³¹P MR Spectroscopic Assessment of Muscle in Patients with Myasthenia Gravis before and after Thymectomy: Initial Experience

Abstract

Mild-MG group patients have muscle oxidative metabolism similar to that of healthy control subjects, whereas moderate-to-severe-MG group patients have impaired V(max) during exercise and a noticeable shift to glycolytic metabolism, but these abnormalities are reversible after thymectomy.

Proton magnetic resonance spectroscopy of the intrinsic tongue muscles in patients with myasthenia gravis with different autoantibodies

“…Kreis et al showed that CP peak on proton MRS of human muscle reflected phosphocreatine rather than creatine levels [21], thus decrease of CP peak in our MG patients was probably due to decrease in phosphocreatine. Previous 31 P spectroscopic study demonstrated poor phosphocreatine recovery during exercise in calf muscles of patients with moderate to severe MG reflecting the presence of mitochondrial dysfunction [22]. Impaired mitochondria probably fails to shift fuel utilization from carbohydrates to lipids [13] and it may be a reason for accumulation of IMCL (and maybe EMCL) in muscles of patients with both forms of MG. Mitochondrial abnormality has been the most frequently reported alternative mechanism in pathogenesis of MG so far [7,20,21] and we found it in both investigated forms of MG.…”

Deficits in Endogenous Adenosine Formation by Ecto‐5′‐Nucleotidase/CD73 Impair Neuromuscular Transmission and Immune Competence in Experimental Autoimmune Myasthenia Gravis

“…Muscle paralysis with μ -conotoxin GIIIB, a toxin that blocks muscle-specific voltage-gated Na + channels without affecting neuronal function [ 37 ], decreased nerve-evoked ATP (~15%) and ADO (>90%) outflow [ 7 ]. Moderate-to-severe MG patients have impaired oxidative metabolism and a noticeable shift to glycolytic metabolism during exercise, which yields to higher-end Pi/ATP ratio and reduced levels of synaptic ADO levels [ 38 ]. Besides the fact that exocytosis of ATP may occur synchronously with ACh in a frequency-dependent manner [ 13 , 39 ], the nucleotide may also be released by tetanic stimulation of skeletal myotubes from healthy animals, through pannexin-1 hemichannels, within a 15 s to 3 min time scale [ 40 ].…”

In vivo 31P spectroscopy by fully adiabatic extended image selected in vivo spectroscopy: A comparison between 3 T and 7 T

“…Long measurement times and relatively low spatial resolution have limited the clinical use of 31 P-MRS (3)(4)(5)(6). Nevertheless, some groups have proved the clinical value of 31 P-MRS for the assessment of metabolic disorders (7)(8)(9) or oncology (2). 31 P-MRS significantly benefits from higher magnetic field strengths (i.e., 7 T) (10)(11)(12).…”