cases)³ and intraparenchymal hemorrhage (57% of cases)¹.

Less commonly, ECG changes are associated with massive ischemic stroke causing cerebral edema, traumatic brain injury, or less commonly cerebral metastases.

 

7. How long do ECG changes last with brain injuries related to elevated ICP, and what are the clinical implications for a finding of prolonged ECG changes? [3]

Normally, as brain injuries and elevated ICP resolve, so will ECG changes. Most ECG changes will resolve within three days but have been reported to last up to eight weeks from the etiology of the elevated ICP.

Some reports have shown that prolonged ECG changes are associated with an increased risk for ischemic neurological deficit, poor outcome, and death following a subarachnoid hemorrhage. Specifically, persistent prolonged QTc is associated with poor clinical outcomes and death, whereas recovery of QTc is associated with good clinical outcomes.

 

SUMMARY & KEY POINTS:

• Be aware of Cushing triad on clinical assessment of patients with potential elevation in ICP (sinus bradycardia, hypertension, and abnormal respiratory pattern).

• There are multiple nonspecific ECG changes associated with an elevation in ICP, including: cerebral T waves, ST elevation/depression, sinus bradycardia, increased U wave amplitude, J waves, and other dysrhythmias.

• The exact pathophysiology for the cause of elevated ICP causing ECG changes is complicated and not fully understood. It is thought to mostly be due to excess catecholamine and norepinephrine exposure, along with a dysregulated inflammatory reaction.

• Subarachnoid hemorrhage and intraparenchymal hemorrhage are the most common causes of ECG changes associated with elevated ICP.

• Be aware that ECG changes related to elevated ICP can mimic acute coronary syndrome, so keep intracranial pathologies on your differential when the above ECG changes are found.

 

Of note, the patient described in the clinical scenario was admitted to neurosurgery and observed for nearly two weeks. He recovered without operative management.

 

REFERENCES:

1. Cadogan M. Raised Intracranial Pressure. Life in the Fast Lane 2020; Last updated: Nov. 3, 2020, Accessed: December 28, 2020. Available from: https://litfl.com/raised-intracranial-pressure-ecg-library/

2. Gregory T and Smith M. Cardiovascular complications of brain injury, Continuing Education in Anaesthesia Critical Care & Pain. 2012; 12:2, 67–71. Available from: https://doi.org/10.1093/bjaceaccp/mkr058

3. Levis JT. ECG Diagnosis: Deep T Wave Inversions Associated with Intracranial Hemorrhage. Perm J. 2017; 21:16, 049. doi:10.7812/TPP/16-049

4. Pinto VL, Tadi P, Adeyinka A. Increased Intracranial Pressure. [Updated 2020 Jul 20]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan. Available from: https://www.ncbi.nlm.nih.gov/books/NBK482119/

5. Tannenbaum L. ECG Pointers: Intracranial Hemorrhage. emDocs.net: Electrocardiography. 2018; Last updated: November 14, 2018. Accessed: December 29, 2020. Available from: http://www.emdocs.net/ecg-pointers-intracranial-hemorrhage/

6. Yogendranathan N, Herath HM, Pahalagamage SP, Kulatunga A. Electrocardiographic changes mimicking acute coronary syndrome in a large intracranial tumour: A diagnostic dilemma. BMC Cardiovasc Disord. 2017;17(1):91. Published 2017 Apr 4. doi:10.1186/s12872-017-0525-2