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

The Movement Disorder Society Criteria for the Diagnosis of Multiple System Atrophy

BACKGROUND

The second consensus criteria for the diagnosis of multiple system atrophy (MSA) are widely recognized as the reference standard for clinical research, but lack sensitivity to diagnose the disease at early stages.

OBJECTIVE

To develop novel Movement Disorder Society (MDS) criteria for MSA diagnosis using an evidence-based and consensus-based methodology.

METHODS

We identified shortcomings of the second consensus criteria for MSA diagnosis and conducted a systematic literature review to answer predefined questions on clinical presentation and diagnostic tools relevant for MSA diagnosis. The criteria were developed and later optimized using two Delphi rounds within the MSA Criteria Revision Task Force, a survey for MDS membership, and a virtual Consensus Conference.

RESULTS

The criteria for neuropathologically established MSA remain unchanged. For a clinical MSA diagnosis a new category of clinically established MSA is introduced, aiming for maximum specificity with acceptable sensitivity. A category of clinically probable MSA is defined to enhance sensitivity while maintaining specificity. A research category of possible prodromal MSA is designed to capture patients in the earliest stages when symptoms and signs are present, but do not meet the threshold for clinically established or clinically probable MSA. Brain magnetic resonance imaging markers suggestive of MSA are required for the diagnosis of clinically established MSA. The number of research biomarkers that support all clinical diagnostic categories will likely grow.

CONCLUSIONS

This set of MDS MSA diagnostic criteria aims at improving the diagnostic accuracy, particularly in early disease stages. It requires validation in a prospective clinical and a clinicopathological study. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Comprehensive Functional Evaluation of the Spectrum of Multi-System Atrophy with 18F-FDG PET/CT and 99mTc TRODAT-1 SPECT: 5 Year's Experience from a Tertiary Care Center

Aim:

To elucidate the patterns of characteristic hypometabolism on ¹⁸F- fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) in multisystem atrophy (MSA) and their correlation with the patterns of uptake on dopamine transporter imaging with ^99mTc TRODAT-1 SPECT.

Material and Methods:

A retrospective analysis of 67 patients with clinically diagnosed MSA was performed. All the subjects underwent ^99mTc TRODAT-1 SPECT and ¹⁸F-FDG PET/CT scanning on two separate days. The ^99mTc-TRODAT-1 scans were analyzed visually for asymmetry and rostro-caudal gradient. The FDG uptake patterns were recorded, and areas of hypometabolism that were two standard deviations from the mean were considered abnormal.

Results:

All the subjects had an abnormal pattern of FDG uptake on PET scan, both on a visual inspection and semiquantitative analysis. In MSA-P subjects (n = 29), diffuse predominant hypometabolism of the globus pallidus-putamen complex was noted, with relative sparing of the caudate nuclei. In MSA-C subjects (n = 25), characteristic hypometabolism was noted in the cerebellum and brainstem. In mixed subtypes (n = 13), variable involvement of the basal ganglia, cerebellum, and brainstem was noted with frontoparietal hypometabolism. A statistically significant difference between MSA-P and MSA-C for gradient reduction and asymmetry with gradient reduction was observed.

Conclusion:

Dopamine transporter imaging with ^99mTc TRODAT-1 SPECT not only helps in confirmation of parkinsonian disorders but also demonstrates varying patterns of distribution in different subtypes of MSA. Characteristic patterns of hypometabolism in ¹⁸F-FDG PET may help in the differentiation of the subtypes of MSA in the presence of clinically overlapping symptoms.

