Trastornos neurocognitivos en la hiperamonemia inducida por ácido valproico / Neurocognitive disorders of Valpoic Acid-Induced Hyperammonemia

El objetivo de este trabajo se orienta a dar cuenta de los trastornos neurocognitivos debidos al uso del ácido valproico, por su capacidad de inducir hiperamonemias, las que en muy pocos casos pueden implicar cuadros clínicos severos, y en otros, los más comunes, ocasionar síntomas cognitivos leves pero que pueden revestir importancia en la vida cotidiana de un paciente. Resulta necesario diferenciarlos de aquellos síntomas cognitivos que son una consecuencia de la enfermedad bipolar en sí misma, cuando dicho fármaco se lo usa como estabilizador del ánimo

The aim of this paper is oriented to account for neurocognitive disorders due to use of valproic acid, their ability to induce hyperammonemias, which in rare cases can lead to severe clinical symptoms, and in others, the most common, cause mild cognitive symptoms but of potential importance in the daily life of a patient. It is necessary to differentiate them from those cognitive symptoms wich are a consequence of bipolar disorder itself, when the drug is used as a mood stabilizer

Encefalopatía inducida por ácido valproico: serie de siete casos / Valproic acid-induced encephalopathy: series of seven cases

Introducción: La encefalopatía inducida por ácido valproico (AV) es una complicación infrecuente caracterizada por disminución del nivel de conciencia, déficits neurológicos focales, enlentecimiento cognitivo, vómitos, somnolencia y letargia, con o sin hiperamonemia. El electroencefalograma (EEG) muestra enlentecimiento difuso. Los hallazgos EEG, las manifestaciones clínicas y la hiperamonemia tienden a normalizarse con la suspensión del AV. Pacientes y Métodos: Se presenta una serie de 7 pacientes que desarrollaron encefalopatía por AV, en el Servicio de Neurología del Hospital del Salvador, entre 2003 y 2010. Se detallan dos casos clínicos ilustrativos. Resultados: La serie está compuesta por 5 mujeres y 2 hombres. Cinco pacientes desarrollaron hiperamonemia (amonemia sobre 50 ug/dl). El promedio de edad fue de 55 años (37 a 82 años). Las dosis de AV fueron de 375 a 2.000 mg (promedio = 903). La latencia entre el inicio o ajuste significativo del AVfue de 3 días hasta 16 años y un mes. Todos los pacientes presentaban daño orgánico cerebral. La politerapia con fenobarbital, fenitoína y carbamazepina fue significativa. El patrón de EEG más frecuente fue el enlentecimiento difuso. Una paciente de 82 años desarrolló actividad pseudoperiódica sugerente de un status epilepticus no convulsivo. En todos los pacientes hubo normalización clínica, de laboratorio y del EEG con la suspensión del AV. Conclusiones: La encefalopatía inducida por ácido valproico es una reacción adversa reversible pero potencialmente fatal que requiere un alto índice de sospecha. El daño orgánico cerebral y la politerapia parecen ser importantes factores de riesgo para su producción.

Introduction: Valproic acid (VA) induced encephalopathy is an unusual complication characterized by decreasing level of consciousness, focal neurological deficits, cognitive slowing, vomiting, drowsiness, and lethargy, with or without hyperammonemia. Electroencephalography (EEG) is characterized by continuous generalized slowing. The EEG findings, as well as clinical manifestations and hyperammonemia, tend to normalize after VA withdrawal. Patients and Methods: We present a series of seven patients who developed VA-induced encephalopathy at the Neurology Department of Hospital Salvador between 2003 and 2010. We report two illustrative cases in extenso. Results: Our series is composed by five women and two men. Five patients developed hyperammonemia (ammonemia above 50 ug/dl). 55years was the average of patients (range: 37 to 82 years). VA dose was between 375 and 2.000 mg (average 903 mg). Latency between start or important change in VA dose was 3 days to 16 years and a month. All patients had brain damage. Polytherapy with phenobarbital, phenytoin and carbamazepine was significant. The most frequent EEG pattern was diffuse slowing. A 82-year-old female developed a seudo-periodic activity suggesting a non-convulsive status epilepticus. The clinical manifestations, EEG findings and laboratory normalized after VA withdrawal. Conclusions: Acid valproic-induced encephalopathy is a reversible but potentially fatal adverse reaction that requires a high index of suspicion. Brain damage and polytherapy seem to be important risk factors.

