Bruno Barbiroli

Abnormal brain and muscle energy metabolism shown by 31P magnetic resonance spectroscopy in patients affected by migraine with aura

We studied brain and muscle energy metabolism by phosphorus 31 magnetic resonance spectroscopy (31P-MRS) in 12 patients affected by migraine with aura (classic migraine) in interictal periods. Brain 31P-MRS disclosed a low phosphocreatine content in all patients, accompanied by high adenosine diphosphate concentration, a high percentage of V/Vmax (adenosine triphosphate), and a low phosphorylation potential—features showing an unstable state of metabolism in classic migraine. Abnormal muscle mitochondrial function, in the absence of clinical signs of muscle impairment, was present in nine of the 12 patients examined.

Deficit of in vivo mitochondrial ATP production in OPA1-related dominant optic atrophy.

Dominant optic atrophy has been associated with mutations in the OPA1 gene, which encodes for a dynamin‐related GTPase, a mitochondrial protein implicated in the formation and maintenance of mitochondrial network and morphology. We used phosphorus magnetic resonance spectroscopy to assess calf muscle oxidative metabolism in six patients from two unrelated families carrying the c.2708‐2711delTTAG deletion in exon 27 of the OPA1 gene. The rate of postexercise phosphocreatine resynthesis, a measure of mitochondrial adenosine triphosphate production rate, was significantly delayed in the patients. Our in vivo results show for the first time to our knowledge a deficit of oxidative phosphorylation in OPA1‐related DOA. Ann Neurol 2004;56:719–723

Defective Brain Energy Metabolism Shown by in vivo 31P MR Spectroscopy in 28 Patients with Mitochondrial Cytopathies

We studied brain energy metabolism by phosphorus magnetic resonance spectroscopy (31P MRS) in 28 patients with mitochondrial cytopathies, and 20 normal control subjects. Fourteen patients had myopathy alone, six had only mild brain symptoms, and eight showed different degrees of brain involvement. Brain 31P MRS showed a low phosphocreatine content in all patients, accompanied by a high inorganic phosphate in 14 of 28 patients. The average value of the Pi concentration in the patient group was significantly (p = 0.009) different from the control group. The cytosolic pH was normal. From these data were derived a high concentration of ADP (calculated from the creatine kinase equilibrium), a high percent value of V/Vmax for ATP biosynthesis, and a low phosphorylation potential, all features showing a derangement of brain energy metabolism, in all patients with mitochondrial cytopathies. 31P MRS proved to be sensitive enough to disclose a deficit of mitochondrial functionality not only in the affected patients, but also in those without clinically evident brain symptoms.

Diffusion-weighted brain imaging study of patients with clinical diagnosis of corticobasal degeneration, progressive supranuclear palsy and Parkinson's disease

Corticobasal degeneration (CBD) and progressive supranuclear palsy (PSP) are two neurodegenerative disorders within the category of tauopathies, which must be considered in differential diagnosis of Parkinsons disease. Although specific clinical and neuroradiological features help to guide the clinician to a likely diagnosis of Parkinsons disease, CBD or PSP, differential diagnosis remains difficult. The aim of our study was to analyse apparent diffusion coefficient (ADC(ave)) maps from patients with clinical diagnosis of CBD (corticobasal syndrome, CBS), classical phenotype of PSP (Richardsons syndrome, RS) and Parkinsons disease (PD) in order to identify objective markers to discriminate between these groups. Thirteen Parkinsons disease patients, 10 RS patients, 7 CBS patients and 9 healthy volunteers were recruited and studied in a 1.5 T MR scanner. Axial diffusion-weighted images were obtained and the ADC(ave) map was generated. Regions of interest (ROIs) included mesencephalon, corpus callosum and left and right superior cerebellar peduncle (SCP), thalamus, caudate, putamen, pallidus, posterior limb of internal capsule, frontal and parietal white matter. Histograms of ADC(ave) were generated for all voxels in left and right cerebral hemispheres and in left and right deep grey matter regions separately, and the 50th percentile values (medians) were determined. The ratio of the smaller to the larger median value (symmetry ratio) was calculated for left and right hemispheres and for left and right deep grey matter regions (1 = perfect symmetry). Putaminal ADC(ave) values in CBS and RS were significantly greater than those in Parkinsons disease and healthy volunteers, but could not distinguish CBS from RS patients. In CBS patients, the values of the medians of cerebral hemispheres histograms were significantly higher than those in RS, Parkinsons disease and healthy volunteers, while the hemispheric symmetry ratio in CBS (0.968, range 0.952-0.976) was markedly reduced compared with RS (0.993, range 0.992-0.994), Parkinsons disease (0.991, range 0.988-0.993) and healthy controls (0.990, range 0.988-0.993). The hemispheric symmetry ratio differentiated CBS patients from RS and Parkinsons disease patients with a sensitivity and specificity of 100%. In RS patients, the ADC(ave) values of the SCPs were significantly greater than those in Parkinsons disease and healthy volunteers. Our findings confirm that putaminal ADC(ave) values evaluation provides a good discrimination between Parkinsons disease and atypical parkinsonisms, including RS and CBS. Furthermore, diffusion-weighted imaging, by detecting the brain microstructural correlates of the typical asymmetric signs and symptoms in CBS and the SCP involvement in RS, was shown to aid characterization and differentiation of atypical parkinsonism.

