Different iron deposition patterns in akinetic/rigid-dominant and tremor-dominant Parkinson's disease.

OBJECTIVE: The loss of dopaminergic cells and excessive iron deposition in some deep brain nuclei are associated with the pathophysiology of PD, and different clinical subtypes may indicate different pathological processes. This study was designed to investigate the relationships between regional iron in the cardinal subcortical nuclei and different clinical subtypes. PATIENTS AND METHODS: Nine Arkinetic/Rigid-dominant Parkinson's disease (PDAR) patients, eight Tremor-dominant (PDTD)patients and 10 matched healthy controls were recruited for this study. The iron content in 8 cardinal subcortical nuclei was measured through SWI sequence scanning (3.0 T), and different patterns of iron deposition were analyzed not only between the PD patients and HC groups but also between the different clinical subtypes. RESULTS: Compared with the healthy controls, the iron content in the substantia nigra pars compacta(SNc), substantia nigra pars reticulata(SNr) from both the severe and milder side in PD groups were significantly increased (P < 0.01 and P < 0.02 for SNc; both P < 0.01 for SNr), and the iron content in the GP of both the severe and milder side of the PDAR patients was significantly increased compared with the PDTD patients (P < 0.01 and P = 0.02, respectively) CONCLUSION: SWI is a very good technique for the in vivo assessment of subcortical nucleus iron content, and abnormal deposition of iron in the SNc and SNr is an obvious characteristic in PD patients. Furthermore, our data indicates that PDAR patients have higher iron content in the GP than PDTD patients and HCs, indicating that abnormal iron deposition in GP is related to the phenotype of Akinetic/Rigid in PD patients.

Acute hypokinetic-rigid syndrome following SARS-CoV-2 infection.

OBJECTIVE: To report a case of a patient infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) who acutely developed a hypokinetic-rigid syndrome. METHODS: Patient data were obtained from medical records from the Hospital Universitario 12 de Octubre in Madrid, Spain. [123I]-ioflupane dopamine transporter (DaT) SPECT images were acquired 4 hours after a single dose of 185 MBq of 123I-FP-CIT. Quantitative analysis was performed with DaTQUANT software providing the specific binding ratio and z score values of the striatum. RESULTS: We report a previously healthy 58-year-old man who developed hyposmia, generalized myoclonus, fluctuating and transient changes in level of consciousness, opsoclonus, and an asymmetric hypokinetic-rigid syndrome with ocular abnormalities after a severe SARS-CoV-2 infection. DaT-SPECT confirmed a bilateral decrease in presynaptic dopamine uptake asymmetrically involving both putamina. Significant improvement in the parkinsonian symptoms was observed without any specific treatment. CONCLUSION: This case study provides clinical and functional neuroimaging evidence to support that SARS-CoV-2 can gain access to the CNS, affecting midbrain structures and leading to neurologic signs and symptoms.

Shear wave velocity is sensitive to changes in muscle stiffness that occur independently from changes in force.

Clinical assessments for many musculoskeletal disorders involve evaluation of muscle stiffness, although it is not yet possible to obtain quantitative estimates from individual muscles. Ultrasound elastography can be used to estimate the material properties of unstressed, homogeneous, and isotropic materials by tracking the speed of shear wave propagation; these waves propagate faster in stiffer materials. Although elastography has been applied to skeletal muscle, there is little evidence that shear wave velocity (SWV) can directly estimate muscle stiffness since this tissue violates many of the assumptions required for there to be a direct relationship between SWV and stiffness. The objective of this study was to evaluate the relationship between SWV and direct measurements of muscle force and stiffness in contracting muscle. Data were collected from six isoflurane-anesthetized cats. We measured the short-range stiffness in the soleus via direct mechanical testing in situ and SWV via ultrasound imaging. Measurements were taken during supramaximal activation at optimum muscle length, with muscle temperature varying between 26°C and 38°C. An increase in temperature causes a decrease in muscle stiffness at a given force, thus decoupling the tension-stiffness relationship normally present in muscle. We found that increasing muscle temperature decreased active stiffness from 4.0 ± 0.3 MPa to 3.3 ± 0.3 MPa and SWV from 16.9 ± 1.5 m/s to 15.9 ± 1.6 m/s while force remained unchanged (mean ± SD). These results demonstrate that SWV is sensitive to changes in muscle stiffness during active contractions. Future work is needed to determine how this relationship is influenced by changes in muscle structure and tension.NEW & NOTEWORTHY Shear wave ultrasound elastography is a noninvasive tool for characterizing the material properties of muscle. This study is the first to compare direct measurements of stiffness with ultrasound measurements of shear wave velocity (SWV) in a contracting muscle. We found that SWV is sensitive to changes in muscle stiffness, even when controlling for muscle tension, another factor that influences SWV. These results are an important step toward developing noninvasive tools for characterizing muscle structure and function.

