Electroencephalographic patterns of lithium poisoning: a study of the effect/concentration relationships in the rat

Iatrogenic encephalopathies are not so rare in psychiatry: A retrospective study about 5217 EEG examinations

OBJECTIVES

Encephalopathy is a severe pathological process induced by multiple factors, which is typically associated with electroencephalogram (EEG) abnormalities. Early diagnosis, management, and treatment improve the patient's prognosis. Psychotropic treatments are a risk for drug-induced encephalopathies. In this study, the prevalence of encephalopathies in a psychiatric hospital has been studied for 5 years (2012 to 2016) using 5217 EEG records.

METHODS

EEGs were performed i) systematically on patient admission, ii) in response to inexplicable modifications of consciousness or behavior, or when metabolic anomalies occurred, and iii) to perform therapeutic monitoring in outpatient consultations. When encephalopathy was suspected, the clinical data (age, sex and concomitant treatment) and biological data (plasma levels of medications) were collected.

RESULTS

Encephalopathy was suspected in 189 patients. Following EEG examination, and monitoring of clinical course, encephalopathy was subsequently determined to be highly probable for 52 patients, (giving a prevalence of 1% per year), and low suspicion of encephalopathy in the other 137 patients. The suspicion of encephalopathy was made on both clinical (n=28) and non-clinical (n=24) signs. Involved drugs were mainly valproic acid (n=14), lithium (n=11) and clozapine (n=11) in the highly probable encephalopathy group.

CONCLUSIONS

Our study demonstrates the importance of EEG in the diagnosis and monitoring of encephalopathies in a psychiatric hospital. Clinical symptoms of encephalopathies are polymorphic and sometimes atypical. This diagnosis is underestimated in a context where behavior or consciousness disorders are generally not attributed to psychotropic drugs used in psychiatry.

Does lithium poisoning induce brain injuries?-A histopathological rat study

Due to a narrow therapeutic index, prolonged lithium treatment and overdose may result in neurotoxicity. Neurotoxicity is deemed reversible with lithium clearance. However, echoing the report of syndrome of irreversible lithium-effectuated neurotoxicity (SILENT) in rare severe poisonings, lithium-induced histopathological brain injuries including extensive neuronal vacuolization, spongiosis and ageing-like neurodegenerative changes were described in the rat following acute toxic and pharmacological exposure. We aimed to investigate the histopathological consequences of lithium exposure in rat models mimicking prolonged treatment and all three patterns of acute, acute-on-chronic and chronic poisonings observed in humans. We performed histopathology and immunostaining-based analyses using optic microscopy of brains obtained from male Sprague-Dawley rats randomly assigned to lithium or saline (controls) and treated according to the therapeutic or to the three poisoning models. No lesion was observed in any brain structure in any of the models. Neuron and astrocyte counts did not differ significantly between lithium-treated rats and controls. Our findings support that lithium-induced neurotoxicity is reversible and brain injury not a common feature of toxicity.

Factors associated with prolonged intensive care stay among self-poisoned patients

CONTEXT

Since recovery or death is generally observed within a few days after intensive care unit (ICU) admission of self-poisoned patients in the developed countries, reasons for the prolonged ICU stay are of interest as they have been poorly investigated. We aimed to identify the characteristics, risk factors, outcome, and predictors of death in self-poisoned patients requiring prolonged ICU management.

METHODS

We conducted an eight-year single-center cohort study including all self-poisoned patients who stayed at least seven days in the ICU. Patients admitted with drug adverse events and chronic overdoses were excluded. Using multivariate analyses, we investigated risk factors for prolonged ICU stay in comparison with a group of similar size of self-poisoned patients with <7day-ICU stay and studied risk factors for death.

RESULTS

Among 2,963 poisoned patients admitted in the ICU during the study period, the number who stayed beyond seven days was small (398/2,963, 13.1%), including 239 self-poisoned patients (125 F/114M; age, 51 years [38-65] (median [25th-75th percentiles]); SAPSII, 56 [43-69]). Involved toxicants included psychotropic drugs (59%), cardiotoxicants (31%), opioids (15%) and street drugs (13%). When compared with patients who stayed <7days in the ICU, acute kidney injury (odds ratio (OR), 3.15; 95% confidence interval (1.36-7.39); p = .008), multiorgan failure (OR, 8.06 (3.43-19.9); p < .001), aspiration pneumonia (OR, 8.48 (4.28-17.3); p < .001), and delayed awakening related to the persistent toxicant effects, hypoxic encephalopathy and/or oversedation (OR, 8.64 (2.58-40.7); p = .002) were independently associated with prolonged ICU stay. In-hospital mortality rate was 9%. Cardiac arrest occurring in the prehospital setting and during the first hours of ICU management (OR, 27.31 (8.99-158.76); p < .001) and delayed awakening (OR, 14.94 (6.27-117.44); p < .001) were independently associated with increased risk of death, whereas exposure to psychotropic drugs (OR, 0.08 (0.02-0.36); p = .002) was independently associated with reduced risk of death.

