Leber's hereditary optic neuropathy: genetic, biochemical, and phosphorus magnetic resonance spectroscopy study in an Italian family

Three siblings of a family affected with Leber's hereditary optic neuropathy (LHON) showed a mitochondrial DNA mutation at position 11778. The lactate response to a standardized effort was increased in only one case. Muscle biopsies and biochemistry of muscle and platelet mitochondrial enzymes were normal. All patients showed an altered energy metabolism during exercise and during recovery after exercise on phosphorus 31-magnetic resonance spectroscopy (31P-MRS) of muscle. Brain 31P-MRS showed a decreased energy reserve (decreased PCr/Pi ratio) in all patients. 31P-MRS noninvasively demonstrated an altered mitochondrial energy metabolism in muscle and, for the first time, in the brains of LHON patients.     

Muscle energy metabolism in female DMD/BMD carriers: a 31P-MR spectroscopy study.

31P nuclear magnetic resonance spectroscopy (31P-MRS) was used to investigate the energy metabolism of the gastrocnemius muscle in 16 DMD/BMD female carriers. No significant difference was found with the controls in the resting muscle, while all carriers showed a decreased ability to perform work, and a higher Pi/PCr ratio for comparable relative levels of steady-state work. The rate of postexercise recovery of PCr/Pi ratio was lower in all carriers. The decreased rate of PCr/Pi recovery appears to be mainly due to a decreased rate of Pi recovery. Our findings show abnormal muscle energy metabolism in DMD/BMD female carriers.     

Cerebral metabolic effects of neonatal seizures measured with in vivo 31P NMR spectroscopy

In vivo phosphorus 31 nuclear magnetic resonance (31P NMR) spectroscopy was used to evaluate changes in cerebral high-energy phosphate compounds in 8 infants with seizures. During the study 4 babies had seizures that caused a 50% decrease in the phosphocreatine to inorganic phosphate (PCr/Pi) ratio. Focal seizures caused lateralized decreases in the PCr/Pi ratio; generalized seizures caused bilateral decreases. Postictal spectra had increased PCr/Pi ratios, presumably due to postictal inhibition. Interictal 31P NMR spectra were normal. One patient's seizures were successfully treated with intravenously administered phenobarbital during NMR data acquisition, causing an immediate increase in the PCr/Pi ratio from 0.7 to 1.2. These studies indicate that cerebral PCr concentration decreases by approximately 33% and that oxidative metabolism increases by approximately 45% during neonatal seizures. Five babies had PCr/Pi ratios of less than 0.8 during seizures and subsequently developed long-term neurological sequelae, which suggests that neonatal seizures may cause or exacerbate cerebral injury by increasing cerebral metabolic demands above energy supply.     

脂质沉积性肌病骨骼肌磁共振31磷波谱的临床价值研究

目的探讨脂质沉积性肌病(LSM)患者骨骼肌磁共振31磷波谱(31P-MRS)改变特征,以及在LSM辅助诊断和疗效评价方面的临床价值。方法对12例LSM患者在治疗前后和11例对照者分别进行31P-MRS扫描,获取波谱图像,计算谱线中无机磷酸盐(Pi)、磷酸肌酸(PCr)及三磷酸腺苷(ATP)的峰下面积,记录Pi/ATP、PCr/ATP和Pi/PCr的比值,计算Pi、PCr、细胞内pH(pHint)、二磷酸腺苷(ADP)和磷酸化潜能(PP)的值,并比较LSM患者治疗前和对照组、LSM患者治疗前后上述31P-MRS指标的差异。结果 LSM患者治疗前的PCr、PCr/ATP和PP较对照组明显降低(P<0.05),Pi/PCr和ADP较对照组明显升高(P<0.05),Pi、Pi/ATP和pHint与对照组比较无明显差异(P>0.05);LSM患者治疗后的PCr、PCr/ATP和PP较治疗前明显升高(P<0.05),ADP较治疗前明显降低(P<0.05),Pi、Pi/ATP、Pi/PCr和pHint与治疗前比较无明显差异(P>0.05)。结论31P-MRS可无创性检测LSM患者肌肉组织的能量代谢变化,有利于LSM的辅助诊断,并可运用于LSM患者的疗效评价。     