GABAergic changes in the thalamocortical circuit in Parkinson's disease.

Parkinson's disease is characterized by bradykinesia, rigidity, and tremor. These symptoms have been related to an increased gamma-aminobutyric acid (GABA)ergic inhibitory drive from globus pallidus onto the thalamus. However, in vivo empirical evidence for the role of GABA in Parkinson's disease is limited. Some discrepancies in the literature may be explained by the presence or absence of tremor. Specifically, recent functional magnetic resonance imaging (fMRI) findings suggest that Parkinson's tremor is associated with reduced, dopamine-dependent thalamic inhibition. Here, we tested the hypothesis that GABA in the thalamocortical motor circuit is increased in Parkinson's disease, and we explored differences between clinical phenotypes. We included 60 Parkinson patients with dopamine-resistant tremor (n = 17), dopamine-responsive tremor (n = 23), or no tremor (n = 20), and healthy controls (n = 22). Using magnetic resonance spectroscopy, we measured GABA-to-total-creatine ratio in motor cortex, thalamus, and a control region (visual cortex) on two separate days (ON and OFF dopaminergic medication). GABA levels were unaltered by Parkinson's disease, clinical phenotype, or medication. However, motor cortex GABA levels were inversely correlated with disease severity, particularly rigidity and tremor, both ON and OFF medication. We conclude that cortical GABA plays a beneficial rather than a detrimental role in Parkinson's disease, and that GABA depletion may contribute to increased motor symptom expression.

Individual parkinsonian motor signs and striatal dopamine transporter deficiency: a study with [I-123]FP-CIT SPECT.

INTRODUCTION: Total parkinsonian motor symptom severity correlates with presynaptic striatal dopamine function in patients with Parkinson's disease. There is a lack of studies that have investigated the associations between parkinsonian motor signs and striatal dopaminergic deficiency in patients with parkinsonism of an unknown origin. Identification of specific motor signs associated with the highest likelihood of striatal dopamine deficiency could aid the differential diagnostics of parkinsonian and tremor syndromes. METHODS: In this cross-sectional clinical and imaging study, detailed motor examinations were performed for 221 patients with parkinsonism or tremor of an unknown origin immediately before dopamine transporter (DAT) [I-123]FP-CIT SPECT imaging. Region-of-interest and voxel-based methods were used to investigate striatal DAT deficiency in relation to individual motor signs. RESULTS: Upper extremity rigidity and facial expression were the only motor signs that differentiated patients with normal and abnormal striatal DAT function. The presence of any upper extremity rigidity showed the highest likelihood of DAT deficiency (OR 4.79, 95% CI 1.56-14.75, P = 0.006) followed by reduced facial expression (OR 2.14, 95% CI 1.14-4.00, P = 0.018). In patients with DAT deficits, reduced facial expression was associated with DAT deficiency specifically in the caudate nucleus, and increased upper extremity rigidity was associated with DAT loss in the dorsal putamen (FWE-corrected P < 0.05). CONCLUSIONS: Increased upper extremity muscle tone and hypomimia are independently associated with a higher likelihood of striatal hypodopaminergic imaging finding. This information can be used as a factor when the clinical need of auxiliary investigations, such as DAT SPECT, is considered for patients with parkinsonism.

Impaired topographic organization in cognitively unimpaired drug-naïve patients with rigidity-dominant Parkinson's disease.

