Hyperammonemia in the ICU

A 47-Year-Old Man With Progressive Mental Deterioration During Ventilator Management of Asthma in the ICU

CASE PRESENTATION

A 47-year-old man was admitted to the ICU with acute hypercapnic respiratory failure caused by a severe asthma attack. He had a history of asthma, atrial septal defect, chronic heart failure, and atrial fibrillation. He underwent surgical closure of the atrial septal defect at 7 years of age and was asymptomatic until 38 years of age when he developed congestive heart failure because of structural cardiac abnormalities, including left ventricular systolic dysfunction, biatrial enlargement, and mild mitral and tricuspid regurgitation. After ICU admission, he received ventilator management for asthma, IV prednisone, beta-2 agonist via inhalation, and ceftriaxone. Enteral feeding was provided since the day of admission. Hypercapnia gradually improved over 3 days. He remained alert and could communicate through writing during ventilator management until the third day in the ICU. Enteral feeding was titrated up to 32 kcal/kg/d with 1.6 g/kg/d of protein. Despite the recovery from the initial respiratory failure, he became inactive and lethargic on the fourth day in the ICU. ICU-acquired delirium was suspected, and administration of sedatives and analgesics was discontinued. On the following day, he was unresponsive to stimuli.

Acute hyperammonemic encephalopathy due to a portosystemic shunt in a non-cirrhotic adult patient

OBJECTIVE

To report a successfully treated hyperammonemia due to a portosystemic shunt in adult patient.

DATA SOURCE

A patient with an altered mental status due to severe elevated ammonia level because of a portosystemic shunt.

CONCLUSIONS

Hyperammonemia is not always related to liver failure in critically ill patients, but should be considered in all unknown origins of an altered mental status. A portosystemic shunt can be the responsible for this phenomenon, and it has a newly treatment technique named plug-assisted retrograde transvenous obliteration (PARTO), which can be quickly performed with high technical success rate and clinical efficacy for the treatment of the splenorenal and/or gastrorenal shunt.

[A case of hyperammonemia resulting from urinary tract infection caused by urease-producing bacteria in a Parkinson's disease patient with drug-induced urinary retention]

A 71-year-old woman with a 9-year history of Parkinson's disease was admitted to our hospital emergently because of consciousness disturbance. Her consciousness level was 200 on the Japan coma scale (JCS), and she presented with tenderness and distension of the lower abdomen. Brain computed tomography showed normal findings. Blood tests showed an increased ammonia level (209 μg/dl) with normal AST and ALT levels. We catheterized the bladder for urinary retention. Five hours after admission, the blood ammonia level decreased to 38 μg/dl, and her consciousness level improved dramatically. Corynebacterium urearyticum, a bacterial species that produces urease, was detected by urine culture. Therefore, she was diagnosed with hyperammonemic encephalopathy resulting from urinary tract infection caused by urease-producing bacteria. In this case, urologic active agents had been administered to treat neurogenic bladder. We suspect that these drugs caused urinary obstruction and urinary tract infection. It is important to recognize that obstructive urinary tract infection caused by urease-producing bacteria can cause hyperammonemia. Neurological disorders, such as Parkinson's disease, tend to complicate neurogenic bladder. This disease should be considered in elderly patients with Parkinson's disease who are receiving urologic active drugs.

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.

Analysis of cerebral blood flow and intracranial hypertension in critical patients with non-hepatic hyperammonemia

Hyperammonemia in adults is generally associated with cerebral edema, decreased cerebral metabolism, and increased cerebral blood flow. The aim of this study was to evaluate the association between non-hepatic hyperammonemia and intracranial hypertension assessed by Doppler flowmetry and measurement of the optic nerve sheath. A prospective cohort study in critically ill patients hospitalized in intensive care units of a University Hospital between March 2015 and February 2016. Clinical data and severity scores were collected and the Glasgow coma scale was recorded. Serial serum ammonia dosages were performed in all study patients. Transcranial Doppler evaluation was carried out for the first 50 consecutive results of each stratum of ammonemia: normal (<35 μmol/L), mild hyperammonemia (≥35 μmol/L and < 50 μmol/L), moderate hyperammonemia (≥50 μmol/L and < 100 μmol/L), and severe hyperammonemia (≥100 μmol/L). The measurement of the optic nerve sheath was performed at the same time as the Doppler examination if the patient scored less than 8 on the Glasgow coma scale. There was no difference in flow velocity in the cerebral arteries between patients with and without hyperammonemia. Patients with hyperammonemia presented longer ICU stay. Optic nerve sheath thickness was higher in the group with severe hyperammonemia and this group presented an association with intracranial hypertension. Higher mortality was observed in the severe hyperammonemia group. There was an association between severe hyperammonemia and signs of intracranial hypertension. No correlation was found between ammonia levels and cerebral blood flow velocity through the Doppler examination.

