68 y/o female with PMH of diabetes, hyperlipidemia, and HTN was brought into the ED by EMS after being found down at home. Per EMS, patient was home when she collapsed and unclear as to whether there was shaking activity or decreased muscle tone. Noted to have recently been started on oxcarbazepine (Trileptal) for unknown reasons. History limited by patient’s mental status (confused) complicated by language barrier. 

Physical Exam - no pertinent PE findings documented

BP 220/107  | Pulse 97  | Resp 16 | SpO2 98%

Neuro: Alert. Moves all extremities

Differential Diagnosis 

• CVA / ICH
• ACS, arrhythmogenic 
• Seizure
• Toxic, metabolic, endocrine

Initial Orders

• Monitor, PIV access, continuous ECG monitoring
• Accu check
• Labs: CBC, BMP, hsTrop
• EKG
• CT head non-contrast

Further history from son: found her unconscious on the floor with her arms and legs tense and her tongue pushed back into her mouth

• He raised the practitioner’s suspicion for seizure. Believed that patient’s fall and confusion likely secondary to seizure and post-ictal state. On limited history, also believed oxcarbazepine was prescribed for seizures. 

Pertinent Results

CT non-contrast head: acute subdural hematoma

BMP: Na 118

Plan

• Started on cardene gtt for BP management
• 1g Keppra load
• Hypertonic saline bolus
• Admitted to trauma ICU with neurosurg and nephrology consulted 

Follow-up:Further history revealed that she was started on oxcarbazepine for mood disorder and had no history of seizures. Oxcarbazepine was stopped in setting of hyponatremia. Required intubation for depressed mental status and eventually discharged with trach. Also required continuous, low rate, hypertonic saline infusion to achieve normonatremia. 

Take Home Points / Conclusions

• Seizure in elderly with no prior history → must ask WHY?
• In this case, seizure likely due to hyponatremia in setting of recently being started on oxcarbazepine 
• Always consider medication side effects / polypharmacy, especially in the elderly!
• Oxcarbazepine: hyponatremia in 1-10% 
• Do not assume reasons for certain meds - was incorrectly assumed that oxcarbazepine was prescribed for seizures 
• Keep the differential broad and do not anchor!