Cardiac MIBG scintigraphy is a sensitive tool for detecting cardiac sympathetic denervation in Parkinson's disease.

[(123)I]Metaiodobenzylguanidine ([(123)I]MIBG) cardiac scintigraphy could be helpful to differentiate Parkinson's disease (PD) from multiple system atrophy (MSA), demonstrating that, in PD with autonomic failure but not in MSA, there is a myocardial postganglionic sympathetic dysfunction. To investigate whether this method is more sensitive than standard autonomic testing to detect early involvement of sympathetic cardiac efferent, we analyse MIBG myocardial uptake in 8 PD patients with normal autonomic testing (nondysautonomia PD group, NDPD) in comparison with 10 PD patients with abnormal autonomic testing (dysautonomia PD group, DPD) and 10 MSA patients. Global MIBG uptake was assessed using the ratio of [(123)I]MIBG uptake in the heart to the upper mediastinum (H/M) on planar scintigraphic data. Regional MIBG uptake was determined on two single photon emission tomography scans in regions of the left ventricle. The mean H/M ratios were significantly different among the three groups (P < 0.0001). H/M ratios of both NDPD and DPD patients groups (H/M = 1.83 +/- 0.50 and 1.24 +/- 0.40, respectively) were significantly lower than in MSA patients (H/M = 2.52 +/- 0.60). However, in NDPD patients, H/M was significantly higher than in DPD patients. When compared to MSA patients, NDPD patients showed a regional reduction in MIBG uptake in all left ventricle regions markedly in the apex and the inferior wall. Our results suggest that MIBG myocardial scintigraphy (analysis of both H/M ratio and regional MIBG uptake) may be more sensitive than standard autonomic testing for the early detection of silent autonomic dysfunction in PD.     

Analysis of the relationship between muscle sympathetic nerve activity and cardiac 123I-metaiodobenzylguanidine uptake in patients with Parkinson's disease.

To analyze the correlation between muscle sympathetic nerve activity (MSNA) and cardiac (123)I-metaiodobenzylguanidine (MIBG) uptake in patients with Parkinson's disease (PD), we measured both parameters in 14 PD patients who were 51 to 82 years of age (mean, 63.1 +/- 8.7 years). The duration of PD was 2 to 26 years, and the disability level (modified Hoehn and Yahr stage) ranged from 2.0 to 4.0 (mean, 3.2 +/- 0.5). MSNA was recorded from the peroneal nerve fascicles using microneurographic methods, and then cardiac MIBG scintigraphy was performed within 1 month. We analyzed the correlation between the standardized MSNA, expressed as a percentage of the predicted value based on control subject data, and the heart-to-mediastinum ratio (H/M) or washout ratio (WR) from early and delayed MIBG images. The relationships between disease duration or disability and MSNA, the H/M ratio, or the WR were also analyzed. No significant correlations were found between MSNA and H/M ratio or WR. Although MSNA was inversely correlated with disease duration and with disability level, neither the H/M ratio nor the WR showed a significant correlation with disease duration or disability level. Because MSNA and MIBG abnormalities were not related, functional changes in addition to organic changes in cardiac sympathetic nerve endings may result in abnormal uptake of MIBG in Parkinson's disease. .     

Cardiac MIBG scintigraphy in Primary Progressive Freezing Gait

Freezing of gait (FOG) generally occurs as a late manifestation of Parkinson's Disease (PD). FOG, however, can present in isolation, constituting the so-called "Primary Progressive Freezing Gait"(PPFG). Myocardial (123)Metaiodiobenzylguanidine (MIBG) enables the assessment of postganglionic sympathetic cardiac nerve terminals. MIBG uptake reflects sympathetic system integrity, and reduced myocardial uptake of the tracer has been observed in nearly all patients with PD. We investigated MIBG uptake in 7 patients with PPFG, 14 patients with mild PD, and 6 patients with advanced PD and FOG (PD-FOG), and 18 control subjects. Our study shows that myocardial MIBG uptake was normal in all patients with PPFG (H/M ratio: mean+/-SD, 1.85+/-0.11 early; 1.71+/-0.15 delayed) and in the controls (H/M ratio: mean+/-SD, 1.94+/-0.18 early; 2.02+/-0.19 delayed) whereas it was markedly decreased in the patients with mild and advanced PD (H/M ratio: mean+/-SD, PD: 1.17+/-0.02 early; 1.16+/-0.02 delayed; PD-FOG: 1.22+/-0.10 early; 1.08+/-0.06 delayed). Our findings demonstrate that cardiac sympathetic denervation did not occur in patients with PPFG, confirming that PPFG and PD are distinct diseases.     