Gait instability in valproate-treated patients: Call to measure ammonia levels

OBJECTIVE

Hyperammonemia induced by valproate (VPA) treatment may lead to several neurological and systemic symptoms as well as to seizure exacerbation. Gait instability and recurrent falls are rarely mentioned as symptoms, especially not as predominant ones.

METHODS

We report five adult patients with frontal lobe epilepsy (FLE) who were treated with VPA and in whom a primary adverse effect was unstable gait and falls.

RESULTS

There were four males and one female patients with FLE, 25-42-year-old, three following epilepsy surgery. All of them were treated with antiepileptic drug polytherapy. Gait instability with falls was one of the principal sequelae of the treatment. Patients also exhibited mild encephalopathy (all patients) and flapping tremor (three patients) that developed following the addition of VPA (three patients) and with chronic VPA treatment (two patients). VPA levels were within the reference range. Serum ammonia levels were significantly elevated (291-407 μmole/L, normal 20-85) with normal or slightly elevated liver enzymes. VPA dose reduction or discontinuation led to the return of ammonia levels to normal and resolution of the clinical symptoms, including seizures, which disappeared in two patients and either decreased in frequency or became shorter in duration in the other three.

CONCLUSIONS

Gait instability due to hyperammonemia and VPA treatment is probably under-recognized in many patients. It can develop when the VPA levels are within the reference range and with normal or slightly elevated liver enzymes.

Hyperammonaemic encephalopathy following an uncomplicated surgery

A 59-year-old woman who underwent an uncomplicated exploratory laparotomy, adhesiolysis, small bowel resection and anterolateral thigh flap had a complicated postoperative period characterised by wound dehiscence and poor nutritional intake. 29 days postoperatively, a tremor developed in her upper limbs associated with weakness. Her Glasgow Coma Scale (GCS) fell to 4 and she was transferred to the intensive care unit. The patient was reviewed by multiple specialists and multiple differentials were considered and eliminated. Eventually, investigations revealed hyperammonaemic encephalopathy, being a result of low arginine and potentially small intestinal bacterial overgrowth. Following treatment with sodium benzoate, sodium phenylbutyrate and arginine along with haemodialysis and rifaximin, GCS and hyperammonaemia rapidly improved. She was stepped down to surgical high-dependency unit, continued arginine therapy with total parenteral nutrition and percutaneous endoscopic gastrostomy feeds. She was discharged with regular follow-up from surgeons and biochemistry and continues oral arginine therapy.

Ammonia Levels and Hepatic Encephalopathy in Patients with Known Chronic Liver Disease

Ammonia is predominantly generated in the gut by intestinal bacteria and enzymes and detoxified primarily in the liver. Since the 1930s, ammonia has been identified as the principal culprit in hepatic encephalopathy (HE). Many physicians utilize serum ammonia to diagnose, assess severity, and determine the resolution of HE in patients with chronic liver disease (CLD) despite research showing that ammonia levels are unhelpful in all of these clinical circumstances. HE in patients with CLD is a clinical diagnosis of exclusion that should not be based on ammonia levels.

Hiding in Plain Sight: A Case of Ornithine Transcarbamylase Deficiency Unmasked Post-Liver Transplantation

Ornithine transcarbamylase deficiency represents the most common inherited defect of the urea cycle. This enzyme, predominantly found in the liver, plays a crucial role in recycling free ammonia, with deficiencies often leading to fatal complications. Here, we present the case of a 63-year-old man with alcoholic cirrhosis who underwent orthotopic liver transplantation, gradual worsening of his mental status, and progressive elevation of ammonia levels. Liver allograft function was deemed normal, raising concern for a donor-derived metabolic disorder of the urea cycle. Evaluation of the donor patient's blood revealed that the donor was heterozygous for the OTC gene. Posttransplantation changes in mental status should prompt a clinician to consider the most likely causes; however, once these have been ruled out, it is important to consider the less common causes of metabolic derangements. The rarity of these disorders makes expertise of diagnosis, standardization of evaluation, and treatment strategies challenging.

