Acute hyperammonemic encephalopathy after fluoropyrimidine-based chemotherapy: A case series and review of the literature

Acute hyperammonemic encephalopathy induced by fluoropyrimidines (FPs) is a rare complication. Its pathophysiology remains unclear, especially given the currently used regimens, including intermediate-doses of 5-fluorouracil (5-FU) or oral FP agents. We aimed to characterize the clinical manifestations in cancer patients who developed hyperammonemic encephalopathy after receiving FP-based chemotherapy.We retrospectively reviewed 1786 patients with gastrointestinal or primary-unknown cancer who received FP-based regimens between 2007 and 2012. Eleven patients (0.6%) developed acute hyperammonemic encephalopathy. The incidence according to the administered anticancer drugs were as follows: 5-FU (8 of 1176, 0.7%), S-1 (1 of 679, 0.1%), capecitabine (2 of 225, 0.9%), and tegafur-uracil (UFT) (0 of 39, 0%). Ten patients (90.9%) had at least 1 aggravating factor, including infection, dehydration, constipation, renal dysfunction, and muscle loss. All the 10 patients met the definition of sarcopenia. Median time to the onset of hyperammonemic encephalopathy in the cycle was 3 days (range: 2-21). Three patients (27.3%) developed encephalopathy during the first cycle of the regimen and the remaining 8 patients during the second or more cycles. Seven patients (63.6%) had received at least 1 other FP-containing regimen before without episodes of encephalopathy.All patients recovered soon after immediate discontinuation of chemotherapy and supportive therapies, such as hydration, infusion of branched-chain amino acids, and oral lactulose intake, with a median time to recovery of 2 days (range: <1-7). Four patients (36.4%) received FP-based regimens after improvement of symptoms; 3 patients were successfully managed with dose reduction, and 1 patient, who had developed encephalopathy due to S-1 monotherapy, received modified FOLFOX-6 therapy without encephalopathy later.FP-associated acute hyperammonemic encephalopathy is extremely rare, but a possible event at any time and even during the administration of oral FP agents. Particular attention is warranted when giving FP-based therapy for patients with aggravating factors, such as sarcopenia. This complication can be properly managed with early detection.

Hyperammonemic coma after craniotomy: Hepatic encephalopathy from upper gastrointestinal hemorrhage or valproate side effect?: Case report and literature review

RATIONALE

Postoperative coma is not uncommon in patients after craniotomy. It generally presents as mental state changes and is usually caused by intracranial hematoma, brain edema, or swelling. Hyperammonemia can also result in postoperative coma; however, it is rarely recognized as a potential cause in coma patients. Hyperammonemic coma is determined through a complicated differential diagnosis, and although it can also be induced as a side effect of valproate (VPA), this cause is frequently unrecognized or confused with upper gastrointestinal hemorrhage (UGH)-induced hepatic encephalopathy. We herein present a case of valproate-induced hyperammonemic encephalopathy (VHE) to illustrate the rarity of such cases and emphasize the importance of correct diagnosis and proper treatment.

PATIENT CONCERNS AND DIAGNOSES

A 61-year-old woman with meningioma was admitted into our hospital. Radical resection of the tumor was performed, and the patient recovered well as expected. After administration of valproate for 7 days, the patient was suddenly found in a deep coma, and her mental state deteriorated rapidly. The diagnoses of hepatic encephalopathy was confirmed. However, whether it origins from upper gastrointestinal hemorrhage or valproate side effect is uncertain.

INTERVENTIONS AND OUTCOMES

The patient's condition fluctuated without improvement during the subsequent 3 days under the treatment of reducing ammonia. With the discontinuation of valproate treatment, the patient regained complete consciousness within 48 hours, and her blood ammonia decreased to the normal range within 4 days.

LESSONS SUBSECTIONS

VHE is a rare but serious complication in patients after craniotomy and is diagnosed by mental state changes and elevated blood ammonia. Thus, the regular perioperative administration of VPA, which is frequently neglected as a cause of VHE, should be emphasized. In addition, excluding UGH prior to providing a diagnosis and immediately discontinuing VPA administration are recommended.

