Lactate stress testing in 155 patients with mitochondriopathy

OBJECTIVE: Few data are available about the diagnostic yield of the lactate stress test (LST) in a large group of patients with mitochondriopathy (MCP). METHODS: Serum lactate was determined once before, three times during, and once after a 15-minute, constant 30W workload on a bicycle in 62 controls, aged 17 to 84 years, 155 patients with MCP, aged 17 to 87 years, and 31 patients with neurological disorders other than MCP. RESULTS: Lactate's upper reference limits at rest, 5, 10, 15 minutes after starting, and 15 minutes after finishing the exercise were 2.0, 2.1, 2.1, 2.1 and 1.8 mmol/l respectively. The test was regarded abnormal if more than two of the five lactate values exceeded the cut-off levels. Among the 103 patients with abnormal LST, 64 (62 %) had normal resting lactate. The sensitivity of the test was 67% and the specificity 94%. CONCLUSION: The LST proved to have a high sensitivity and specificity in the detection of patients with MCP, being thus a simple but powerful tool to assess the impaired oxidative metabolism in MCP patients.     

LACTATE STRESS TESTING IN SPORADIC AMYOTROPHIC LATERAL SCLEROSIS

Mitochondrial dysfunction is frequently observed in ALS. Mitochondrial dysfunction may result in increased serum lactate at rest or low levels of exercise, being used for diagnostic purposes. The study investigated if resting-lactate-determination is superior to lactate-stress-testing (LST) in demonstrating mitochondrial dysfunction in ALS. Included were 15 ALS patients, 4 women, 11 men, aged 37–72. Severity of the disease was assessed by the Norris-score. The control group comprised 66 healthy subjects, 40 women, 26 men, aged 36–76. Serum lactate was determined before, three times during, and once after a constant workload with 30 W on a bicycle ergometer. According to the EIEscorial criteria 8 patients had definite, 4 probable, 3 possible ALS. Resting lactate was increased in 2 patients, 1 with definite and 1 with possible ALS. The LST was abnormal in 5 patients with definite, 1 with probable and 1 with possible ALS. The mean Norris-score was 67.8 in patients with abnormal LST and 74.6 in patients with normal LST. In conclusion, the LST is more suitable than resting-lactate-determination in demonstrating mitochondrial dysfunction in ALS. The LST suggests mitochondrial dysfunction in half of the ALS patients. Mitochondrial dysfunction in ALS is related to the clinical severity of the disease.     

Lactate stress testing in sporadic amyotrophic lateral sclerosis

Mitochondrial dysfunction is frequently observed in ALS. Mitochondrial dysfunction may result in increased serum lactate at rest or low levels of exercise, being used for diagnostic purposes. The study investigated if resting-lactate-determination is superior to lactate-stress-testing (LST) in demonstrating mitochondrial dysfunction in ALS. Included were 15 ALS patients, 4 women, 11 men, aged 37-72. Severity of the disease was assessed by the Norris-score. The control group comprised 66 healthy subjects, 40 women, 26 men, aged 36-76. Serum lactate was determined before, three times during, and once after a constant workload with 30 W on a bicycle ergometer. According to the EIEscorial criteria 8 patients had definite, 4 probable, 3 possible ALS. Resting lactate was increased in 2 patients, 1 with definite and 1 with possible ALS. The LST was abnormal in 5 patients with definite, 1 with probable and 1 with possible ALS. The mean Norris-score was 67.8 in patients with abnormal LST and 74.6 in patients with normal LST. In conclusion, the LST is more suitable than resting-lactate-determination in demonstrating mitochondrial dysfunction in ALS. The LST suggests mitochondrial dysfunction in half of the ALS patients. Mitochondrial dysfunction in ALS is related to the clinical severity of the disease.     

Lactate-stress testing in 54 patients with mitochondriopathy

Since there are only few data available about the lactate stress test in a group of patients with mitochondrial myopathy, we investigated the sensitivity of this test in a larger cohort of such patients. Serum lactate was determined before, during and after a 15 minute, constant 30 W workload on a bicycle ergometer in 47 controls, aged 15 to 72 years and 54 patients with mitochondrial myopathy, aged 15 to 74 years. Lactate’s upper reference limits at rest, 5, 10, 15 minutes after starting, and 15 minutes after finishing the exercise were 2.0, 2.1, 2.1, 2.1 and 1.8 mmol/l respectively. The sensitivity of the lactate-stress test was 69%. The lactate-stress test complements electrophysiological and bioptical findings and proved to be helpful in diagnosing mitochondrial myopathy. Received: 2 March 1999 / Accepted: 25 October 1999     

Diagnostic yield of the lactate stress test in respiratory chain disorders under absolute and relative workload.