Imaging spectrum of central nervous system complications of hematopoietic stem cell and solid organ transplantation

Neurologic complications are common after hematopoietic stem cell transplantation (HSCT) and solid organ transplantation (SOT) and affect 30-60% of transplant recipients. The aim of this article is to provide a practical imaging approach based on the timeline and etiology of CNS abnormalities, and neurologic complications related to transplantation of specific organs. The lesions will be classified based upon the interval from HSCT procedure: pre-engraftment period <30 days, early post-engraftment period 30-100 days, late post-engraftment period >100 days, and the interval from SOT procedure: postoperative phase 1-4 weeks, early posttransplant syndromes 1-6 months, late posttransplant syndromes >6 months. Further differentiation will be based on etiology: infections, drug toxicity, metabolic derangements, cerebrovascular complications, and posttransplantation malignancies. In addition, differentiation will be based on complications specific to the type of transplantation: allogeneic and autologous hematopoietic stem cells (HSC), heart, lung, kidney, pancreas, and liver. Thus, in this article we emphasize the strategic role of neuroradiology in the diagnosis and response to treatment by utilizing a methodical approach in the work up of patients with neurologic complications after transplantation.

Neurologic complications of transplantation

Major neurologic morbidity, such as seizures and encephalopathy, complicates 20-30% of organ and stem cell transplantation procedures. The majority of these disorders occur in the early posttransplant period, but recipients remain at risk for opportunistic infections and other nervous system disorders for many years. These long-term risks may be increasing as acute survival increases, and a greater number of "sicker" patients are exposed to long-term immunosuppression. Drug neurotoxicity accounts for a significant proportion of complications, with posterior reversible leukoencephalopathy syndrome, primarily associated with calcineurin inhibitors (i.e., cyclosporine and tacrolimus), being prominent as a cause of seizures and neurologic deficits. A thorough evaluation of any patient who develops neurologic symptoms after transplantation is mandatory, since reversible and treatable conditions could be found, and important prognostic information can be obtained.

Hyperammonemia: A Silent Killer

Hyperammonemia is most commonly associated with liver disease. Nonhepatic causes of hyperammonemia are uncommon. We present a case of nonhepatic hyperammonemia that turned fatal within a short period of time and discuss the possible treatment modalities for the same.

Hyperammonemia: What Urea-lly Need to Know: Case Report of Severe Noncirrhotic Hyperammonemic Encephalopathy and Review of the Literature

Purpose. A 66-year-old man who presented with coma was found to have isolated severe hyperammonemia and diagnosed with a late-onset urea-cycle disorder. He was treated successfully and had full recovery. Methods. We report a novel case of noncirrhotic hyperammonemia and review the literature on this topic. Selected literature for review included English-language articles concerning hyperammonemia using the search terms “hyperammonemic encephalopathy”, “non-cirrhotic encephalopathy”, “hepatic encephalopathy”, “urea-cycle disorders”, “ornithine transcarbamylase (OTC) deficiency”, and “fulminant hepatic failure”. Results. A unique case of isolated hyperammonemia diagnosed as late-onset OTC deficiency is presented. Existing evidence about hyperammonemia is organized to address pathophysiology, clinical presentation, diagnosis, and treatment. The case report is discussed in context of the reviewed literature. Conclusion. Late-onset OTC deficiency presenting with severe hyperammonemic encephalopathy and extensive imaging correlate can be fully reversible if recognized promptly and treated aggressively.

Hyperammonemia Syndrome After Lung Transplantation: A Single Center Experience

BACKGROUND

Hyperammonemia is a rare, often fatal complication after transplantation. The etiology is unknown, but recognition and rapid treatment may help to improve the survival of this unusual syndrome. We present the largest case series to date of hyperammonemia after lung transplantation (LTx) and discuss a treatment protocol that has been developed at our institution.

