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Neuropathology Of Neuro-Ophthalmic Disorders
Published in Vivek Lal, A Clinical Approach to Neuro-Ophthalmic Disorders, 2023
Ultrastructural examination can show abnormal mitochondria, including variable size and shape, paracrystalline inclusions (parking lot inclusions) and abnormal swollen cristae (Figure 25.4). The findings of electron microscopy need correlation with light microscopy and clinical features, biochemical mitochondrial assays and genetic testing before a confirmed diagnosis of mitochondrial myopathy is made.4 For mtDNA analysis, muscle biopsy serves as an appropriate sample since the amount of abnormal mtDNA is highest in muscle tissue as compared to tissue fibroblasts or white blood cells.
Metabolic Myopathy
Published in Maher Kurdi, Neuromuscular Pathology Made Easy, 2021
In muscle biopsy, the muscle tissue is either unremarkable or it may show minimal myopathic features with focal mitochondrial dysfunction. The latter is histologically seen as subsarcolemmal basophilia in muscle fibers (Figure 19.2a). This basophilic aggregation is visualized as either ragged-red fibers by Gomori trichrome stain or ragged-blue fibers with oxidative stain (SDH and NADH stain) (Figure 19.2b–d). A single muscle fiber with ragged red fiber is enough to diagnose mitochondrial myopathy. COX-negative fibers are other specific histological features of mitochondrial myopathy (Figure 19.2e). Bear in mind, ragged fibers should be differentiated from necrotizing degenerating fibers accumulating mitochondria. This can be distinguished by electron microscopy (EM). Ultrastructural examination of diseased tissue of mitochondrial dysfunction shows abnormal mitochondrial aggregation, mitochondrial bloating and enlargement, and paracrystallin inclusions (Figure 12.1d, l-Chapter 12).
Implication of Mitochondrial Coenzyme Q10 (Ubiquinone) in Alzheimer’s Disease *
Published in Abhai Kumar, Debasis Bagchi, Antioxidants and Functional Foods for Neurodegenerative Disorders, 2021
Sayantan Maitra, Dibyendu Dutta
Mitochondrial myopathy is a disease condition which leads to damage of the mitochondria, energy-producing structure in cells. It has been observed that the level of CoQ10 is frequently reduced in the muscle tissues of the patients with mitochondrial myopathy [55]. Numerous studies have reported that CoQ10 supplementation in a dose of 30–300 mg/day alters the severity of mitochondrial disorders [56,57].
The Diagnostic Yield of Electromyography at Detecting Abnormalities on Muscle Biopsy: A Single Center Experience
Published in The Neurodiagnostic Journal, 2021
Patrick B. Moloney, Stela Lefter, Aisling M. Ryan, Michael Jansen, Niamh Bermingham, Brian McNamara
A normal EMG may be falsely reassuring in some instances. We identified 17 “false negative” EMGs, with specific myopathic pathology demonstrated on 6 corresponding muscle biopsies. Four of these cases were ultimately diagnosed with mitochondrial myopathy. Approximately 1/5 of patients with mitochondrial myopathy have normal EMGs (Petty et al. 1986). Central core myopathy and glycogen storage disorders (e.g., McArdle’s disease) when examined between attacks may be associated with normal EMG (Lacomis 2012), as was seen in 2 cases in our cohort. When the history, clinical examination or ancillary tests are suggestive of a myopathy, it may be prudent to perform a muscle biopsy despite a normal EMG. The severity of myopathic or neurogenic pathological changes in some of the remaining 11 patients with abnormal muscle biopsy and normal EMG studies, may have been below the threshold to produce significant EMG abnormalities. “False positive” EMG studies may result from selective or transient muscle involvement (Pugdahl et al. 2017). Non-targeted single site biopsy is associated with missed diagnosis in approximately 1/3 of cases (Prayson 2006).
Can miR-34a be suitable for monitoring sensorineural hearing loss in patients with mitochondrial disease? A case series
Published in International Journal of Neuroscience, 2020
Roberta Marozzo, Valentina Pegoraro, Laura Dipietro, Massimo Ralli, Corrado Angelini, Arianna Di Stadio
Patient 1 was a 75 year-old man, affected by mitochondrial myopathy with multiple mitochondrial DNA (mtDNA) deletions, suffering from chronic obstructive pulmonary disease, hypertension, and Still disease. At the time of the study, the patient was being treated with corticosteroids (4 mg), rabeprazole (20 mg), idebenone (2700 mg), carnitine (2 g), alpha-lipoic acid (600 mg), oral supplement “Creatinine Plus” (1/die), tamsulosin (0.4 mg), verapamil chloralhydrate (180 mg), umeclidinium bromide (1 puff), beclomethasone (160 mg), formoterol (6 mg) (1 puff) and calcium carbonate and cholecalciferol (1 capsule). Also, the patient took 35 mg of Risedronic acid sodic salt weekly and 25.000 UI of vitamin D3 every 15 days. PTA showed a moderate to severe form of bilateral SNHL and normal impedance with bilateral absence of stapedius reflexes. The DPOAE test showed cochlear function impairment in the 1500-8000 Hz frequency range. ABR waves I and II were absent bilaterally, while waves III and V were normal.
The therapeutic potential of a calorie-restricted ketogenic diet for the management of Leber hereditary optic neuropathy
Published in Nutritional Neuroscience, 2019
Mithu Storoni, Matthieu P. Robert, Gordon T. Plant
The possibility that increased mitochondrial biogenesis may afford protection from developing the disease has shifted attention towards pharmacological agents that promote mitochondrial biogenesis as potential treatment options for LHON. Agents such as Bezafibrate and 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR), which target the transcriptional activator PGC-1α, show promise in early studies. Bezafibrate is a PPAR agonist. In a mouse model of cytochrome oxidase mitochondrial myopathy (Cox 10), it promoted mitochondrial biogenesis within skeletal muscle through the increased expression of PGC-1α genes.43 The effects of Bezafibrate, may, however, be unpredictable. In the ACTA-Cox15 model of mitochondrial myopathy, Bezafibrate resulted in death within 48 hours.44 The stimulation of fatty acid oxidation through the effect on PPAR may contribute to the hepatomegaly and toxicity seen in mouse models and although the orthologous difference in PPAR between humans and mice may protect humans from hepatomegaly, Bezafibrate has been associated with rhabdomyolysis and renal disease in humans.45–47 AICAR is thought to increase mitochondrial biogenesis through the activation of PGC-1α via the AMP kinase pathway. It has been shown to be beneficial in mouse models of mitochondrial myopathy, but it does not penetrate the blood–brain barrier well.44,48