31P-magnetic resonance spectroscopy in migraine without aura

We investigated 22 patients with migraine without aura, all drug-free and in headache-free periods, by means of 31P-magnetic resonance spectroscopy (MRS) of brain and muscle. Brain 31P-MRS showed significantly low phosphocreatine, increased adenosine diphosphate, and decreased phosphorylation potential. There was a slow rate of phosphocreatine recovery after exercise in the muscle of 12 of 22 patients. Energy metabolism is abnormal in migraine without aura, as previously demonstrated in patients with migraine stroke and migraine with aura.

Diffusion tensor MRI changes in cerebellar structures of patients with familial essential tremor

Objective: The aim of our study was to investigate the microstructural integrity of brain regions functionally involved in the tremor loop in patients with familial essential tremor (FET), using diffusion tensor imaging (DTI). Methods: Twenty-five patients with FET, 15 patients with Parkinson disease (PD), and 15 healthy subjects were studied. DTI was performed to measure fractional anisotropy (FA) and mean diffusivity (MD) in various regions of interest: red nucleus, dentate nucleus (DN), cerebellar white matter, middle (MCP) and superior cerebellar peduncle (SCP), and ventrolateral thalamus. Results: In patients with FET, FA values in the DN (median 0.19, range 0.13–0.23) were reduced (p < 0.001) compared with patients with PD (median 0.37, range 0.32–0.58) and healthy controls (median 0.36, range 0.33–0.40). In patients with FET, FA was also reduced (p = 0.003) and MD values increased (p < 0.001) in the SCP compared with patients with PD and healthy controls. Among patients with FET, those with longer disease duration showed FA values in the DN lower than those with shorter disease duration (p = 0.018). Patients with FET could be completely distinguished from both patient with PD and healthy controls using FA values of the DN alone. Conclusion: Neuroimaging evidence of microstructural changes consistent with neurodegeneration was found in the dentate nucleus (DN) and SCP of patients with familial essential tremor. This suggests that neurodegenerative pathology of cerebellar structures may play a role in essential tremor. Further studies are needed to assess the role of fractional anisotropy and mean diffusivity changes in DN and SCP in the differential diagnosis of essential tremor and Parkinson disease, which may present similar clinical signs at the onset of disease.

Diffusion MRI shows increased water apparent diffusion coefficient in the brains of cirrhotics

Background: Brain edema and increased intracranial pressure worsen prognosis in patients with end-stage chronic cirrhosis. Objective: To use diffusion-weighted imaging (DWI) to quantify water apparent diffusion coefficient (ADC) in different brain regions of patients with chronic liver failure with or without hepatic encephalopathy. Methods: The authors studied 14 patients with viral liver cirrhosis and 12 sex- and age-matched healthy volunteers. Seven patients had no clinical evidence of hepatic encephalopathy; six had grade I hepatic encephalopathy; and one had grade II hepatic encephalopathy. Brain DWI was obtained using a single-shot echo-planar imaging sequence, and four gradient strengths (b values = 0, 300, 600, and 900 s/mm2) were applied to calculate the average diffusivity maps. Results: Mean ADC values in the brains of patients with cirrhosis were significantly increased in all selected regions of interest (caudate, putamen, and pallidus nuclei; occipital, parietal, and frontal lobe white matter) except in the thalamus. Venous ammonia was linearly related to ADC values in deep gray and white matter regions of interest. Conclusions: Brain water apparent diffusion coefficient is increased in patients with chronic liver disease and may be useful in monitoring patients with hepatic encephalopathy.