Energy metabolism measured by 31P magnetic resonance spectroscopy in the healthy human brain

Background and purposePhosphorous magnetic resonance spectroscopy (31P-MRS) allows a non-invasive analysis of phosphorus-containing compounds in vivo. The present study investigated the influence of brain region, hemisphere, age, sex and brain volume on 31P-MRS metabolites in healthy adults.Materials and methodsSupratentorial brain 31P-MRS spectra of 125 prospectively recruited healthy volunteers (64 female, 61 male) aged 20 to 85 years (mean: 49.4 ± 16.9 years) were examined with a 3D-31P-MRS sequence at 3T, and the compounds phosphocreatine (PCr), inorganic phosphate (Pi) and adenosine triphosphate (ATP) were measured. From this data, the metabolite ratios PCr/ATP, Pi/ATP and PCr/Pi were calculated for different brain regions. In addition, volumes of gray matter, white matter and cerebrospinal fluid were determined.ResultsFor all metabolite ratios significant regional differences and in several regions sex differences were found. In some brain regions and for some metabolites hemispheric differences were detected. In addition, changes with aging were found, which differed between women and men.ConclusionsThe present results indicate that 31P-MRS metabolism varies throughout the brain, with age and between sexes, and therefore have important practical implications for the design and the interpretation of future 31P-MRS studies under physiological conditions and in patients with various cerebral diseases.     

Early-onset cerebellar ataxia,myoclonus and hypogonadism in a case of mitochondrial complex III deficiency treated with vitamins K3 and C

A 16-year-old girl presented with early-onset cerebellar ataxia, myoclonus, elevated lactic acidosis and hypogonadotropic hypogonadism. Muscle biopsy specimens revealed fibres with a ragged appearance with increased mitochondria and lipid droplets. Biochemical investigation revealed a deficiency of complexbc ₁ (complex III) of the mitochondrial respiratory chain. Genetic analysis did not show either deletions or known mutations of mitochondrial DNA (mtDNA). Phosphorus magnetic resonance spectroscopy (³¹P-MRS) showed defective energy metabolism in brain and gastrocnemius muscle. A decreased phosphocreatine (PCr) content was found in the occipital lobes accompanied by normal inorganic phosphate (Pi) and cytosolic pH. These findings represented evidence of a high cytosolic adenosine diphosphate concentration and a relatively high rate of metabolism accompanied by a low phosphorylation potential. Muscle³¹P-MRS showed a high Pi content at rest, abnormal exercise transfer pattern and a low rate of PCr post-exercise recovery. These findings suggested a deficit of mitochondrial function. Therapy with vitamins K₃ and C normalized brain³¹P-MRS indices, whereas it did not affect muscle bioenergetic metabolism. In this patient, the endocrinological disorder is putatively due to a mitochondrial cytopathy. Although an unknown mtDNA mutation cannot be ruled out, the genetic defect may lie in the nuclear genome.     

Lipoic (thioctic) acid increases brain energy availability and skeletal muscle performance as shown by in vivo31P-MRS in a patient with mitochondrial cytopathy

A woman affected by chronic progressive external ophthalmoplegia and muscle mitochondrial DNA deletion was studied by phosphorus magnetic resonance spectroscopy (³¹P-MRS) prior to and after 1 and 7 months of treatment with oral lipoic acid. Before treatment a decreased phosphocreatine (PCr) content was found in the occipital lobes, accompanied by normal inorganic phosphate (Pi) level and cytosolic pH. Based on these findings, we found a high cytosolic adenosine diphosphate concentration [ADP] and high relative rate of energy metabolism together with a low phosphorylation potential. Muscle MRS showed an abnormal work-energy cost transfer function and a low rate of PCr recovery during the post-exercise period. All of these findings indicated a deficit of mitochondrial function in both brain and muscle. Treatment with 600 mg lipoic acid daily for 1 month resulted in a 55% increase of brain [PCr], 72% increase of phosphorylation potential, and a decrease of calculated [ADP] and rate of energy metabolism. After 7 months of treatment MRS data and mitochondrial function had improved further. Treatment with lipoate also led to a 64% increase in the initial slope of the work-energy cost transfer function in the working calf muscle and worsened the rate of PCr resynthesis during recovery. The patient reported subjective improvement of general conditions and muscle performance after therapy. Our results indicate that treatment with lipoate caused a relevant increase in levels of energy available in brain and skeletal muscle during exercise.     

