Adult nonhepatic hyperammonemia: a case report and differential diagnosis

Personalized antiseizure medication therapy in critically ill adult patients

Precision medicine has the potential to have a significant impact on both drug development and patient care. It is crucial to not only provide prompt effective antiseizure treatment for critically ill patients after seizures start but also have a proactive mindset and concentrate on epileptogenesis and the underlying cause of the seizures or seizure disorders. Critical illness presents different treatment issues compared with the ambulatory population, which makes it challenging to choose the best antiseizure medications and to administer them at the right time and at the right dose. Since there is a paucity of information available on antiseizure medication dosing in critically ill patients, therapeutic drug monitoring is a useful tool for defining each patient's personal therapeutic range and assisting clinicians in decision-making. Use of pharmacogenomic information relating to pharmacokinetics, hepatic metabolism, and seizure etiology may improve safety and efficacy by individualizing therapy. Studies evaluating the clinical implementation of pharmacogenomic information at the point-of-care and identification of biomarkers are also needed. These studies may make it possible to avoid adverse drug reactions, maximize drug efficacy, reduce drug-drug interactions, and optimize medications for each individual patient. This review will discuss the available literature and provide future insights on precision medicine use with antiseizure therapy in critically ill adult patients.

Older Adult Woman in a Coma After Acute Laryngitis

CASE PRESENTATION

A 72-year-old woman with a history of adenocarcinoma of the lung, for which she was receiving tyrosine kinase inhibitor therapy with osimertinib, was admitted to the ED because of clinical deterioration with extreme fatigue and fever. She was already receiving antibiotic therapy initiated by her general practitioner because of symptoms of an upper respiratory tract infection. She was febrile (38.5 °C) with normal laboratory values except for leukocytosis and elevated C-reactive protein. She was hospitalized because of profound general malaise. On the basis of the physician's working hypothesis of severe viral laryngitis, the antibiotic therapy was stopped, and only supportive measures were taken. Over the next 3 days, her condition deteriorated, and she developed respiratory symptoms with a right-sided pleural effusion demonstrated by ultrasound examination. Over time, the patient became increasingly confused and drowsy. There was preserved urinary output and a stable glomerular filtration rate of 57 mL/min. Further on, bilirubin levels as well as coagulation were normal, indicating the absence of any relevant underlying chronic liver condition. Clinically, there were no signs of meningitis. No sedative medications that would explain her confusion were given except for low-dose opioid analgesics. On day 4 after hospitalization, she was transferred to the shock room for immediate stabilization and diagnostics because of profound encephalopathy and increasing oxygen requirements.

A comprehensive review on pharmacological applications and drug-induced toxicity of valproic acid

Valproic acid, a branching short chain fatty acid, is a popular drug to treat epilepsy and acts as a mood-stabilizing drug. The obstruction of ion channels and Gamma Amino Butyrate transamino butyrate GABA has been linked to antiepileptic effects. Valproic acid has been characterized as a Histone deacetylase inhibitor, functioning directly transcription of gene levels by blocking the deacetylation of histones and increasing the accessibility of transcription sites. Study has been extensively focused on pharmaceutical activity of valproic acid through various pharmacodynamics activity from absorption, distribution and excretion particularly in patients who are resistant to or intolerant of lithium or carbamazepine, as well as those with mixed mania or rapid cycling.

Hyperammonemia syndrome in immunosuppressed individuals

PURPOSE OF REVIEW

Hyperammonemia syndrome is an increasingly recognized and often fatal condition that occurs in immunosuppressed individuals, most commonly lung transplant recipients. Growing evidence suggests hyperammonemia syndrome is associated with systemic infections caused by urease-producing organisms, namely Ureaplasma spp., an organism unable to grow with routine culturing techniques. This review will summarize the epidemiology and clinical manifestations of hyperammonemia syndrome, as well as diagnostic and management strategies once hyperammonemia syndrome is suspected.

RECENT FINDINGS

Hyperammonemia syndrome is being described in increasing frequency in the solid organ transplant population. Morbidity and mortality, even with treatment, is high once hyperammonemia syndrome occurs. Surveillance studies indicate the prevalence of lung donor colonization with Ureaplasma spp. is high, suggesting screening and treatment may be of benefit. Antibiotic resistance is common, and rapid diagnostics can facilitate appropriate antimicrobial therapy in the peri-transplant period.