METHODS

We conducted a retrospective cohort series of patients who underwent LTx between January 1, 2000, and December 31, 2013. Patients who developed hyperammonemia syndrome in the posttransplantation period, which was defined as symptoms of encephalopathy and plasma ammonia level exceeding 200 μmol/L on at least 1 occasion, were included. Data including demographics, antimicrobial and immunosuppression regimens, ammonia levels and other pertinent laboratory data, treatments administered, and outcomes were recorded.

RESULTS

Eight of 807 lung transplant recipients developed hyperammonemia syndrome postoperatively during this time period. Median time to onset was 9.0 days, and median peak ammonia level was 370 μmol/L. All 8 patients were treated with hemodialysis, 7 of 8 patients were treated with bowel decontamination, and 5 of 8 patients were treated with nitrogen scavenging agents. Six of the 8 patients died.

CONCLUSIONS

The incidence of hyperammonemia syndrome in LTx patients was approximately 1%. Future research is needed to determine the efficacy of treatment, including hemodialysis, bowel decontamination, antibiotics, and the use of nitrogen scavenging agents in lung recipients with hyperammonemia.

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.

Guanosine Exerts Neuroprotective Effect in an Experimental Model of Acute Ammonia Intoxication

The nucleoside guanosine (GUO) increases glutamate uptake by astrocytes and acts as antioxidant, thereby providing neuroprotection against glutamatergic excitotoxicity, as we have recently demonstrated in an animal model of chronic hepatic encephalopathy. Here, we investigated the neuroprotective effect of GUO in an acute ammonia intoxication model. Adult male Wistar rats received an intraperitoneal (i.p.) injection of vehicle or GUO 60 mg/kg, followed 20 min later by an i.p. injection of vehicle or 550 mg/kg of ammonium acetate. Afterwards, animals were observed for 45 min, being evaluated as normal, coma (i.e., absence of corneal reflex), or death status. In a second cohort of rats, video-electroencephalogram (EEG) recordings were performed. In a third cohort of rats, the following were measured: (i) plasma levels of glucose, transaminases, and urea; (ii) cerebrospinal fluid (CSF) levels of ammonia, glutamine, glutamate, and alanine; (iii) glutamate uptake in brain slices; and (iv) brain redox status and glutamine synthetase activity in cerebral cortex. GUO drastically reduced the lethality rate and the duration of coma. Animals treated with GUO had improved EEG traces, decreased CSF levels of glutamate and alanine, lowered oxidative stress in the cerebral cortex, and increased glutamate uptake by astrocytes in brain slices compared with animals that received vehicle prior to ammonium acetate administration. This study provides new evidence on mechanisms of guanine-derived purines in their potential modulation of glutamatergic system, contributing to GUO neuroprotective effects in a rodent model of by acute ammonia intoxication.

Model-guided identification of a therapeutic strategy to reduce hyperammonemia in liver diseases

BACKGROUND & AIMS

Recently, spatial-temporal/metabolic mathematical models have been established that allow the simulation of metabolic processes in tissues. We applied these models to decipher ammonia detoxification mechanisms in the liver.

METHODS

An integrated metabolic-spatial-temporal model was used to generate hypotheses of ammonia metabolism. Predicted mechanisms were validated using time-resolved analyses of nitrogen metabolism, activity analyses, immunostaining and gene expression after induction of liver damage in mice. Moreover, blood from the portal vein, liver vein and mixed venous blood was analyzed in a time dependent manner.

RESULTS

Modeling revealed an underestimation of ammonia consumption after liver damage when only the currently established mechanisms of ammonia detoxification were simulated. By iterative cycles of modeling and experiments, the reductive amidation of alpha-ketoglutarate (α-KG) via glutamate dehydrogenase (GDH) was identified as the lacking component. GDH is released from damaged hepatocytes into the blood where it consumes ammonia to generate glutamate, thereby providing systemic protection against hyperammonemia. This mechanism was exploited therapeutically in a mouse model of hyperammonemia by injecting GDH together with optimized doses of cofactors. Intravenous injection of GDH (720 U/kg), α-KG (280 mg/kg) and NADPH (180 mg/kg) reduced the elevated blood ammonia concentrations (>200 μM) to levels close to normal within only 15 min.