31P-NMR spectroscopy of skeletal muscle in Becker dystrophy and DMD/BMD carriers. Altered rate of phosphate transport.

Muscle energy metabolism was studied by phosphorus nuclear magnetic resonance spectroscopy (31P-NMR) in 6 patients with Becker dystrophy, and in 24 female DMD/BMD carriers (n = 18) and non-carriers (n = 6). At rest all patients showed a high Pi/PCr ratio due to low PCr and high Pi contents, and a high intracellular IpH. 31P-NMR of carriers and non-carriers did not differ from controls. In patients and carriers in-magnet exercise revealed a reduced ability to perform work and Pi/PCr ratios higher than controls for comparable relative levels of steady-state work. Post-exercise Pi recovery was found abnormal in patients and in carriers. The 31P-NMR abnormalities found in the working muscle of both BMD patients and female DMD/BMD carriers indicate a defect of phosphate metabolism that, be it primary or secondary, reflects a deficit of energy metabolism.     

Low brain intracellular free magnesium in mitochondrial cytopathies.

The authors studied, by in vivo phosphorus magnetic resonance spectroscopy (31P-MRS), the occipital lobes of 19 patients with mitochondrial cytopathies to clarify the functional relation between energy metabolism and concentration of cytosolic free magnesium. All patients displayed defective mitochondrial respiration with low phosphocreatine concentration [PCr] and high inorganic phosphate concentration [Pi] and [ADP]. Cytosolic free [Mg2+] and the readily available free energy (defined as the actual free energy released by the exoergonic reaction of ATP hydrolysis, i.e., deltaG(ATPhyd)) were abnormally low in all patients. Nine patients were treated with coenzyme Q10 (CoQ), which improved the efficiency of the respiratory chain, as shown by an increased [PCr], decreased [Pi] and [ADP], and increased availability of free energy (more negative value of deltaG(ATPhyd)). Treatment with CoQ also increased cytosolic free [Mg2+] in all treated patients. The authors findings demonstrate low brain free [Mg2+] in our patients and indicate that it resulted from failure of the respiratory chain. Free Mg2+ contributes to the absolute value of deltaG(ATPhyd). The results also are consistent with the view that cytosolic [Mg2+] is regulated in the intact brain cell to equilibrate, at least in part, any changes in rapidly available free energy.     

Neuroprotection of creatine supplementation in neonatal rats with transient cerebral hypoxia-ischemia

We hypothesized that creatine (Cr) supplementation would preserve energy metabolism and thus ameliorate the energy failure and the extent of brain edema seen after severe but transient cerebral hypoxia-ischemia (HI) in the neonatal rat model. Six-day-old (P6) rats received subcutaneous Cr monohydrate injections for 3 consecutive days (3 g/kg body weight/day), followed by 31P-magnetic resonance spectroscopy (MRS) at P9. In a second group, P4 rats received the same Cr dose as above for 3 days prior to unilateral common carotid artery ligation followed 1 h later by 100 min of hypoxia (8% O2) at P7. Rats were maintained at 37 degrees C rectal temperature until magnetic resonance imaging was performed 24 h after HI. Cr supplementation for 3 days significantly increased the energy potential, i.e. the ratio of phosphocreatine to beta-nucleotide triphosphate (PCr/betaNTP) and PCr/inorganic phosphate (PCr/Pi) as measured by 31P-MRS. Rats with hemispheric cerebral hypoxic-ischemic insult that had received Cr showed a significant reduction (25%) of the volume of edemic brain tissue compared with controls as calculated from diffusion-weighted images (DWI). Thus, prophylactic Cr supplementation demonstrated a significant neuroprotective effect 24 h after transient cerebral HI. We hypothesize that neuroprotection is probably due to the availability of a larger metabolic substrate pool leading to a reduction of the secondary energy failure because DWI has been reported to correlate with the PCr/Pi ratio in the acute phase of injury. Additional protection by Cr may be related to prevention of calcium overload, prevention of mitochondrial permeability transition pore opening and direct antioxidant effects.     