SUMMARY

Hyperammonemia syndrome is most commonly seen in lung transplant recipients and has a high mortality rate once it occurs. Screening for Ureaplasma spp. should be considered in all lung transplant donors.

A 36-year-old Man with Repeated Short-term Transient Hyperammonemia and Impaired Consciousness with a Confirmed Carbamoyl Phosphate Synthase 1 Gene Monoallelic Mutation

A 36-year-old man experienced severely impaired consciousness twice after drinking because of hyperammonemia. No abnormal blood tests were found other than ammonia levels. However, magnetic resonance imaging (MRI) showed atrophy of the brain parenchyma. One the second occasion, the patient suffered severe impairment of consciousness, and because of seizures and glossoptosis, mechanical ventilation was started. Urea cycle disorders (UCDs) were assumed to be involved. Genetic testing revealed a monoallelic mutation of the carbamoyl phosphate synthase 1 (CPS1) gene. When transient hyperammonemia of unknown cause occurs repeatedly in adults, an active investigation for UCDs should be conducted.

Unexplained Fatal Hyperammonemia in a Patient With New Diagnosis of Acute Monoblastic Leukemia

Idiopathic hyperammonemia is a serious condition that can arise after induction of chemotherapy and is characterized by plasma ammonia levels greater than two times the normal upper limit but within the context of normal liver function. While this dangerous complication usually appears several weeks after the start of chemotherapy, we report a fatal case of idiopathic hyperammonemia that was detected only nine days after induction chemotherapy in a 22-year-old man with no liver pathology or other risks for hyperammonemia. The patient’s initial emergent presentation was altered mental status. Laboratory workup showed acute monoblastic leukemia and radiological investigation showed cerebral hemorrhagic foci secondary to leukostasis. He received leukoreduction apheresis and he was started on induction chemotherapy with daunorubicin and cytarabine. On the ninth day of induction chemotherapy, it was noted that he developed worsening neurological findings. Investigations showed significant elevation in ammonia level and associated cerebral edema. Although hyperammonemia was mitigated, the patient’s cerebral status worsened and he died 15 days after initial presentation. This case shows that critical hyperammonemia can occur quickly after chemotherapy induction and that strategies for preventing a rise in plasma ammonia are necessary.

Nonhepatic hyperammonemic encephalopathy complications following bariatric surgery: a case report and review of the literature

Background

Hyperammonemic encephalopathy, a rare but fatal condition, is increasingly being reported as a possible complication of bariatric surgery. Here, we present a case of hyperammonemic encephalopathy, focusing on the clinical presentation, diagnostic measures, and our treatment methods, which resulted in a rare favorable outcome, emphasizing the unique role of renal replacement treatment. We also provide a detailed discussion of the mechanism through which hyperammonemia occurs secondarily to bariatric surgery.

Case presentation

A 44-year-old Moroccan Jew woman with a history of obesity presented in the hospital with urea cycle disorder that manifested after bariatric surgery. A rapid diagnostic process, together with conservative treatment with lactulose, nutritional supplementation, dietary protein restriction, and ammonia scavengers did not result in adequate improvement. Therefore, hemofiltration was performed, which yielded a favorable outcome.

Conclusions

The case findings indicate an association between hyperammonemic encephalopathy and bariatric surgery, and support early treatment with ammonia scavengers, as currently accepted. Nevertheless, if rapid improvement is not seen, it is advisable to consider hemodialysis or hemofiltration as early invasive strategies.

SOFAMONIA: Comparison of the original SOFA score with the proposed new score including serum ammonia

Introduction:

Hyperammonemia can represent organic dysfunction of the brain, kidney, or liver. Evaluation of serum ammonia concentrations as a parameter for organ dysfunction may be justified.

Objective:

To evaluate the performance of serum ammonia as an additional or substitute variable for organ systems in the Sequential Organ Failure Assessment (SOFA) score.

Methods:

A prospective cohort study including 173 patients admitted to the intensive care unit between March 2015 and February 2016. SOFAMONIA scores were defined as follows: SOFAMONIA1 (Glasgow coma scale replaced by serum ammonia), SOFAMONIA2 (serum bilirubin replaced by serum ammonia), SOFAMONIA3 (renal system score replaced by serum ammonia), and SOFAMONIA4 (addition of serum ammonia to the original SOFA as the seventh variable, changing the maximum score from 24 to 28).

