Parkinson plus syndrome: diagnosis using high field MR imaging of brain iron

T2 shortening in childhood moyamoya disease

We examined T2 shortening in six children with infarcts due to moyamoya disease to clarify whether there are characteristic patterns of T2 shortening in the deep grey and white matter. Profound T2 shortening in the deep grey and white matter was observed in the acute stage of infarct in two cases, which changed to high intensity in the chronic stage; in this stage no T2 shortening was demonstrated in any case. Neither haemorrhagic infarction nor calcification was seen on CT or MRI. There could be longitudinally different T2 shortening patterns between infarcts due to moyamoya disease and other disorders.

Progressive supranuclear palsy: MRI and pathological findings

Our purpose was to investigate brain atrophy and signal intensity changes on MRI in patients with progressive supranuclear palsy (PSP) and to correlate them with pathological features. We reviewed MRI and brain specimens of six patients with PSP, nine with Parkinson's disease (PD) and six with striatonigral degeneration (SND). Sagittal T1-weighted images showed that four patients with PSP had obvious reduction of anteroposterior midbrain diameter. T2-weighted images demonstrated diffuse high-signal lesions in the tegmentum and tectum of the midbrain of four patients, the upper pontine tegmentum of four, and the lower pontine tegmentum of two, but in no patient with PD or SND. The inferior olivary nuclei gave high signal intensity on T2-weighted images in one patient with PSP. These signal intensity changes were consistent with the pathological findings. One patient with PSP showed abnormal signal intensity in the upper pontine tegmentum without atrophy of the midbrain. Midbrain atrophy and diffuse high-signal lesions on T2-weighted images in the tegmentum and tectum of the brain stem are characteristic of PSP.

Diagnostic testing in movement disorders

The diagnosis of movement disorders is essentially clinical. Work-up depends on patient age, part of the body affected, drug response, and presence of other systemic or neurologic symptoms and signs. Typical Parkinson's disease, essential tremor, and tics need only minimal work-up if any. Brain magnetic resonance imaging/computed tomography, positron emission tomography and single photon emission computed tomography, and DNA studies are promising diagnostic tools. Exclusion of Wilson's disease and neuroacanthocytosis is emphasized in children and young adults with movement disorders.

Magnetic resonance imaging of brain iron in health and disease

Brain iron is a major contributor to magnetic resonance imaging (MRI) contrast in normal gray matter, and its role in the pathogenesis of different neurological disorders has also become apparent. Non-heme brain iron is present in the brain mainly in the form of ferritin. The unique magnetic properties of ferritin determine different signal changes on both T1- and T2-weighted images, and the T2 relaxation rates have a linear dependence on applied field strength. This finding is typical for ferric oxyhydroxide cores. The resulting T2-shortening also depends on echo-spacing used in the imaging sequence as well as on the water diffusion coefficient and the size of the ferritin cluster. Quantitation of non-heme brain iron by MRI aids in the diagnosis and monitoring of different neurological diseases.

Imaging of brain iron by magnetic resonance: T2 relaxation at different field strengths

Soon after the advent of magnetic resonance imaging (MRI) as a diagnostic modality in the 1980s, it was recognized that some of the contrast found in brain imaging correlated with patterns of iron deposition. The presence of non-heme iron had previously been established by pathological studies on post-mortem brains. The iron concentration is highest in specific nuclei of the basal ganglia and some associated structures. It is low at birth and increases with age until a relatively constant level is reached at an age of 20-30 years. There is evidence for further increases in very elderly persons. Although iron is ubiquitous in human tissues, only in a few situations is the concentration large enough to affect MRI. Because MRI has the ability to detect, in a noninvasive fashion, the naturally occurring iron in the basal ganglia and related nuclei, it may be used to study the physiology and pathology of these important structures. Magnetic resonance imaging has confirmed the results of earlier post mortem studies of the anatomical localization and age-dependence of brain iron. Initial steps have been toward the use of MRI to study disorders of thought, movement, and behavior that are believed to be related to brain iron. However, additional understanding is required of the physical details of the contrast mechanism, the physiology of the iron accumulation, and the significance of abnormal patterns of iron deposition. In this report, data are presented on the normal variation in MRI parameters and their dependence on magnetic field strength. The potential clinical and basic science applications are briefly reviewed. Information from widely differing fields is relevant to the study of the physical and pathological significance of brain iron, and for this reason, extensive, although not exhaustive, literature references are included.

Low intensity areas observed on T2-weighted magnetic resonance imaging of the cerebral cortex in various neurological diseases

The cerebral cortex of patients with Alzheimer's disease (AD) or amyotrophic lateral sclerosis (ALS) may show low signal intensity on T2-weighted magnetic resonance images (MRI). Since these low intensity areas (LIA) are also often observed in aged patients with other diseases, we suspected that they might be a non-specific finding. We conducted a retrospective study of LIA in 139 patients with various diseases of the central and peripheral nervous systems, and evaluated their relationship to age and other MRI findings. Brain atrophy, ventricular dilatation, white matter lesions, and LIA were visually evaluated on axial images of the spin echo sequences obtained with a 1.5 tesla (T) system. We found that LIA appeared after age 50 and became more common with advancing age. Their presence correlated with brain atrophy and white matter lesions. They were most frequent in the motor cortex, followed by the occipital and sensory cortices. Their incidence in the motor cortex was significantly higher in patients with central nervous system diseases than in those with peripheral neuropathy. We conclude that LIA are common in old patients with various neurological diseases and suggest that the deposition of iron in the cerebral cortices causes their development.