Cerebral energy metabolism measured in vivo by 31P-NMR in middle cerebral artery occlusion in the cat--relation to severity of stroke

The energy metabolism of the brain has been measured in a middle cerebral artery (MCA) occlusion model in the cat utilizing 31P-nuclear magnetic resonance (NMR). 31P-NMR spectra were serially obtained during 2 h of ischemia and a subsequent 4-h recovery period. The ratio of creatine phosphate (PCr) to inorganic phosphate (Pi) (PCr/Pi) showed a precipitous decrease in parallel with changes in electroencephalographic (EEG) amplitude in severe strokes during ischemia as well as during recirculation. Animals with mild strokes, as determined by EEG criteria, exhibited a much smaller decrease in PCr/Pi during ischemia. In the severe strokes, there was a splitting and significant shift of the Pi peak immediately after occlusion. In addition, the shifted Pi peak rapidly increased and remained elevated throughout the study. In the mild strokes, Pi also increased, but not as markedly. Intracellular pH determination by chemical shift of the Pi peak revealed a decrease from 7.1 to 6.2-6.3 during ischemia and the subsequent recovery period in the animals with severe strokes, whereas the pH in the animals with mild strokes did not show a significant change. A gradual decrease in adenosine triphosphate (ATP) to 57-79% of the control was exhibited in severely stroked animals during both the ischemia and the recovery period, whereas there was no change in ATP in the mild stroked animals. These results suggest that the dynamic process of pathophysiological changes in an MCA occlusion model in the cat leads to significant differences in cerebral metabolism between animals with mild and severe strokes.     

Preliminary observations on brain energy metabolism in migraine studied by in vivo phosphorus 31 NMR spectroscopy

We measured brain energy phosphate metabolism and intracellular pH (pHi) in a cross-sectional study of migraine patients by in vivo phosphorus 31 NMR spectroscopy. During a migraine attack the ratio ATP/total phosphate signal (mole % ATP) was preserved, but there was a decrease in mole % phosphocreatine (PCr) and an increase in mole % inorganic phosphate (Pi) resulting in a decrease of the PCr/Pi ratio, an index of brain phosphorylation potential. This was found in classic but not common migraine. Mole % Pi was also increased in combined brain regions between attacks. There was no alteration in brain pHi during or between attacks. Energy phosphate metabolism but not pHi appears disordered during a migraine attack.     

Frontal lobe bioenergetic metabolism in depressed adolescents with bipolar disorder: a phosphorus-31 magnetic resonance spectroscopy study