Clinical Neurology and Epidemiology of the Major Neurodegenerative Diseases

Neurodegenerative diseases are a common cause of morbidity and cognitive impairment in older adults. Most clinicians who care for the elderly are not trained to diagnose these conditions, perhaps other than typical Alzheimer's disease (AD). Each of these disorders has varied epidemiology, clinical symptomatology, laboratory and neuroimaging features, neuropathology, and management. Thus, it is important that clinicians be able to differentiate and diagnose these conditions accurately. This review summarizes and highlights clinical aspects of several of the most commonly encountered neurodegenerative diseases, including AD, frontotemporal dementia (FTD) and its variants, progressive supranuclear palsy (PSP), corticobasal degeneration (CBD), Parkinson's disease (PD), dementia with Lewy bodies (DLB), multiple system atrophy (MSA), and Huntington's disease (HD). For each condition, we provide a brief overview of the epidemiology, defining clinical symptoms and diagnostic criteria, relevant imaging and laboratory features, genetics, pathology, treatments, and differential diagnosis.

Neuroimaging in Dementia

Although the diagnosis of dementia still is primarily based on clinical criteria, neuroimaging is playing an increasingly important role. This is in large part due to advances in techniques that can assist with discriminating between different syndromes. Magnetic resonance imaging remains at the core of differential diagnosis, with specific patterns of cortical and subcortical changes having diagnostic significance. Recent developments in molecular PET imaging techniques have opened the door for not only antemortem but early, even preclinical, diagnosis of underlying pathology. This is vital, as treatment trials are underway for pharmacological agents with specific molecular targets, and numerous failed trials suggest that earlier treatment is needed. This article provides an overview of classic neuroimaging findings as well as new and cutting-edge research techniques that assist with clinical diagnosis of a range of dementia syndromes, with an emphasis on studies using pathologically proven cases.

Functional imaging with positron emission tomography in multiple system atrophy

Although the current guidelines for the clinical diagnosis of multiple system atrophy (MSA) do not require structural or functional brain imaging, investigations utilizing positron emission tomography (PET) have been helpful diagnostically in differentiating between MSA and primary autonomic failure; idiopathic Parkinson's disease; and sporadic olivopontocerebellar atrophy. These investigations have demonstrated different patterns of cerebral glucose utilization and of nigrostriatal projection abnormalities among these disorders and between the cerebellar and parkinsonian forms of MSA. Most of the studies have focused upon patients with well-established disease and none have examined the utility of PET imaging in early stage patients with follow-up of clinical course and autopsy verification to ensure accuracy of diagnosis and to determine the sensitivity and specificity of PET techniques for diagnosis. Recent PET studies have revealed denervation of myocardial post-ganglionic sympathetic neurons in some MSA patients, indicating that this disorder can affect the peripheral autonomic as well as the central nervous system. Investigations utilizing ligands to quantify central nervous system dopaminergic and cholinergic terminals have begun to provide insight into the neurochemical disorders that may underlie two of the sleep disturbances common in MSA, rapid eye movement sleep behavior disorder and obstructive sleep apnea.

PET studies in dementia

Measurement of local cerebral glucose metabolism (lCMRGlc) by positron emission tomography (PET) and 18F-2-fluoro-2-deoxy-D-glucose (FDG) has become a standard technique during the past 20 years and is now available at many university hospitals in all highly developed countries. Many studies have documented a close relation between lCMRGlc and localized cognitive functions, such as language and visuoconstructive abilities. Alzheimer's disease (AD) is characterized by regional impairment of cerebral glucose metabolism in neocortical association areas (posterior cingulate, temporoparietal and frontal multimodal association cortex), whereas primary visual and sensorimotor cortex, basal ganglia, and cerebellum are relatively well preserved. In a multicenter study comprising 10 PET centers (Network for Efficiency and Standardisation of Dementia Diagnosis, NEST-DD) that employed an automated voxel-based analysis of FDG PET images, the distinction between controls and AD patients was 93% sensitive and 93% specific, and even in very mild dementia (at MMSE 24 or higher) sensitivity was still 84% at 93% specificity. Significantly abnormal metabolism in mild cognitive deficit (MCI) indicates a high risk to develop dementia within the next two years. Reduced neocortical glucose metabolism can probably be detected with FDG PET in AD on average one year before onset of subjective cognitive impairment. In addition to glucose metabolism, specific tracers for dopamine synthesis (18F-F-DOPA) and for (11C-MP4A) are of interest for differentiation among dementia subtypes. Cortical acetylcholine esterase activity (AChE) activity is significantly lower in patients with AD or with dementia with Lewy bodies (DLB) than in age-matched normal controls. In LBD there is also impairment of dopamine synthesis, similar to Parkinson disease.

