Effect of basal ganglia injury on central dopamine activity in Gulf War syndrome: correlation of proton magnetic resonance spectroscopy and plasma homovanillic acid levels.

BACKGROUND: Many complaints of Gulf War veterans are compatible with a neurologic illness involving the basal ganglia. METHODS: In 12 veterans with Haley Gulf War syndrome 2 and in 15 healthy control veterans of similar age, sex, and educational level, we assessed functioning neuronal mass in both basal ganglia by measuring the ratio of N-acetyl-aspartate to creatine with proton magnetic resonance spectroscopy. Central dopamine activity was assessed by measuring the ratio of plasma homovanillic acid (HVA) and 3-methoxy-4-hydroxyphenlyglycol (MHPG). RESULTS: The logarithm of the age-standardized HVA/MHPG ratio was inversely associated with functioning neuronal mass in the left basal ganglia (R(2) = 0.56; F(1,27) = 33.82; P<.001) but not with that in the right (R(2) = 0. 04; F(1,26) = 1.09; P =.30). Controlling for age, renal clearances of creatinine and weak organic anions, handedness, and smoking did not substantially alter the associations. CONCLUSIONS: The reduction in functioning neuronal mass in the left basal ganglia of these veterans with Gulf War syndrome seems to have altered central dopamine production in a lateralized pattern. This finding supports the theory that Gulf War syndrome is a neurologic illness, in part related to injury to dopaminergic neurons in the basal ganglia.

Safety of MR scanning in patients with nonferromagnetic aneurysm clips.

The purpose of this study was to report our surveillance of patients with nonferromagnetic aneurysm clips (NFAC) who have undergone magnetic resonance imaging (MRI). Forty-six patients with NFAC underwent MRI over a 7-year period. Medical records were studied for evidence of subjective or objective clinical findings as a result of the MRI scan. In two patients with subjective complaints, computed tomograms (CT) were reviewed and patient interviews conducted. No significant neurologic signs or longterm symptoms were experienced. Two patients did not complete their MRI scans due to transient unilateral head pain in one and head "pressure" in another. CT scans in these patients demonstrated no evidence for hemorrhage or visible change in clip position. We documented no objective adverse outcome of patients undergoing MRI with NFAC, confirming that MRI can be performed safely in patients with nonferromagnetic aneurysm clips. The cause of subjective complaints in two of our patients is unknown.

Brain abnormalities in Gulf War syndrome: evaluation with 1H MR spectroscopy.

PURPOSE: To test for neuronal brain damage in the basal ganglia and brainstem in Gulf War veterans by using magnetic resonance (MR) spectroscopy. MATERIALS AND METHODS: Twenty-two Gulf War veterans with one of three factor analysis-derived syndromes (case patients); 18 well veterans matched for age, sex, and education level (control subjects); and six Gulf War veterans with syndrome 2 from a different population (replication sample) underwent long echo time (272 msec) proton (hydrogen 1) MR spectroscopy on a 4 x 2 x 2-cm voxel in the basal ganglia bilaterally and a 2 x 2 x 2-cm voxel in the pons. Syndromes 1-3 are described as "impaired cognition," "confusion-ataxia," and "central pain," respectively. RESULTS: The N-acetylaspartate-to-creatine (NAA/Cr) ratio, which reflects functional neuronal mass, was significantly lower in the basal ganglia and brainstem of Gulf War veterans with the three syndromes than in those structures of the control subjects (P =.007). The finding was corroborated in the replication sample (P =.002). Veterans with syndrome 2 (the most severe clinically) had evidence of decreased NAA/Cr in both the basal ganglia and the brainstem; those with syndrome 1, in the basal ganglia only; and those with syndrome 3, in the brainstem only. CONCLUSION: Veterans with different Gulf War syndromes have biochemical evidence of neuronal damage in different distributions in the basal ganglia and brainstem.