Cardiac 123I-MIBG scintigraphy in patients with essential tremor.

In some cases, it is difficult to differentiate essential tremor (ET) from Parkinson's disease (PD), especially in the early stages of the disease. We investigated cardiac sympathetic dysfunction using (123)I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy in 22 patients with ET, in comparison with early PD and tremor-dominant PD (TDPD). The mean ratio of (123)I-MIBG uptake in the region of interest in the heart to that in the mediastinum (H/M ratio) was significantly greater in patients with ET (1.99 +/- 0.21) than in those with either TDPD (1.28 +/- 0.11) or early PD (1.28 +/- 0.17; each P < 0.001). The H/M ratio in all patients with ET was greater than two standard deviations above the range of the ratio in the patients with early PD or TDPD.     

Dobutamine stress test unmasks cardiac sympathetic denervation in Parkinson's disease

OBJECTIVE: Cardiac uptake of [(123)I]metaiodobenzyl guanidine (MIBG) is reduced in patients with Parkinson's disease (PD). However, the cardiac sympathetic abnormality associated with this reduction is unclear. To unmask this abnormality in PD patients we examined the functional consequences of cardiac beta-receptor activation. METHODS: Cardiovascular responses to stepwise administration of the beta1-receptor agonist, dobutamine (DOB), were assessed in 25 PD patients and 12 age-matched controls. Changes in blood pressure were compared to determine the optimal dose at which to detect denervation supersensitivity, and cardiac contractility was measured by DOB echocardiography, based on peak aortic flow velocity. The relations of these cardiovascular responses to the ratio of MIBG uptake into the heart vs. that into the mediastinum (H/M ratio) were analyzed. RESULTS: At 4 microg/kg/min DOB, systolic blood pressure increased more in PD patients than in controls (PD, 17.5+/-12.3 mm Hg; control, 7.2+/-6.2 mm Hg, p<0.01), suggesting the presence of denervation supersensitivity. At this DOB dose cardiac contractility also increased more in PD than in controls (PD, 39.0+/-15.7%; control, 23.5+/-5.2%, p<0.005) and this hyperdynamic response was significantly correlated with reduced H/M ratios (early: r=-0.63, p<0.01, delayed: r=-0.66, p<0.01). CONCLUSION: Low-dose DOB unmasks cardiac sympathetic denervation in PD patients, and decreased MIBG uptake indicates the presence of denervation supersensitivity within the heart, resulting in hyperdynamic cardiac contractility in response to a beta 1-stress condition.     

123I-MIBG cardiac uptake and smell identification in parkinsonian patients with LRRK2 mutations

Reduced uptake of (123)I- metaiodobenzylguanidine (MIBG) on cardiac gammagraphy and impaired odor identification are markers of neurodegenerative diseases with Lewy bodies (LB) as a pathological hallmark, such as idiopathic Parkinson's disease (IPD). LRRK2 patients present with a clinical syndrome indistinguishable from IPD, but LB have not been found in some cases. Patients with such mutations could behave differently than patients with IPD with respect to MIBG cardiac uptake and olfaction. We studied 14 LRRK2 patients, 14 IPD patients matched by age, gender, disease duration and severity, and 13 age and gender matched control subjects. Olfaction was analyzed through the University of Pennsylvania Smell Identification Test (UPSIT). MIBG cardiac uptake was evaluated through the H/M ratio. The late H/M was 1.44 ± 0.31 for LRRK2 patients, 1.19 ± 0.15 for PD patients, and 1.67 ± 0.16 for control subjects. LRRK2 patients presented lower but not statistically significant MIBG cardiac uptake than controls (p = 0.08) and significant higher uptake than PD patients (p = 0.04). UPSIT mean scores were 21.5 ± 7.3 for LRRK2 patients, 18.7 ± 6.2 for IPD patients and 29.7 ± 5.7 for control subjects. UPSIT score was lower in both LRRK2 and PD than in controls. In LRRK2 patients a positive correlation was found between myocardial MIBG uptake and UPSIT scores, (R = 0.801, p < 0.001). In LRRK2 patients, MIBG cardiac uptake was less impaired than in PD; a positive correlation between MIBG cardiac uptake and UPSIT scores was observed. As MIBG cardiac reduced uptake and impaired odor identification are markers of LB pathology, this findings may represent neuropathological heterogeneity among LRRK2 patients.     