Shi X‐F, Kondo DG, Sung Y‐H, Hellem TL, Fiedler KK, Jeong E‐K, Huber RS, Renshaw PF. Frontal lobe bioenergetic metabolism in depressed adolescents with bipolar disorder: a phosphorus‐31 magnetic resonance spectroscopy study. Bipolar Disord 2012: 14: 607–617. © 2012 The Authors. Journal compilation © 2012 John Wiley & Sons A/S. Objectives: To compare the concentrations of high‐energy phosphorus metabolites associated with mitochondrial function in the frontal lobe of depressed adolescents with bipolar disorder (BD) and healthy controls (HC). Methods: We used in vivo phosphorus‐31 magnetic resonance spectroscopy (³¹P‐MRS) at 3 Tesla to measure phosphocreatine (PCr), beta‐nucleoside triphosphate (β‐NTP), inorganic phosphate (Pi), and other neurometabolites in the frontal lobe of eight unmedicated and six medicated adolescents with bipolar depression and 24 adolescent HCs. Results: Analysis of covariance, including age as a covariate, revealed differences in PCr (p = 0.037), Pi (p = 0.017), and PCr/Pi (p = 0.002) between participant groups. Percentage neurochemical differences were calculated with respect to mean metabolite concentrations in the HC group. Post‐hoc Tukey–Kramer analysis showed that unmedicated BD participants had decreased Pi compared with both HC (17%; p = 0.038) and medicated BD (24%; p = 0.022). The unmedicated BD group had increased PCr compared with medicated BD (11%; p = 0.032). The PCr/Pi ratio was increased in unmedicated BD compared with HC (24%; p = 0.013) and with medicated BD (39%; p = 0.002). No differences in β‐NTP or pH were observed. Conclusions: Our results support the view that frontal lobe mitochondrial function is altered in adolescent BD and may have implications for the use of Pi as a biomarker. These findings join volumetric studies of the amygdala, and proton MRS studies of n‐acetyl aspartate in pointing to potential differences in neurobiology between pediatric and adult BD.     

Canine X-linked muscular dystrophy studied with in vivo phosphorus magnetic resonance spectroscopy.

Duchenne muscular dystrophy (DMD) is an X-linked disease characterized by progressive muscle weakness and degeneration. Dystrophin is the product of the missing gene in this disorder. However, the cause of the dystrophic process is not understood. Transient muscle injury is normally seen after muscle exercise, and may be a necessary process in muscle growth and preservation. We, therefore, chose to evaluate the role of exercise in Duchenne dystrophy by studying the canine X-linked animal model (CXMD). These dogs also lack dystrophin and have clinical signs similar to humans. Exercise was initiated by electrical stimulation, and muscle metabolism was monitored with phosphorus magnetic resonance spectroscopy (P-MRS). Dogs with CXMD had abnormal muscle pathology and markedly elevated serum CK. The inorganic phosphate (Pi) to phosphocreatine (PCr) ratio was increased in CXMD dogs at rest compared with normal dogs (Pi/(Pi + PCr) = 0.166 +/- 0.054 for CXMD and 0.073 +/- 0.017 for normals, mean +/- SE). No changes in resting ATP, pH, phosphomonoesters (PME), and phosphodiesters (PDE) were seen. The mean Pi/(Pi + PCr) and pH values during stimulation were normal in the CXMD dogs. Two to three days after electrical stimulation, resting Pi/(Pi + PCr) ratios were significantly increased in the CXMD dogs (0.127 +/- 0.029 compared with 0.172 +/- 0.054, mean +/- SD). Normal dogs showed no increase in Pi/(Pi + PCr) following stimulation. There was a 50-fold greater increase in serum CK in CXMD compared with normal dogs following exercise. These results indicate greater muscle injury in CXMD muscle, and suggest that in the absence of dystrophin, exercise-induced muscle injury may play a role in the dystrophic process.     

Alterations in brain phosphate metabolite concentrations in patients with human immunodeficiency virus infection

Human immunodeficiency virus (HIV)-infected individuals often demonstrate neuropsychiatric impairment; however, it is unclear how brain metabolism may be altered in such patients. We used in vivo phosphorus 31 magnetic resonance spectroscopy to noninvasively assess brain energy and phospholipid metabolism by measuring brain concentrations of adenosine triphosphate (ATP), phosphocreatine (PCr), and inorganic phosphate (Pi), as well as phospholipid compounds and intracellular pH. In study 1, 17 HIV-seropositive men with varying degrees of neuropsychiatric impairment and six control subjects were studied. Localized spectra were obtained from a heterogeneous 5 x 5 x 5-cm volume of interest (VOI). Patients with HIV infection had a significantly lower ATP/Pi ratio and a trend for a lower PCr/Pi ratio than did the control group. In addition, the ATP/Pi and PCr/Pi ratios were both significantly negatively correlated with overall severity of neuropsychiatric impairment. In study 2, three HIV-seropositive men with neuropsychiatric impairment were compared with 11 HIV-seronegative men. Localized phosphorus 31 magnetic resonance spectra were obtained from two relatively homogeneous VOIs: (1) a predominantly white matter VOI, and (2) a predominantly subcortical gray matter VOI. The three HIV-infected patients demonstrated significantly decreased ATP and PCr concentrations in the white matter VOI. These results suggest that HIV infection of the brain may impair brain cellular oxidative metabolism and that the degree of metabolic compromise may be related to the severity of neuropsychiatric impairment.     