Effect of exercise on (23)Na MRI and relaxation characteristics of the human calf muscle.

The acute affect of voluntary muscle contractions performed by healthy volunteers was evaluated using (23)Na nuclear magnetic resonance (NMR). Three-dimensional gradient-echo (23)Na images, pulse-acquired spectra, and transverse relaxation times were obtained before and after ankle flexion-extension exercise. The muscle sodium concentration was calculated from (23)Na images using a 40 mM NaCl standard and the measured T(2) values. Before exercise the muscle sodium concentration was 26+/-4 mmole/kg wet weight. This agrees closely with literature values, suggesting that muscle Na(+) is fully NMR visible. The (23)Na image intensity increased by 34%+/-7% in the exercised muscle and diminished with a half-life of 30+/-6 minutes. The pulse-acquired spectra, however, did not show any significant change in muscle signal intensity following exercise, but the relative contribution of the slow T(2) component increased. The calculated sodium concentration also did not change significantly after the exercise. We therefore infer that the changes in (23)Na magnetic resonance imaging (MRI) were due to a change in sodium-macromolecular interaction rather than a change in tissue sodium content. We believe that this report represents the first study of (23)Na MRI of skeletal muscle.

MRI of neuromuscular disease: the basics.

Neuromuscular diseases are numerous and challenging to a variety of clinicians because patients may present to a variety of caregivers with nonspecific complaints. Difficulties in diagnosis and treatment toughen the management of this group. Advancements in the ability to see muscle lesions with magnetic resonance imaging (MRI) introduce radiologists to this complex field and at the same time confront clinicians with new issues, such as if and when to tap this technology on behalf of their patients. Like other published reviews on this topic, this article summarizes the current literature regarding MRI applications and limitations in neuromuscular diseases. It also asks, Given the obvious increment that MRI affords the evaluation of neuromuscular conditions, why is the test not applied more often?

Muscle physiology and pathophysiology: magnetic resonance imaging evaluation.

Just as the overlying skin hides skeletal muscle from direct assessment in clinical evaluation of muscle disease, so does it hamper studies that probe basic mechanisms underlying muscle use in exercise science. As a test of organ function, magnetic resonance imaging (MRI) of muscle activation expanded the breadth and type of information available to scientists by allowing the noninvasive dissection of muscle activity, merging functional and morphologic information that link directly to classical tests of muscle performance. Extending to sequellae of overexertion, from the self-limited condition of sore muscles that all of us experience to the more burdensome problems of acute muscle injuries and complications, MRI continues to develop as an important tool to unveil hidden mysteries that underlie and limit locomotion. This article reviews a substantial body of data accumulated over the last 10 years in these interesting, albeit slightly unconventional, applications.

St. Louis encephalitis and the substantia nigra: MR imaging evaluation.

Neuroimaging findings in cases of St. Louis encephalitis (StLE) have yet to be reported despite the relatively high frequency of this entity. An epidemic permitted the documentation of isolated hyperintensity of the substantia nigra on T2-weighted images in two patients with StLE. This distribution of MR imaging abnormality in cases of StLE mirrors the reports presented in the literature that implicate the substantia nigra as peculiarly susceptible to the StLE virus. Isolated lesions of the substantia nigra revealed by T2-weighted imaging should suggest the possibility of StLE.

Adipose tissue distribution pattern in patients with familial partial lipodystrophy (Dunnigan variety).

