Combined General and Regional Anesthetic in a Child with Aromatic l-Amino Acid Decarboxylase Deficiency

Anaesthesia management of a child with aromatic L-amino acid decarboxylase deficiency

Aromatic L-amino acid decarboxylase deficiency is an autosomal recessive disorder that results in a lack of neurotransmitters including serotonin, dopamine, noradrenaline and adrenaline. It is characterised by developmental delay, severe hypotonia and autonomic disturbance. In patients with this condition, catecholamine deficiency and autonomic dysfunction, resulting in haemodynamic instability under anaesthesia is a primary concern. There is increased sensitivity to exogenous catecholamines and indirect acting agents, such as ephedrine, are ineffective. Hypoglycaemia, difficult airway status and drug interactions such as with monoamine oxidase inhibitors are also of concern, and these patients are at risk of dystonic crises peri-operatively. A 6-year-old boy with aromatic L-amino acid decarboxylase deficiency presented for gastrointestinal endoscopy. Following multidisciplinary discussion, we elected to provide general anaesthesia with a propofol target-controlled infusion, which proceeded without incident. In this report, we describe the precautions taken in this case, and discuss the provision of general anaesthesia for children with rare neurometabolic disorders.

Anesthesia Management for Cesarean Delivery in a Woman With Aromatic L-Amino Acid Decarboxylase Deficiency: A Case Report

Aromatic L-amino acid decarboxylase deficiency (AADCD) is a rare autosomal recessive disorder of neurotransmitter synthesis with lack of sympathetic autoregulation. Owing to hemodynamic regulatory dysfunction and impairment of sympathetic regulation of heart rate, anesthesia is challenging. We report the successful management of anesthesia in a 26-year-old pregnant woman presenting with a mild phenotype of AADCD. Neuraxial anesthesia was administered, as she had not developed complications previously. Thus, neuraxial anesthesia can also be used safely for a cesarean delivery with appropriate anticipation of potential autonomic disturbances and lack of adrenergic neurotransmission.

Prevalence of Aromatic l-Amino Acid Decarboxylase Deficiency in At-Risk Populations

BACKGROUND

Aromatic l-amino acid decarboxylase (AADC) deficiency is an autosomal recessive metabolic disorder that results from disease-causing pathogenic variants of the dopa decarboxylase (DDC) gene. Loss of dopamine and serotonin production in the brain from infancy prevents achievement of motor developmental milestones.

METHODS

We retrospectively evaluated data obtained from requests to Medical Neurogenetics Laboratories for analyses of neurotransmitter metabolites in the cerebrospinal fluid, AADC enzyme activity in plasma, and/or Sanger sequencing of the DDC gene. Our primary objective was to estimate the prevalence of AADC deficiency in an at-risk population.

RESULTS

Approximately 20,000 cerebrospinal fluid samples were received with a request for neurotransmitter metabolite analysis in the eight-year study period; 22 samples tested positive for AADC deficiency based on decreased concentrations of 5-hydroxyindoleacetic acid and homovanillic acid, and increased 3-O-methyldopa, establishing an estimated prevalence of approximately 0.112%, or 1:900. Of the 81 requests received for plasma AADC enzyme analysis, 25 samples had very low plasma AADC activity consistent with AADC deficiency, resulting in identification of nine additional cases. A total of five additional patients were identified by Sanger sequencing as the primary request leading to the diagnosis of AADC deficiency.

CONCLUSIONS

Overall, these analyses identified 36 new cases of AADC deficiency. Sequencing findings showed substantial diversity with identification of 26 different DDC gene variants; five had not previously been associated with AADC deficiency. The results of the present study align with the emerging literature and understanding of the epidemiology and genetics of AADC deficiency.

Consensus guideline for the diagnosis and treatment of aromatic l-amino acid decarboxylase (AADC) deficiency

Aromatic L-amino acid decarboxylase deficiency (AADCD) is a rare, autosomal recessive neurometabolic disorder that leads to a severe combined deficiency of serotonin, dopamine, norepinephrine and epinephrine. Onset is early in life, and key clinical symptoms are hypotonia, movement disorders (oculogyric crisis, dystonia, and hypokinesia), developmental delay, and autonomic symptoms.In this consensus guideline, representatives of the International Working Group on Neurotransmitter Related Disorders (iNTD) and patient representatives evaluated all available evidence for diagnosis and treatment of AADCD and made recommendations using SIGN and GRADE methodology. In the face of limited definitive evidence, we constructed practical recommendations on clinical diagnosis, laboratory diagnosis, imaging and electroencephalograpy, medical treatments and non-medical treatments. Furthermore, we identified topics for further research. We believe this guideline will improve the care for AADCD patients around the world whilst promoting general awareness of this rare disease.