Slower recovery of muscle phosphocreatine in malignant hyperthermia-susceptible individuals assessed by 31P-MR spectroscopy

Our aim was to develop an exercise protocol using ³¹P-magnetic resonance spectroscopy (³¹P-MRS), which can discriminate between malignant hyperthermia-susceptible (MHS) individuals and controls. MRS spectra of the forearm muscles were recorded at rest, during and after a standardized exercise protocol in 10 MHS patients and compared with spectra obtained in 10 controls. There was no difference in resting intracellular pH (pHi) or PCr/ (Pi+PCr) ratio between the groups (PCr = phosphocreatine, Pi = inorganic phosphorus). At the end of the exercise and during the initial recovery phase, the pHi and PCr/(Pi+PCr) ratio were significantly lower in the MHS group ([pHi: 6.37 (0.07) for MHS vs 6.70 (0.05) for controls, P < 0.005; PCr/(Pi+PCr): 0.784 (0.017) for MHS vs 0.954 (0.020) for controls, P < 0.0005]). For PCr/ (Pi+PCr), complete separation between the two groups was observed during the initial recovery phase. The mean recovery time of PCr/ (Pi+PCr) was 0.57 min for the control group and 1.28 min for the MHS group. The slower recovery of PCr/ (Pi+PCr) is likely to be caused by a combination of several factors, including the lower pHi in MHS subjects at the start of recovery (inhibiting ATP production) and excessive sarcoplasmic calcium overload (causing continued enzyme activation and ATP consumption). Our exercise protocol can be a valuable adjunct to discriminate between MHS and non susceptible subjects. Received: 10 July 1996 Received in revised form: 7 August 1997 Accepted: 11 August 1997     

Multinuclear magnetic resonance spectroscopy of high-energy phosphate metabolites in human brain following oral supplementation of creatine-monohydrate

Alterations in brain high-energy phosphate metabolism, determined by in vivo magnetic resonance spectroscopy (MRS), have been reported in subjects with a number of brain disorders including major depression, schizophrenia, and substance abuse. It is not clear to what extent these changes can be modified by pharmacological or nutritional means. To address this possibility, we evaluated changes in brain chemistry that were associated with oral creatine (Cr) administration. We hypothesized that oral Cr supplementation, by increasing brain creatine and high-energy phosphate stored in phosphocreatine, would result in an increase in the creatine resonance, as measured using proton 1H-MRS, and a decrease in the beta-nucleoside triphosphate (NTP) peak and an increase in the phosphocreatine (PCr) peak, as measured by phosphorus 31P-MRS, in brain of healthy human subjects. Fifteen healthy male subjects (age=22.9+/-2.2; body mass index=22.9+/-1.7), who were without any axis I disorders or physical or neurological illness, were recruited. Ten subjects took creatine-monohydrate, 0.3 g/kg/day for the first 7 days and 0.03 g/kg/day for the next 7 days (creatine group). Five comparison subjects took equivalent amounts of sucrose as placebo (placebo group). Both 1H- and 31P-MRS scans were acquired at baseline, as well as at day 7 and day 14 of oral supplementation. 1H-MRS: Water suppressed localized spectra were acquired using a single-voxel (1.5 cm x 2 cm x 2 cm) proton MRS PRESS sequence in the left frontal lobe. 31P-MRS: Phosphorus spectral data were recorded from a 5-cm-thick axial brain slice using a short-TE slice selective spin-echo pulse sequence. The creatine group had significantly increased brain creatine levels (8.1% and 9.3%, in creatine/N-acetyl aspartate and creatine/choline ratios, respectively) compared to the placebo group over the 2-week period. The creatine group had significantly decreased beta-NTP levels (7.8%) and marginally increased PCr (3.4%) over the same period. In addition, the brain inorganic phosphate level increased over the same period in the creatine group (9.8%). The current study is the first multinuclear (1H and 31P) MRS study to evaluate changes in brain high-energy phosphate metabolism following oral creatine supplementation in healthy human subjects. These findings suggest the possibility of using oral creatine supplementation to modify brain high-energy phosphate metabolism in subjects with various brain disorders, including major depression, schizophrenia, cocaine and opiate abuse, where alterations in brain high-energy phosphate metabolism have been reported.     