Usually, the lactate stress test is carried under a constant, low workload maintained for 15 min, although there are indications that the lactate response to exercise is a function of the relative workload, and that a workload for only 5 min does not decrease its sensitivity. Thus, this study compared the diagnostic yield of the lactate stress test when carried out under a constant workload of 30 W (LSTA) and under a workload of 30% of maximum (LSTR), and when the workload was maintained for 5 and 15 min. In 16 patients with respiratory chain disorders, 12 women, four men, aged 27--88 years, the LSTA and LSTR were carried out on 2 different days, within 48 h. For both tests serum lactate was determined before, during and after a 15-min workload on a bicycle. Upper reference limits at rest, 5, 10, 15 min after starting, and 15 min after finishing the exercise were 1.9, 2.0, 2.0, 2.0, and 1.6 mmol/l for the LSTA, and 2.3, 3.0, 3.2, 3.4 and 2.7 mmol/l for the LSTR. The sensitivity was 88% for the LSTA and 63% for the LSTR. The specificity of the LSTA was 94%. The diagnostic yield of both tests was similar when the workload was maintained for 5 or 15 min. In conclusion, the LSTA should be preferred to the LSTR. Three lactate determinations during 15 min have no advantage over a single lactate determination after a 5 min workload of 30 W.     

Muscle fatigue,lactate, and pyruvate in mitochondrial myopathy with progressive external ophthalmoplegia

We studied muscle fatigue and serum lactate and pyruvate levels in 20 patients with mitochondrial myopathy with progressive external ophthalmoplegia (PEO). Fatigue was assessed in the adductor pollicis muscle (AP) using a low-intensity exercise protocol (20 min). Forces (TFs) and relaxation times of ulnar nerve evoked twitches, compound muscle action potentials (CMAPs), and maximal voluntary contractions (MVCs) were monitored. Serum lactate and pyruvate levels were independently measured at rest and after exercise on a bicycle (15 min, 30 W). Most patients showed abnormal fatigue of the AP with a reduction of TFs and MVCs and normal CMAPs. The reduced TFs were significantly correlated with lactate levels at rest (r = −0.60, P < 0.05) and less so with those after exercise (r = −0.47, P < 0.05). Pyruvate levels revealed a similar correlation although they were widely scattered. We conclude that abnormal fatigue in PEO is metabolic, is localized beyond the muscle fiber membrane, and involves the electromechanical coupling and the contractile apparatus. Serum lactate levels at rest are good predictors of fatigue in PEO. © 1996 John Wiley & Sons, Inc.     

Cycle ergometry is not a sensitive diagnostic test for mitochondrial myopathy

Cycle exercise has repeatedly been used to diagnose patients suspected of having mitochondrial myopathy (MM), in whom exercise intolerance and lactic acidosis are common. No standardized test, however, has been established. We evaluated the diagnostic value of incremental and constant workload (20 min at 65 % VO(2max)) cycle tests for the diagnosis of MM. Plasma lactate and oxidative capacity (VO(2) and workload) were measured in 15 well-characterized MM patients during cycling. Findings were compared with those in 10 myotonic dystrophy patients and 18 sedentary, healthy subjects.All MM patients had ragged red or COX-negative fibers on muscle biopsy. VO(2max) and maximal workload were lower in MM than in control groups (P < 0.02). Resting plasma lactate was higher in MM than in control groups (P < 0.005; sensitivity = 93 %; specificity = 85 %), while exercise-induced increases in plasma lactate were only higher during the constant workload protocol in MM patients vs. control groups (P < 0.05; sensitivity = 27 %; specificity = 86 %). The findings indicate that the diagnostic value of a constant workload protocol is superior to an incremental cycle test, but that the test is less sensitive for MM than simple testing of resting lactate and muscle morphology. Cycle testing of MM patients remains an important research tool, but should not be a standard diagnostic procedure for MM.     

