Increased pH and Seizure Foci Inorganic Phosphate in Temporal Demonstrated by [<sup>31</sup>P]MRS

Laxer, Kenneth D.; Hubesch, Bruno; Sappey-Marinier, Dominique; Weiner, Michael W.

doi:10.1111/j.1528-1157.1992.tb02337.x

Cited by 73 publications

(34 citation statements)

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“…(Pi) and pH were higher and (PME) was lower throughout the entire ipsilateral temporal lobe of TLE patients as compared with the contralateral side, and there were no significant asymmetries outside the temporal lobe. This new finding adds to the previous reports in studies in which singlevolume techniques (19,20) were used to detect asymmetries in the temporal lobe. The finding that these metabolite changes occur throughout the temporal lobe indicates that these changes involve more than just the epileptogenic region and are occurring outside the seizure focus.…”

Section: Discussionsupporting

confidence: 47%

“…Studies using single-voxel (19,20) and MRSI techniques (21) in our laboratory (19,21) and others (20) have shown that [31P]MRS demonstrates interictal metabolic changes in the tempsral lobe containing the seizure focus as compared with the contralateral temporal lobe (i.e., asymmetry of 31P metabolites). These asymmetries include increased pH (19,21), increased Pi (19,21), decreased PME (19,21), and decreased PWPi (20) in the ipsilateral temporal lobe. Although we previously reported increased pH in the region of the ipsilateral hippocampus (19,21), other investigators did not observe increased pH (20,22).…”

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confidence: 99%

“…These asymmetries include increased pH (19,21), increased Pi (19,21), decreased PME (19,21), and decreased PWPi (20) in the ipsilateral temporal lobe. Although we previously reported increased pH in the region of the ipsilateral hippocampus (19,21), other investigators did not observe increased pH (20,22). The previous [31P]MRS and ['HIMRSI studies of epilepsy [except one study of frontal lobe epilepsy (23)] have focused on asymmetries in the temporal lobe.…”

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confidence: 99%

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Regional Distribution of Interictal ³¹P Metabolic Changes in Patients with Temporal Lobe Epilepsy

et al. 1998

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Summary: Purpose:We compared the 3LP metabolites in different brain regions of patients with temporal lobe epilepsy (TLE) with those from controls.Methods: Ten control subjects and 1 1 patients with TLE were investigated with magnetic resonance imaging (MRI) and [31P]MR spectroscopic imaging (MRSI).[31P]MR spectra were selected from a variety of brain regions inside and outside the temporal lobe.Results: There were no asymmetries of inorganic phosphate (Pi), pH, or phosphomonoesters (PME) between regions in the left and right hemispheres of controls. In patients with TLE, Pi and pH were higher and PME was lower throughout the entire ipsilateral temporal lobe as compared with the contralateral side and there were no significant asymmetries outside the Temporal lobe epilepsy (TLE), with mesial temporal sclerosis (MTS) as the pathology, is a common neurological disorder of unknown etiology (1,2). Current diagnostic tests to lateralize and localize the seizure focus include scalp and depth electrode EEG, computed tomography (CT), positron emission tomography (PET), single photon emission CT (SPECT), and magnetic resonance imaging (MRI) (3-5). MRI is abnormal in -60-70% of cases with MTS (2-5) and is more sensitive than CT (6-8). Patients with unilateral hippocampal atrophy or increased hippocampal T, signal intensity concordant with the ictal EEG focus have -90% chance of becoming seizure-free after temporal lobectomy (9). However, in patients with a normal MRI scan (i.e., not concordant), the prognosis for a seizure-free outcome is 550% (10). PET with [ '8F]fluorodeoxyglucose (FDG) has also been temporal lobe. The degree of ipsilateralkontralateral asymmetry for all three metabolites was substantially greater for the temporal lobe than for the frontal, occipital, and parietal lobes, and these asymmetries provided additional data for seizure localization. As compared with levels in controls, Pi and pH were increased and PME were decreased on the ipsilateral side in patients with TLE. There were changes in Pi, pH, and PME on the contralateral side in persons with epilepsy as compared with controls, contrary to changes on the ipsilateral side.Conclusions: Our findings provide some insight into the metabolic changes that occur in TLE and may prove useful adjuncts for seizure focus lateralization or localization. Key Words: Magnetic resonance spectroscopic imagingPhosphorus metabolism-Focal epilepsy-Localization.used to lateralize the seizure focus, showing hypometabolism of the temporal lobe with an incidence of 60-90% (7,11,12). However, the hypometabolic zone in PET scans in patients with TLE is usually larger than the underlying lesion and the region that generates the epileptic seizures (13). Interictal SPECT shows decreased regional cerebral blood flow in 40-80% of all patients with TLE (14-17), but has a high frequency of false positives (1 1).Phosphorous (31P) MR spectroscopy (MRS) noninvasively detects a variety of 31P metabolites, including ATP, phosphocreatine (PCr), inorganic phosphate (Pi), phosphomonoester...