An imaging study of parkinsonism among African-Caribbean and Indian London communities

We previously reported on 131 parkinsonian patients of African-Caribbean and Indian origin attending movement disorders clinics in six London Hospitals, of whom approximately 20% manifested atypical parkinsonism with a late-onset, akinetic-rigid predominant syndrome, postural instability and minimal resting tremor refractory to levodopa therapy and dopamine agonists (see Hu et al., Neurology 2000;54[Suppl.3]: A188 and Hu et al., Mov Disord 2000;15[Suppl.3]:S212). To better elucidate the phenotype of these atypical patients (18)FDG/(18)F-dopa positron emission tomography (PET) were performed in a subgroup to look for cortical and striatal metabolic changes suggestive of multiple system atrophy (MSA), progressive supranuclear palsy (PSP), corticobasal degeneration (CBD), or dementia with Lewy bodies. Magnetic resonance imaging (MRI) rating of cerebral vascular lesion load, putaminal atrophy, and neuropsychological testing were also performed. Discriminant function analysis of (18)F-dopa/(18)FDG striatal metabolism in 43 patients failed to separate atypical ethnic minority from typical Caucasian Parkinson's disease (PD) patients. Additionally, atypical Indian and African-Caribbean patients did not show cortical reductions in glucose metabolism suggestive of PSP, CBD, or DLB. Cerebral vascular lesion load rated in these patients did not differ between atypical and typical PD groups, and none of the atypical patients had MRI changes suggestive of MSA or PSP. Our results suggest the atypical parkinsonian phenotype seen in African-Caribbean and Indian patients represents a levodopa-refractory form of PD separate from MSA or PSP in most patients.

Differentiating multiple system atrophy from Parkinson's disease: contribution of striatal and midbrain MRI volumetry and multi-tracer PET imaging

OBJECTIVES

The differential diagnosis between typical idiopathic Parkinson's disease (PD) and the striatonigral variant of multiple system atrophy (MSA-P) is often difficult because of the presence of signs and symptoms common to both forms of parkinsonism, particularly at symptom onset. This study investigated striatal and midbrain findings in MSA-P and PD patients in comparison with normal controls with the use of positron emission tomography (PET) and three dimensional magnetic resonance imaging (3D MRI) based volumetry to increase the differential diagnostic accuracy between both disease entities.

METHODS

Nine patients with MSA-P, 24 patients with PD, and seven healthy controls were studied by MRI and PET with 6-[(18)F]-fluoro-L-dopa (FDOPA), [(18)F]fluoro-deoxyglucose (FDG), and 11-C-Raclopride (RACLO). Striatal and extrastriatal volumes of interest (VOI) were calculated on the basis of the individual MRI data. The PET data were transferred to the VOI datasets and subsequently analysed.

RESULTS

MSA-P differed significantly from PD patients in terms of decreased putaminal volume, glucose metabolism, and postsynaptic D2 receptor density. The striatal FDOPA uptake was equally impaired in both conditions. Neither MRI volumetry nor PET imaging of the midbrain region further contributed to the differential diagnosis between PD and MSA-P.

CONCLUSIONS

The extent and spatial distribution of functional and morphological changes in the striatum permit the differentiation of MSA-P from PD. Both, multi-tracer PET and 3D MRI based volumetry, may be considered equivalent in the assessment of different striatal abnormality in both disease entities. In contrast, MRI and PET imaging of the midbrain does not provide a further gain in diagnostic accuracy.