BACKGROUND: Resting-state functional magnetic resonance imaging (fMRI) and graph theory approaches have been combined to investigate the topographic organization in Parkinson's disease (PD). METHOD: Twenty cognitively unimpaired drug-naïve patients with rigidity-dominant PD (PDAR) and 20 age-, sex-, and education-matched healthy controls were included. Small-world profile and topographic properties (clustering coefficient (Cp), characteristic path length (Lp), local efficiency (Eloc), global efficiency (Eglob), nodal efficiency (Enod), nodal degree (NDeg), and nodal betweenness (NBet)) were measured and compared between two groups, with age, gender and education as covariates. Correlation analyses between topographic features and the unified PD rating scale part-III (UPDRS-III) scores, cognitive scores were performed. RESULTS: PDAR patients presented the small-world property, and abnormalities at the nodal level (Enod, NDeg, and NBet) but not at the global level (Cp, Lp, Eloc, and Eglob). Our results revealed lower nodal centralities mainly in the occipital lobe and areas of the limbic system (including amygdala nucleus), and higher nodal centralities in distributed frontal and temporal regions. Notably, the decreased nodal efficiency of occipital regions (including the calcarine area, lingual area and superior occipital gyrus (SOG)) was negatively correlated with UPDRS-III scores. And the nodal efficiency of the calcarine area was positively correlated with visuospatial scores. CONCLUSION: Our results may provide insights into the underlying pathophysiology of PDAR and aid the development of potential biomarkers of the disease progression and cognitive decline in PDAR patients.

Impaired muscle growth precedes development of increased stiffness of the triceps surae musculotendinous unit in children with cerebral palsy.

AIM: If increased muscle stiffness and contractures in children with cerebral palsy (CP) are related to impaired muscle growth, reduced muscle growth should precede or coincide with increased muscle stiffness during development. Here, we compared the volume of the medial gastrocnemius muscle and the passive (non-neural) stiffness of the triceps surae musculotendinous unit in typically developing children and children with CP from birth until 4 years of age. METHOD: Forty-one children with CP and 45 typically developing children were included. Freehand three-dimensional ultrasound was used to evaluate the volume of the medial gastrocnemius muscle. Biomechanical and electrophysiological measures were used to determine passive and reflex mediated stiffness of the triceps surae musculotendinous unit. RESULTS: Medial gastrocnemius muscle volume increased with the same rate in typically developing and children with CP until 12 months of age, when a significant smaller rate of growth was observed in children with CP. Passive stiffness of the triceps surae musculotendinous unit showed a linear increase with age in typically developing children. Children with CP older than 27 months showed a significant increase in passive stiffness. Reflex mediated stiffness was only pathologically increased in four children with CP. INTERPRETATION: The deviation of medial gastrocnemius muscle volume, earlier than musculotendinous unit stiffness, is consistent with the hypothesis. The data also point out that muscle atrophy and muscle stiffness already develops within the first 1 to 2 years. This emphasizes the necessity of early interventions to promote lower limb muscle growth in this population. WHAT THIS PAPER ADDS: Medial gastrocnemius muscle growth is reduced in children with cerebral palsy (CP) around 12 months after birth. Triceps surae musculotendinous unit stiffness is increased in children with CP around 27 months after birth. Reflex excitability is rarely increased in children with CP. Reduced muscle growth may be involved in the pathophysiology of contractures.

Patterns of grey matter loss associated with motor subscores in early Parkinson's disease.

Classical motor symptoms of Parkinson's disease (PD) such as tremor, rigidity, bradykinesia, and axial symptoms are graded in the Movement Disorders Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) III. It is yet to be ascertained whether parkinsonian motor symptoms are associated with different anatomical patterns of neurodegeneration as reflected by brain grey matter (GM) alteration. This study aimed to investigate associations between motor subscores and brain GM at voxel level. High resolution structural MRI T1 scans from the Parkinson's Progression Markers Initiative (PPMI) repository were employed to estimate brain GM intensity of PD subjects. Correlations between GM intensity and total MDS-UPDRS III and its four subscores were computed. The total MDS-UPDRS III score was significantly negatively correlated bilaterally with putamen and caudate GM density. Lower anterior striatal GM intensity was significantly associated with higher rigidity subscores, whereas left-sided anterior striatal and precentral cortical GM reduction were correlated with severity of axial symptoms. No significant morphometric associations were demonstrated for tremor subscores. In conclusion, we provide evidence for neuroanatomical patterns underpinning motor symptoms in early PD.

Magnetic Resonance Imaging-guided Focused Ultrasound Thalamotomy for Parkinson's Disease.