Reversible Encephalopathy due to Valproic Acid Induced Hyperammonemia in a Patient with Bipolar I Disorder: A Cautionary Report

Valproic acid (VPA) is an FDA-approved medication widely prescribed for seizures, migraines, and mixed or manic episodes in bipolar disorder. Hyperammonemia is a rare complication of VPA use, which can result in high morbidity and occasionally fatal encephalopathy. The scant literature on Valproate Induced Hyperammonemic Encephalopathy (VIHE) is characterized by acute onset of decreasing level of consciousness, drowsiness, lethargy which in rare instances can lead to seizures, stupor, coma, and persistent morbidity and cortical damage. Below we describe a case report of a patient with Bipolar I Disorder with no primary evidence of hepatic dysfunction that was initiated on VPA and olanzapine to address manic and psychotic symptoms. This patient subsequently developed elevated ammonia (NH4) levels that led to a reversible encephalopathy. This cautionary case report highlights the potential for a rare but serious complication from VPA, a medication increasingly used in both neurologic and neuropsychiatric settings. It is imperative that clinicians perform a thorough physical, neurological and diagnostic evaluation, routinely check NH4 and VPA levels when prescribing these agents and exercise caution when VPA is concomitantly prescribed with antipsychotics and cytochrome P450 inducing antiepileptic medications.

Acute ammonia toxicity in crucian carp Carassius auratus and effects of taurine on hyperammonemia

The four experimental groups were carried out to test the response of crucian carp Carassius auratus to ammonia toxicity and taurine: group 1 was injected with NaCl, group 2 was injected with ammonium acetate, group 3 was injected with ammonium acetate and taurine, and group 4 was injected with taurine. Fish in group 2 had the highest ammonia and glutamine contents, and the lowest glutamate content in liver and brain. Serum superoxide dismutase (SOD), glutathione (GSH) activities, red cell count (RBC), white cell count (WBC), lysozyme (LYZ) activity, complement C3 content of fish in group 2 reflected the lowest, but malondialdehyde content was the highest. Importantly, serum SOD and GSH activites, RBC, WBC, and LYZ activity, C3, C4 and total immunoglobulin contents of fish in group 3 were significantly higher than those of fish in group 2. This study indicates that ammonia exerts its toxic effects by interfering with amino acid transport, inducing ROS generation, leading to malondialdehyde accumulation and immunosuppression of crucian carp. The exogenous taurine could mitigate the adverse effect of high ammonia level on fish physiological disorder.

Hyperammonemic Encephalopathy Associated With Fibrolamellar Hepatocellular Carcinoma: Case Report, Literature Review, and Proposed Treatment Algorithm

We report a case of a 31-year-old man with metastatic fibrolamellar hepatocellular carcinoma (FLHCC) treated with gemcitabine and oxaliplatin complicated by hyperammonemic encephalopathy biochemically consistent with acquired ornithine transcarbamylase deficiency. Awareness of FLHCC-associated hyperammonemic encephalopathy and a pathophysiology-based management approach can optimize patient outcome and prevent serious complications. A discussion of the management, literature review, and proposed treatment algorithm of this rare metabolic complication are presented.

IMPLICATIONS FOR PRACTICE

Pathophysiology-guided management of cancer-associated hyperammonemic encephalopathy can improve patient outcome and prevent life-threatening complications. Community and academic oncologists should be aware of this serious metabolic complication of cancer and be familiar with its management.

Fluorouracil-induced Hyperammonemia in a Patient with Colorectal Cancer

Fluorouracil (5-FU; Adrucil®) is a pyrimidine analog antineoplastic chemotherapy agent which works by interfering with DNA and RNA synthesis. It has an uncommon toxicity called hyperammonemic encephalopathy. This neurotoxicity is associated with a high-dose administration of 5-FU (2,600 mg/m(2)/week), with an incidence rate of 5.7%, and is not normally seen with the current dose of 1,200 mg/m(2) infused over 46 h. The mechanism behind this neurotoxicity is not known but is possibly due to accumulation of fluorocitrate, a byproduct of 5-FU metabolism. This by-product inhibits the Krebs cycle, which causes impairment of the adenosine triphosphate-dependent urea cycle. By impairing this cycle, ammonia is not converted to urea, which in turn this leads to an accumulation of ammonia. The accumulated ammonia in the brain is metabolized to glutamine, which has been suggested to cause an increase in intracranial pressure and cerebral edema. This case report discusses how a 40-year-old male with colorectal cancer experienced 5FU-induced hyperammonemia and was treated for it and how reducing the dose by 50% led to resolution of this symptom from reoccurring.