The nature of the autonomic dysfunction in multiple system atrophy

The concept that multiple system atrophy (MSA, Shy-Drager syndrome) is a disorder of the autonomic nervous system is several decades old. While there has been renewed interest in the movement disorder associated with MSA, two recent consensus statements confirm the centrality of the autonomic disorder to the diagnosis. Here, we reexamine the autonomic pathophysiology in MSA. Whereas MSA is often thought of as "autonomic failure", new evidence indicates substantial persistence of functioning sympathetic and parasympathetic nerves even in clinically advanced disease. These findings help explain some of the previously poorly understood features of MSA. Recognition that MSA entails persistent, constitutive autonomic tone requires a significant revision of our concepts of its diagnosis and therapy. We will review recent evidence bearing on autonomic tone in MSA and discuss their therapeutic implications, particularly in terms of the possible development of a bionic baroreflex for better control of blood pressure.

Cerebral metabolic changes in early multiple system atrophy: a PET study

Previous positron emission tomography (PET) studies have shown widespread hypometabolism in the brain of advanced MSA but the time course of these metabolic abnormalities is largely unknown. In order to clarify the principal disease processes in multiple system atrophy (MSA) in the early stage, we investigated regional cerebral glucose metabolism (rCMGglc) and nigral dopaminergic function in nine patients with early stage of MSA using [(18)F]fluorodeoxyglucose (FDG) and 6-L-[(18)F]fluorodopa ((18)F-Dopa) positron emission tomography (PET) (two men and seven women; age, 59.3+/-5.4 years; disease duration, 29.7+/-14.6 months). The rCMRglc in the early MSA patients significantly decreased in the cerebellum, brainstem, and striatum compared with that in nine normal subjects. A significant correlation was found between the severity of autonomic dysfunction and rCMRglc within the brainstem. The severity of extrapyramidal signs also correlated with the decline of F-Dopa uptake but not that of rCMRglc within the striatum. The degree of atrophy on MRI has correlated with neither the clinical symptoms nor rCMRglc at the cerebellum and the brainstem. Our PET studies demonstrated widespread metabolic abnormalities except for the cerebral cortex in the brain of MSA even in the early stage. The hypometabolism in the brainstem was tightly linked to the autonomic dysfunction. Not the striatal dysfunction but the nigral damage may be responsible for the extrapyramidal symptoms in early MSA.

Impaired novelty P3 potentials in multiple system atrophy--correlation with orthostatic hypotension

Although neuropsychological tests demonstrate frontal lobe dysfunction in multiple system atrophy (MSA), assessment of frontal function using event-related brain potentials (ERPs) has not been sufficiently performed in MSA. The correlation between frontal lobe dysfunction and orthostatic hypotension (OH), which is known to cause frontal hypoperfusion, remains unclear. Our objectives were to assess frontal lobe dysfunction in MSA patients using ERPs and to elucidate the relevance of OH to changes in ERPs. Nine consecutive patients with MSA and nine age- and gender-matched healthy controls were compared by performance in the Wisconsin Card Sorting Test (WCST) and somatosensory ERPs to target and novel stimuli, namely, parietal maximal P3 (target P3) and fronto-central P3 (novelty P3), respectively. The correlation between novelty P3 and OH was evaluated in the MSA group. The MSA group showed a poorer performance in categories achieved (CA), total errors (TE) and perseverative errors by Nelson's (PEN) method in the WCST compared with the control group (CA and PEN: p<0.01; TE: p<0.02). Novelty and target P3s in the MSA group showed significantly prolonged latency (novelty: p<0.05; target: p<0.01) and reduced amplitude (novelty: p<0.02; target: p<0.01) compared with the control group. There was a significant negative correlation between novelty P3 latency and a drop in systolic blood pressure (r=0.76; p<0.02). Abnormalities of novelty P3 in the MSA group might reflect frontal lobe dysfunction, namely failure of attentional set-shifting, that was identified by the WCST. OH may play a role in the development of frontal lobe dysfunction in MSA.

Nocturnal body core temperature falls in Parkinson's disease but not in Multiple-System Atrophy

OBJECTIVE

To evaluate whether the circadian rhythm of body core temperature (CRT degrees ) can differentiate Multiple-System Atrophy (MSA) from Idiopathic Parkinson's disease (IPD).