Cardiac denervation occurs independent of orthostatic hypotension and impaired heart rate variability in Parkinson's disease

Patients with idiopathic Parkinson's disease (PD) have impaired sympathetically mediated neurocirculatory innervation. Here we analyzed the correlation between cardiac (123)I-metaiodobenzylguanidine (MIBG) uptake, orthostatic hypotension and heart rate variability in treated patients with PD. Orthostatic hypotension (OH) as a hallmark of sympathetic neurocirculatory failure was found with a high prevalence in PD. PD is known to affect cardiac innervation, resulting in a suppressed heart rate variability and a postganglionic noradrenergic lesion. We measured continuous arterial blood pressure in rest and 70 degrees head-up tilt for at least 20 min, heart rate variability in the supine position, standing, deep respiration and Valsalva manoeuvre in 58 patients with PD (27 male, 31 female; mean age 71 years, mean PD duration 5.1 years, Hoehn and Yahr 3.1+/-0.8). Sympathovagal balance was estimated by the low-frequency (LF: 0.04-0.15Hz) and high-frequency bands (HF: 0.15-0.4Hz) ratio in the analysis of heart rate variability in each condition. Myocardial adrenergic function was analyzed by imaging MIBG using the single-photon emission computed tomography technique. MIBG uptake expressed as heart-to-mediastinum ratio was reduced in all PD patients (H/M-ratio: 1.14+/-0.16). We found no correlation between myocardial MIBG uptake and sympathovagal balance, blood pressure or other autonomic findings. The LF/HF ratio in tilt-table testing was significantly more reduced in PD with OH than without OH (2.18 vs. 1.49, p=0.022). MIBG uptake did not differ. It is concluded that scintigraphy with MIBG appears to be a highly sensitive and useful tool to demonstrate sympathetic postganglionic cardiac nerve disturbances. Loss of sympathetic innervation of the heart seems to occur early and independent of orthostatic hypotension, baroreflex failure and impaired heart rate variability in PD.     

Cardiac sympathetic denervation in Parkinson’s disease patients with SWEDDs

Dopamine transporter scans of some patients who have been clinically diagnosed with Parkinson’s disease (PD) fail to reveal abnormal dopaminergic functioning and are referred to as scans without evidence of dopaminergic deficits (SWEDDs). In this study, we investigated the differences between SWEDDs patients and PD patients using ¹²³I-metaiodobenzylguanidine (MIBG) scans. This study enrolled 20 patients with SWEDDs, 30 patients with early PD and 50 healthy controls. Cardiac ¹²³I-MIBG scans were performed on all subjects, and parameters including the early and delayed heart-to-mediastinum ratios (H/M) and the washout rate were compared among the three groups. The mean delayed H/M ratio in the PD group (mean ± standard deviation, 1.45 ± 0.23) was the lowest of the three groups, and the scans in the group without evidence of dopaminergic deficits exhibited a lower mean delayed H/M ratio (2.15 ± 0.48) than the control group (2.56 ± 0.55) (p < 0.05). The intermediate status of cardiac MIBG uptake in the SWEDDs patients in our study may have been due to the heterogeneity of the SWEDDs patients; some of these patients had Parkinsonism with unknown characteristics, some may have had early PD with false-negative dopamine transporter imaging, and some have had primary dystonia that was misdiagnosed as PD. These uncharacterised SWEDDs patients accounted for a larger proportion of the heterogeneous SWEDDs than observed in previous studies, but our results suggest that cardiac ¹²³I-MIBG scans may help to differentiate patients with SWEDDs from patients with PD.     