[A Case of Consciousness Disturbance Caused by Hyperammonemia during a mFOLFOX6 Regimen for Metastatic Colon Cancer]

Systemic chemotherapy based on 5-fluorouracil (5-FU) is a standard treatment for unresectable or recurrent colorectal cancer. Although hyperammonemia is known as one of the adverse side effects of 5-FU, a disturbance of consciousness caused by hyperammonemia is not a usual finding. We encountered a case of 5-FU-related consciousness disturbance with respiratory depression. A woman in her sixties was diagnosed with metastatic cecum cancer, involving peritoneal dissemination and hydronephrosis due to retroperitoneal invasion. After resection of the primary lesion, systemic chemotherapy, including capecitabine, irinotecan, bevacizumab and cetuximab, was administered for the metastatic lesions. As a third-line of treatment, the mFOLFOX6 plus bevacizumab regimen was administered. On the second day of the first course, the patient complained of nausea and vomiting. On third day, her consciousness level was deteriorating. The level of ammonia in the blood was abnormally high. Therefore, we diagnosed consciousness disturbance caused by hyperammonemia resulting from high-dose 5-FU infusion. The symptom improved immediately after mechanical ventilation and intravenous infusion. Renal dysfunction is considered a risk factor for hyperammonemia caused by 5-FU, and it is necessary to pay particular attention in patients with renal dysfunction who receive chemotherapy with 5-FU.

Ammonia encephalopathy and awake craniotomy for brain language mapping: cause of failed awake craniotomy

We report the case of an aborted awake craniotomy for a left frontotemporoinsular glioma due to ammonia encephalopathy on a patient taking Levetiracetam, valproic acid and clobazam. This awake mapping surgery was scheduled as a second-stage procedure following partial resection eight days earlier under general anesthesia. We planned to perform the surgery with local anesthesia and sedation with remifentanil and propofol. After removal of the bone flap all sedation was stopped and we noticed slow mentation and excessive drowsiness prompting us to stop and control the airway and proceed with general anesthesia. There were no post-operative complications but the patient continued to exhibit bradypsychia and hand tremor. His ammonia level was found to be elevated and was treated with an infusion of l-carnitine after discontinuation of the valproic acid with vast improvement. Ammonia encephalopathy should be considered in patients treated with valproic acid and mental status changes who require an awake craniotomy with patient collaboration.

Fatal hyperammonemia and carbamoyl phosphate synthetase 1 (CPS1) deficiency following high-dose chemotherapy and autologous hematopoietic stem cell transplantation

Fatal hyperammonemia secondary to chemotherapy for hematological malignancies or following bone marrow transplantation has been described in few patients so far. In these, the pathogenesis of hyperammonemia remained unclear and was suggested to be multifactorial. We observed severe hyperammonemia (maximum 475 μmol/L) in a 2-year-old male patient, who underwent high-dose chemotherapy with carboplatin, etoposide and melphalan, and autologous hematopoietic stem cell transplantation for a neuroblastoma stage IV. Despite intensive care treatment, hyperammonemia persisted and the patient died due to cerebral edema. The biochemical profile with elevations of ammonia and glutamine (maximum 1757 μmol/L) suggested urea cycle dysfunction. In liver homogenates, enzymatic activity and protein expression of the urea cycle enzyme carbamoyl phosphate synthetase 1 (CPS1) were virtually absent. However, no mutation was found in CPS1 cDNA from liver and CPS1 mRNA expression was only slightly decreased. We therefore hypothesized that the acute onset of hyperammonemia was due to an acquired, chemotherapy-induced (posttranscriptional) CPS1 deficiency. This was further supported by in vitro experiments in HepG2 cells treated with carboplatin and etoposide showing a dose-dependent decrease in CPS1 protein expression. Due to severe hyperlactatemia, we analysed oxidative phosphorylation complexes in liver tissue and found reduced activities of complexes I and V, which suggested a more general mitochondrial dysfunction. This study adds to the understanding of chemotherapy-induced hyperammonemia as drug-induced CPS1 deficiency is suggested. Moreover, we highlight the need for urgent diagnostic and therapeutic strategies addressing a possible secondary urea cycle failure in future patients with hyperammonemia during chemotherapy and stem cell transplantation.