The ND1 gene of complex I is a mutational hot spot for Leber's hereditary optic neuropathy

A novel mitochondrial DNA (mtDNA) transition (3733G→A) inducing the E143 K amino acid change at a very conserved site of the NADH dehydrogenase subunit 1 (ND1) was identified in a family with six maternally related individuals with Lebers hereditary optic neuropathy (LHON) and in an unrelated sporadic case, all negative for known mutations and presenting with the canonical phenotype. The transition was not detected in 1,082 control mtDNAs and was heteroplasmic in several individuals from both pedigrees. In addition, the mtDNAs of the two families were found to belong to different haplogroups (H and X), thus confirming that the 3733G→A mutation occurred twice independently. Phosphorus magnetic resonance spectroscopy disclosed an in vivo brain and skeletal muscle energy metabolism deficit in the four examined patients. Muscle biopsy from two patients showed slight mitochondrial proliferation with abnormal mitochondria. Biochemical investigations in platelets showed partially insensitive complex I to rotenone inhibition. We conclude that the 3733G→A transition is a novel cause of LHON and, after those at positions 3460 and 4171, is the third ND1 mutation to be identified in multiple unrelated families. This finding shows that, in addition to ND6, the ND1 subunit gene is also a mutational hot spot for LHON. Ann Neurol 2004;56:631–641

Clinical and brain bioenergetics improvement with idebenone in a patient with Leber's hereditary optic neuropathy: a clinical and 31P-MRS study

We used phosphorus magnetic resonance spectroscopy (31P-MRS) to study in vivo brain and muscle bioenergetics in a male patient with Lebers hereditary optic neuropathy (LHON) and mtDNA mutation at 11,778 bp who developed spastic paraparesis with white matter lesions on brain MR imaging. The study was performed before and during treatment with idebenone (135 mg t.i.d.) and after withdrawal. Clinical amelioration and worsening were associated with parallel changes in brain and skeletal muscle bioenergetics following the administration or withdrawal of idebenone. Reversal of paraparesis by idebenone was paralleled by normalization of 31P-MRS, serum lactate and central motor conduction. Extra-ocular neurological dysfunction in LHON may be amenable to treatment by appropriate quinones.

Apparent diffusion coefficient of the superior cerebellar peduncle differentiates progressive supranuclear palsy from Parkinson's disease

The early diagnosis of progressive supranuclear palsy (PSP) may be challenging, because of clinical overlapping features with Parkinsons disease (PD) and other parkinsonian syndromes such as the Parkinsonian variant of multiple system atrophy (MSA‐P). Conventional MRI can help in differentiating parkinsonian disorders but its diagnostic accuracy is still unsatisfactory. On the basis of the pathological demonstration of superior cerebellar peduncle (SCP) atrophy in patients with PSP, we assessed the SCP apparent diffusion coefficient (ADC) values in patients with PSP, PD, and MSA‐P in order to evaluate its differential diagnostic value in vivo. Twenty‐eight patients with PSP (14 with possible‐PSP and 14 with probable‐PSP), 15 PD, 15 MSA‐P, and 16 healthy subjects were studied by using diffusion weighted imaging (DWI). ADC was calculated in regions of interest defined in the left and right SCP by two clinically blinded operators. Intrarater (r = 0.98, P < 0.001) and interrater reliability (r = 0.97; P < 0.001) for SCP measurements were high. Patients with PSP had higher SCP rADC values (median 0.98 × 10−3mm2/s) than patients with PD (median 0.79 × 10−3 mm2/s, P < 0.001), MSA‐P (median 0.79 × 10−3 mm2/s, P < 0.001), and healthy controls (median 0.80 × 10−3 mm2/s, P < 0.001). DWI discriminated patients with PSP from PD and healthy subjects on the basis of SCP rADC individual values (100% sensitivity and specificity) and from patients with MSA‐P (96.4% sensitivity and 93.3% specificity). The higher values of rADC in SCP of patients with PSP correspond with the in vivo microstructural feature of atrophy detected postmortem and provide an additional support for early discrimination between PSP and other neurodegenerative parkinsonisms.