Results:

The original SOFA presented an area under the curve–receiver operating characteristic of 0.697 to predict hospital mortality. There was a positive correlation between SOFA and SOFAMONIA scores. SOFAMONIA1 presented a cut-off point of 5 for area under the curve 0.684 (0.610–0.753, 95% confidence interval), SOFAMONIA2 presented a cut-off point of 9 for area under the curve 0.701 (0.626–0.768, 95% confidence interval), SOFAMONIA3 presented a cut-off point of 8 for area under the curve 0.674 (0.598–0.743, 95% confidence interval), and SOFAMONIA4 presented a cut-off point of 8 for area under the curve 0.702 (0.628–0.769, 95% confidence interval).

Conclusions:

The addition of ammonia as the seventh parameter of the SOFA score showed the best performance to predict hospital mortality. The addition of ammonia as a representative of metabolic dysfunction may be useful in the follow-up of critically ill patients.

Hyperammonemic encephalopathy associated with post-radiotherapy vesicointestinal fistula following cervical cancer

The majority of hyperammonemic encephalopathy is due to liver cirrhosis. However, urinary tract infection caused by urease-producing bacteria increases ammonia in urine and can lead to hyperammonemic encephalopathy, especially in cases with obstructive uropathy and vesicointestinal fistula. This is the first case report of hyperammonemic encephalopathy in a cervical cancer patient associated with postradiotherapy vesicointestinal fistula. A 52-year-old woman developed diarrhea due to vesicosigmoidal fistula 14 years after radical hysterectomy and radiotherapy to treat cervical cancer. She refused urinary and/or fecal diversion. Twelve months after the diagnosis of fistula, she was admitted due to somnolence. Blood examination showed hyperammonemia without liver dysfunction. Urine culture showed Proteus rettgeri and Klebsiella pneumoniae. She recovered after intravenous antibiotics. Eight months after recovery, she was readmitted due to somnolence reoccurring with failed intravenous, but successful oral antibiotic treatment. She finally agreed to undergo percutaneous nephrostomy and hyperammonemia never recurred during 7 years of follow-up.

Recurrent noncirrhotic hyperammonemia causing acute metabolic encephalopathy in a patient with a continent ileocecal pouch: a case report

Introduction

Acute encephalopathy, while a common presentation in the emergency department, is typically caused by a variety of metabolic, vascular, infectious, structural, or psychiatric etiologies. Among metabolic causes, hyperammonemia is relatively common and typically occurs in the setting of cirrhosis or liver dysfunction. However, noncirrhotic hyperammonemia is a rare occurrence and poses unique challenges for clinicians.

Case presentation

Here we report a rare case of a 50-year-old Caucasian female with history of bladder cancer status post chemotherapy, radical cystectomy, and ileocecal diversion who presented to the emergency department with severe altered mental status, combativeness, and a 3-day history of decreased urine output. Her laboratory tests were notable for hyperammonemia up to 289 μmol/L, hypokalemia, and hyperchloremic nonanion gap metabolic acidosis; her liver function tests were normal. Urine cultures were positive for Enterococcus faecium. Computed tomography imaging showed an intact ileoceal urinary diversion with chronic ileolithiasis. Upon administration of appropriate antibiotics, lactulose, and potassium citrate, she experienced rapid resolution of her encephalopathy and a significant reduction in hyperammonemia. Her hyperchloremic metabolic acidosis persisted, but her hypokalemia had resolved.

Conclusion

This case is an example of one of the unique consequences of urinary diversions. Urothelial tissue is typically impermeable to urinary solutes. However, when bowel segments are used, abnormal absorption of solutes occurs, including exchange of urinary chloride for serum bicarbonate, leading to a persistent hyperchloremic nonanion gap metabolic acidosis. In addition, overproduction of ammonia from urea-producing organisms can lead to abnormal absorption into the blood and subsequent oversaturation of hepatic metabolic capacity with consequent hyperammonemic encephalopathy. Although this is a rare case, prompt identification and treatment of these metabolic abnormalities is critical to prevent severe central nervous system complications such as altered mental status, coma, and even death in patients with urinary diversions.