Clinical and magnetic resonance image correlation in idiopathic cerebellar ataxia

Sixty-one patients who fulfilled the clinical criteria for idiopathic cerebellar ataxia and who had symptoms at least for 3 years were examined clinically and by magnetic resonance imaging (MRI). Based on the clinical signs, they were divided into patients with pure cerebellar signs (Group 1), patients with additional mild rigidity and/or hyperreflexia (Group 2) and patients with additional severe rigidity and hypokinesia (Group 3). Patients in Group 1 had milder disability and better prognosis than patients in Group 2 or Group 3 (ataxic score: 14.9 vs. 28.6 and 36.0; annual progression ratio: 0.26 vs. 0.65 and 0.70, respectively). We measured the area of the cerebellar vermis, ventral pons and dorsal brainstem on midsagittal T1-weighted MR images for all patients and age- and sex-matched controls. The cerebellar vermis as well as the ventral pons of patients were significantly smaller than corresponding structures in controls (p < 0.001). The ventral pons of patients in Group 2 and Group 3 was significantly smaller than that of patients in Group 1 (p < 0.0001, respectively), and the dorsal brainstem of patients in Group 2 and Group 3 was also significantly smaller than that of patients in Group 1 (p < 0.001, respectively). The ventral pons of patients in Group 3 was significantly smaller than that of patients in Group 2 (p < 0.05) as well. There was a significant correlation between the area of the ventral pons and the annual progression ratio (p < 0.001). With MRI, slight but definite hyperintensities were demonstrated in the pontine base and the medulla of 22 patients on proton density images. In the longitudinal study, patients in Group 2 and Group 3 had atrophy of the ventral pons already at an early stage. The ventral pons of patients in Group 3 was smaller at the initial MR examination than that of patients in Group 2. These observations suggest that patients with smaller ventral pons may have rapid progression and poor prognosis. Thus, even a relatively simple quantitation of the area of the ventral pons may be useful to predict the prognosis of patients, in addition to neurologic assessment at intervals.

Periventricular haemosiderin deposition in patients with congenital hemiplegia

Two patients with congenital hemiplegia without obvious prenatal, perinatal or neonatal difficulties showed linear low signal intensity lesions along the wall of the dilated lateral ventricles without any parenchymal lesions on T2- and proton density weighted MRI. Haemosiderin deposition secondary to intra-uterine subependymal haemorrhage with intraventricular haemorrhage was considered most likely from the signal intensity, distribution and clinical histories. MRI, which is the only means of detecting haemosiderin deposition, could be beneficial for evaluating the pathogenetic cause of congenital hemiplegia.

Multiple system atrophy presenting as parkinsonism: clinical features and diagnostic criteria

To evaluate the possibility that parkinsonian signs may be the only presenting feature of multiple system atrophy (MSA), parkinsonian patients were studied who had no atypical clinical signs and had no symptoms of autonomic dysfunction, but who reported that they had not experienced the anticipated good response to dopaminergic treatment. These stringent criteria identified 20 patients from a series of 298 consecutive parkinsonian outpatients. The following clinical pointers were analysed: (a) rate of disease progression; (b) symmetry of parkinsonian symptoms and signs; (c) occurrence of resting tremor during the first three years from onset. In addition, all patients underwent (d) acute and chronic challenge with dopaminergic drugs; (e) cardiovascular reflex autonomic function tests; (f) high field MRI. Rapid progression of disease was seen in 45% of patients, onset was symmetric in 25%, tremor was absent at onset in 70%, response to dopaminergic drug challenges was inadequate in 40%, abnormal cardiovascular reflexes occurred in 50%, and some abnormal MRI finding occurred in 35% of cases. Each of these features was equally weighted by giving to each patient a 0 to 6 point score corresponding to the number of abnormal findings. Fifteen patients scoring higher than 1 were considered at risk for having MSA: five of them were classified as clinically possible (score 2), six as clinically probable (score 3-4), and four patients were classified as clinically definite multiple system atrophy (score 5). The six pointers considered were variably combined in each patient, none of them being universally abnormal in patients with high scores. The patients were followed up for a mean 2.1 (SEM 0.65) years. All but one of the 10 patients prospectively classified as probable or definite MSA developed unequivocal clinical signs of fully symptomatic MSA. A receiver operator characteristic cure was plotted for the prospective score based on follow up diagnosis. The best compromise for trade off between sensitivity and specificity was a cut off value at a score of 3. The sensitivity and specificity of the individual pointers considered to predict fully symptomatic MSA varied considerably, and no single item could predict whether patients presenting with just parkinsonian signs went on during the two year follow up period to develop fully symptomatic MSA. Instead, the number of abnormalities offered a predictive value for the clinical prognosis of these parkinsonian patients.

Manganese and chronic hepatic encephalopathy

Clinical observations and animal studies have raised the hypothesis that increased concentrations of manganese (Mn) in whole blood might lead to accumulation of this metal within the basal ganglia in patients with end-stage liver disease. We studied ten patients with liver failure (and ten controls) by magnetic resonance imaging (MRI) and measurement of Mn in brain tissue of three patients who died of progressive liver failure (and three controls) was also done. Whole blood Mn concentrations in patients with liver cirrhosis were significantly increased (median 34.4 micrograms/L vs 10.3 micrograms/L in controls; p = 0.0004) and pallidal signal intensity indices correlated with blood Mn (Rs = 0.8, p = 0.0058). Brain tissue samples reveal highest Mn concentrations in the caudate nucleus, followed by the quadrigeminal plate and globus pallidus. Mn accumulates within the basal ganglia in liver cirrhosis. Similarities between Mn neurotoxicity and chronic hepatic encephalopathy suggest that this metal may have a role in the pathogenesis of chronic hepatic encephalopathy. Further studies are warranted because the use of chelating agents could prove to be a new therapeutic option to prevent or reverse this neuropsychiatric syndrome.