Familial partial lipodystrophy, Dunnigan type (FPLD), is a rare autosomal dominant genetic disorder characterized by gradual loss of sc fat from the extremities, commencing at the time of puberty. Excess fat deposition may occur in the face and neck area. Limited information is available about adipose tissue distribution in patients with FPLD. To investigate whether there is a unique pattern of fat distribution in both affected men and women with FPLD, we performed whole-body magnetic resonance imaging in one male and three female patients from two pedigrees. Magnetic resonance imaging studies confirmed the clinical findings of near-total absence of sc fat from all extremities. Reduction in sc adipose tissue from the truncal area was more prominent anteriorly than posteriorly. Increased fat stores were observed in the neck and face. Intermuscular adipose tissue in the extremities and pelvic area were subjectively increased. Intraabdominal and intrathoracic adipose tissue was not reduced. Bone marrow fat, as well as mechanical adipose tissue, was present in normal amounts. The pattern of fat distribution in the male and females was similar. We conclude that FPLD results in a characteristic absence of sc fat from the extremities, with preservation of intermuscular fat stores.

Submaximal delayed-onset muscle soreness: correlations between MR imaging findings and clinical measures.

PURPOSE: To assess correlations between muscle edema on magnetic resonance (MR) images and clinical indexes of muscle injury in delayed-onset muscle soreness (DOMS) produced by submaximal exercise protocols. MATERIALS AND METHODS: Sixteen subjects performed 36 elbow flexions ("biceps curls") at one of two submaximal workloads that emphasized eccentric contractions. Changes in MR imaging findings, plasma levels of creatine kinase, and pain scores were correlated. RESULTS: Both exercise protocols produced DOMS in all subjects. The best correlation was between change in creatine kinase level and volume of muscle edema on MR images, regardless of the workload. Correlations tended to be better with the easier exercise protocol. CONCLUSION: Whereas many previous studies of DOMS focused on intense exercise protocols to ensure positive results, the present investigation showed that submaximal workloads are adequate to produce DOMS and that correlations between conventionally measured indexes of injury may be enhanced at lighter exercise intensities.

Magnetic resonance imaging of muscle in amyotrophic lateral sclerosis.

OBJECTIVE: To characterize leg muscle abnormalities in patients with ALS using MRI, and to correlate MRI with standard neurologic measures of motor neuron dysfunction. METHODS: Eleven ALS patients were studied twice (once at baseline and again after 4 months) and compared with eight normal control subjects. MRI data of the lower extremities were compared with tibialis anterior compound muscle action potential amplitude (CMAPa) and foot dorsiflexion maximal voluntary isometric contraction (MVIC). RESULTS: Muscle MRI was abnormal by visual inspection in six of 11 patients. The mean muscle T1 time and muscle volume were not different in patients compared with normal control subjects (p > 0.1). However, the mean T2 times were increased in the patients compared with normal control subjects (p = 0.009). T1 times did not correlate with CMAPa or MVIC. Muscle volume correlated with MVIC (r = 0.73 to 0.78, p < 0.02) but not with CMAPa (p > 0.05). There was a strong negative correlation (r < -0.8, p < or = 0.01) between muscle T2 time and MVIC and CMAPa. Also, the change in T2 relaxation time correlated with the change in CMAPa as the disease progressed (r = -0.63, p = 0.037). CONCLUSION: Of the MRI characteristics studied, T2 relaxation time was the best indicator of motor neuron dysfunction and may have a role in objective evaluation of motor neuron dysfunction.

The MR appearance of volume overload in the lower extremities.

PURPOSE: Our goal was to describe the MR findings of volume overload (VO) in the lower extremities. METHOD: Fifteen individuals were studied, including eight healthy controls and seven patients with VO (four cardiac, three renal). MR evaluation included various SE techniques. Edema detection, localization, and symmetry were assessed subjectively. Relaxation time estimates were also made of the subcutaneous tissue, marrow, and three muscles. RESULTS: Subcutaneous tissue was markedly edematous in seven of seven patients and asymmetric in four of seven, whereas marrow was normal in all patients. Muscle edema was mild and asymmetric in six and two of seven patients, respectively. Perifascial fluid collections were identified in six of seven patients. CONCLUSION: Subcutaneous tissue edema is the dominant feature of VO in the lower extremities. Perifascial fluid is common but does not necessarily distribute symmetrically. Muscle edema is relatively mild. These findings should aid in identifying VO as the potential cause of swelling in patients with swollen legs.