A case of anti-VGKC antibody encephalitis and prolonged encephalopathy despite spontaneous resolution of imaging abnormalities

Anti-voltage-gated potassium channel (anti-VGKC) antibody encephalitis is a common form of autoimmune encephalitis (AE). AE is usually associated with autoimmune diseases or paraneoplastic phenomena such as seen in small cell lung cancer. Clinical presentation can include memory impairment, seizures, and psychiatric symptoms. We report a case of a 72-year-old male with non-small lung cancer in remission who presented with erosive gastritis and acute severe encephalopathy. Anti-VGKC antibody limbic encephalitis was diagnosed. Spontaneous resolution of encephalitis-associated changes on brain Magnetic Resonance (MR) with concomitant decreased circulating antibody levels were observed despite lack of overall cognitive improvement.

Abbreviations

AE: autoimmune encephalitis; AMPAR: antibody limbic encephalitis - anti-α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor encephalitis; Anti-VGKC encephalitis: anti-Voltage-gated potassium channel antibody encephalitis; CRP: c-reactive protein; CT: computed tomography; EEG: electroencephalography; ESR: erythrocyte sedimentation rate; GCS: Glasgow Coma Scale; MRImaging: Magnetic resonance imaging; NMDA-R encephalitis: Anti-N-methyl D-aspartate receptor encephalitis; PCR: polymerase chain reaction.

Valproic Acid and Epilepsy: From Molecular Mechanisms to Clinical Evidences

After more than a century from its discovery, valproic acid (VPA) still represents one of the most efficient antiepi-leptic drugs (AEDs). Pre and post-synaptic effects of VPA depend on a very broad spectrum of actions, including the regu-lation of ionic currents and the facilitation of GABAergic over glutamatergic transmission. As a result, VPA indirectly mod-ulates neurotransmitter release and strengthens the threshold for seizure activity. However, even though participating to the anticonvulsant action, such mechanisms seem to have minor impact on epileptogenesis. Nonetheless, VPA has been reported to exert anti-epileptogenic effects. Epigenetic mechanisms, including histone deacetylases (HDACs), BDNF and GDNF modulation are pivotal to orientate neurons toward a neuroprotective status and promote dendritic spines organization. From such broad spectrum of actions comes constantly enlarging indications for VPA. It represents a drug of choice in child and adult with epilepsy, with either general or focal seizures, and is a consistent and safe IV option in generalized convulsive sta-tus epilepticus. Moreover, since VPA modulates DNA transcription through HDACs, recent evidences point to its use as an anti-nociceptive in migraine prophylaxis, and, even more interestingly, as a positive modulator of chemotherapy in cancer treatment. Furthermore, VPA-induced neuroprotection is under investigation for benefit in stroke and traumatic brain injury. Hence, VPA has still got its place in epilepsy, and yet deserves attention for its use far beyond neurological diseases. In this review, we aim to highlight, with a translational intent, the molecular basis and the clinical indications of VPA.

Characteristics and outcomes of critically ill patients with severe hyperammonemia

PURPOSE

To determine the etiology and outcomes of critically ill patients with severe hyperammonemia.

MATERIALS AND METHODS

Retrospective observational study of adults (18 years or older) admitted to a MICU from 2007 to 2016 who had a serum ammonia level >180 μmol/L (3 times the upper limit of normal).

RESULTS

The 78 patients (45 male, 32 female) had a median age of 52 (interquartile range [IQR] 46-58) years. Hyperammonemia occurred most often with acute-on-chronic liver failure (ACLF) (49 %) or decompensated cirrhosis (27 %) and less often as a consequence of prior gastric bypass (9%), acute hepatic failure (6%), or valproic acid (3%). Median serum ammonia level was 201 μmol/L (IQR 126-265, range 18-736) on admission, with peak value of 245 μmol/L (IQR 205-336, range 185-842). Fifty (64%) patients died during the hospitalization. Cerebral edema was documented in 8 (10%) patients, only one of whom survived. Six of the 8 patients with cerebral edema had hyperammonemia related to ACLF, giving an incidence of 14% in this subset of patients. Neither mortality nor cerebral edema was associated with peak ammonia level.

CONCLUSIONS

Critically ill patients with severe hyperammonemia have a high mortality rate and are at risk of developing cerebral edema.

Transient splenial lesion due to non-cirrhotic hyperammonaemia in dengue fever

Transient splenial lesion(TSL) is seen in a variety of conditions and is detectable only on MRI of the brain. Dengue fever (DF) is a common viral infection encountered in the tropics. The affected patients may face neurological complications like encephalopathy and intracranial haemorrhage, or even ischaemic stroke. Non-cirrhotic hyperammonaemia is a rare scenario; and its occurrence in DF is unknown. The patient being described had DF and developed dysarthria. His MRI brain showed splenial hyperintensity. Further evaluation revealed non-cirrhotic hyperammonaemia. To the best of our knowledge, TSL due to non-cirrhotic hyperammonaemia in DF is an unreported scenario.