Hyperhomocysteinaemia; with reference to its neuroradiological aspects

Severe or even mild hyperhomocysteinaemia can cause a wide range of neurological problems. In recent years its vascular complications, including cerebral stroke, in children and young adults have gained special interest, because hyperhomocysteinaemia is treatable and recurrence of vascular incidents may be preventable. Current knowledge about biochemical mechanisms leading to hyperhomocysteinaemia, the pathogenesis of vascular pathology and neurological disfunction, and the various patterns of cerebral damage are reviewed. The significance of MRI in diagnosis, follow-up and research on hyperhomocysteinaemia is discussed.

MR vs CT in progressive supranuclear palsy

Nine progressive supranuclear palsy (PSP) patients were studied with computerized tomography (CT) and magnetic resonance (MR) in order to determine the efficacy of each in detecting atrophy of the brainstem. Three additional PSP patients were evaluated with MRI for quantitative (electronic) measurements of the colliculi, pons and midbrain tegmentum. Both CT and MRI were equally effective in demonstrating midbrain atrophy. The MR was able to utilize the sagittal view to visualize thinning of the collicular (quadrigeminal) plate, a useful sign in PSP. Atrophy of the thinned collicular plate is more pronounced in the superior colliculus, one of the most common sites of pathology in PSP. The MR is able to make quantitative measurements of the degree of atrophy of the colliculi, pons and midbrain tegmentum.

Resting tremor only: a variant of Parkinson's disease or of essential tremor

Resting tremor is one of the characteristic features of Parkinson's disease. However, there are a number of patients who typically have resting tremor alone for at least 5 years without development of other parkinsonian signs or symptoms. The etiology of an isolated resting tremor is still obscure. Recently, positron emission tomography was used to study these patients with isolated resting tremor, and demonstrated a markedly decreased striatal uptake of fluoro-dopa to the range of Parkinson's disease. These findings suggested the existence of a separate subtype, namely, tremulous Parkinson's disease with a manifestation of resting tremor alone. In order to confirm the existence of this subgroup of tremulous Parkinson's disease and further investigate its morphological changes and the usefulness of magnetic resonance imaging, we collected 5 patients who typically have resting tremor for at least 8 years in the absence of other features of Parkinson's disease. MRI was performed and the results of the images showed typical findings of Parkinson's disease with smudging or decreased distance between substantia nigra and red nucleus. Quantitative analysis also demonstrated a significant decrease of the above-noted distance when the resting tremor group was compared to the essential tremor group. Therefore, patients with an isolated resting tremor can have morphological abnormalities in addition to functional disturbances shown by positron emission tomography. To our knowledge, this is the first paper to report that resting tremor is a variant of Parkinson's disease rather than essential tremor, by using a double-blind method, with magnetic resonance imaging to support.

"Pure" striatonigral degeneration and Parkinson's disease: a comparative clinical study

Striatonigral degeneration (SND) is difficult to diagnose in vivo. The purpose of this study was to detect the best indicators for an early and reliable diagnosis of the disease. Eighteen patients clinically diagnosed as having SND were selected with rigorous inclusion criteria and compared to 18 patients with Parkinson's disease (PD) matched for age and disease duration. Apart from dysautonomia, the principal discriminant clinical features that distinguished SND from PD were the early appearance of the following symptoms and signs: (a) severe and atypical progressive parkinsonism characterized by bilateral bradykinesia and rigidity, slowness of gait, postural instability, and falls, and poor or absent response to adequate levodopa treatment; (b) increased tendon reflexes associated or not with frank pyramidal signs, severe dysarthria, and less consistently, dysphagia, stridor, antecollis, and stimulus-sensitive myoclonus, which, when present, are highly suggestive of the disease.

Type 3 GM1 gangliosidosis: clinical and neuroradiological findings in an 11-year-old girl

An 11-year-old Japanese girl was diagnosed as having type 3 GM1 gangliosidosis by clinical symptoms and enzyme assay. She was the youngest among the patients with type 3 GM1 gangliosidosis whose clinical and neuroradiological findings have been documented. Clumsiness since early infancy and dystonia since early childhood which progressed slowly without mental deterioration and dysmorphism led us to the diagnosis of type 3 GM1 gangliosidosis. Genotype determination showed point mutation in exon 2 of the beta-galactosidase gene, which is common among the patients reported in Japan. T2-weighted MRI demonstrated bilateral symmetrical hypointensity in the putamen and globus pallidus. Single photon emission computed tomography using 99mTc-HMPAO showed bilateral hyperperfusion in the basal ganglia which decreased gradually during 1 year of observation. Twenty-two patients with type 3 GM1 gangliosidosis reported in the literature whose onset was at under 15 years of age were reviewed.