Modified exercise test in screening for mitochondrial myopathies--adjustment of workload in relation to muscle strength

The aim of this study was to evaluate the usefulness of a modification of the bicycle ergometer test, the subanaerobic threshold exercise test (SATET), as a screening test for patients with mitochondrial myopathies. Since the original SATET is frequently found to be strenuous for weak patients, a new variable (relative muscle strength) was added to the workload formula. Plasma lactate levels were recorded at rest, then after 5 and 15 min of cycling on an ergometer, with constant workload. Nine patients with mitochondrial myopathy, 10 patients with other neuromuscular diseases and 9 healthy but sedentary volunteers undertook the test. An upper reference limit after exercise for plasma lactate was settled at 2.9 mmol/l. The modified SATET showed a sensitivity of 78% and a specificity compared to the healthy subjects of 100%. Compared to patients with other neuromuscular diseases, the specificity was lower (60%). All subjects completed the test without severe fatigue or pain.     

脑梗死急性期血清MMP-9的动态变化及其与脑梗死分型关系的研究

目的　探讨微循环分子标志物的改变与脑梗死临床分型和病情的关系 ,以指导临床的诊治。方法　收集急性脑梗死病人 4 7例 ,分别测定 4 8小时内、第 3天和第 5天的血清MMP 9含量 ,然后分析它与病情轻重、临床分型及预后的关系。结果　脑梗死后MMP 9的含量升高 ,升高幅度和变化规律在OCSP各亚型不同 ;MMP 9在大梗死组的含量显著高于其它组 ;MMP 9与NIHSS呈正相关 ,r=0 4 87;Logistic回归显示 4 8小时内的血清MMP 9含量是预后的独立预测因素。结论　脑梗死后血清MMP 9水平升高 ,并与病灶大小成正比 ,但与病变部位关系不大 ;此外 ,MMP 9可能对病情的严重程度和预后有预示作用。     

Energy dysfunction as a predictor of outcome after moderate or severe head injury: indices of oxygen, glucose, and lactate metabolism.

The purpose of this study was to determine if the relationship between abnormalities in glucose, lactate, and oxygen metabolism were predictive of neurologic outcome after moderate or severe head injury, relative to other known prognostic factors. Serial assessments of the cerebral metabolic rates for glucose, lactate, and oxygen were performed using a modified Kety-Schmidt method. In total, 31 normal control subjects were studied once, and 49 TBI patients (mean age 36+/-16 years, median GCS 7) were studied five times median per patient from postinjury days 0 to 9. Univariate and multivariate analyses were performed. Univariate analysis showed that the 6-month postinjury Glasgow Outcome Scale (GOS) was most strongly associated with the mean cerebral metabolic rate of oxygen (CMRO2) (P = 0.0001), mean arterial lactate level (P = 0.0001), mean arterial glucose (P = 0.0008), mean cerebral blood flow (CBF), (P = 0.002), postresuscitation GCS (P = 0.003), and pupillary status (P = 0.004). Brain lactate uptake was observed in 44% of all metabolic studies, and 76% of patients had at least one episode of brain lactate uptake. By dichotomized GOS, patients achieving a favorable outcome (GOS 4-5) were distinguished from those with an unfavorable outcome (GOS1-3) by having a higher CMRO2 (P = 0.003), a higher rate of abnormal brain lactate uptake relative to arterial lactate levels (P = 0.04), and lesser degrees of blood-brain barrier damage based on CT findings (P = 0.03). Conclusions: During the first 6 days after moderate or severe TBI, CMRO2 and arterial lactate levels are the strongest predictors of neurologic outcome. However, the frequent occurrence of abnormal brain lactate uptake despite only moderate elevations in arterial lactate levels in the favorable outcome patients suggests the brain's ability to use lactate as a fuel may be another key outcome predictor. Future studies are needed to determine to what degree nonglycolytic energy production from alternative fuels such as lactate occurs after TBI and whether alternative fuel administration is a viable therapy for TBI patients.     

The dexamethasone suppression test. An indicator of depression in stroke but not a predictor of rehabilitation outcome

The dexamethasone suppression test (DST) result was found to be abnormal in 49% of patients who were an average of seven weeks post stroke. The DST response correlated with depressive symptoms as measured by both the Zung and modified Hamilton Depression scales. The specificity of the DST for clinically diagnosed depression reached 87% for the 8 AM cortisol determination, with a corresponding sensitivity of 47%. It was not related to the patient's final level of self-care function as measured by the Barthel score, need for nursing home placement following discharge, or duration of rehabilitation needed to achieve maximum benefit. Abnormal responses were more prevalent in cerebral hemisphere than in brain-stem or cerebellar strokes. The more extensive the stroke the more likely the possibility of an abnormal DST response. The DST response is stable, with test-retest replicability being 84% at two weeks and 74% at seven weeks.     