CONCLUSION

If successfully translated to patients the GDH-based therapy might provide a less aggressive therapeutic alternative for patients with severe hyperammonemia.

Valproate Induced Hyperammonemic Delirium

Sodium valproate induced hyperammonaemic delirium with normal liver function tests is a relatively uncommon adverse effect. It may be mistaken for psychosis or worsening of mania leading to wrong diagnosis and improper management. Plasma ammonia levels should be monitored in all patients developing altered mental status after receiving valproate therapy. This is a case series of hyperammonaemic delirium due to valproate reported to the Department of Pharmacology from Department of Psychiatry over a period of one year.

Topiramate-induced hyperammonemic encephalopathy in a patient with mental retardation: A case report and review of the literature

Hyperammonemia is an uncommon side effect of topiramate (TPM) that has only been reported when it is used as an adjunct to valproate. We report a patient with mental retardation who developed reversible encephalopathy from TPM. Ammonia level was monitored during the course of TPM treatment. This patient had recurring, reversible elevations in serum ammonia levels that coincided with the administration of TPM. To our knowledge, symptomatic hyperammonemia has not been reported to occur with TPM monotherapy.

Idiopathic Hyperammonemia That Developed During Initial Treatment With Steroid in a Patient With Newly Diagnosed Leukemia

Idiopathic hyperammonemia (IHA) has been described as a complication of intensive chemotherapy for the treatment of hematologic malignancy but has subsequently been found in patients undergoing bone marrow transplantation and in those with solid tumors treated with 5-fluorouracil. Although IHA is a rare complication, it is sometimes associated with high mortality in hematologic malignancies. Here we report the case of a 15-year-old boy in whom hyperammonemia developed during the initial treatment with prednisolone for newly diagnosed acute lymphoblastic leukemia and who survived after early detection and oral lactulose therapy. To the best of our knowledge, this is the first report of IHA that was not induced by intensive chemotherapy, stem cell transplantation, or asparaginase therapy in a patient with newly diagnosed leukemia, but developed during an initial treatment with a steroid. Early detection of IHA by measuring the plasma ammonia level in patients with neurological symptoms may improve the outcome.

A(a)LS: Ammonia-induced amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a dreadful, devastating and incurable motor neuron disease. Aetiologically, it is a multigenic, multifactorial and multiorgan disease. Despite intense research, ALS pathology remains unexplained. Following extensive literature review, this paper posits a new integrative explanation. This framework proposes that ammonia neurotoxicity is a main player in ALS pathogenesis. According to this explanation, a combination of impaired ammonia removal- mainly because of impaired hepatic urea cycle dysfunction-and increased ammoniagenesis- mainly because of impaired glycolytic metabolism in fast twitch skeletal muscle-causes chronic hyperammonia in ALS. In the absence of neuroprotective calcium binding proteins (calbindin, calreticulin and parvalbumin), elevated ammonia-a neurotoxin-damages motor neurons. Ammonia-induced motor neuron damage occurs through multiple mechanisms such as macroautophagy-endolysosomal impairment, endoplasmic reticulum (ER) stress, CDK5 activation, oxidative/nitrosative stress, neuronal hyperexcitability and neuroinflammation. Furthermore, the regional pattern of calcium binding proteins' loss, owing to either ER stress and/or impaired oxidative metabolism, determines clinical variability of ALS. Most importantly, this new framework can be generalised to explain other neurodegenerative disorders such as Huntington's disease and Parkinsonism.

Fatal hyperammonemia after repeat renal transplantation

A 35-year-old man had symptomatic hyperammonemia and normal liver function after repeat kidney transplantation. He presented with gastrointestinal symptoms, which quickly progressed to altered mental status. Therapy was instituted to clear the ammonia, but the ammonia level continued to rise. Eventually, the patient became unresponsive, and an emergent computed tomographic scan showed cerebral herniation. Urine acids and serum organic acids were not diagnostic of any urea cycle disorder. Histology did not reveal a clear etiology for the hyperammonemia.