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Section: Discussionsupporting

confidence: 47%

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confidence: 99%

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confidence: 99%

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Regional Distribution of Interictal ³¹P Metabolic Changes in Patients with Temporal Lobe Epilepsy

et al. 1998

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“…Prior to the wide spread availability of 1 H spectroscopy on clinical MR systems, Weiner and colleagues (35) evaluated the use of 31 P spectroscopy for the lateralization of epileptogenic regions. In these initial studies at 2.0T, significant alterations in inorganic phosphate (73% increase) and brain pH (0.17 unit increase) were reported.…”

Section: P Spectroscopy and Lasteralization Of Epileptogenic Regionsmentioning

confidence: 99%

¹H and ³¹P spectroscopy and bioenergetics in the lateralization of seizures in temporal lobe epilepsy

Hetherington

Pan

Spencer

2002

Magnetic Resonance Imaging

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Over the past decade, 1 H and 31 P spectroscopy measurements have demonstrated that significant metabolic alterations occur in temporal lobe epilepsy. However, to most accurately interpret these changes, metabolic heterogeneity and differences between gray and white matter must be accounted for. These alterations, decreased NAA and the ratio of phosphocreatine/inorganic phosphate, can be reversed with successful treatment of seizures. The reversibility of these two measures is consistent with the localization of NAA synthesis to neuronal mitochondria and the important role for bioenergetics in the pathophysiology of temporal lobe epilepsy.

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“…31P MRS has revealed interictal increases in pH and Pi and a decrease in phosphomonoesters (5,6). These changes accurately lateralize the seizure focus in patients with medically refractory temporal lobe epilepsy (TLE) (7) and frontal lobe epilepsy (FLE) (8).…”

Section: Early Studiesmentioning

confidence: 99%

Clinical Applications of Magnetic Resonance Spectroscopy

Laxer¹

1997

Epilepsia

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Summary: Magnetic resonance spectroscopy (MRS) is a new tool for evaluation of patients with epilepsy, demonstrating abnormalities of energy and lipid metabolism ictally and, more recently, interictally. These metabolic abnormalities include increased inorganic phosphate, pH, and decreased phosphomonoesters as determined by "P MRS, as well as decreased Nacetylaspartate determined by 'H MRS. Furthermore, increased lactic acid has been detected postictally. These metabolic changes appear to be confined to the region of seizure origination and can be detected interictally. Therefore, they can be used for lateralization of the epileptogenic focus. Ongoing research suggests that these abnormalities may also be useful in localization of the focus, demonstrating metabolic alterations in temporal lobe epilepsy (TLE) similar to those in neocortical epilepsy. However, further technical development will be required before the goal of using these techniques for localization of the epileptogenic focus can be realized. For TLE lobe epilepsy at least, the clinical utility of 'H MRS to lateralize the seizure focus has clearly been demonstrated by several centers. The consistent findings in TLE suggest that 'H MRS is ready to become part of the evaluation process of patients with medically refractory epilepsy being evaluated for seizure surgery. Key Words: Neurological diagnosis-Magnetic resonance spectroscopy-Frontal lobe epilepsy-Temporal lobe epilepsy-Partial seizures-Phosphorous-N-acetylaspartate.Magnetic resonance spectroscopy (MRS) has been used extensively over the past 30 years in molecular physics, but only recently has it been applied to medicine and, in particular, to the study of epilepsy. MRS is the only technique that can noninvasively measure the chemical constituents of tissue in vivo. When placed in a magnetic field, chemically distinct nuclei in a compound resonate at slightly differing frequencies. This resonance depends not only on the strength of the externally applied magnetic field but also on the local magnetic environment due to the surrounding electron cloud. The separation of compounds based on these resonant frequency shifts (chemical shift) is the basis of MRS [see Matson and Weiner (1) for review]. The chemical shift allows, for example, the detection of a wide variety of proton signals on a given protein or the different phosphates in ATP. In addition, the MRS signals from many compounds can be measured simultaneously in a single MRS experiment. Because the same instrument can be used for MRI and MRS, the overwhelming proliferation of MRI units throughout the world will allow this technique to flourish. EARLY STUDIESMany of the metabolites involved in energy metabolism can be measured by 3'P MRS, including phosphocreatine (PCr), ATP, and inorganic phosphate (Pi), which allows the determination of intracellular pH. This technique applied to experimental seizures in animals and human neonatal seizures has demonstrated intraictal depletion of PCr and ATP and increases in Pi and H+ (2,3). Similarly, in...

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Increased pH and Seizure Foci Inorganic Phosphate in Temporal Demonstrated by [³¹P]MRS

Cited by 73 publications

References 30 publications

Regional Distribution of Interictal ³¹P Metabolic Changes in Patients with Temporal Lobe Epilepsy

Regional Distribution of Interictal ³¹P Metabolic Changes in Patients with Temporal Lobe Epilepsy

¹H and ³¹P spectroscopy and bioenergetics in the lateralization of seizures in temporal lobe epilepsy

Clinical Applications of Magnetic Resonance Spectroscopy

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Increased pH and Seizure Foci Inorganic Phosphate in Temporal Demonstrated by [31P]MRS

Cited by 73 publications

References 30 publications

Regional Distribution of Interictal 31P Metabolic Changes in Patients with Temporal Lobe Epilepsy

Regional Distribution of Interictal 31P Metabolic Changes in Patients with Temporal Lobe Epilepsy

1H and 31P spectroscopy and bioenergetics in the lateralization of seizures in temporal lobe epilepsy

Clinical Applications of Magnetic Resonance Spectroscopy

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Product

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Increased pH and Seizure Foci Inorganic Phosphate in Temporal Demonstrated by [³¹P]MRS

Regional Distribution of Interictal ³¹P Metabolic Changes in Patients with Temporal Lobe Epilepsy

Regional Distribution of Interictal ³¹P Metabolic Changes in Patients with Temporal Lobe Epilepsy

¹H and ³¹P spectroscopy and bioenergetics in the lateralization of seizures in temporal lobe epilepsy