Acute hyperammonaemia induces a sustained decrease in vigilance, which is modulated by caffeine

Hyperammonaemia is observed after prolonged, intense exercise, or in patients with hepatic failure. In the latter, it is associated with a set of neurological and psychiatric abnormalities termed hepatic encephalopathy.

THE AIMS OF OUR STUDY WERE

1. to measure vigilance in a condition of induced hyperammonaemia; 2. to assess whether caffeine modulates the effects of hyperammonaemia on vigilance, if any. Ten healthy volunteers (28.5 ± 5 years; 5 males) underwent three experimental sessions consisting of two-hourly measurements of capillary ammonia, subjective sleepiness (Karolinska Sleepiness Scale) and vigilance (Psychomotor Vigilance Task, PVT), in relation to the intake of breakfast (+/-coffee), an amino acid mixture which induces hyperammonaemia (amino acid challenge; AAC), and AAC+coffee (only for participants who had coffee with their standard breakfast). The AAC resulted in: 1. the expected increase in capillary ammonia levels, with highest values at approximately 4 h after the administration; 2. a significant increase in subjective sleepiness ratings; 3. a sustained increase in PVT-based reaction times. When caffeine was administered after the AAC, both subjective sleepiness and the slowing in RTs were significantly milder than in the AAC-only condition. In conclusion, acute hyperammonaemia induces an increase in subjective sleepiness and a sustained decrease in vigilance, which are attenuated by the administration of a single espresso coffee.

[FOLFIRINOX-induced hyperammonemic encephalopathy in a patient with pancreatic cancer]

Hyperammonemic encephalopathy is a rare adverse event of chemotherapies based on high-dose 5-fluorouracil. We present a woman in her 70s with metastatic pancreatic adenocarcinoma who underwent FOLFIRINOX therapy. She developed acute onset disturbance of consciousness after completing the first 5-fluorouracil infusion cycle (2400 mg/m(2)/46h). We suspected hyperammonemic encephalopathy induced by 5-fluorouracil and administered branched-chain amino acids solutions and she recovered within a few hours of treatment. Brain computed tomography and magnetic resonance imaging revealed no abnormal findings. She subsequently received chemotherapy with gemcitabine and developed no further hyperammonemia. To the best of our knowledge, this is the first report of FOLFIRINOX-induced hyperammonemic encephalopathy in a patient with pancreatic cancer.

Risk factors of hyperammonemia in patients with epilepsy under valproic acid therapy

Hyperammonemia has been reported to be associated with patients who receive valproic acid (VPA) therapy. This study aimed to determine the risk factors for hyperammonemia in patients with epilepsy treated with VPA. One hundred and fifty-eight adult patients with epilepsy aged older than 17 years who received VPA therapy were enrolled into this study. Blood samples were taken during the interictal state and analyzed for the blood level of ammonia. Statistical analysis was conducted between different groups of patients. The results showed that the frequency of hyperammonemia associated with VPA therapy was 27.8% (ammonia level >93 µg/dL), and 5.1% of the patients had severe hyperammonemia (ammonia level >150 µg/dL). The blood ammonia level was significantly correlated with the dosage of VPA and the plasma concentration of VPA. An increase of 1 mg in the dosage of VPA increased the risk of hyperammonemia by 0.1%. In addition, combination treatment with liver enzyme inducing antiepileptic drugs (AEDs) and antipsychotic drugs increased the risk of hyperammonemia. In conclusion, the use of VPA in adult patients with epilepsy was associated with a dose-dependent increase in blood concentrations of ammonia. Combination treatment with liver enzyme-inducing AEDs and antipsychotic drugs increased the risk of VPA-induced hyperammonemia. Most of the patients with VPA-induced hyperammonemia were asymptomatic; however, if patients taking VPA present with symptoms such as nausea, fatigue, somnolence, ataxia, and consciousness disturbance, the blood ammonia level should be measured.