Diagnostic and ethical challenges in disorders of consciousness and locked-in syndrome: a survey of German neurologists

Diagnosis and decisions on life-sustaining treatment (LST) in disorders of consciousness, such as the vegetative state (VS) and the minimally conscious state (MCS), are challenging for neurologists. The locked-in syndrome (LiS) is sometimes confounded with these disorders by less experienced physicians. We aimed to investigate (1) the application of diagnostic knowledge, (2) attitudes concerning limitations of LST, and (3) further challenging aspects in the care of patients. A vignette-based online survey with a randomized presentation of a VS, MCS, or LiS case scenario was conducted among members of the German Society for Neurology. A sample of 503 neurologists participated (response rate 16.4%). An accurate diagnosis was given by 86% of the participants. The LiS case was diagnosed more accurately (94%) than the VS case (79%) and the MCS case (87%, p?相似文献   

Response of serum enzymes and other biochemical constituents to strenuous exercise in control subjects and patients with motor neurone disease

Serum enzymes were estimated in 10 patients with motor neurone disease (MND) and in 5 control subjects at rest and after strenuous exercise. Creatine phosphokinase (CPK) levels were abnormally increased at rest in 6 of the MND patients, 1 of whom had the only abnormal increase in resting level of malate dehydrogenase (MDH). MDH and CPK increased, sometimes to abnormal levels, in response to exercise in control subjects. The mean rise in MDH after exercise in the MND patients closely paralleled that of the control group. In spite of higher resting CPK levels in MND patients compared to controls, the percentage increase in CPK activity immediately after exercise in this group was significantly lower than for controls. No significant changes in aspartate aminotransferase (GOT), sodium, total protein or urea were observed in either group before or after exercise, but significant differences were noted in the response patterns of potassium and bicarbonate.We suggest that abnormal resting CPK activities recorded in MND patients are caused by near maximal efflux from actively necrotic muscle cells, and any superimposed rise in CPK levels after exercise may be contributed by enzyme efflux from the remaining normal muscle cell mass.     

Exploring the presence of multiple abnormal non-motor features in patients with cervical dystonia

This study’s aim was to investigate prevalence of four non-motor symptoms in patients with cervical dystonia and healthy controls to explore whether the presence of multiple non-motor features is associated with cervical dystonia diagnosis. Fifteen patients with cervical dystonia and 15 healthy controls underwent non-invasive testing of spatial discrimination threshold, temporal discrimination threshold, vibration-induced illusion of movement, and kinesthesia. All spatial discrimination threshold, temporal discrimination threshold, and vibration-induced illusion of movement measures were converted to standardized Z scores with scores >2.0 considered abnormal. Any incorrect kinesthesia response was considered abnormal. Prevalence of each abnormal non-motor feature was compared between groups using a chi-squared test. A higher proportion of patients with cervical dystonia had abnormal spatial discrimination threshold (p = 0.01) and abnormal kinesthesia (p = 0.03) scores compared to healthy control subjects. There were no significant differences between the proportion of patients with cervical dystonia versus healthy controls for abnormal temporal discrimination threshold (p = 0.07) or abnormal vibration-induced illusion of movement (p = 0.14). Forty-seven percent of patients with cervical dystonia (7/15) demonstrated one abnormal non-motor feature, 20% (3/15) displayed two abnormal features, and 13% (2/15) displayed three abnormal features. Kinesthesia was the only non-motor feature identified as abnormal in the control group (20%, 3/15). All four tests demonstrated high specificity (80–100%) and low-moderate sensitivity (13–60%). These findings suggest that non-motor feature testing, specifically for spatial discrimination threshold and kinesthesia, could be a highly specific diagnostic tool to inform cervical dystonia diagnosis. Further investigation is needed to confirm these findings.     