Evaluation of neurologic function in Gulf War veterans. A blinded case-control study.

OBJECTIVE: To determine whether Gulf War-related illnesses are associated with central or peripheral nervous system dysfunction. DESIGN: Nested case-control study. PARTICIPANTS: Twenty-three veterans with factor analysis-derived syndromes (the cases), 10 well veterans deployed to the Gulf War (the deployed controls), and 10 well veterans not deployed to the Gulf War (the nondeployed controls). METHOD: With investigators blinded to group identities, participants underwent objective neurophysiological, audiovestibular, neuroradiological, neuropsychological, and blood tests. MAIN OUTCOME MEASURES: Evidence of neurologic dysfunction. RESULTS: Compared with the 20 controls, the 23 cases had significantly more neuropsychological evidence of brain dysfunction on the Halstead Impairment Index (P=.01), greater interside asymmetry of the wave I to wave III interpeak latency of brain stem auditory evoked potentials (P=.02), greater interocular asymmetry of nystagmic velocity on rotational testing, increased asymmetry of saccadic velocity (P=.04), more prolonged interpeak latency of the lumbar-to-cerebral peaks on posterior tibial somatosensory evoked potentials (on right side, P=.03, and on the left side, P=.005), and diminished nystagmic velocity after caloric stimulation bilaterally (P values range from .02 to .04). Cases (n=5) with syndrome 1 ("impaired cognition") were the most impaired on brain stem auditory evoked potentials (P=.005); those (n=13) with syndrome 2 ("confusion-ataxia") were the most impaired on the Halstead Impairment Index (P=.006), rotational testing (P=.01), asymmetry of saccadic velocity (P=.03), and somatosensory evoked potentials (P< or =.01); and those (n=5) with syndrome 3 ("arthro-myo-neuropathy") were the most impaired on caloric stimulation (P< or =.01). CONCLUSIONS: The 3 factor-derived syndromes identified among Gulf War veterans appear to represent variants of a generalized injury to the nervous system.

Central nervous system lymphoma not detectable on single-photon emission CT with thallium 201.

A 33-year-old man with acquired immunodeficiency syndrome had an erosive supraglottic mass visible on CT scans of the neck; biopsy was postponed because of the patient's debilitated condition. Two weeks later, he was admitted with altered mental status; an MR image of the brain obtained at that time showed multiple bilateral mass lesions, the largest of which was 5 cm. Findings on a thallium-201 single-photon emission CT (SPECT) scan of the brain were normal. Ten days later, the patient died and autopsy showed both the neck and the brain lesions to be large-cell lymphoma. This case is counterevidence to the reported 100% sensitivity of thallium-201 brain SPECT for demonstrating lymphoma of the central nervous system.

Isolated neck extensor myopathy: a common cause of dropped head syndrome.

We report four patients with "dropped head syndrome," a recently described nonprogressive myopathy characterized by severe neck extensor weakness. This relatively benign condition may be confused with more ominous neuromuscular disorders that also present with prominent neck weakness. We compared clinical and laboratory data from the patients with dropped head syndrome with findings from patients with head drop caused by other neuromuscular conditions. Patients with "isolated neck extensor myopathy," a term we prefer to "dropped head syndrome," could be readily identified with electrophysiologic, radiographic, and histologic studies.

Inflammatory myopathies: radiologic evaluation.

Clinical evaluation of skeletal muscle in patients with inflammatory myopathies (IM) has long been hampered by difficulty in assessing the morphology and functional integrity of skeletal muscles. Advances in radiologic techniques, particularly MR imaging, have improved the ability to manage patients with neuromuscular disease in general and IM in particular. MR imaging can probe beyond the skin to identify focal muscle structural lesions, determine their extent, characterize their composition, direct invasive procedures, and monitor therapies. This article reviews the clinical, pathologic, and imaging aspects of these diseases.