Thalamotomy is effective in treating refractory tremor in Parkinson's disease (PD). We herein report a PD patient who underwent left ventral intermediate nucleus and ventro oralis posterior nucleus thalamotomy using magnetic resonance imaging-guided focused ultrasound (MRgFUS). Right-side resting tremor and rigidity were abolished immediately following the ultrasound energy delivery. In addition, left-side resting tremor and rigidity also improved. No adverse events occurred during the procedure. We observed the exacerbation of bradykinesia, which might have been caused by edema around the target. This is the first report of thalamotomy using MRgFUS for PD patient from Japan. Further investigations concerning the efficacy and safety of this procedure are necessary.

Default-mode network connectivity in cognitively unimpaired drug-naïve patients with rigidity-dominant Parkinson's disease.

Parkinson's disease (PD) with akinetic rigidity (PDAR) is more likely to develop cognitive deficits compared to PD with tremor-dominant symptoms (PDTD). The default mode network (DMN) is highly relevant for cognitive processes, so this study tested the functional connectivity (FC) of DMN in cognitively unimpaired PDAR patients. Resting-state fMRI data were collected in 21 cognitively unimpaired early stage drug-naïve patients with PDAR and 21 healthy controls (HC). PD patients were matched closely to HCs for demographic and cognitive variables. FC of DMN was evaluated by seed-based correlation approach. Compared to HCs, despite comparable cognitive performance and no statistically discernible GM volume differences, a disruption in the DMN of PDAR subjects was detected. A decreased FC of DMN was found, specifically prominent in the posterior DMN. We also found a significantly increased FC of the anterior DMN. Three parts of left medial prefrontal regions (anterior, ventral, and dorsal) had significantly increased FC with the cerebellum. In addition, increased FC values of the anterior and ventral parts were negatively correlated with cognitive scores. An evident decline of FC of posterior DMN and enhanced compensatory FC of anterior DMN suggested an early functional disruption of DMN in PDAR prior to clinical evidence of cognitive impairment. It could be hypothesized that the dysfunction of DMN connectivity may have a role in the development of cognitive decline in PD. However, further longitudinal studies are warranted to understand the underlying neural mechanisms and their relevance to clinical and cognitive outcomes in PDAR subtype.

Degeneration of the corticofugal tract from the secondary motor area in a Parkinson's disease patient with limb-kinetic apraxia: A case report.

RATIONALE: In this case report, we describe a Parkinson's disease (PD) patient with limb-kinetic apraxia (LKA) in whom degeneration of the corticofugal tract (CFT) from the supplementary motor area (SMA) was observed in diffusion tensor tractography (DTT). PATIENT CONCERNS: A 63-year-old woman presented with a loss of dexterity in both upper extremities, which indicated LKA, and typical PD-related symptoms, including a gait disturbance with a short step, resting tremor in both upper extremities, and rigidity, and these symptoms had been present for 2 years. The F-florinated-N-3-fluoropropyl-2-ß-carboxymethoxy-3-ß-(4-lodophenyl) nortropane positron emission tomography scanning findings were consistent with PD. Based on the clinical symptoms and imaging findings, we diagnosed the patient with PD. In a coin-rotation test that was used to evaluate the severity of the LKA, the patient's results significantly decreased compared to the results of the normal controls. DIAGNOSES: The DTT showed that the CFTs from the SMAs in both hemispheres were partially torn and thinned. The fractional anisotropy values and CFT volumes in both SMAs were >2 standard deviations lower than those of the normal controls. INTERVENTIONS: The patient was treated with an initial dose of 150/37.5 mg/day of levodopa/benserazide, and the dose was gradually increased to 400/100 mg/day. OUTCOMES: After treatment, although the bradykinesia, rigidity, and resting tremor of the patient significantly decreased, the dexterity of the patient's hands did not improve. LESSONS: These observations indicated degeneration of the CFTs from the SMAs in both hemispheres in the patient. This degeneration might have, at least in part, contributed to the patient's LKA. The results of this study suggest that CFT degeneration could be one of the pathological mechanisms underlying LKA in patients with PD.

Ultrasound strain elastography in assessment of resting biceps brachii muscle stiffness in patients with Parkinson's disease: a primary observation.