Differentiation of multiple system atrophy from idiopathic Parkinson's disease using proton magnetic resonance spectroscopy

Proton magnetic resonance spectroscopy, localized to the lentiform nucleus, was carried out in 7 patients with the pure or predominantly striatonigral variant (SND) of multiple system atrophy (MSA), 5 patients with the olivopontocerebellar variant of MSA, 9 patients with a clinical diagnosis of idiopathic Parkinson's disease (IPD), and 9 healthy age-matched controls. The MSA group with predominantly striatonigral involvement showed a significant reduction in the N-acetylaspartate (NAA)/creatine ratio (median, 1.19; range, 0.96-2.0; p < 0.02) compared with the NAA/creatine ratio from the control group (median, 1.76; range, 1.61-2.0). In contrast, the IPD group had a normal NAA/creatine ratio (median, 1.82; range, 1.19-2.31; p > 0.05). The NAA/creatine ratio was markedly reduced in 6 of the SND patients and in only 1 IPD patient. The choline/creatine ratio was also significantly lower in the SND group (median, 1.02; range, 0.91-1.23; p < 0.04) compared with the control group (median, 1.22; range, 1.05-1.65). The IPD group showed a normal lentiform choline/creatine ratio (median, 1.13; range, 0.89-1.65; p = 0.25) compared with controls. The olivopontocerebellar group also showed a significant reduction in the NAA/creatine ratio from the lentiform nucleus (median, 1.47; range, 1.22-1.68; p < 0.01) compared with the controls as well as a nonsignificant reduction in the choline/creatine ratio (median, 0.93; range, 0.85-1.27; p < 0.4).(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical and magnetic resonance imaging study of extrapyramidal symptoms in multiple system atrophy

Slit-hyperintensity in the outer margin of the putamen on T2 weighted MRI was found in 17 out of 28 patients with clinically diagnosed multiple system atrophy. Thirteen of these 17 patients showed extrapyramidal signs. Five patients had only unilateral slit-hyperintensity; four of them had contralateral rigidity; and one had bradykinesia. Despite mild rigidity, one case showed no slit-hyperintensity. One of the 14 cases with parkinsonism showed no hyperintensity, and four of the 14 cases without parkinsonism showed hyperintensity. On the other hand, slit-hyperintensity was not seen in any of 25 patients with clinically diagnosed Parkinson's disease. Putaminal slit-hyperintensity is a useful MRI feature in the differential diagnosis between Parkinson's disease and multiple system atrophy predominantly affecting the extrapyramidal system.

Striatonigral degeneration: iron deposition in putamen correlates with the slit-like void signal of magnetic resonance imaging

We report three patients with striatonigral degeneration highlighting the correlation between magnetic resonance imaging (MRI) and the pathological changes. The "slit-like void signal" observed in the putamen is typical of striatonigral degeneration and can be used to assist diagnosis during life. Our histochemical studies support the concept that increased iron deposition in the putamen is responsible for this MRI picture.

A study of parkinsonism in multiple system atrophy: clinical and MRI correlation

We investigated clinical and MRI correlation in 18 patients with clinically-diagnosed multiple system atrophy (MSA) and 16 age-matched controls, using 1.5 T magnetic resonance imaging (MRI). We evaluated the severity of parkinsonism in each MSA patient. In assessing the MRI findings, we examined three parameters quantitatively: width of the pars compacta of the substantia nigra (SNc); putaminal hypointensity on T2-weighted images; and putaminal atrophy. As in previous studies, SNc width was narrowed and the putaminal signal intensity was decreased in patients with MSA compared with controls. The clinical severity of parkinsonism did not correlate significantly with the SNc width or the score of putaminal hypointensity in MSA. However, not only did putaminal atrophy occur, but correlated well with the severity of parkinsonism in MSA. A significant correlation could not be established between narrowing of SNc and shrinkage of the putamen. These findings suggest that putaminal atrophy is associated with the clinical manifestations of parkinsonism and do not support the hypothesis that transsynaptic degeneration occurs in MSA.

Multiple system atrophy: natural history, MRI morphology, and dopamine receptor imaging with 123IBZM-SPECT

Sixteen patients with a clinical diagnosis of probable multiple system atrophy (MSA) were examined clinically by MRI and by 123I-iodobenzamide single photon emission computed tomography (IBZM-SPECT). The clinical records of another 16 patients were also analysed retrospectively. On the basis of their clinical presentation, patients were subdivided into those with prominent parkinsonism (MSA-P, n = 11) and those with prominent cerebellar ataxia (MSA-C, n = 21). Autonomic symptoms were present in all patients and preceded the onset of motor symptoms in 63% of patients. Calculated median lifetime and the median time to become wheelchair bound after onset of disease were significantly shorter for MSA-P than for MSA-C (lifetime: 4.0 v 9.1 years; wheelchair: 3.1 vs 5.0 years) suggesting a better prognosis for cerebellar patients. A significant loss of striatal dopamine receptors (below 2 SD threshold) was detected by IBZM-SPECT in 63% of the patients (56% below 2.5 SD threshold). There was no difference between patients with MSA-C and those with MSA-P in the proportion with significant receptor loss and the extent of dopamine receptor loss. Planimetric MRI evaluation showed cerebellar and brainstem atrophy in both groups. Atrophy was more pronounced in patients with MSA-C than in those with MSA-P. Pontocerebellar hyperintensities and putaminal hypointensities on T2 weighted MRI were found in both groups. Pontocerebellar signal abnormalities were more pronounced in MSA-C than in MSA-P, whereas the rating scores for area but not for intensity of putaminal abnormalities were higher in MSA-P. MRI and IBZM-SPECT provide in vivo evidence for combined basal ganglia and pontocerebellar involvement in almost all patients in this series.

Magnetic resonance imaging of neurodegenerative diseases

Magnetic resonance imaging (MRI) has become an important diagnostic tool in the evaluation of neurodegenerative diseases. Although MRI currently does not yield sufficient predictive power to provide a diagnosis in most individual cases, important features have been identified in population studies that help support or exclude a clinical diagnosis under consideration. In parkinsonian patients, putamenal signal hypointensity is commonly observed in patients with atypical parkinsonism. In demented patients, hippocampal atrophy and prolonged T2 relaxation may help identify individuals with Alzheimer's disease. Caudate and putamenal atrophy are seen in Huntington's disease and may serve as markers of disease progression.

Is cranial computerized tomography useful in the diagnosis of multiple system atrophy?