Decreased myocardial 123 I-MIBG uptake in Parkinson's disease

We studied myocardial ¹²³ I-metaiodobenzylguanidine (MIBG) accumulation in 12 patients with Parkinson's disease (PD). MIBG is an analog of norepinephrine (NE) and a tracer for sympathetic neuron integrity and function. MIBG uptake of the myocardium was significantly lower in PD than in controls. The heart to mediastinum ratio (H/M) was calculated by using the average count per pixel for the heart and mediastinum. In PD, H/M was lower than in controls ( P <0.0001), while the washout ratio of the heart was higher ( P <0.001). A decrease in myocardial accumulation of MIBG was observed in the early stage of PD. This suggests that the measurement of MIBG may help the diagnosis of early PD, and the causative factor underlying in PD may be operating the NE neuron as well as dopamine neuron.     

Decreased cardiac MIBG uptake, its correlation with clinical symptoms in dementia with Lewy bodies

Recent studies have demonstrated the usefulness of ¹²³I-meta-iodobenzylguanidine (MIBG) myocardial scintigraphy for the diagnosis of dementia with Lewy bodies (DLB). In this study, we investigated the relationship between decreased cardiac MIBG uptake and clinical symptoms in DLB. Thirty-six patients with probable DLB and six normal controls underwent MIBG scintigraphy. We measured the early and delayed heart-to-mediastinum (H/M) ratios, and the results between subgroups based on the presence and absence of clinical symptoms were compared. The mean early and delayed H/M ratios were 1.55 ± 0.29 and 1.42 ± 0.30, and 30 (83.3%) and 33 (91.7%) subjects showed lower values compared to the cutoff, respectively. A statistically significant difference was found only between groups with and without orthostatic hypotension (OH). Among 10 DLB subjects without Parkinsonism, nine patients had a decreased H/M ratio in the delayed image. To our knowledge, this is the first study to correlate decreased MIBG uptake with the clinical symptoms of DLB, and to show a significantly lower H/M ratio in subjects with OH. Furthermore, we found that MIBG scintigraphy could detect cardiac sympathetic denervation regardless of clinically evident Parkinsonism. These results suggest that MIBG myocardial scintigraphy could be a valuable diagnostic test in the clinical diagnosis of DLB.     

Metaiodobenzylguanidine (MIBG) scintigraphy at various parts of the body in Parkinson's disease and multiple system atrophy

We compared MIBG uptake at various parts of the body in controls and patients with Parkinson's disease and multiple system atrophy. In the heart, MIBG uptake in Parkinson's disease (early H/M: 1.668+/-0.325, late H/M: 1.500+/-0.402) was less than that in multiple system atrophy (early H/M: 2.395+/-0.186, late H/M: 2.530+/-0.391) and controls (early H/M: 2.635+/-0.508, late H/M: 2.575+/-0.635) (early: P<0.0001, late: P<0.0001). There were no significant differences in uptake by the lung, thyroid, or liver in the three groups. Only on early images, uptake in the shoulder in multiple system atrophy (early S/M: 0.473+/-0.78) and Parkinson's disease (early S/M: 0.470+/-0.710) was decreased compared to that in controls (early S/M: 0.560+/-0.118) (P=0.0252). MIBG is reported to be taken up in the terminal part of sympathetic nerves and demonstrates sympathetic nerve activity, especially on late images. The cause of differences between the heart and other parts of the body remains unknown. We consider the following possibilities: (a) differences in the sympathetic nervous system between Parkinson's disease and multiple system atrophy are more subtle in organs other than the heart; (b) the cause of MIBG uptake reduction by the heart in Parkinson's disease involves factors in addition to sympathetic nervous system damage; and (c) MIBG uptake by organs other than the heart involves not only the sympathetic nervous system but also non-neuronal components. In conclusion, MIBG uptake by organs other than the heart cannot differentiate Parkinson's disease from multiple system atrophy at present.     