[A case of metastatic colorectal cancer with hyperammonemic encephalopathy induced by 5-FU in a patient continuously treated with XELOX therapy]

We report a rare case of a patient with metastatic colorectal cancer who experienced hyperammonemic encephalopathy induced by 5 -fluorouracil(5-FU)and was continuously treated with capecitabine plus oxaliplatin(XELOX)therapy. A 60 years man with anorexia and weight loss was diagnosed with Stage IV rectal cancer, and chemotherapy with XELOX was initiated. When the second course of XELOX therapy was administered, the patient found it difficult to take oral capecitabine. Subsequently, modified FOLFOX6 was administered. Complications such as nausea and vomiting were observed on day 2, with confusion and cognitive disturbances on day 3 . Laboratory examination revealed hyperammonemia, and therefore, branched-chain amino acid solutions were administered as treatment. The patient's symptoms disappeared entirely on day 4. He is currently receiving XELOX therapy.

Risperidone, a risk factor for valproate-induced encephalopathy?

Valproate-induced encephalopathy (ViE) has been increasingly reported and several risk factors have been proposed. We report a case whereby a patient became encephalopathic while treated with valproate and upon initiation of risperidone. The underlying mechanism could be risperidone's interference with valproate's binding to albumin, raising free valproate levels, which would impair the urea cycle and reduce ammonia conversion, leading to a hyperammonemic encephalopathy. The present case suggests a causal link, although further studies will be necessary to establish this. Nevertheless, clinicians should be aware of this possible interaction and consider carefully before concomitant administration of valproate and risperidone, mainly in patients with other risk factors for ViE, so this complication can be avoid or promptly diagnosed and treated.

Valproate (VPA)-associated hyperammonemic encephalopathy independent of elevated serum VPA levels: 21 cases in China from May 2000 to May 2012

Valproate (VPA) is a medication that is widely used in the treatment of neurological and psychiatric disorders, such as epilepsy and bipolar disorder. Valproate-induced hyperammonemic encephalopathy (VHE) is a rare central nervous system adverse effect of this medication that is characterized by impaired consciousness, which can range from drowsiness to coma; increased seizure frequency; acute cognitive symptoms; and gastrointestinal symptoms. In this manuscript, we report a single case and also review previous cases of VHE (n=20) in Chinese patients to identify risk factors for VHE. Increasing clinicians' awareness of VHE during concomitant VPA therapy is of utmost importance. Serum ammonia level is a useful and important diagnostic test. The discontinuation of VPA is currently the mainstay of treatment for VHE.

[A case of hyperammonemic encephalopathy related to 5-FU in an aged patient with recurrent colon cancer treated with FOLFIRI therapy]

We report a case of hyperammonemic encephalopathy related to 5-FU in an aged patient with recurrent colon cancer treated with FOLFIRI therapy. An 80-year-old man underwent right hemicolectomy for cecal cancer. After 10 months, surgical resection was performed for its local recurrence. He was then treated with FOLFIRI therapy, and during the fifth course, he presented with a sudden onset of congestive disturbances. Through radiographic examination and laboratory data, only hyperammonemia was found; he was therefore diagnosed with hyperammonemic encephalopathy. By starting branchedamino acid solutions for its treatment, his consciousness and serum ammonia were promptly improved. Hyperammonemic encephalopathy related 5-FU is caused by increasing ammonia production and its metabolic inhibition, and is worsened by renal dysfunction, dehydration, constipation, infections, or body weight loss. On account of the potential decrease of metabolic function of liver and kidney, an aged person tends to have hyperammonnemia more than a youth. Clinicians should be aware of the adverse events associated with hyperammonemia when then administer a large amount of 5-FU to elderly patients.

[Risk factors for hyperammonemia during mFOLFOX6 treatment]

Patients undergoing mFOLFOX6 treatment were classified into a hyperammonemia group (NH3 group) or a non-hyperammonemia group (Non-NH3 group) in order to investigate risk factors related to the onset of hyperammonemia. The NH3 group demonstrated significantly lower lymphocyte counts, hemoglobin and albumin levels, and estimated glomerular filtration rates compared to the Non-NH3 group, suggesting that the NH3 group was experiencing renal dysfunction and loss of skeletal muscle mass due to malnutrition. Amino acid fractionation in the NH3 group revealed high urea levels, and delayed urea excretion was identified. Fluorocitric acid, a fluorouracil metabolite, inhibits aconitase in the tricarboxylic acid cycle. In addition, decreased renal urea transporter function due to renal impairment leads to delayed urea excretion. These factors may induce secondary decreases in urea cycle function, leading to hyperammonemia.

