Ammoniagenic coma following ureterosigmoidostomy

Survival and Neurologic Recovery After Prompt Diagnosis and Aggressive Management of Severe Idiopathic Hyperammonemic Encephalopathy in a Patient with Acute Myeloid Leukemia

A case of a 19-year-old female with low-risk acute myeloid leukemia is presented who was diagnosed with idiopathic hyperammonemic encephalopathy following the development of abrupt neurologic decline, respiratory alkalosis, and elevated plasma ammonia levels of unknown etiology. Delayed symptom recognition of this exceedingly rare condition contributes to the often fatal outcomes of idiopathic hyperammonemic encephalopathy. As illustrated by this case, prompt diagnosis and utilization of a variety of ammonia-modulating treatment modalities can result in remarkable clinical recovery. This case provides guidance to clinicians in counseling families about the possibility of neurologic recovery in similar clinical scenarios.

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.

Intermittent hyperammonemic encephalopathy after ureterosigmoidostomy: spontaneous onset in the absence of hepatic failure

Intermittent hyperammonemic encephalopathy after ureterosigmoidostomy is a rare, but if unrecognized, potentially lethal condition. Ureterosigmoidostomy was performed in a male patient with bladder extrophy. After 35 years, he developed hyperammonemic encephalopathy. Diagnostic procedures did not reveal hepatic nor metabolic disorders. Despite administration of preventive medical treatment, several episodes recurred. A durable prevention was finally achieved by conversion into an ileal conduit.

Intermittent hyperammonemic encephalopathy can occur decades after ureterosigmoidostomy. In the case of absence of metabolic disorders and resistance to medical treatment, conversion into a urinary diversion using an ileal segment constitutes an effective ultima ratio.

Ammonium metabolism in humans

Free ammonium ions are produced and consumed during cell metabolism. Glutamine synthetase utilizes free ammonium ions to produce glutamine in the cytosol whereas glutaminase and glutamate dehydrogenase generate free ammonium ions in the mitochondria from glutamine and glutamate, respectively. Ammonia and bicarbonate are condensed in the liver mitochondria to yield carbamoylphosphate initiating the urea cycle, the major mechanism of ammonium removal in humans. Healthy kidney produces ammonium which may be released into the systemic circulation or excreted into the urine depending predominantly on acid-base status, so that metabolic acidosis increases urinary ammonium excretion while metabolic alkalosis induces the opposite effect. Brain and skeletal muscle neither remove nor produce ammonium in normal conditions, but they are able to seize ammonium during hyperammonemia, releasing glutamine. Ammonia in gas phase has been detected in exhaled breath and skin, denoting that these organs may participate in nitrogen elimination. Ammonium homeostasis is profoundly altered in liver failure resulting in hyperammonemia due to the deficient ammonium clearance by the diseased liver and to the development of portal collateral circulation that diverts portal blood with high ammonium content to the systemic blood stream. Although blood ammonium concentration is usually elevated in liver disease, a substantial role of ammonium causing hepatic encephalopathy has not been demonstrated in human clinical studies. Hyperammonemia is also produced in urea cycle disorders and other situations leading to either defective ammonium removal or overproduction of ammonium that overcomes liver clearance capacity. Most diseases resulting in hyperammonemia and cerebral edema are preceded by hyperventilation and respiratory alkalosis of unclear origin that may be caused by the intracellular acidosis occurring in these conditions.

Hyperammonemia encephalopathy: an important cause of neurological deterioration following chemotherapy

Idiopathic hyperammonemic encephalopathy is an uncommon but frequently fatal complication of chemotherapy. It is characterised by abrupt alteration in mental status with markedly elevated plasma ammonia levels in the absence of obvious liver disease or any other identifiable cause, and frequently results in intractable coma and death. It usually occurs in patients with haematologic malignancies during the period of neutropenia following cytoreductive therapy or bone marrow transplantation, and in solid organ malignancies treated with 5-fluorouracil. Although the aetiology of this syndrome is yet to be determined, it appears to be multi-factorial in nature. Optimal management remains to be formally established, and the critical step is increased awareness of the syndrome by measurement of plasma ammonium levels in patients with neurological symptoms, leading to early diagnosis and the prompt implementation of therapy.

[Metabolic aspects of bowel use in urologic surgery]

Urinary diversion, pouches and orthotopic bladder replacement have been made possible by the use of bowel segments in urologic surgery. The most important complications at short and long-term are metabolic disorders due to the permanent contact of urine with the bowel segment or the exclusion of this segment from bowel continuity. Metabolic acid-base problems occur immediately after the derivation beginning and depend on the renal capacity to compensating. The metabolic disorder due to the exclusion of a bowel segment appears generally years later, after complete depletion of physiologic reserves (vitamin B12). Perfect knowledge of early and late metabolic complications of urinary diversion allows a more accurate indication, a more adequate selection of the derivation type, an improved patient followup, and better long-term results. Metabolic complications constitute the best selection criteria for urinary diversion; subsequently, only a few techniques are likely to persist in the future.

