A Case of Lithium Encephalopathy with Therapeutic Lithium Levels: The Diagnostic Role of EEG

Abstract

Introduction. Lithium is considered a first-line therapy for both the acute phase and the maintenance of bipolar disorder. Many studies highlighted its neuroprotective and neuroplastic capacity suggesting a potential usefulness in the treatment of neurodegenerative diseases. Despite the undeniable efficacy, lithium clearly presents several adverse effects including neurotoxicity, also known as lithium encephalopathy, regarding both neurological, psychiatric, and cognitive side effects. In this case, adverse reactions are not always related to its serum levels, possibly appearing within the therapeutic range. Case Presentation. We analyzed the case of a bipolar patient who has been uncontinuosly treated with lithium salts since the onset of the psychopathological picture. Over the years, the average values of lithemia always remained around 0.60-0.70 mEq/L, but in 2019, the patient begun to manifest distal tremors and in the mandibular district accompanied, in the following months, by psychomotor slowdown, generalized tremors, reduced alertness, spatiotemporal disorientation, and aphasia. While alterations referable to neurodegenerative diseases were excluded, EEG maintained rhythm alteration 1 year after the probable intoxication. Discussion. This case confirms the central role of EEG for lithium neurotoxicity, while its dosages are in therapeutic range, being plasma levels are not always indicative of liquoral and neuronal lithium’s levels. We highlight the importance of an early diagnosis of lithium encephalopathy proposing EEG as an indispensable tool for assessing lithium neurotoxicity both in acute and chronic intoxication.

New Onset Encephalopathy with Toxic Triphasic Waves

“…7,8 The main obstacle in front of the clinician while considering lithium toxicity is the fact that there need not always be a direct correlation between the blood levels of lithium and the toxic manifestations. 2 In a study comprising of a retrospective audit of prescriptions for lithium monitoring, 3% of 4,359 prescriptions resulted in toxicity and out of them 60% were in therapeutic range. 3 Rather than plasma lithium levels, red blood cell (RBC) lithium levels correlate better with toxicity and if available an RBC-plasma ratio of lithium would have more utility.…”

“…Acyclovir and steroids were stopped and a decision to dialyze her was made considering the possibility of lithium toxicity with normal lithium levels as described in literature. 2 3 Her sensorium improved to E3V4 M6 post the first cycle of hemodialysis; hence, she was continued on the same for a total of three cycles till her GCS was E4V5M6 and her EEG abnormalities disappeared ( Fig. 3 ).…”