Cranial computer tomographic (CT) images of 33 patients with multiple system atrophy (MSA) and of 40 age-matched controls were blindly analyzed by two neuroradiologists. All patients had autonomic dysfunction, all but one had parkinsonism, and 13 had cerebellar signs. The scans were judged entirely normal in 21%. Moderate or severe infratentorial atrophy was found in 42%. Cerebellar atrophy was present in 39%, and pontine atrophy was present in 18%. Of the 13 patients with cerebellar signs, only eight had cerebellar atrophy. Of the 20 patients without cerebellar signs, five had cerebellar atrophy. Supratentorial involvement was much less common and less severe. Thus, CT demonstrated system involvement that was not evident clinically in five of 33 cases (15%). However, in all five the clinical diagnosis was already evident from the presence of both autonomic and pyramidal signs in addition to parkinsonism. We conclude that CT imaging is of limited diagnostic use in individual patients with MSA.

Iron accumulation in the substantia nigra of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced hemiparkinsonian monkeys

The mechanism of abnormal iron accumulation in the substantia nigra (SN) pars compacta of patients with Parkinson's disease (PD) is unknown. To explore this question, we made a hemiparkinsonism model in monkeys by injecting 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) into the caudate or putamen on one side, and compared iron content in the SN and other basal ganglia structures by histochemistry. The injected side, especially the SN pars compacta, showed a marked increase in iron staining. Our study indicates that an injury to the nigrostriatal system by MPTP injection can induce iron accumulation in the SN.

Magnetic resonance imaging in progressive supranuclear palsy and other parkinsonian disorders

High field intensity MRI may demonstrate signal abnormalities consistent with deposits of iron or other paramagnetic substances in several extrapyramidal disorders. Hallervorden-Spatz disease was the only disorder widely known to have iron deposits in the pallidum, that are now easily demonstrated in vivo by MRI. However, lower field intensity MRI may also demonstrate characteristic findings. In progressive supranuclear palsy, definite atrophy of the midbrain and of the region around the third ventricle is seen in slightly more than half of the cases. Minimal signal abnormalities are sometimes seen in the periaqueductal region, but MRI studies remain of little help in establishing the diagnosis of the disease. Asymmetric atrophy in the parietal regions is seen in corticobasal degeneration, as expected from pathological studies. Minimal alterations may be seen in the substantia nigra in Parkinson's disease. The most interesting MRI findings are observed in multiple system atrophies. Variable abnormal signal intensities, depending on the field intensity, are visible in the putamen in striatonigral degeneration and in Shy-Drager syndrome; in this latter condition the abnormalities are due to its striatonigral degeneration component. Atrophy of the pons, middle cerebellar peduncles, and cerebellum, and signal abnormalities in a characteristic distribution are visible in olivopontocerebellar atrophy. A combination of these posterior fossa abnormalities and putaminal alterations may confirm the involvement of the cerebellar and extrapyramidal systems in multiple system atrophies.

Basal ganglia iron in tardive dyskinesia: an MRI study

Alterations in brain iron could play an important role in the development of tardive dyskinesia in patients receiving neuroleptic medication. To test this hypothesis, magnetic resonance imaging scans of the brain were performed on 21 chronic schizophrenic patients. Ten patients met research diagnostic criteria for persistent tardive dyskinesia, and 11 were free of tardive dyskinesia. All patients had received long-term neuroleptic treatment and were on a stable neuroleptic dose for at least 3 months before scanning. The signal intensity of basal ganglia structures was obtained as a quantitative estimate of brain iron content. No difference was found in the signal intensity ratios between the two groups. This suggests that iron deposition in the basal ganglia, at least as assessed by this measure, does not play a role in the pathophysiology of tardive dyskinesia.

Striatonigral degeneration with neurofibrillary tangles

An autopsy was performed on a 48-year-old woman with clinical features of parkinsonism-plus syndrome with dominating akinesia. Neuropathological examination revealed striato-nigral degeneration (SND) and neurofibrillary tangles (NFT) characterizing progressive supranuclear palsy. Such an unusual combination of pathological findings may constitute a distinct clinico-pathological entity, with akinesia as the main clinical symptom, and with a pathological substrate of SND and NFT. We suggest that such cases may establish a separate variant within multisystem atrophies syndromes.

Magnetic resonance imaging of brain and the neuromotor disorder in endemic cretinism

Neurological endemic cretinism, resulting from severe iodine deficiency, is characterized by mental deficiency, deafmutism, and a spastic-rigid motor disorder. Its neuropathology and pathophysiology have been investigated very little. We report the clinical and magnetic resonance imaging brain scan findings of 3 adult Chinese cretins. All show an apparent magnetic resonance imaging abnormality in the globus pallidus and substantia nigra, with hyperintensity on T1-weighted images and hypointensity on T2-weighted images. The motor abnormality, characterized by truncal and proximal limb-girdle rigidity and spasticity, with relative sparing of the hands and feet, is analogous to other extrapyramidal disorders. Endemic cretinism is a unique form of cerebral palsy of potential interest for students of human neuromotor development.