Metabolic complications of urinary diversions: an overview

Patients with urinary diversions present unique challenges to internists who have an important role in their long-term management. Advances in surgical techniques over the past 30 years have given rise to a number of urinary diversion procedures that use various intestinal segments. In its normal function, the intestine absorbs water and solutes. When placed in contact with the urinary stream, the intestine can create numerous metabolic abnormalities. These include bone disease, hepatobiliary disease, infection, malignancy, neurologic complications, nutritional deficiencies, and a number of electrolyte and acid-base disorders. An overview of these metabolic abnormalities and their causes is provided, as well as recommendations for screening and management of patients.

Urease and the acidosis of urinary intestinal diversion

Previous investigators have suggested that urinary tract infections with urea-splitting organisms may be a primary etiologic factor in the acidosis which is seen after urinary diversion. This study employs a model in which small intestinal segments are perfused with an artificial urine solution over a three hour period. Urease is then added in order to determine its effect on acid-base balance and net intestinal electrolyte transport. Urease created no significant increase in acid load (delta HCO3- = -7.5 +/- 2.2 for controls vs. -8.7 +/- 2.9 for urease group), but did increase the osmolality of the intestinal contents and resulted in a 24% increase in free water loss (p = .037). Analysis of sodium and chloride movement following the addition of urease to the perfusate suggests that both ammonium and bicarbonate are absorbed by the intestinal segment. Thus any acidosis resulting from increased ammonium absorption following the addition of urease appears to be offset by concomitant bicarbonate absorption. The azotemia of urinary diversion appears to be primarily the result of urea absorption, partially the result of ammonium absorption, and is not significantly increased by urease.

Ammonia levels in paediatric ureterosigmoidostomy patients: a screen for hyperammonaemia?

Hyperammonaemia in the urological patient is a rare and potentially grave condition. It has been reported most frequently in association with ureterosigmoidostomy, where clinical neurological symptoms have developed abruptly in association with markedly elevated plasma ammonia levels. The purpose of this study was to determine whether ureterosigmoidostomy patients might have subclinically elevated plasma ammonia levels, which would put them at risk of subsequently developing hyperammonaemic encephalopathy. Both urine and plasma ammonia levels were assayed in 10 asymptomatic paediatric urological patients with ureterosigmoidostomy. Ten paediatric colocystoplasty patients served as controls. Urine pH and urine ammonia levels were significantly higher in the ureterosigmoidostomy group. There was no significant difference in plasma ammonia levels between ureterosigmoidostomy and colocystoplasty patients. In none of the patients was the plasma ammonia level elevated, but 1 ureterosigmoidostomy patient had an exceedingly high urine ammonia level. It was concluded that an annual serum ammonia level in an asymptomatic ureterosigmoidostomy patient is probably not a valuable screen for subclinical hyperammonaemia.

Hyperammonaemic coma in ureterosigmoid urinary diversion

We report on a patient with ureterosigmoid anastomosis, who presented with recurrent episodes of confusion, agitation and aggressive behaviour, culminating in coma. Investigations revealed profound hyperammonaemia, which responded to treatment with sodium benzoate and sodium phenylacetate. No definite cause was found for the abnormality, apart from possible urinary tract infection. The patient remains well on a protein restricted diet with mildly elevated levels of plasma ammonia.

Periodic hyperammonemic encephalopathy associated with a ureterosigmoidostomy

Ureterosigmoidostomy, a urinary diversion procedure performed for treatment congenital urologic defects or bladder cancer, may be associated with hyperammonemia. A delayed periodic encephalopathy, characterized by dysarthria, ataxia, and coma, developed in a 44-year-old woman who had undergone this procedure. Hyperammonemia-associated neurotoxicity resolved after surgical revision of the ureterosigmoidostomy to a uretero-ileostomy. Therefore, a treatable episodic encephalopathy may occur in association with hyperammonemia in patients who have undergone ureterosigmoidostomy.

Ureterocolonic anastomosis in ten dogs with transitional cell carcinoma

Ureterocolonic anastomosis (UCA) was performed in 10 dogs with transitional cell carcinoma of the urinary bladder trigone or the urethra, or both. All grossly visible tumor was excised. All of the dogs recovered from anesthesia and surgery and had anal continence with no urine leakage. One dog died of undetermined causes 7 days after surgery. Nine dogs survived 1 to 5 months. The owners of eight of the dogs considered their dog's quality of life to be acceptable. Four dogs were euthanatized because of neurologic disease, three of which also had nausea and vomiting. The neurologic and gastrointestinal signs may have been caused by hyperammonemia, metabolic acidosis, and uremia. Blood ammonia levels were elevated in two dogs with neurologic signs. Hyperchloremic metabolic acidosis that was reversible with bicarbonate therapy was diagnosed in five dogs. All of the dogs were azotemic because of intestinal recycling of urea. Serum creatinine concentrations increased in four dogs after surgery. Drug-induced renal disease may have developed in two dogs. Pyelonephritis developed in five kidneys, two of which had outflow obstruction and two had bilateral hydroureteronephrosis before the UCA. In this small number of dogs, surgical excision of transitional cell carcinoma was not curative with six dogs having confirmed metastatic lesions at the time of death.