BRAIN METABOLIC PROFILES OBTAINED BY PROTON MRS IN 2 FORMS OF MITOCHONDRIOPATHIES - LEBERS HEREDITARY OPTIC NEUROPATHY AND CHRONIC PROGRESSIVE EXTERNAL OPHTHALMOPLEGIA

The status of brain metabolism has been evaluated using monovoxel shor t echo time (20 ms) H-1 magnetic resonance spectroscopy in 6 patients with two forms of mitochondrial disorders without clinical cerebral in volvement: 2 patients with Leber's hereditary optic neuropathy (LHON) and 4 patients with chronic progressive external ophthalmoplegia (CPEO ). Patients with LHON displayed normal spectra. In all patients with C PEO, the brain metabolic profiles were abnormal, with no single unifor m pattern. No typical cerebral metabolic profile was found even when t hese disorders were classified either by syndrome or by biochemical de fect. No lactate signal was detected. The metabolic alterations observ ed in CPEO patients contrasted with the absence of clinical signs of e ncephalopathy. The absence of a typical metabolic profile reflects the large variability in the clinical expression of biochemical defects i n mitochondriopathies, and the lack of convergence between genetic del etions, biochemical anomalies and clinical syndromes.