CONCLUSION

Self-poisoned patients with prolonged ICU stay of ≥7days are characterized by concerning high rates of morbidities and poisoning-attributed complications. Acute kidney injury, multiorgan failure, aspiration pneumonia, and delayed awakening are associated with ICU stay prolongation. Cardiac arrest occurrence and delayed awakening are predictive of death. Further studies should focus on the role of early goal-directed therapy and patient-targeted sedation in reducing ICU length of stay among self-poisoned patients.

[Neurological complications attributable to lithium: An update]

Lithium intoxication may induce neurological complications, initially characterised by a conscience alteration and an encephalopathy clinical picture with a risk of death or sever long-term consequences. With an occurrence sometimes atypical and possibly without initial hyperlitemia, the diagnosis delay of these complications might be important. Moreover, no specific guidelines focused on these complications are available. The aim of this article is to propose an update on diagnosis and treatment of neurological complications attributable to lithium, as encephalopathy.

Assessment of Extracorporeal Treatments in Poisoning criteria for the decision of extracorporeal toxin removal in lithium poisoning

AIMS

To assess recommendations provided by the EXtracorporeal TReatments In Poisoning (EXTRIP) workgroup on extracorporeal toxin removal (ECTR) in lithium poisoning.

METHODS

Retrospective assessment in a 128 lithium-poisoned patient cohort previously used to identify ECTR initiation criteria that could improve outcome (Paris criteria). ECTR requirement using EXTRIP criteria was compared to the actual practice or if Paris criteria were used. The potential impact on outcome if these different criteria were used was investigated.

RESULTS

Using the recommended (Rec-EXTRIP) or recommended + suggested (All-EXTRIP) EXTRIP criteria, ECTR would have been indicated in more patients than was actually done (P < .001), or if Paris criteria were used (P < .01). The non-actually ECTR-treated patients fulfilling Rec-EXTRIP or All-EXTRIP criteria had shorter intensive care unit stay (P < .05) and no significant increase in fatalities and neurological impairment on discharge in comparison to the actually ECTR-treated patients. ECTR requirements using EXTRIP vs Paris criteria were not concordant (P < .001). In the non-actually ECTR-treated patients, 31/106 and 55/106 patients fulfilled Rec-EXTRIP or All-EXTRIP but not Paris criteria, respectively. Those patients had longer stay (P < .01) but no worse neurological impairment on discharge than the patients not fulfilling any of these criteria (50/106 and 26/106, respectively). In the non-actually ECTR-treated patients, 7/106 fulfilled Paris but not Rec-EXTRIP criteria. Those patients had longer stay (P < .05) and worse neurological impairment on discharge (P < .01) than the 50/106 patients not fulfilling any of these criteria.

CONCLUSION

In this cohort of lithium poisonings, EXTRIP criteria may lead to more ECTR than actually performed or if the Paris criteria were used, with no demonstrated improvement in outcome.

Baclofen-induced encephalopathy in overdose - Modeling of the electroencephalographic effect/concentration relationships and contribution of tolerance in the rat

Baclofen, a γ-amino-butyric acid type-B receptor agonist with exponentially increased use at high-dose to facilitate abstinence in chronic alcoholics, is responsible for increasing poisonings. Baclofen overdose may induce severe encephalopathy and electroencephalographic (EEG) abnormalities. Whether prior prolonged baclofen treatment may influence the severity of baclofen-induced encephalopathy in overdose has not been established. We designed a rat study to characterize baclofen-induced encephalopathy, correlate its severity with plasma concentrations and investigate the contribution of tolerance. Baclofen-induced encephalopathy was assessed using continuous EEG and scored based on a ten-grade scale. Following the administration by gavage of 116 mg/kg baclofen, EEG rapidly and steadily impaired resulting in the successive onset of deepening sleep followed by generalized periodic epileptiform discharges and burst-suppressions. Thereafter, encephalopathy progressively recovered following similar phases in reverse. Periodic triphasic sharp waves, non-convulsive status epilepticus and even isoelectric signals were observed at the most critical stages. Prior repeated baclofen administration resulted in reduced severity (peak: grade 7 versus 9; peak effect length: 382 ± 40 versus 123 ± 14 min, P = 0.008) and duration of encephalopathy (18 versus > 24 h, P = 0.0007), supporting the acquisition of tolerance. The relationship between encephalopathy severity and plasma baclofen concentrations fitted a sigmoidal E_max model with an anticlockwise hysteresis loop suggesting a hypothetical biophase site of action. The baclofen concentration producing a response equivalent to 50% of E_max was significantly reduced (8947 μg/L, ±11.3% versus 12,728 μg/L, ±24.0% [mean, coefficient of variation], P = 0.03) with prior prolonged baclofen administration. In conclusion, baclofen overdose induces early-onset and prolonged marked encephalopathy that is significantly attenuated by prior repeated baclofen treatment. Our findings suggest a possible role for the blood-brain barrier in the development of tolerance; however, its definitive involvement remains to be demonstrated.