Features of Adult Hyperammonemia Not Due to Liver Failure in the ICU

OBJECTIVES

To evaluate the epidemiology of hyperammonemia unrelated to liver failure in the critical care setting.

DESIGN

Retrospective case series.

SETTING

Critically ill patients admitted to ICUs at Mayo Clinic, Rochester, MN (medical ICU, two mixed medical-surgical ICUs, coronary care unit, or the cardiosurgical ICU) between July 1, 2004, and October 31, 2015.

PATIENTS

Adult critically ill patients with hyperammonemia not related to acute or chronic liver failure. We excluded patients with diagnosis of moderate or severe liver disease, hyperbilirubinemia, and patients who denied the use of their medical records.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Of 3,908 ICU patients with hyperammonemia, 167 (4.5%) had no evidence of acute or chronic liver failure. One-hundred one patients (60.5%) were male with median age of 65.7 years (interquartile range, 50-74.5 yr) and median serum ammonia level of 68 µg/dL (interquartile range, 58-87 µg/dL). Acute encephalopathy was present in 119 patients (71%). Predisposing conditions included malnutrition 27 (16%), gastric bypass six (3.6%), total parenteral nutrition four (2.4%); exposure to valproic acid 17 (10%); status epilepticus 11 (6.6%), high tumour burden 19 (11.3%), and renal failure 82 (49.1%). Urea cycle defects were diagnosed in seven patients (4.1%). Hospital mortality was high (30%), and median ammonia level was higher among the nonsurvivors (74 vs 67 µg/dL; p = 0.05). Deaths were more likely in hyperammonemic patients who were older (p = 0.016), had greater illness severity (higher Acute Physiology and Chronic Health Evaluation III score, p < 0.01), malignancy (p < 0.01), and solid organ transplantation (p = 0.04), whereas seizure disorder was more common in survivors (p = 0.02). After adjustment, serum ammonia level was not associated with increased mortality.

CONCLUSIONS

Hyperammonemia occurs in a substantial minority of critically ill patients without liver failure. These patients have a poor prognosis, although ammonia level per se is not independently associated with mortality. Serum ammonia should be measured when risk factors are present, such as nutritional deficiencies and protein refeeding, treatment with valproic acid, high tumour burden, and known or suspected urea cycle abnormalities.

Hyperammonemia Presenting as Refractory Status Epilepticus after Lung Transplant in a Patient Positive for Ureaplasma parvum

Hyperammonemia is a rare complication of lung transplant with a high mortality rate. It presents as encephalopathy and progresses to seizures, status epilepticus, coma, cerebral edema, and brain death. Multiple treatments have been documented including administration of medications, gut decontamination, and dialysis. However, no definitive treatments exist and mortality remains between 67% and 75%. We present the case of a 65-year-old male with idiopathic pulmonary fibrosis who developed refractory status epilepticus secondary to hyperammonemia following lung transplant. The patient presented on postoperative day 7 with super-refractory status epilepticus and normal computed tomography scan of the head. Hyperammonemia was suspected due to refractory seizures and confirmed with peak ammonia level >1000 μmol/L. Despite aggressive treatment, the patient developed global cerebral edema and died. Postmortem investigations revealed that the patient was positive for Ureaplasma parvum. Additional studies are needed to elucidate the exact mechanism of disease and investigate successful treatment options.

'All that glitters is not gold': when hyperammonaemia is not from hepatic aetiology

Hyperammonaemia is often caused by decompensated liver disease. However, non-hepatic causes can sometimes result in hyperammonaemia, severe enough to cause symptoms.We report a case of a 65-year-old man with a history of hypertension and bilateral peripelvic renal cyst who presented with acute confusion. Laboratory investigations revealed hyperammonaemia and normal liver function test. The abdominal ultrasound did not reveal any finding of liver disease or portal-systemic shunting but demonstrated bilateral peripelvic cysts with no hydronephrosis.Hyperammonaemia was attributed to urinary tract infection with a urea-splitting Escherichia coli bacterium.Antibiotic therapy and lactulose were administered. His neurological status rapidly normalised over the next 48 hours, concomitantly with a decrease in ammonia level. Clinician awareness of non-hepatic causes of hyperammonaemic encephalopathy like urinary tract infection can contribute to early diagnosis and timely initiation of appropriate and potentially life-saving treatment including antimicrobial therapy, alleviating urinary obstruction, if present, and lactulose.