METHODS

We evaluated 14 patients with probable MSA, seven with IPD, and eight controls. After a preliminary evaluation of cardiovascular autonomic function, rectal temperature and sleep-wake cycle were monitored continuously for 48 hours in a temperature-controlled room, at constant bed rest with controlled food intake and fixed light-dark schedule.

RESULTS

MSA patients showed cardiovascular autonomic sympathetic and parasympathetic failure. IPD had normal cardiovascular autonomic function. A 24-hour rhythm of body core temperature (BcT degrees ) was present in all subjects. IPD had CRT degrees comparable to controls. In MSA the mesor was higher and mean BcT degrees of each hour was significantly higher from 11 p.m. to 7 a.m. The analysis of mean BcT degrees during the different sleep phases showed significantly higher values during both NREM (1--2, 3--4) and REM sleep stages in MSA.

CONCLUSIONS

The physiological nocturnal fall of BcT degrees is blunted in MSA patients mainly because BcT degrees did not decrease during sleep. This CRT degrees pattern is not justified by differences in sleep structure and may reflect an impairment of central sympathetic nervous system function.

Distinction of idiopathic Parkinson's disease from multiple-system atrophy by stimulation of growth-hormone release with clonidine

BACKGROUND

Idiopathic Parkinson's disease is a common neurodegenerative disease that is difficult to distinguish from other parkinsonian syndromes such as multiple-system atrophy (MSA). In MSA, autonomic dysfunction is common and is associated with either parkinsonian or cerebellar features, or both. Differentiation of idiopathic Parkinson's disease from MSA is important because prognosis, complications, and response to therapy vary according to disorder. Our aim was to find out whether clonidine/growth hormone (GH) testing distinguishes idiopathic Parkinson's disease from MSA.

METHODS

Clonidine is a centrally active alpha 2-adrenoceptor agonist that raises concentrations of GH in serum in healthy people and those with pure autonomic failure (with peripheral lesions), but not in those with MSA (with a central autonomic deficit). We investigated the effects of clonidine on 14 people with idiopathic Parkinson's disease (without autonomic deficits). 31 people with MSA of the three different clinical forms (parkinsonian, cerebellar, and mixed), 19 people with pure autonomic failure, and 27 healthy participants. In nine people with parkinsonian MSA (MSA-P), the GH response to levodopa was also assessed.

FINDINGS

Clonidine raised serum GH concentrations in patients with idiopathic Parkinson's disease (median increase 8.98 [IQR 6.6-16.6] mU/L), normal participants (13.2 [7.0-18.6] mU/L), and patients with pure autonomic failure (12.5 [5.6-18.2] mU/L). In those with MSA who had central autonomic failure, GH concentrations were unchanged (MSA-P; 0.41 [-0.30 to 2.09] mU/L and cerebellar MSA [MSA-C] 1.67 [0-4.49] mU/L). The GH response to clonidine in idiopathic Parkinson's disease was significantly different from that in MSA-P (p < 0.0002). In MSA-P, the dopamine precursor levodopa raised GH concentrations (from mean 2.7 [SE 1.0] mU/L to mean 18.2 [6.0] mU/L, p < 0.05) and GH-releasing hormone (GHRH) concentrations (from mean 20.6 [3.25] ng/L to mean 68.0 [10.6] ng/L, p < 0.05), excluding dysfunction of pituitary somatotrophs or GHRH neurons as a cause for the absent GH response to clonidine in MSA.

INTERPRETATION

The GH responses to clonidine clearly differentiated idiopathic Parkinson's disease from MSA-C and MSA-P. Together with the levodopa studies they indicated a specific alpha 2-adrenoceptor-hypothalamic deficit in MSA. The clonidine-GH test may provide further insight into central neurotransmitter and alpha 2-adrenoceptor-hypothalamic abnormalities in MSA.