Striatal hypometabolism distinguishes striatonigral degeneration from Parkinson's disease

Regional and global metabolic rates for glucose were estimated using 18F-fluorodeoxyglucose and positron emission tomography in 10 patients with a clinical likelihood of striatonigral degeneration (2 men and 8 women; mean age, 61.8 +/- 6.9 years; mean disease duration, 4.7 +/- 2.2 years; mean Hoehn and Yahr score, 3.5 +/- 0.8). Measures of brain glucose metabolism in these patients were compared with those for 10 age-matched normal volunteers, 10 disease severity-matched patients with Parkinson's disease (PD), and 10 disease duration-matched patients with PD. Normalized glucose metabolism was significantly reduced in the caudate (p < 0.03) and putamen (p < 0.003) as compared with that in normal and PD control subjects, and discriminated patients with striatonigral degeneration from control subjects (p < 0.002). Putamenal hypometabolism in patients with striatonigral degeneration correlated significantly with quantitative ratings of motor disability (p < 0.02). These results suggest that quantitative 18F-fluorodeoxyglucose positron emission tomography techniques may be useful in supporting a diagnosis of striatonigral degeneration in life, and in objectively assessing disease severity and potential therapeutic interventions.

Infusion of iron into the rat substantia nigra: nigral pathology and dose-dependent loss of striatal dopaminergic markers

Iron has recently been suggested to contribute to the pathogenesis of Parkinson's disease (PD) because of the finding of increased iron levels in the substantia nigra pars compacta (SNc) above those of control patients. Iron is capable of catalyzing numerous reactions which could lead to free radical formation and oxidative damage to DNA, proteins, lipid membranes, and other biological molecules. Neurodegeneration in the SNc of the PD brain may be a consequence of increased iron, which promotes these cytotoxic reactions. To test whether excess iron could play a causative role in the degeneration of nigral neurons, we infused 1.25-6.3 nmol of iron into the rat substantia nigra (SN) unilaterally utilizing two different infusion protocols. All infusates were isosmotic and pH-balanced in a citrate-bicarbonate vehicle. Animals were decapitated at either 1 or 2 months postinfusion. Striatal tissue was assayed for biogenic amines by HPLC and the remaining brainstem was processed for histological analysis. Iron-stained coronal sections revealed 1) no left/right staining difference with vehicle infusion, 2) a dose-dependent iron accumulation in the infused SN that was restricted to the zona compacta and dorsal-most zona reticularis when the lowest iron concentration was infused, and 3) a dose-dependent reduction in SN volume. Thionine-stained sections revealed neuronal loss and accompanying reactive gliosis within an area that corresponded closely to that of increased iron staining. These degenerative changes were more extensive in animals infused via a side-by side vs. a sequential protocol. Neurochemically, there was a highly significant correlation between the amount of iron infused intranigrally and magnitude of reductions in striatal DA, DOPAC, and HVA within the ipsilateral striatum. These data indicate that iron infusion into the SN can cause degenerative changes within the SN and that these changes can be restricted to the SNc region when low amounts of iron are infused. The data further support the hypothesis that iron-induced degeneration may contribute to the pathogenesis of PD.

Age distribution and iron dependency of the T2 relaxation time in the globus pallidus and putamen

Heavily T2-weighted spin echo sequences of the brain show age-dependent low signal intensity in many extrapyramidal nuclei. Although it has been suggested that this low intensity results from non-haem iron, the specific influence of non-haem iron on the T2 relaxation time has not been quantified and remains controversial. The T2 relaxation times of the globus pallidus and putamen were measured from MRI at 1.5T in 27 healthy patients, by using a mathematical model. They were then plotted as a function of age and compared to the curve of age-dependent iron concentration determined post mortem. The curves of T2 relaxation time in the basal ganglia are congruent with published curves of iron concentration, indicating a high probability that the changes in T2 relaxation times and the low signal in the basal ganglia result from the local, age-dependent iron deposition. Individual measurements of T2 relaxation time show less variation before than after 45 years of age, indicating the influence of a second, more individual factor.

The possible role of iron in the etiopathology of Parkinson's disease

The identification of 6-hydroxydopamine (6-OHDA) and N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) as dopaminergic neurotoxins that can induce parkinsonism in humans and animals has contributed to a better understanding of Parkinson's disease (PD). Although the involvement of similar neurotoxins has been implicated in PD, the etiology of the disease remains obscure. However, the recently described pathology of PD supports the view for a state of oxidative stress in the substantia nigra (SN), resulting as a consequence of the selective accumulation of iron in SN zona compacta and within the melanized dopamine neurons. Whether iron is directly involved cannot be ascertained. Nevertheless, the biochemical changes due to oxidative stress resulting from tissue iron overload (siderosis) are similar to those now being identified in parkinsonian SN. These include the reduction of mitochondrial electron transport, complex I and III activities, glutathione peroxidase activity, glutathione (GSH) ascorbate, calcium-binding protein, and superoxide dismutase and increase of basal lipid peroxidation and deposition of iron. The participation of iron-induced oxygen free radicals in the process of nigrostriatal dopamine neuron degeneration is strengthened by recent studies in which the neurotoxicity of 6-OHDA has been linked to the release of iron from its binding sites in ferritin. This is further supported by experiments with the prototype iron chelator, desferrioxamine (Desferal), a free-radical inhibitor, which protects against 6-OHDA-induced lesions in the rat. Indeed, intranigral iron injection in rats produces a selective lesioning of dopamine neurons, resulting in a behavioral and biochemical parkinsonism.

MRI, brain iron and experimental Parkinson's disease

Abnormal levels of brain iron have been reported in parkinsonism, which is characterized principally by degeneration of dopaminergic (DA) nigrostriatal neurons. There are conflicting reports, however, of both increased and decreased iron in parkinsonism. An animal model of parkinsonism was used to clarify the contribution of the loss of nigrostriatal DAergic neurons to abnormal iron accumulations. In rats with 6-hydroxydopamine induced unilateral DA depletion, brain iron deposition and its day-to-day stability was studied in vivo using T2-weighted magnetic resonance imaging (MRI) scans taken on 4 consecutive days beginning 1-2 months post-surgery and post-mortem by Perls'-DAB histochemical stain. Unilateral DA depletion (parkinsonism model) produced large day-to-day fluctuations in T2 relaxation time in the striatum. The T2 relaxation time in Sham control rats was relatively minor. The uptake and transport of iron by intrinsic cells of the striatum may vary, and this variability may have been exaggerated by the destruction of DAergic nigrostriatal neurons, which are known to modulate the activity of the intrinsic cells. Inconsistent reports of increased or decreased iron in parkinsonism may reflect, in part, single time-point measures of widely fluctuating iron.