Hyperammonemia as a Marker of Subclinical Seizures After Traumatic Cardiac Arrest

This report details the presence of hyperammonemia in a patient who sustained cardiac arrest after a traumatic amputation. Serum ammonia levels may rise due to numerous etiologies; however, few reports detail its usefulness in diagnosing subclinical seizures. In this case, we successfully utilized persistently elevated serum ammonia levels as a marker of subclinical seizures in a patient who sustained traumatic cardiac arrest.

Pharmacogenomics in epilepsy

•

Genetic variation can influence response to antiepileptic drug (AED) treatment through various effector processes.

•

Metabolism of many AEDs is mediated by the cytochrome P450 (CYP) family; some of the CYPs have allelic variants that may affect serum AED concentrations.

•

‘Precision medicine’ focuses on the identification of an underlying genetic aetiology allowing personalised therapeutic choices.

•

Certain human leukocyte antigen, HLA, alleles are associated with an increased risk of idiosyncratic adverse drug reactions.

•

New results are emerging from large-scale multinational efforts, likely imminently to add knowledge of value from a pharmacogenetic perspective.

There is high variability in the response to antiepileptic treatment across people with epilepsy. Genetic factors significantly contribute to such variability. Recent advances in the genetics and neurobiology of the epilepsies are establishing the basis for a new era in the treatment of epilepsy, focused on each individual and their specific epilepsy. Variation in response to antiepileptic drug treatment may arise from genetic variation in a range of gene categories, including genes affecting drug pharmacokinetics, and drug pharmacodynamics, but also genes held to actually cause the epilepsy itself.

From a purely pharmacogenetic perspective, there are few robust genetic findings with established evidence in epilepsy. Many findings are still controversial with anecdotal or less secure evidence and need further validation, e.g. variation in genes for transporter systems and antiepileptic drug targets. The increasing use of genetic sequencing and the results of large-scale collaborative projects may soon expand the established evidence.

Precision medicine treatments represent a growing area of interest, focussing on reversing or circumventing the pathophysiological effects of specific gene mutations. This could lead to a dramatic improvement of the effectiveness and safety of epilepsy treatments, by targeting the biological mechanisms responsible for epilepsy in each specific individual.

Whilst much has been written about epilepsy pharmacogenetics, there does now seem to be building momentum that promises to deliver results of use in clinic.

Clinical aspects of urea cycle dysfunction and altered brain energy metabolism on modulation of glutamate receptors and transporters in acute and chronic hyperammonemia

In living organisms, nitrogen arise primarily as ammonia (NH3) and ammonium (NH4(+)), which is a main component of the nucleic acid pool and proteins. Although nitrogen is essential for growth and maintenance in animals, but when the nitrogenous compounds exceeds the normal range which can quickly lead to toxicity and death. Urea cycle is the common pathway for the disposal of excess nitrogen through urea biosynthesis. Hyperammonemia is a consistent finding in many neurological disorders including congenital urea cycle disorders, reye's syndrome and acute liver failure leads to deleterious effects. Hyperammonemia and liver failure results in glutamatergic neurotransmission which contributes to the alteration in the function of the glutamate-nitric oxide-cGMP pathway, modulates the important cerebral process. Even though ammonia is essential for normal functioning of the central nervous system (CNS), in particular high concentrations of ammonia exposure to the brain leads to the alterations of glutamate transport by the transporters. Several glutamate transporters have been recognized in the central nervous system and each has a unique physiological property and distribution. The loss of glutamate transporter activity in brain during acute liver failure and hyperammonemia is allied with increased extracellular brain glutamate concentrations which may be conscientious for the cerebral edema and ultimately cell death.