Ammonia metabolism and hyperammonemic disorders

Human adults produce around 1000 mmol of ammonia daily. Some is reutilized in biosynthesis. The remainder is waste and neurotoxic. Eventually most is excreted in urine as urea, together with ammonia used as a buffer. In extrahepatic tissues, ammonia is incorporated into nontoxic glutamine and released into blood. Large amounts are metabolized by the kidneys and small intestine. In the intestine, this yields ammonia, which is sequestered in portal blood and transported to the liver for ureagenesis, and citrulline, which is converted to arginine by the kidneys. The amazing developments in NMR imaging and spectroscopy and molecular biology have confirmed concepts derived from early studies in animals and cell cultures. The processes involved are exquisitely tuned. When they are faulty, ammonia accumulates. Severe acute hyperammonemia causes a rapidly progressive, often fatal, encephalopathy with brain edema. Chronic milder hyperammonemia causes a neuropsychiatric illness. Survivors of severe neonatal hyperammonemia have structural brain damage. Proposed explanations for brain edema are an increase in astrocyte osmolality, generally attributed to glutamine accumulation, and cytotoxic oxidative/nitrosative damage. However, ammonia neurotoxicity is multifactorial, with disturbances also in neurotransmitters, energy production, anaplerosis, cerebral blood flow, potassium, and sodium. Around 90% of hyperammonemic patients have liver disease. Inherited defects are rare. They are being recognized increasingly in adults. Deficiencies of urea cycle enzymes, citrin, and pyruvate carboxylase demonstrate the roles of isolated pathways in ammonia metabolism. Phenylbutyrate is used routinely to treat inherited urea cycle disorders, and its use for hepatic encephalopathy is under investigation.

Hyperammonemia secondary to asparaginase: A case series

OBJECTIVE

To report on hyperammonemia noted in a series of patients receiving asparaginase products at our institution.

SUMMARY OF CASES

We present four patients who experienced symptomatic hyperammonemia after receiving either pegaspargase (three patients) or Erwinia asparaginase (one patient). Presenting symptoms included lethargy, difficulty awakening, confusion, dizziness, numbness and tingling, hallucinations, and paranoia. All patients were treated with lactulose, which led to a decrease in ammonia level and resolution of symptoms.

DISCUSSION

Hyperammonemia secondary to asparaginase products has been reported in the literature. The signs and symptoms of increased ammonia should be included in consent documents and discussed with patients and their families. Monitoring of ammonia or asparagine levels may help individualize therapy with asparaginase products in the future.

CONCLUSION

Hyperammonemia can occur during treatment of acute lymphoblastic leukemia with asparaginase products. Lactulose appears to be a useful treatment strategy. Further study is warranted to determine whether dose modifications are required for pegaspargase in some patients. Whether these dose modifications would be in the dose itself or frequency of administration remains to be determined.

Late-onset ornithine transcarbamylase deficiency: treatment and outcome of hyperammonemic crisis

Hyperammonemic crises in ornithine transcarbamylase deficiency (OTC) can be associated with devastating cerebral edema resulting in severe long-term neurologic impairment and death. We present an 8-year-old boy who had late-onset OTC deficiency in which early and aggressive management of hyperammonemia and associated cerebral edema, including therapeutic hypothermia and barbiturate-induced coma, resulted in favorable neurologic outcome. Our patient presented with vomiting and altered mental status, and was found to have a significantly elevated serum ammonia level of 1561 μmol/L. Hyperammonemia was managed with hemodialysis, 10% sodium phenylacetate, 10% sodium benzoate, L-arginine, intravenous 10% dextrose, intralipids, and protein restriction. He developed significant cerebral edema with intracranial pressures >20 mm Hg, requiring treatment with 3% saline and mannitol. Despite this treatment our patient continued to have elevated intracranial pressures, which were treated aggressively with non-conventional modalities including therapeutic hypothermia, barbiturate-induced coma, and external ventricular drainage. This therapy resulted in stabilization of hyperammonemia and resolution of cerebral edema. Molecular testing later revealed a hemizygous mutation within the OTC gene. Neuropsychological testing 1 year after discharge showed normal intelligence with no visual-motor deficits, minor deficits in working memory and processing speed, and slightly below average processing speed and executive functioning.