Evaluation of enzymes in serum and cerebrospinal fluid in cases of stroke

Levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH) and creatine kinase (CK) were estimated in serum and cerebrospinal fluid of 25 patients of stroke, and were correlated with severity of disease. 21 (84%) patients had ischemic stroke and four (16%) had hemorrhagic stroke. Serum and CSF AST levels were significantly elevated in the study group. The rise in CSF AST was more in the hemorrhagic subtype than in the ischemic subtype. Serum ALT and CSF LDH levels were also significantly elevated in patients with ischemic stroke. None of the enzyme levels were related to the severity of disease as assessed by the Glasgow coma scale.     

Short-term electrical stimulation of the lower esophageal sphincter increases sphincter pressure in patients with gastroesophageal reflux disease

Background Electrical stimulation (ES) of the lower esophageal sphincter (LES) increases resting LES pressure (LESP) in animal models. Our aims were to evaluate the safety of such stimulation in humans, and test the hypothesis that ES increases resting LESP in patients with gastroesophageal reflux disease (GERD). Methods A total of 10 subjects (nine female patients, mean age 52.6 years), with symptoms of GERD responsive to PPIs, low resting LES pressure, and abnormal 24‐h intraesophageal pH test were enrolled. Those with hiatal hernia >2 cm and/or esophagitis >Los Angeles Grade B were excluded. Bipolar stitch electrodes were placed longitudinally in the LES during an elective laparoscopic cholecystectomy, secured by a clip and exteriorized through the abdominal wall. Following recovery, an external pulse generator delivered two types of stimulation for periods of 30 min: (i) low energy stimulation; pulse width of 200 μs, frequency of 20 Hz and current of 5–15 mA (current was increased up to 15 mA if LESP was less than 15 mmHg), and (ii) high energy stimulation; pulse width of 375 ms, frequency of 6 cpm, and current 5 mA. Resting LESP, amplitude of esophageal contractions and residual LESP in response to swallows were assessed before and after stimulation. Symptoms of chest pain, abdominal pain, and dysphagia were recorded before, during, and after stimulation and 7‐days after stimulation. Continuous cardiac monitoring was performed during and after stimulation. Key Results All patients were successfully implanted nine subjects received high frequency, low energy, and four subjects received low frequency, high energy stimulation. Both types of stimulation significantly increased resting LESP: from 8.6 mmHg (95% CI 4.1–13.1) to 16.6 mmHg (95% CI 10.8–19.2), P < 0.001 with low energy stimulation and from 9.2 mmHg (95% CI 2.0–16.3) to 16.5 mmHg (95% CI 2.7–30.1), P = 0.03 with high energy stimulation. Neither type of stimulation affected the amplitude of esophageal peristalsis or residual LESP. No subject complained of dysphagia. One subject had retrosternal discomfort with stimulation at15 mA that was not experienced with stimulation at 13 mA. There were no adverse events or any cardiac rhythm abnormalities with either type of stimulation. Conclusions & Inferences Short‐term stimulation of the LES in patients with GERD significantly increases resting LESP without affecting esophageal peristalsis or LES relaxation. Electrical stimulation of the LES may offer a novel therapy for patients with GERD.     

Diffusion-weighted imaging and proton magnetic resonance spectroscopy in perinatal hypoxic-ischemic encephalopathy: association with neuromotor outcome at 18 months of age

We evaluated early diffusion-weighted imaging findings, the quantitative apparent diffusion coefficient, and magnetic resonance spectroscopy (the presence of lactate and ratios of N-acetylaspartate to total creatine and choline to total creatine) in the prediction of the 18-month neuromotor outcome of term newborns with hypoxic-ischemic encephalopathy. Conventional T1- and T2-weighted and diffusion-weighted imaging was performed in 20 asphyxiated term newborns, with additional basal ganglia magnetic resonance spectroscopy in 15 newborns between 2 and 18 days of life (mean 7.3 days). Neuromotor outcome was dichotomized into normal and abnormal for statistical analysis. Statistically significant differences in the ratios of N-acetylaspartate to total creatine, but not apparent diffusion coefficient values and ratios of choline to total creatine, were found between infants with a normal and an abnormal outcome (Mann-Whitney U-test, P = .010). There was a significant association between the presence of a lactate peak and an abnormal outcome (chi-square test, P = .017). The presence of a lactate peak for predicting an abnormal outcome had a sensitivity of 100% and a specificity of 80%, and the odds ratio was 37.4. Ischemic lesions were more conspicuous and/or extensive on diffusion-weighted imaging in all except one neonate. The presence of normal findings on both diffusion-weighted imaging and conventional magnetic resonance imaging is predictive of a normal neuromotor outcome, whereas lactate and a reduced ratio of N-acetylaspartate to total creatine in the basal ganglia, but not an apparent diffusion coefficient, are associated with an abnormal outcome at 18 months of age.     