Fatal Nonhepatic Hyperammonemia in ICU Setting: A Rare but Serious Complication following Bariatric Surgery

Bariatric surgery is well established in reducing weight and improving the obesity-associated morbidity and mortality. Hyperammonemic encephalopathy following bariatric surgery is rare but highly fatal if not diagnosed in time and managed aggressively. Both macro- and micronutrients deficiencies play a role. A 42-year-old Hispanic female with a history of Roux-en-Y Gastric Bypass Procedure was brought to ED for progressive altered mental status. Physical exam was remarkable for drowsiness with Glasgow Coma Scale 11, ascites, and bilateral pedal edema. Labs showed elevated ammonia, low hemoglobin, low serum prealbumin, albumin, HDL, and positive toxicology. She remained obtunded despite the treatment with Narcan and flumazenil and the serum ammonia level fluctuated despite standard treatment with lactulose and rifaximin. Laboratory investigations helped to elucidate the etiology of the hyperammonemia most likely secondary to unmasking the functional deficiency of the urea cycle enzymes. Hyperammonemia in the context of normal liver function tests becomes diagnostically challenging for physicians. Severe hyperammonemia is highly fatal. Early diagnosis and aggressive treatment can alter the prognosis favorably.

A case of advanced rectal cancer with rectovesical and ileal fistulae that developed hyperammonemic encephalopathy

Hyperammonemic encephalopathy is rarely caused by a urinary diversion. We herein experienced a case of rectal carcinoma with rectovesical and ileal fistulae that developed hyperammonemic encephalopathy. A 72-year-old man suffered from a fever, diarrhea, pneumaturia, and fecaluria beginning in April 2013 and was referred to our hospital in May 2013. He developed a loss of consciousness and whole body cramping on the first hospital day. The laboratory data indicated an inflammatory reaction and hyperammonemia with a highly elevated serum ammonia (NH3) level of 703 μg/dl.

The patient was diagnosed to have rectal carcinoma with rectovesical and ileal fistulae according to computed tomography (CT) and a water-soluble contrast enema.

We administered a solution of branched chain amino acids (BCAA) and antibiotics. Furthermore, we repeatedly irrigated bladder through the urethral catheter. The patient’s symptoms recovered, and the serum ammonia levels on the second and third hospital day were decreased to 210 and 135 μg/dl, respectively. However, the symptoms of infection and confusion were suspected to repeat; we elected to perform surgical treatment. An ileal disconnection with ileocecal bypass and sigmoidostomy were effective for preventing hyperammonemic encephalopathy.

Noncirrhotic hyperammonemia causing relapsing altered mental status

Hyperammonemia is a recognized cause of encephalopathy. However, it is commonly seen in patients with liver disease. The clinical entity of noncirrhotic hyperammonemia is now being increasingly recognized. We report a man who presented to our hospital with relapsing altered mental status later diagnosed as noncirrhotic hyperammonemia.

Adult-onset seizures in a patient with Down syndrome and portosystemic shunt

OBJECTIVE

The prevalence of epilepsy in patients with Down syndrome (DS) is 5-13%, which is higher than the prevalence in the general population. Transient hyperammonemia is often observed following seizure, but it typically resolves within a day. Here, we describe the case a 37-year-old woman who had DS and a history of adult-onset epilepsy and was admitted to our hospital with recurrent seizures. After admission, her ammonia levels fluctuated without any apparent cause, and dynamic computed tomography revealed a portosystemic shunt. The findings suggest that her seizures possibly precipitated from hyperammonemia secondary to a portosystemic shunt, and we reviewed the relevant literature.

METHODS

We conducted PubMed, Web of Science, and EMBASE searches without language restrictions for articles published between 1970 and February 2013.

RESULTS

In addition to the present case, 7 cases were ultimately included in this review. Four patients were newborns, 2 patients were 1 month old, and 1 patient was 3 years old. No adult cases were described until now.

CONCLUSION

Adult patients with DS diagnosed with epilepsy are not routinely assessed for portosystemic venous shunts. Measuring ammonia levels in patients with DS the day after admission would help detect portosystemic shunts, even if the patients have been previously diagnosed with epilepsy.

PRACTICE IMPLICATIONS

If ammonia levels fluctuate without any apparent cause after seizure, dynamic computed tomography should be performed, especially for patients with DS, whether or not they have been previously diagnosed with epilepsy.

Late-onset urea cycle disorder in adulthood unmasked by severe malnutrition

Urea cycle disorders (UCDs) most often involve inherited deficiencies in genes that code for enzymes normally used by the urea cycle to breakdown nitrogen. UCDs lead to serious metabolic complications, including severe neurologic decompensation related to hyperammonemia. Although the majority of UCDs are revealed soon after birth, stressful events in adulthood can lead to unmasking of a partial, late-onset UCDs. In this report, we describe a late-onset UCD unmasked by severe malnutrition. Early, specialized nutrition therapy is a fundamental aspect of treating hyperammonemic crises in patients with UCD. The case presented here demonstrates the importance of early recognition of UCD and appropriate interventions with nutrition support.