Hallervorden-Spatz disease: clinical and MRI study of 11 cases diagnosed in life

The diagnosis of Hallervorden-Spatz disease (HSD) has usually been made post mortem, although the recent description of characteristic abnormalities in the globus pallidus has suggested the possibility of an in vivo diagnosis. We present the clinical histories, neurological features and MRI findings of 11 patients, diagnosed as having HSD. Generalized dystonia with predominance of oromandibular involvement, behavioural changes followed by dementia and retinal degeneration were present in all the patients. MRI pallidal abnormalities consisted of decreased signal intensity in T2-weighted images, compatible with iron deposits, and of a small area of hyperintensity in its internal segment ("eye of the tiger" sign). We propose that the combination of these neurological signs with these MRI findings could be considered as highly suggestive of a diagnosis of HSD in living patients.

T1 and T2 of ferritin at different field strengths: effect on MRI

Nuclear magnetic relaxation times T1 and T2 were measured in ferritin solutions at field strengths from 0.04 to 1.5 T. T1 was relatively constant, but 1/T2 increased linearly with field strength, in agreement with earlier MRI observations in the monkey brain. This finding supports the theory that ferritin is responsible for T2 shortening in brain nuclei containing iron. The linear dependence of 1/T2 on magnetic field is unique and not explained by present theories of the magnetic properties of ferritin.

Magnetite biomineralization in the human brain

Although the mineral magnetite (Fe3O4) is precipitated biochemically by bacteria, protists, and a variety of animals, it has not been documented previously in human tissue. Using an ultrasensitive superconducting magnetometer in a clean-lab environment, we have detected the presence of ferromagnetic material in a variety of tissues from the human brain. Magnetic particle extracts from solubilized brain tissues examined with high-resolution transmission electron microscopy, electron diffraction, and elemental analyses identify minerals in the magnetite-maghemite family, with many of the crystal morphologies and structures resembling strongly those precipitated by magnetotactic bacteria and fish. These magnetic and high-resolution transmission electron microscopy measurements imply the presence of a minimum of 5 million single-domain crystals per gram for most tissues in the brain and greater than 100 million crystals per gram for pia and dura. Magnetic property data indicate the crystals are in clumps of between 50 and 100 particles. Biogenic magnetite in the human brain may account for high-field saturation effects observed in the T1 and T2 values of magnetic resonance imaging and, perhaps, for a variety of biological effects of low-frequency magnetic fields.

Increased iron content in the putamen of patients with striatonigral degeneration

We measured the total content of iron, copper, zinc and manganese in the putamen of four patients with striatonigral degeneration (SND) and age- and gender-matched normal controls. The iron content in the SND patients was five times greater than in the controls. Electron microscopic histochemistry revealed the iron reaction products in the pigments showing a triphasic pattern of coarse, electron-dense globules, fine granular and fibrillary materials, and lamellated structures. These findings suggest that increased iron deposition may be related to pigment formation in the putamen of SND.

Progressive subcortical gliosis and progressive supranuclear palsy can have similar clinical and PET abnormalities

In studies of cerebral glucose metabolism utilising positron emission tomography (PET) with 18F-fluoro-2-deoxy-D-glucose, patients with the clinical picture of progressive supranuclear palsy (PSP) have shown predominantly frontal glucose hypometabolism. This is presumed to represent deafferentation of cerebral cortical from subcortical structures. In these studies, however, the diagnosis of PSP has not been verified by pathological examination. Necropsy examinations were performed in three patients with the clinical features of PSP in whom PET had demonstrated predominantly frontal hypometabolism. In two of these patients the diagnosis of PSP was confirmed pathologically, and no morphological abnormalities were found in the cerebral cortex. The third patient had extensive cortical and subcortical neuronal loss and gliosis without neurofibrillary tangles, consistent with the diagnosis of progressive subcortical gliosis (PSG). Even in retrospect no unique clinical neurological abnormality or finding on laboratory investigation could be identified that distinguished this latter patient from those with pathologically confirmed PSP. We conclude that PSG and PSP may be indistinguishable during life, and necropsy confirmation is needed for definite diagnosis.

Hemi-parkinsonism in multiple system atrophy: a PET and MRI study

We selected 6 patients presenting with hemi-parkinsonism from a total of 20 patients with probable multiple system atrophy (MSA) and studied their nigrostriatal lesions using magnetic resonance (MR) imaging and positron emission tomography (PET) with 18F-labeled 2-deoxy-2-fluoro-D-glucose (FDG). T2 weighted MR images demonstrated a decreased signal intensity in the putamen of all patients. This decreased signal was more intense in the nucleus contralateral to the affected body side in 5 patients. A decreased signal in the substantia nigra was found, expanding more on the contralateral side in 3 patients. T1-weighted images showed that the contralateral putamen was smaller in size than the ipsilateral. These findings indicated that the iron deposit and the neuronal cell loss in the degenerative process were more remarkable in the contralateral nuclei. FDG uptake in 5 patients had likewise declined more in the contralateral than in the ipsilateral putamen. The study shows that these patients have the nigrostriatal lesions as described in previous reports on MSA and that an asymmetric lesion relating to clinical signs is present in the nigrostriatal system. When a patient presents with hemi-parkinsonism alone, MR imaging and PET/FDG are useful for the clinical diagnosis of MSA.

