J Neurocrit Care.  2024 Dec;17(2):67-74. 10.18700/jnc.240020.

Unreactive alpha or alpha-theta coma electroencephalogram patterns with favorable neurologic outcomes: a report of three cases and literature review

• Amoranto MJS
• Fernandez MLL

• KMID: 2563024
• DOI: http://doi.org/10.18700/jnc.240020

Abstract

Background
Alpha coma and its variants theta coma and alpha-theta coma (ATC) are clinical coma states characterized by electroencephalographic patterns resembling those of wakefulness. The complete (unreactive) form of these states is invariably associated with poor outcomes among post-anoxic comatose patients.
Case Report
Herein, we present three adult comatose patients (aged 21, 45, and 51 years) with unreactive ATC patterns, who exhibited remarkable neurological improvement. Two patients experienced post-cardiopulmonary arrest (due to electrocution and viral myocarditis, respectively), while the third had severe septic encephalopathy. Electroencephalograms (EEGs) taken at least 24 hours after coma onset revealed unreactive ATC patterns. All patients survived, achieving significant neurological improvement. Remarkably, in one patient, the only symptom was minor incoordination during ambulation upon discharge.
Conclusion
These cases challenge the grave prognosis associated with this EEG pattern, particularly in post-anoxic comatose patients. Factors such as younger age, presence of shockable rhythms, and cause of arrest may have contributed to these favorable outcomes.

Keyword

Coma; Electroencephalography; Prognosis

Figure

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  Fig. 1. Electroencephalogram (EEG) of case 1, a 21-year-old male who developed fatal arrhythmia following electrocution. The EEG was performed 24 hours off sedation with a Glasgow Coma Scale of 3. An anteriorly predominant 8–9 Hz alpha and occasional 6–7 Hz theta rhythm can be observed. There was no reactivity to external stimuli. The bipolar montage is shown in this epoch with a sensitivity of 70 µV/cm.

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  Fig. 2. Electroencephalogram (EEG) of case 2, a 45-year-old female who developed a fatal arrhythmia due to viral myocarditis. A diffuse and continuous background activity of medium voltage 8–9 Hz alpha with 6–7 Hz theta rhythm with absence of antero-posterior gradient can be observed. There was no reactivity to external stimuli. The EEG was performed 24 hours off sedation with a Glasgow Coma Scale of 3. The bipolar montage is shown in this epoch with a sensitivity of 70 µV/cm.

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  Fig. 3. Electroencephalogram (EEG) of case 3, a 51-year-old female who was comatose due to severe septic shock. The EEG was performed without sedation with a Glasgow Coma Scale of 3. A diffuse and continuous 8–9 Hz alpha admixed with occasional 6–7 Hz theta activity with the absence of antero-posterior gradient can be observed. There was no reactivity to external stimuli. The bipolar montage is presented in this epoch, with a sensitivity of 70 µV/cm.

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