Follow-up study of cardiac 123I-MIBG scintigraphy in idiopathic REM sleep behavior disorder

Background: Cardiac ¹²³I‐metaiodobenzylguanidine (¹²³I‐MIBG) uptake in patients with idiopathic rapid eye movement (REM) sleep behavior disorder (iRBD) is markedly reduced, as in Parkinson’s disease (PD). Methods: We performed ¹²³I‐MIBG scintigrams on patients with iRBD and PD. After the initial ¹²³I‐MIBG scintigram, we retested subjects after a mean of 2.8 years. Results: The delayed heart‐to‐mediastinum (H/M) ratio of cardiac ¹²³I‐MIBG uptake was not significantly reduced between the first and second study in either group (P = 0.050, P = 0.091, respectively) . Follow‐up imaging revealed a mean decline of 4.21 ± 9.06% or 6.40 ± 19.02% in the delayed H/M ratio in those with iRBD or PD, respectively. Conclusions: The ¹²³I‐MIBG uptake findings might indicate progression early in the course of iRBD or PD, but the progression is heterogeneous and independent of development of motor symptoms.     

The role of 123I-metaiodobenzylguanidine myocardial scintigraphy in the diagnosis of Lewy body disease in patients with dementia in a memory clinic

Reduction in cardiac (123)I-metaiodobenzylguanidine (MIBG) uptake is a characteristic feature of Parkinson's disease (PD) and dementia with Lewy bodies (DLB), and is useful in distinguishing them from other neurodegenerative disorders. The aim of this study was to investigate the role of this method of scintigraphy in the differential diagnosis of dementia in our Memory Clinic. We performed MIBG scintigraphy in patients with dementia referred to the Memory Clinic and compared the heart-to-mediastinum (H/M) ratio of MIBG uptake. Thirty out of 32 patients with DLB and all 9 PD with dementia patients had reduced H/M ratios, whereas 37 out of 40 patients with Alzheimer's disease had normal H/M ratios. Most patients with vascular dementia, frontotemporal dementia, and other dementias had normal H/M ratios. The overall sensitivity to positively identify patients with Lewy body disease (including DLB and PD with dementia) was 95%, and the specificity to distinguish them from patients with other types of dementias was 87%. MIBG scintigraphy showed a high sensitivity for the detection of Lewy body disease, and also a high specificity for discrimination from other types of dementia. The scintigraphy may provide a valuable and adjunctive method in the diagnosis of Lewy body disease and a differential diagnostic tool for patients with dementias.     

Cardiac 123I-MIBG scintigraphy can assess the disease severity and phenotype of PD

Objective: Cardiac ¹²³I-metaiodobenzylguanidine (MIBG) scintigraphy studies of patients with idiopathic Parkinson's disease (PD) found decreased uptake. Whether this decrease is associated with clinical severity as assessed by the Unified Parkinson's Disease Rating Scale (UPDRS) and the phenotypes of PD has not been determined. Methods: Cardiac MIBG scintigraphy was performed on 34 patients with PD, 7 with multiple system atrophy (MSA), 4 with dementia with Lewy bodies (DLB), and 11 normal controls (NCs). Early and delayed MIBG heart/mediastinum (H/M) ratios were evaluated. PD severity was assessed by the Hoehn and Yahr (H–Y) stage and UPDRS. Patients were grouped in two phenotypes, tremor and postural instability gait difficulty (PIGD)-dominant groups based on UPDRS components. Associations between MIBG uptake and age at onset, UPDRS, and disease phenotype were analyzed in each group. Results: The early H/M ratio was significantly lower in patients with PD (1.45±0.207) than in the NCs (2.08±0.231), and in those with MSA (1.99±0.284), but not in those with DLB (1.29±0.0435). The delayed H/M ratio for PD (1.33±0.276) also was significantly decreased as compared to the ratios for NCs (2.17±0.286) and MSA (2.16±0.414) but not DLB (1.16±0.0949). The early H/M ratio was significantly correlated with both UPDRS score and age at onset, whereas the delayed H/M ratio only was significantly correlated with age at onset. The PIGD-dominant group had significantly higher UPDRS scores and lower H/M ratios than the tremor-dominant group. Conclusion: Cardiac MIBG scintigraphy can be used to differentiate PD from MSA and NC, and to determine the disease severity and phenotypes of PD.     