Decreased striatal monoaminergic terminals in olivopontocerebellar atrophy and multiple system atrophy demonstrated with positron emission tomography

We used [11C]dihydrotetrabenazine, a new ligand for the type 2 vesicular monoamine transporter (VMAT2), with positron emission tomography to study striatal monoaminergic presynaptic terminals in 4 patients with multiple system atrophy, 8 with sporadic olivopontocerebellar atrophy, and 9 normal control subjects. Specific binding in the striatum was significantly reduced in the multiple system atrophy patients as compared with the normal control group, with average reductions of 61% in the caudate nucleus (p = 0.002) and 58% in the putamen (p = 0.009). Smaller reductions were found in the sporadic olivopontocerebellar atrophy group, averaging 26% in the caudate nucleus (p = 0.05) and 24% in the putamen (p = 0.11). Mean blood-to-brain [11C]dihydrotetrabenazine transport (K1) was significantly different between groups only in the cerebellum, with values for the sporadic olivopontocerebellar atrophy group diminished compared with the normal control group. Cerebellar K1 was not significantly decreased in the multiple system atrophy group. The finding of reduced striatal VMAT2 in sporadic olivopontocerebellar atrophy patients suggests nigrostriatal pathology, indicating that some may later develop symptomatic extrapyramidal disease.

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.

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.

Patterns of cerebral glucose metabolism detected with positron emission tomography differ in multiple system atrophy and olivopontocerebellar atrophy

We used positron emission tomography with [18F]fluorodeoxyglucose to study local cerebral metabolic rates for glucose (ICMRglc) in patients with multiple system atrophy (MSA), sporadic olivopontocerebellar atrophy (sOPCA), and dominantly inherited olivopontocerebellar atrophy (dOPCA) in comparison with normal control subjects. IN MSA, absolute lCMRglc was significantly decreased in the brainstem, cerebellum, putamen, thalamus, and cerebral cortex. In sOPCA, absolute lCMRglc was significantly decreased in the brainstem, cerebellum, putamen, thalamus, and cerebral cortex. In dOPCA, absolute lCMRglc was significantly decreased in the brainstem and cerebellum but not in the other structures. Examination of lCMRglc normalized to the cerebral cortex in comparison with normal controls revealed in MSA significant decreases in the brainstem, cerebellum, and putamen but, in both sOPCA and dOPCA, significant decreases only in the brainstem and cerebellum. The findings indicate that these three disorders all show a marked decrease of lCMRglc in the brainstem and cerebellum but differ in the degree of hypometabolism in forebrain and cerebral cortical structures. The results are consistent with the possibility that, in many cases, sOPCA will evolve into MSA. Moreover, positron emission tomography may provide helpful diagnostic information in these neurodegenerative diseases.

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.

Sympathetic nervous system disorders in man

The sympathetic nervous system innervates most organs in the body and controls their function. A variety of disease processes, surgery or drugs can result in disordered sympathetic nerve function, which can be either localized or more generalized. Malfunction can result in either sympathetic underactivity (causing postural hypotension, impotence or anhidrosis) or overactivity (causing paroxysmal hypertension or hyperhidrosis). The investigation of sympathetic disorders depends upon the system and organs involved and should include, where relevant, investigation of the possible aetiological processes. The clinical features and management of some of the major disorders affecting the sympathetic nervous system, including the recently described syndrome of DBH deficiency, are described.

Functional imaging in relation to parkinsonian syndromes

Parkinsonism is a feature not only of Parkinson's disease but also of many other diseases affecting basal ganglia function. Functional imaging (PET and SPECT) can demonstrate the various resting patterns of disruption of regional cerebral blood flow, metabolism, and neuropharmacology associated with different parkinsonian disorders. 18F-dopa PET also has the potential to detect subclinical dysfunction of dopaminergic terminals in at-risk subjects. Finally, functional imaging can help us understand the nature of the networks involved in performing different motor tasks, and can reveal how these networks malfunction in the presence of bradykinesia or parkinsonian tremor.