Mitochondrial dysfunction in a patient with Joubert syndrome

Anesthetic considerations of Joubert syndrome in patients with mitochondrial disease - A case report

Background

Joubert syndrome and mitochondrial disease are rare congenital diseases in which a wide range of symptoms affects multiple organs. Patients with these diseases present characteristic symptoms related to the musculoskeletal, respiratory, and neurological systems, which make it difficult for anesthesiologists to manage the patient’s airway and choose appropriate anesthetic drugs.

Case

A 13-year-old male patient with Joubert syndrome and mitochondrial disease underwent elective surgery to insert a continuous ambulatory peritoneal dialysis catheter. Anesthesia was induced and maintained with propofol, remifentanil, and rocuronium. An I-gel was inserted to secure the airway; however, the fitting did not work properly, so the patient was intubated. The operation was completed without any major problems, and the intubated patient was transferred to the intensive care unit.

Conclusions

Anesthesiologists should determine the method of anesthesia and prepare for unintended complications based on a full understanding of these congenital diseases.

Visual Evoked Potentials in Joubert Syndrome: A Suggested Useful Method for Evaluating Future Approaches Targeted to Improve Visual Pathways' Function

Introduction

Joubert syndrome (JS) is a recessive disorder characterized by a congenital malformation of the mid-hindbrain and a large spectrum of clinical features including optic nerve morphologic abnormalities. The function of the visual pathways, including the optic nerve, can be objectively evaluated by visual evoked potential (VEP) recordings. Our work aims to employ VEP to evaluate the neural conduction along the visual pathways in JS patients with or without optic nerve morphologic abnormalities (ONMA).

Methods

In this observational and prospective study, 18 children with genetic diagnosis of JS (mean age 8.78 ± 5.87 years) and 17 healthy age-similar control subjects (control group, 9.05 ± 6.02 years) were enrolled.

Based on presence/absence of ONMA at fundus examination, JS patients were divided into two groups: the JS-A group (eight patients with ONMA) and JS-N group (ten patients without ONMA). Following the ISCEV standards, pattern VEPs were recorded in patients and controls in response to 60’ and 15’ checks to obtain a prevalent activation of large or small axons, respectively.

Results

Compared to controls, both the JS-A and JS-N groups showed significant abnormalities in 60’ and 15’ VEP implicit time and amplitude. Only in the JS-N group were values of 15’ VEP implicit significantly correlated with the corresponding values of visual acuity.

Conclusions

Our results suggest that a visual pathways dysfunction (of both large and small axons) detectable by VEP may occur in JS patients regardless of the presence of ONMA. Since clinical trials are envisaged in the near future to address JS-related ocular problems, our results might provide information about the potential usefulness of VEP recordings to assess the efficacy of treatments targeted to improve the visual pathways’ function.

Mitochondrial energy production correlates with the age-related BMI

Besides characteristic neurologic and musculoskeletal symptoms, children with mitochondrial dysfunction often present with feeding problems and failure to thrive. Substrate depletion for the respiratory chain has an effect on energy expenditure. Secondary mitochondrial dysfunction has been reported in severe chronic malnutrition. We evaluated the nutritional state, the growth parameters, and the metabolic condition in 172 children undergoing muscle biopsy for a suspected disorder of the oxidative phosphorylation system (OXPHOS). We performed dietary evaluation and initiated nutritional intervention when needed before the biopsy. Mitochondrial dysfunction was confirmed by detection of enzyme-complex deficiencies and/or by mutations in 83 children, in 14 patients no biochemical abnormalities were found. In the whole study group, and in the subgroup with enzyme-complex deficiency and/or mutation, a significant correlation was found between the mitochondrial production of adenosine triphosphate (ATP) and the age-related body mass index (BMI). Nutritional state and growth should be considered by interpreting the results of ATP-production in fresh muscle biopsy. Because of a positive correlation between the age-appropriate BMI and the ATP-production, we strongly advise optimizing the nutritional state preceding the muscle biopsy in children with a suspected OXPHOS-disorder. Dietary intervention remains although challenging because of frequent gastrointestinal problems and eating disorders.

Measurement of the Energy-Generating Capacity of Human Muscle Mitochondria: Diagnostic Procedure and Application to Human Pathology

Background: Diagnosis of mitochondrial disorders usually requires a muscle biopsy to examine mitochondrial function. We describe our diagnostic procedure and results for 29 patients with mitochondrial disorders.

Methods: Muscle biopsies were from 43 healthy individuals and 29 patients with defects in one of the oxidative phosphorylation (OXPHOS) complexes, the pyruvate dehydrogenase complex (PDHc), or the adenine nucleotide translocator (ANT). Homogenized muscle samples were used to determine the oxidation rates of radiolabeled pyruvate, malate, and succinate in the absence or presence of various acetyl Co-A donors and acceptors, as well as specific inhibitors of tricarboxylic acid cycle or OXPHOS enzymes. We determined the rate of ATP production from oxidation of pyruvate.

Results: Each defect in the energy-generating system produced a specific combination of substrate oxidation impairments. PDHc deficiencies decreased substrate oxidation reactions containing pyruvate. Defects in complexes I, III, and IV decreased oxidation of pyruvate plus malate, with normal to mildly diminished oxidation of pyruvate plus carnitine. In complex V defects, pyruvate oxidation improved by addition of carbonyl cyanide 3-chlorophenyl hydrazone, whereas other oxidation rates were decreased. In most patients, ATP production was decreased.

Conclusion: The proposed method can be successfully applied to the diagnosis of defects in PDHc, OXPHOS complexes, and ANT.