TCD, MRA and MRI in acute cerebral ischemia

Objectives - The aim of this study was to determine accuracy of transcranial Doppler ultrasound (TCD) and compare efficacy of three non-invasive tests [TCD, magnetic resonance angiography (MRA), and magnetic resonance imaging (MRI)] in patients with acute cerebral ischemia. Material and methods - This prospective study involved 30 patients. MRI, MRA, and TCD were performed within 24 h after onset of ictus. The 2nd MRI was repeated at 48–72 h and was used as the standard for the evaluation of sensitivity and specificity of MRA, TCD, and initial MRI. Results - TCD showed a sensitivity of 96% and a specificity of 33% for recognizing abnormal cerebral blood flow velocities. MRA showed a sensitivity of 46% and a specificity of 75% for assessing intracranial vascular anatomy, while initial MRI revealed a sensitivity of 84% and a specificity of 100% for evaluation of ischemic parenchymal changes. Conclusion - Our results revealed that TCD is an accurate indicator of blood flow status and correlated well with MRI, MRA abnormalities in acute stroke.     

血清基质金属蛋白酶-9、白细胞计数与脑梗死体积及近期预后的关系

目的研究血清基质金属蛋白酶-9(MMP-9)水平、白细胞计数与缺血性脑卒中的梗死灶体积大小以及预后的关系,并探讨其潜在的机制.方法对124名缺血性脑卒中患者在发病后24 h抽取肘静脉血,用酶联免疫吸附测定法测定MMP-9水平,并进行白细胞计数.根据脑卒中患者临床神经功能缺损程度评分标准对患者入院以及出院时进行评分,所有患者均进行CT/MRI检查.结果脑梗死组MMP-9水平及白细胞计数均明显高于腔隙性脑梗死组以及对照组.相关分析结果表明,MMP-9水平与预后呈等级正相关(r=0.180,P=0.046).白细胞数增高组脑梗死与腔梗构成比、病死率、MMP-9水平明显高于白细胞数正常组,而治疗有效率则明显低于白细胞数正常组.结论脑梗死急性期血清MMP-9水平、白细胞计数可能与脑梗死患者梗死体积大小以及近期预后有密切的关系.     

<Superscript>31</Superscript>P-MRS of skeletal muscle is not a sensitive diagnostic test for mitochondrial myopathy

Clinical phenotypes of persons with mitochondrial DNA (mtDNA) mutations vary considerably. Therefore, diagnosing mitochondrial myopathy (MM) patients can be challenging and warrants diagnostic guidelines. (31)phosphorous magnetic resonance spectroscopy ((31)P-MRS) have been included as a minor diagnostic criterion for MM but the diagnostic strength of this test has not been compared with that of other commonly used diagnostic procedures for MM. To investigate this, we studied seven patients with single, large-scale deletions-, nine with point mutations of mtDNA and 14 healthy subjects, who were investigated for the following: 1) (31)P-MRS of lower arm and leg muscles before and after exercise, 2) resting and peak-exercise induced increases of plasma lactate, 3) muscle morphology and -mitochondrial enzyme activity, 4) maximal oxygen uptake (VO(2max)), 5) venous oxygen desaturation during handgrip exercise and 6) a neurological examination. All MM patients had clinical symptoms of MM, > 2% ragged red fibers in muscle, and impaired oxygen desaturation during handgrip. Fourteen of 16 patients had impaired VO(2max), 10/16 had elevated resting plasma lactate, and 10/11 that were investigated had impaired citrate synthase-corrected complex I activity. Resting PCr/P(i) ratio and leg P(i) recovery were lower in MM patients vs. healthy subjects. PCr and ATP production after exercise were similar in patients and healthy subjects. Although the specificity for MM of some (31)P-MRS variables was as high as 100%, the sensitivity was low (0-63%) and the diagnostic strength of (31)P-MRS was inferior to the other diagnostic tests for MM. Thus, (31)P-MRS should not be a routine test for MM, but may be an important research tool.