Sudden severe hyperammonemia and status epilepticus -a case report-

There are various causes to a low level of consciousness in patients in the intensive care unit. Neurological injury, infection, and metabolic disarray are considered as some of the causes. A 39 year-old female patient was transferred to our hospital with septic shock due to ascending colon perforation. The patient had previously received ovarian cancer surgery and a cycle of chemotherapy at another hospital. Emergent operation for colon perforation was successful. After the operation, she was treated in the intensive care unit for infectious and pulmonary complications. She suddenly showed deterioration in her level of consciousness and had a generalized seizure. At the time of her seizure, she had severe hyperammonemia. Brain CT showed severe cerebral edema that was absent in the CT scan taken 2 days before. Continuous renal replacement therapy was conducted but was ineffective in lowering the level of serum ammonia and the patient subsequently died.

Symptomatic hyperammonemia after lung transplantation: lessons learnt

Hyperammonemia, post-orthotopic lung transplantation, is a rare but mostly fatal complication. Various therapies, including those to decrease ammonia generation, increase nitrogen excretion, and several dialytic methods for removing ammonia have been tried. We describe three lung transplant recipients who developed acute hyperammonemia early after transplantation. Two of the three patients survived after a multidisciplinary approach including discontinuation of drugs, which impair urea cycle, aggressive ammonia reduction with prolonged daily intermittent hemodialysis (HD), and overnight slow low-efficiency dialysis in conjunction with early weaning of steroids and other therapeutic measures. Our experience suggests that early initiation of dialysis, high dialysis dose, increased frequency, and HD preferably to less efficient modalities increases survival in these patients.

Abdominal manifestations of neurologic disorders

A variety of disorders-including infectious, inflammatory, hereditary, and metabolic diseases-may affect both the brain and abdominal cavity, and the findings in one region may help establish the diagnosis or limit the differential diagnosis. Establishing an accurate early diagnosis enables clinicians to adequately manage these unusual diseases and potentially avert life-threatening complications. For example, an early diagnosis of Gardner syndrome enables annual sigmoid- or colonoscopy and ultrasonography. In many conditions, abdominal manifestations precede neurologic manifestations and may have prognostic significance. Patients with celiac disease more often present with abdominal manifestations such as duodenitis, slow transit time, reversal of the jejunal-ileal fold pattern, and transient small bowel intussusception than with intracranial manifestations. In other conditions, the neurologic manifestations may be the same as the presenting symptoms. For example, patients with Gardner syndrome may initially present with multiple mandibular or sinonasal osteomas. In addition, sarcoidosis may manifest with multifocal enhancing dural masses. Abdominal and neurologic manifestations may even occur simultaneously, as in several of the phakomatoses such as neurofibromatosis type 1, tuberous sclerosis complex, and von Hippel-Lindau syndrome. Ultimately, familiarity with the appearances of these conditions allows radiologists to pinpoint a diagnosis, even when imaging findings in either location are nonspecific.

Simultaneous double hemodialysis for the control of refractory hyperammonemia

INTRODUCTION

In adults, hyperammonemia is generally associated with hepatic dysfunction or as a complication of urinary diversions when infected or obstructed. Hyperammonemia has also rarely been reported in association with multiple myeloma. With modest elevations, hyperammonemia often leads to encephalopathy. However, when ammonia reaches extreme levels cerebral edema and herniation may occur leading to coma, seizures, or death.

CASE

We describe a 72-year-old Caucasian male with a history of end-stage renal disease (ESRD) and multiple myeloma who developed profound encephalopathy and eventual obtundation. He was found to have severe hyperammonemia that was not due to any identified hepatic impairment. His hyperammonemia proved to be refractory to medical therapy with cathartics and antibiotics, prolonged high-flux hemodialysis, and even continuous venovenous hemodialysis (CVVHD). This metabolic derangement as well as encephalopathy was eventually reversed with simultaneous CVVHD and extended daily hemodialysis (EDD). A more durable response was achieved after vincristine and dexamethasone were administered, which allowed the patient to resume his previous intermittent hemodialysis (IHD) schedule. The patient regained his full sensorium and was eventually discharged to home.

CONCLUSIONS

Simultaneous double hemodialysis may be used as an important adjunct in treating refractory hyperammonemia.