Abstracts

Rationale: Lithium is one of the commonly prescribed medications for bipolar disorder and other psychiatric illnesses. Lithium toxicity has been known to cause systemic effects (Kaplan et al. Epilepsia. 2006;47(12):2071-2074). Cases have been reported in which lithium toxicity has caused triphasic waves, rhythmic anterior delta activity and periodic sharp waves (Kaplan et al. Epilepsia. 2006;47(12):2071-2074); Primavera A J Neurol Neurosurg Psychiatry. 1989;52(3):423; Smith SJ. J Neurol Neurosurg Psychiatry. 1988;51(1):120-123). We present a case where the EEG (ElectroEncephaloGram) pattern in a patient with lithium toxicity showed high amplitude and polymorphic psuedo-periodic 2-3 Hz epileptiform discharges which disappeared after elimination of toxic levels of lithium. Methods: Patient's chart was reviewed in the electronic medical database of the Jewish Hospital, Louisville (Kentucky). Literature review was conducted in Pub Med and Ovid database using the terms "Lithium toxicity" and "EEG". Results: Case: A 41 year old Caucasian male with history of bipolar disorder and schizophrenia presented with acute confusion. Clinically, he was tremulous, ill appearing, followed simple commands and had rhythmic asynchronous jerking of all four extremities. It was noted that he had acute renal failure from post-obstructive cause (Creatinine 2.96) and lithium toxicity (1.9 mmol/l). Non contrast brain MRI did not show any intracranial abnormality. A possibility of lithium induced seizures was considered. A continuous EEG revealed the background to be polymorphic, poorly sustained high amplitude 45 Hz activity seen over the posterior region. The most significant feature of the record was the occurrence of high amplitude polymorphic and pseudo-periodic 2-3 Hz generalized epileptiform discharges, which did not respond to intravenous administration of lorazepam. Lacosamide was started for seizure protection. Patient was hemodialyzed and lithium levels were normalized. Gradually, he showed improved mentation which correlated with reduction in the lithium levels in blood and disappearance of pseudo-periodic generalized epileptiform discharges. Patient was discharged to the rehabilitation center with return to the previous baseline functioning. Conclusions: In a patient with acute encephalopathy and an EEG pattern consistent with generalized pseudo-periodic epileptiform discharges the differential diagnosis is broad. This specific pattern is seen in peri-ictal states, or as an ictal pattern in meningo-encephalitis, with degenerative brain disorders or with lithium and tricyclic intoxication. Of all, the latter carries the best prognosis and is important to be recognized and addressed to prevent further end organ damage. This case also highlights the importance of EEG monitoring in patients with lithium toxicity and adds to the various waveform patters described in the literature. Funding: None