Adverse drug reactions induced by valproic acid

Valproic acid is a widely-used first-generation antiepileptic drug, prescribed predominantly in epilepsy and psychiatric disorders. VPA has good efficacy and pharmacoeconomic profiles, as well as a relatively favorable safety profile. However, adverse drug reactions have been reported in relation with valproic acid use, either as monotherapy or polytherapy with other antiepileptic drugs or antipsychotic drugs. This systematic review discusses valproic acid adverse drug reactions, in terms of hepatotoxicity, mitochondrial toxicity, hyperammonemic encephalopathy, hypersensitivity syndrome reactions, neurological toxicity, metabolic and endocrine adverse events, and teratogenicity.

Valproic acid-induced hyperammonemic encephalopathy - a potentially fatal adverse drug reaction

Background

A patient with an early diagnosed epilepsy Valproic acid is one of the most widely used antiepileptic drugs. Hyperammonemic encephalopathy is a rare, but potentially fatal, adverse drug reaction to valproic acid.

Case description

A patient with an early diagnosed epilepsy, treated with valproic acid, experienced an altered mental state after 10 days of treatment. Valproic acid serum levels were within limits, hepatic function tests were normal but ammonia levels were above the normal range.

Valproic acid was stopped and the hyperammonemic encephalopathy was treated with lactulose 15 ml twice daily, metronidazole 250 mg four times daily and L-carnitine 1 g twice daily.

Discussion and evaluation

Monitoring liver function and ammonia levels should be recommended in patients taking valproic acid. The constraints of the pharmaceutical market had to be taken into consideration and limited the pharmacological options for this patient's treatment.

Conclusions

Idiosyncratic symptomatic hyperammonemic encephalopathy is completely reversible, but can induce coma and even death, if not timely detected.

Clinical pharmacists can help detecting adverse drug reactions and provide evidence based information for the treatment.

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.

A rare case of hyperammonemia complication of high-protein parenteral nutrition

Hyperammonemia is a metabolic derangement that can be potentially fatal. Primary hyperammonemia due to urea cycle enzyme deficiency is usually discovered in neonates but rarely can present in adulthood. Late-onset manifestations of urea cycle disorders can go unnoticed, until they become life threatening. The authors report a 28-year-old man who developed hyperammonemia in the hospital following parenteral nutrition (PN), leading to cerebral edema, which was fatal despite resolution of the hyperammonemia with cessation of PN and the use of continuous renal replacement therapy.

Severe hyperammonaemia in adults not explained by liver disease

Ammonia is produced continuously in the body. It crosses the blood-brain barrier readily and at increased concentration it is toxic to the brain. A highly integrated system protects against this: ammonia produced during metabolism is detoxified temporarily by incorporation into the non-toxic amino acid glutamine. This is transported safely in the circulation to the small intestine, where ammonia is released, carried directly to the liver in the portal blood, converted to non-toxic urea and finally excreted in urine. As a result, plasma concentrations of ammonia in the systemic circulation are normally very low (<40 μmol/L). Hyperammonaemia develops if the urea cycle cannot control the ammonia load. This occurs when the load is excessive, portal blood from the intestines bypasses the liver and/or the urea cycle functions poorly. By far, the commonest cause is liver damage. This review focuses on other causes in adults. Because they are much less common, the diagnosis may be missed or delayed, with disastrous consequences. There is effective treatment for most of them, but it must be instituted promptly to avoid fatality or long-term neurological damage. Of particular concern are unsuspected inherited defects of the urea cycle and fatty acid oxidation presenting with catastrophic illness in previously normal individuals. Early identification of the problem is the challenge.

Late-onset carbamoyl phosphate synthetase 1 deficiency in an adult cured by liver transplantation

Urea cycle disorders (UCDs) are rare causes of hyperammonemic encephalopathy in adults. Most UCDs present in childhood and, if unrecognized, are rapidly fatal. Affected individuals who survive to adulthood may remain undiagnosed because of clinicians' unawareness of the condition or atypical presentations. We describe the case of a 49-year-old man who initially presented with a stroke and developed hyperammonemic encephalopathy over a period of 8 months. A diagnosis of carbamoyl phosphate synthetase type 1 deficiency was made, and the patient was referred for liver transplantation. One year after liver transplantation, the patient had normal plasma ammonia concentrations and had returned to work.