Encefalopatía asociada a Valproato / Val proate-associated hyperammonemic encephalopathy. Report of one case

Valproate can be associated to hyperammonemic encephalopathy, characterized by fluctuating sudden-onset alterations of sensorium, focal symptoms and an increase in the frequency of seizures. We report a 78 year-old female using valproate 1,000 mg/ day for 10 months for the treatment to tonic-clonic seizures. She was admitted on three occasions in the last fourth months for self limited clouding of sensorium. Laboratory, imaging and electroencephalografic studies were non-contributory Blood ammonia levels were 123 fig/dl (normal: 15-50 fig/dl). Due to the possibility of a hyperammonemic encephalopathy secondary to valproate, the drug was discontinued and she was treated with lactulose and intravenous L-carnitine, 1 g/day The patient showed a complete recovery within 48 hours. This drug-associated encephalopathy is a reversible but potentially fatal cause, probably underdiagnosed, that requires a high index of suspicion.

Hiperamonemia secundaria a ácido valproico / Secondary hyperammonemia to valproic acid

Hyperammonemia, one of the clinical expressions of hepatological disease, can be observed as a secondary effect from the use of valproic acid. It usually appears without presenting any hepatic function alteration, and it is observed in almost half of the patients who receive this drug. In spite of this, most patients remain asymptomatic, without evidencing encephalopathy or they can present a slight compromise in cognitive functions such as attention and memory, leading to a negative influence on treatment adhesion, especially in young adolescents and adults going under academic exigencies. By taking preventive measures and treating this condition, the patients can improve the ammonium plasmatic values, without the necessity to suspend the use of a drug long studied and used successfully in psychiatry, particularly in bipolar disease.

La hiperamonemia, expresión clínica de algunas enfermedades hepáticas, puede observarse como efecto secundario al uso del ácido valproico, en ausencia de falla o compromiso funcional hepático, en casi la mitad de los pacientes que reciben dicho tratamiento. Pese a lo anterior, la inmensa mayoría de los pacientes permanece asintomático, sin evidencia de encefalopatía, o bien presentan un compromiso leve en algunas funciones cognitivas como la atención y la memoria, lo que podría impactar negativamente en la adherencia al tratamiento, especialmente en adolescentes y adultos jóvenes bajo exigencias académicas. Mediante medidas de prevención y secundariamente de tratamiento, podrían mejorar los valores plasmáticos de amonio y la clínica que de ella se desprende, sin la necesidad de suspender un fármaco largamente estudiado y utilizado con éxito en psiquiatría, particularmente en la enfermedad bipolar.

Hiperamonemia secundária ao uso terapêutico de ácido valpróico: relato de caso / Hyperammonemia secondary to the use of valproic acid: case report

O ácido valpróico tem sido amplamente utilizado no tratamento da epilepsia, sendo usualmente bem tolerado, não obstante alguns efeitos colaterais que lhe são atribuídos. Um efeito ainda pouco conhecido é a hiperamonemia, independente da hepatotoxicidade da droga. A hiperamonemia se estabelece no início ou no decurso do tratamento, sendo caracterizada por vômitos, alteração progressiva da consciência, sinais neurológicos focais e aumento na freqüência das crises epilépticas. Descrevemos o caso de menino de seis anos de idade que desenvolveu hiperamonemia pelo uso terapêutico de ácido valpróico. Os exames descartaram aminoacidopatias, acidemias orgânicas e distúrbios do ciclo da uréia, sendo a hipótese de efeito secundário reiterada pela normalização da concentração sangüínea de amônia, após a retirada do medicamento. Os mecanismos da hiperamonemia são discutidos, concluindo-se que o monitoramento da amônia é importante nos pacientes que utilizam o ácido valpróico.

Two cases of valproate-induced hyperammonemic encephalopathy without hepatic failure.

We report two children with localization related epilepsies, who presented with somnolence, seizure exacerbation, behavioral alteration, decline in speech and cognitive abilities, and ataxia while being treated with a combination of valproate and topiramate, but had previously tolerated valproate with other antiepileptic drugs. These children had elevated serum ammonia, normal transaminase levels, and generalized slowing of EEG background activity during encephalopathy, which promptly reverted back to normal along with clinical improvement following withdrawal of valproate. To our knowledge, this is the first documentation of valproate-induced hyperammonemic encephalopathy enhanced by topiramate from India. We intend to alert internists, pediatricians, psychiatrists and neurologists about this underrecognized adverse effect of antiepileptic drug polytherapy.