Creatine has no beneficial effect on skeletal muscle energy metabolism in patients with single mitochondrial DNA deletions: a placebo-controlled, double-blind 31P-MRS crossover study

The purpose of our randomized, double-blind, placebo-controlled crossover study in 15 patients with chronic progressive external ophthalmoplegia (CPEO) or Kearns-Sayre syndrome (KSS) because of single large-scale mitochondrial (mt) DNA deletions was to determine whether oral creatine (Cr) monohydrate can improve skeletal muscle energy metabolism in vivo. Each treatment phase with Cr in a dosage of 150 mg/kg body weight/day or placebo lasted 6 weeks. The effect of Cr was estimated by phosphorus-31 magnetic resonance spectroscopy ((31)P-MRS), clinical and laboratory tests. (31)P-MRS analysis prior to treatment showed clear evidence of severe mitochondrial dysfunction. However, there were no relevant changes in (31)P-MRS parameters under Cr. In particular, phosphocreatine (PCr)/ATP at rest did not increase, and there was no facilitation of post-exercise PCr recovery. Clinical scores and laboratory tests did not alter significantly under Cr, which was tolerated without major side-effects in all patients. Cr supplementation did not improve skeletal muscle oxidative phosphorylation in our series of patients. However, one explanation for our negative findings may be the short study duration or the limited number of patients included.     

Dynamics of cerebral blood flow and metabolism in patients with cranioplasty as evaluated by 133Xe CT and 31P magnetic resonance spectroscopy.

OBJECTIVE--Prolonged improvement in neurological and mental disorders has been seen after only cranioplasty in patients initially treated with external decompression for high intracranial pressure. The objective was to evaluate, using 133Xe CT and 31P magnetic resonance spectroscopy (MRS), how restoring the bone itself can influence cerebral blood flow and cerebral energy metabolism after high intracranial pressure is attenuated. METHODS--Seven patients (45-65 years old) who had undergone external decompression to prevent uncontrollable intracranial hypertension after acute subarachnoid haemorrhage were evaluated. Cerebral blood flow and metabolic changes were evaluated before and after cranioplasty. RESULTS--The ratio of phosphocreatine to inorganic phosphate (PCr/Pi), which is a sensitive index of cerebral energy depletion, was calculated and beta-ATP was measured. The cerebral blood flow value in the thalamus was normalised, from 44 (SD 9) to 56 (SD 8) ml/100 g/min (P < 0.01) and the value in the hemisphere increased from 26 (SD 3) to 29 (SD 4) ml/100 g/min on the side with the bone defect. The PCr/Pi ratio improved greatly from 2.53 (SD 0.45) to 3.01 (SD 0.24) (P < 0.01). On the normal side, the values of cerebral blood flow and PCr/Pi increased significantly (P < 0.01) after cranioplasty, possibly due to transneural suppression. The pH of brain tissue was unchanged bilaterally after cranioplasty. CONCLUSION--Cranioplasty should be carried out as soon as oedema has disappeared, because a bone defect itself may decrease cerebral blood flow and disturb energy metabolism.