Exacerbation of mood symptoms associated to primary and secondary carnitine deficiency: a case report

Rarely screened in psychiatric patients, primary and/or secondary Carnitine deficiency could be influencing and/or mimicking the mood symptoms of our patient population. The brain and specifically neurons are highly vulnerable to impairments in oxidative metabolism, which can lead to neuronal cell death and disorders of neurotransmitters causing changes in cognition and behavior. For this reason, identification of this disorder is important since its treatment could result in symptom improvement and better quality of life of our patients. We present a case where exacerbation of mood symptoms was associated to primary and secondary Carnitine deficiency.

Valproic acid induced hyperammonaemic encephalopathy

OBJECTIVE

To observe clinical and laboratory features of valproic acid-induced hyperammonaemic encephalopathy in patients taking valproic acid.

METHODS

Observational study was conducted at the Neurology Department, Dow University of Health Sciences, Civil Hospital, Karachi, from February 26, 2010 to March 20, 2011. Ten patients on valproic acid therapy of any age group with idiopathic or secondary epilepsy, who presented with encephalopathic symptoms, were registered and followed up during the study. Serum ammonia level, serum valproic acid level, liver function test, cerebrospinal fluid examination, electroencephalogram and brain imaging of all the patients were done. Other causes of encephalopathy were excluded after clinical and appropriate laboratory investigations. Microsoft Excell 2007 was used for statistical analysis.

RESULTS

Hyperammonaemia was found in all patients with encephalopathic symptoms. Rise in serum ammonia was independent of dose and serum level of valproic acid. Liver function was also found to be normal in 80% (n = 8) of the patients. Valproic acid was withdrawn in all patients. Three (30%) patients improved only after the withdrawal of valproic acid. Six (60%) patients improved after L-Carnitine replacement, one (10%) after sodium benzoate. On followup, serum ammonia had reduced to normal in five (50%) patients and to more than half of the baseline level in two (20%) patients. Three (30%) patients were lost to followup after complete clinical improvement.

CONCLUSION

Within therapeutic dose and serum levels, valproic acid can cause symptomatic hyperammonaemia resulting in encephalopathy. All patients taking valproic acid presenting with encephalopathic symptoms must be monitored for the condition.

Valproate-induced hyperammonaemia superimposed upon severe neuropsychiatric lupus: a case report and review of the literature

This paper presents a case of systemic lupus erythematosus (SLE) with neuropsychiatric features, where the outcome was influenced by the development of hyperammonaemia, probably induced by sodium valproate. A case of severe SLE occurring in a 20-year-old Maori girl is described. Her disease had been characterised by neuropsychiatric features for several years, culminating in persistent seizure activity at the time of her final presentation. Her management with anticonvulsants was complicated by the development of intractable hyperammonaemia which contributed to irreversible clinical deterioration. We have reviewed the English literature for reports of valproate-related hyperammonaemia which has often been described in the setting of seizure and mood disorders. This is the first case where it has been reported, superimposed upon severe neuropsychiatric SLE (NP-SLE). The mechanism by which valproate induces hyperammonaemia remains incompletely understood but is likely to relate to the urea cycle. Under normal metabolic conditions, acyl-CoA is transported into the mitochondria via a carnitine transport system. It is then converted to acetyl-CoA via β-oxidation and eventually to N-acetyl glutamate. This pathway can be interrupted by the introduction of sodium valproate, leading to a reduction of free coenzyme A, acetyl-CoA and carnitine, and resulting in the decreased availability of cofactors necessary for the function of the urea cycle. As this is the primary means of ammonia metabolism, serious elevation in serum ammonia levels may occur in patients on this anticonvulsant medication. In this patient with active NP-SLE, the combined autoimmune and metabolic brain insult contributed to a fatal outcome.