Effects of the interaction between ferric iron and L-dopa melanin on T1 and T2 relaxation times determined by magnetic resonance imaging

T1 and T2 relaxation times of agar phantoms containing L-dopa melanin and Fe3+ were measured under MRI conditions. Fe3+ shortened T1 and T2 relaxation times. Melanin influenced relaxation times only in the presence of Fe3+; thus, contrast in MR images of the basal ganglia may depend upon levels of both paramagnetic iron and neuromelanin.

Atypical MR presentation of Wilson disease: a possible consequence of paramagnetic effect of copper?

A 53-year-old patient with Wilsons's disease and without autonomic dysfunction presented on T2-weighted MR study an atypical decreased signal intensity of the putamina and the caudate nuclei. Possible explanations of such a signal abnormalities are discussed.

Iron-melanin interaction and lipid peroxidation: implications for Parkinson's disease

The vulnerability of substantia nigral (SN) melaninized dopamine neurons to neurodegeneration in Parkinson's disease and the selective increases of iron and basal lipid peroxidation in SN indicate that iron-melanin interaction could be crucial to the pathogenesis of this disease. The present study describes, for the first time, the identification and characterization of a high-affinity (KD = 13 nM) and a lower affinity (KD = 200 nM) binding site for iron on dopamine melanin. The binding of iron to melanin is dependent on pH and the concentration of melanin. Iron chelators, U74500A, desferrioxamine, and to less extent 1,10-phenanthroline and chlorpromazine, but not the Parkinson-inducing neurotoxin, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, can inhibit the binding of iron to melanin and iron-induced lipid peroxidation. Although melanin alone diminishes basal lipid peroxidation in rat cortical homogenates, it can also potentiate that initiated by iron, a reaction inhibited by desferrioxamine. In the absence of an identifiable exogenous or endogenous neurotoxin in idiopathic Parkinson's disease, iron-melanin interaction in pars compacta of SN may be a strong candidate for the cytotoxic component of oxygen radical-induced neurodegeneration of melaninized dopamine neurons.

Abnormally increased iron concentration in basal ganglia in Shy-Drager syndrome. MR imaging and autonomic study

Report of an early case of Shy-Drager syndrome in a 67 year-old woman patient. Autonomic failure was diagnosed by functional evaluation as well as laboratory tests. MR imaging disclosed a prominent putamina hypodensity in T2-weighted images at high field strength due to iron increased depositing in this basal ganglia. MR imaging evidences confirm Shy-Drager syndrome diagnosis, and contributes for differential diagnosis of idiopathic hypotension (pure autonomic failure) in special in SDS early cases.

Neuropsychological deficits accompanying striatonigral degeneration

This study presents a structural and functional description of a case of striatonigral degeneration (SND) and emphasizes neuropsychological findings. The patient, a 55-year-old woman with progressive and relatively intractable rigidity and bradykinesia, particularly of the right side, was studied with brain MR scans and with a wide variety of sensory, motor, and cognitive tests known to be subserved by specific brain regions. T2-weighted MR images revealed curvilinear areas of high signal in the lateral putamen at low magnetic field strength (0.3T) and adjacent regions of marked low signal in the posterior-lateral putamen at high magnetic field (1.5T). High signal changes in the insular cortex were also noted on the high field images. Letter fluency and short-term memory as well as motor speed, strength, and sequencing were selectively impaired. Taken together, the data of this case suggest that structural involvement of the putamen resulted in dysfunctions usually associated with the primary motor cortex and orbitofrontal cortex, while sparing functions of other frontal regions as well as temporal and parietal cortices.

Selective increase of iron in substantia nigra zona compacta of parkinsonian brains

Histochemical and biochemical determinations of total iron, iron (II), and iron (III) contents in brain regions from Parkinson's and Alzheimer's diseases have demonstrated a selective increase of total iron content in parkinsonian substantia nigra zona compacta but not in the zona reticulata. The increase of iron content is mainly in iron (III). The ratio of iron (II):iron (III) in zona compacta changes from almost 2:1 to 1:2. This change is thought to be relevant and may contribute to the selective elevation of basal lipid peroxidation in substantia nigra reported previously. Iron may be available in a free state and thus can participate in autooxidation of dopamine with the resultant generation of H2O2 and oxygen free radicals.

Computed tomography, magnetic resonance imaging and positron emission tomography with [18F]fluorodeoxyglucose in multiple system atrophy and pure autonomic failure

We studied 45 patients who had autonomic failure with computed tomography, magnetic resonance imaging and positron emission tomography with [18F]fluorodeoxyglucose to characterize the neuroimaging features of multiple system atrophy and pure autonomic failure and determine the utility of these techniques in distinguishing multiple system atrophy from pure autonomic failure. There were 30 patients with multiple system atrophy and 15 with pure autonomic failure. In the multiple system atrophy group, eight patients had mainly cerebellar signs, seven extrapyramidal and 15 had combinations of cerebellar and extrapyramidal signs. Cerebellar atrophy on computerized tomography and magnetic resonance imaging, signal hypointensity in the posterolateral putamen on magnetic resonance imaging and a generalized reduction in glucose utilization rate with positron emission tomography with [18F]fluorodeoxyglucose, were the main findings and were seen only in the patients with multiple system atrophy. Decreased glucose utilization (hypometabolism) was most prominent in the cerebellum, brainstem, striatum and frontal and motor cortices. These results indicate clear differences, using neuroimaging studies, between multiple system atrophy and pure autonomic failure.