Abnormal cardiac [123I]‐meta‐iodobenzylguanidine uptake in multiple system atrophy

[¹²³I]‐Meta‐iodobenzylguanidine (MIBG) myocardial scintigraphy is useful for distinguishing multiple system atrophy (MSA) from Parkinson disease. In this study, longitudinal observation using MIBG myocardial scintigraphy was carried out in patients with MSA to evaluate the association of myocardial MIBG uptake with clinical features. A total of 96 MIBG examinations were performed in 52 patients with MSA. The heart/mediastinum (H/M) ratio of MIBG uptake at 240 minutes after injection was below the lower limit in 16 patients with MSA (31.3%). Overall, the H/M ratio correlated with neither disease duration nor severity. In the follow‐up observations, the H/M ratio did not show any specific trends, in contrast with the continuous decrease observed in patients with Parkinson's disease. This data clearly showed that cardiac MIBG uptake cannot necessarily be preserved in patients with MSA and that approximately 30% of patients with MSA showed decreased MIBG uptake without any correlation to disease duration or severity. © 2010 Movement Disorder Society     

Impaired myocardial 123I-metaiodobenzylguanidine uptake in Lewy body disease: comparison between dementia with Lewy bodies and Parkinson's disease

BACKGROUND: Iodine-123-labeled metaiodobenzylguanidine (123I-MIBG) myocardial scintigraphy has been used to evaluate cardiac sympathetic denervation in Lewy body disease (LBD) including Parkinson's disease (PD) and dementia with Lewy bodies (DLB). Patients with LBD had marked reductions in cardiac MIBG accumulation, indicative of severe impairment of the cardiac sympathetic nervous systems. However, the differences in scintigraphy between DLB and PD have not been determined. OBJECTIVE: To compare cardiac sympathetic function in early disease stage measured with 123I-MIBG scintigraphy between DLB and PD. METHODS: 123I-MIBG myocardial scintigraphy was performed in 22 patients with early-stage DLB, 41 patients with early idiopathic PD and 15 normal control subjects who were matched for age and disease duration. The heart-to-mediastinum (H/M) ratio was calculated. RESULTS: 123I-MIBG uptake of the myocardium was significantly lower in patients with early DLB than in controls. The mean value of H/M ratio in patients with DLB was significantly lower than those in patients with PD, independent of the Hoehn and Yahr stage. CONCLUSIONS: Our findings suggest that cardiac sympathetic function in DLB is severely impaired even in the early disease stage.     

A useful marker for differential diagnosis of Parkinson's disease--MIBG myocardial scintigraphy]

We performed [123I]-meta-iodobenzylguanidine (MIBG) myocardial scintigraphy in 180 patients with PD, 24 patients with DLB and 73 patients with the other related diseases. The heart-to-mediastinum (H/M) ratio in PD and DLB was significantly low compared to that in MSA, PSP, CBD and AD. The H/M ratio tended to decrease with the disease progression in PD. These findings suggest that MIBG myocardial scintigraphy could be a marker for differential diagnosis of PD and DLB. We immunohistochemically examined heart tissues from patients with pathologically confirmed PD, DLB and the other related diseases using monoclonal antibody against tyrosine hydroxylase (TH). The number of TH-immunoreactive nerve fibers in the epicardium was moderate or abundant in most patients with MSA, PSP, CBD and AD as well as in the control subjects. Contrarily, the number of TH-immunoreactive nerve fibers in the epicardium had almost completely disappeared in nearly all the patients with PD and DLB. These findings suggest that postganglionic cardiac sympathetic nerve denervation occurs in PD and DLB but not in MSA, PSP, CBD and AD, which accounts for the decreased cardiac uptake of MIBG in PD and DLB, but not in the other diseases.     

