Differential Diagnosis for Bipleds in EEG in a Patient with Fever and Altered Sensorium

Single Most Likely Diagnosis

• Herpes Simplex Encephalitis (HSE): This is a common cause of altered sensorium and fever, and bipleds (bilateral periodic lateralized epileptiform discharges) in EEG are characteristic of HSE, especially in the context of fever and altered mental status.

Other Likely Diagnoses

• Seizures due to other causes: Other conditions such as meningitis, encephalitis due to other viruses, or bacterial infections can also cause seizures and altered sensorium, leading to bipleds in EEG.
• CNS Infections: Infections like cerebral malaria, toxoplasmosis, or other parasitic infections can present with fever, altered sensorium, and abnormal EEG findings.
• Autoimmune Encephalitis: Conditions like NMDA receptor encephalitis can cause altered mental status, seizures, and characteristic EEG abnormalities.

Do Not Miss Diagnoses

• Subarachnoid Hemorrhage: Although less likely to cause bipleds, a subarachnoid hemorrhage can present with sudden onset of fever (due to blood in the subarachnoid space irritating the meninges), altered sensorium, and seizures. Missing this diagnosis could be catastrophic.
• Brain Abscess: A brain abscess can cause focal neurological signs, fever, altered sensorium, and seizures. The EEG might show focal abnormalities, including bipleds, especially if the abscess is causing focal irritation of the cortex.
• Status Epilepticus: Prolonged or recurrent seizures without full recovery between them can lead to altered sensorium and bipleds on EEG. Recognizing and treating status epilepticus promptly is crucial.

Rare Diagnoses

• Creutzfeldt-Jakob Disease: This prion disease can cause rapid neurological deterioration, including altered sensorium, myoclonus, and characteristic EEG changes (periodic sharp wave complexes), although bipleds are not the most common finding.
• Hashimoto's Encephalopathy: A rare condition associated with autoimmune thyroiditis, characterized by altered sensorium, seizures, and various EEG abnormalities, including bipleds, although it is less commonly associated with fever.
• Mitochondrial Encephalomyopathies: Certain mitochondrial disorders can cause encephalomyopathy with seizures, altered sensorium, and abnormal EEG findings, including bipleds, especially in the context of a systemic illness like fever.