Sequential imaging analysis using MIBG scintigraphy revealed progressive degeneration of cardiac sympathetic nerve in Parkinson’s disease

Background: Metaiodobenzylguanidine (MIBG) cardiac scintigraphy was used to differentiate Parkinson’s disease (PD) with Lewy body pathology from other degenerative parkinsonisms. MIBG cardiac scintigraphy demonstrates the extent of degeneration of myocardial post‐ganglionic sympathetic nerves in patients with PD. Because of its specificity for Lewy body (LB) pathology, MIBG scan might also be useful biomarker for the neurodegeneration attributed to PD. To estimate the utility of the imaging technique as a biomarker, we conducted sequential imaging analysis and power analysis. Methods: Sixty‐three patients who met the UK PD Society Brain Bank criteria were enrolled in this study. ¹²³I‐MIBG myocardial scintigraphy was performed on all subjects, and the heart to mediastinum (H/M) ratio was calculated. A second imaging session was carried out after a mean interval of 268 days. Results: Sequential imaging revealed a 2.9% decline of the H/M ratio from the baseline to the follow‐up image, which reached statistical significance, but the power analysis showed that a relatively large number of patients would be required to demonstrate the neuroprotective effects of any therapy. Conclusions: Sequential imaging using ¹²³I‐MIBG myocardial scintigraphy revealed progressive degeneration of the cardiac sympathetic nerve in 63 patients with PD. Although careful elimination of other disease conditions that damage the cardiac sympathetic nerve system is necessary, ¹²³I‐MIBG myocardial scintigraphy may be a useful addition to clinical trials that intend to prove neuroprotection among patients with PD.     

Correlation between cardiac 123I-MIBG and odor identification in patients with Parkinson's disease and multiple system atrophy.

We investigated an association between olfaction and cardiac (123)I-metaiodobenzylguanidine (MIBG) uptake in patients with Parkinson's disease (PD) and multiple system atrophy (MSA). There was a significant positive correlation between cardiac MIBG uptake and the Cross-Cultural Smell Identification (CCSI) score in patients with PD (r = 0.56; P = 0.003) independent of the disease duration or clinical rating of motor status. However, patients with MSA did not show a significant correlation between cardiac MIBG uptake and the CCSI score. Our findings suggest that the functional losses of the olfactory and cardiac sympathetic systems are closely coupled in PD.     

Systemic blood pressure profile correlates with cardiac 123I-MIBG uptake in patients with Parkinson's disease

To examine the correlation between the systemic blood pressure profile and cardiac (123)I-metaiodobenzylguanidine (MIBG) uptake in patients with Parkinson's disease (PD), we monitored circadian blood pressure patterns of 37 PD patients of 49 to 85 years of age (mean, 71.8±8.4 years) using a portable blood pressure monitoring device. The duration of PD was 0.5 to 15 years, and the disability level (modified Hoehn and Yahr stage) ranged from 1.0 to 4.0 (mean, 2.7±0.7). There were 37 age- and sex-matched control subjects. Cardiac MIBG scintigraphy was performed for the 37 PD patients. Based on the nocturnal fall in mean arterial blood pressure (MABP), we classified patients into extreme dippers (nocturnal reduction of MABP >20%), dippers (>10% but <20%), nondippers (<10% but >0%), and inverted dippers (<0%). Average 24-hour MABP values revealed reduced BP variability in PD patients. The percentage nocturnal fall in MABP was significantly different between PD patients and control subjects (p<0.05). Significant correlations were found between % MABP reduction and the heart-to-mediastinum (H/M) ratio on early and delayed images (p<0.01). The UPDR motor score, early and delay H/M ratios were also significantly different between patients who were and were not dippers (p<0.05). The present results reported for the first time a significant correlation between the systemic blood pressure profile and cardiac (123)I-MIBG uptake in patients with PD. The degeneration between the brainstem and the postganglionic neurons of myocardial sympathetic nerves may progress in parallel in patients with PD.