The aim of this study was to evaluate the feasibility of ultrasound strain elastography (SE) for the assessment of resting biceps brachii muscle (BBM) stiffness in patients with Parkinson's diseases (PD). From May 2014 to December 2014, we prospectively performed SE of BBM in 14 patients with PD and 10 healthy controls. Based on the Unified Parkinson's Disease Rating Scale for scoring muscle rigidity (UPDRS, part III), muscle rigidity scores in 14 patients with PD included 3 patients with high rigidity (UPDRS III-IV) and 11 patients with low rigidity (UPDRS I-II). Ultrasound strain was represented by the deformation of the BBM and subcutaneous soft tissues that was produced by external compression with a sand bag (1.5 kg) tied onto an ultrasound transducer. Deformation was estimated with two-dimensional speckle tracking. The difference in strain ratio (SR, defined as mean BBM strain divided by mean subcutaneous soft tissue strain) between PD and healthy controls was tested by unpaired t test. The correlation between SR and muscle rigidity score was analyzed by Pearson correlation coefficient. The reliability of SR in assessment of BBM stiffness was tested using intraclass correlation coefficient. In our result, the SR in PD and healthy controls measured 2.65±0.36 and 3.30±0.27, respectively. A significant difference in SR was noted between the healthy controls and PD (P=.00011). A negative correlation was found between SR and UPDRS rigidity score (r=-0.78). Our study suggests that the SR of BBM to reference tissue can be used as a quantitative biomarker in assessing resting muscle stiffness associated with muscle rigidity in PD.

Dopamine transporter availability in motor subtypes of de novo drug-naïve Parkinson's disease.

Tremor dominant (TD) and akinetic-rigid type (ART) are two motor subtypes of Parkinson's disease associated with different disease progression and neurochemical/neuropathological features. The role of presynaptic nigrostriatal dopaminergic damage is still controversial, poorly explored, and only assessed in medicated patients. In this study, we investigated with FP-CIT SPECT the striatal dopamine transporter (DAT) availability in drug-naïve PD patients with ART and TD phenotypes. Fifty-one de novo, drug-naïve patients with PD underwent FP-CIT SPECT studies. Patients were evaluated with Unified Parkinson's Disease Rating Scale (UPDRS) part III and Hoehn and Yahr scale (H&Y) and divided into ART (24/51) and TD (27/51) according to UPDRS part III. ART and TD patients were not different with regard to age, gender, and disease duration. However, compared to TD, ART patients presented higher UPDRS part III (p = 0.01) and H&Y (p = 0.02) and lower DAT availability in affected and unaffected putamen (p = 0.008 and p = 0.007, respectively), whereas no differences were found in caudate. Moreover, in the whole group of patients, rigidity and bradykinesia, but not tremor scores of UPDRS part III were significantly related to FP-CIT binding in the putamen. These results suggest that in newly diagnosed drug-naïve PD patients DAT availability might be different between ART and TD in relation to different disease severity.

Associations of muscle stiffness and thickness with muscle strength and muscle power in elderly women.

AIM: The aims of this study were to investigate the influence of age on muscle stiffness and to examine the relationships among muscle stiffness, muscle thickness, subcutaneous fat thickness, muscle strength and muscle power in elderly women. METHODS: The subjects were 16 young (mean age 20.3 years) and 34 elderly (mean age 84.2 years) women. Muscle stiffness of the right quadriceps femoris muscle was measured at rest and during a maximal voluntary isometric muscle contraction using a myotonometer, a computerized, electronic tissue compliance meter. Thicknesses of the rectus femoris and the vastus intermedius muscles and the overlying subcutaneous fat were measured using ultrasound. Quadriceps strength and the chair stand test were used to represent muscle strength and muscle power, respectively. RESULTS: There were significant differences in muscle stiffness between rest and contraction conditions among the young but not the elderly women. Muscle stiffness during contraction, the rate of change in muscle stiffness during contraction, and muscle thickness were significantly greater in young than in elderly subjects. Pearson correlation coefficient analyses showed that muscle stiffness was significantly associated with muscle power, but not with muscle strength. CONCLUSION: This study suggests that the increase in muscle stiffness during voluntary muscle contraction is limited in elderly women compared with young women, and that muscle stiffness may be related to muscle power rather than muscle strength in elderly persons.

Akinetic-rigid and tremor-dominant Parkinson's disease patients show different patterns of FP-CIT single photon emission computed tomography.

OBJECTIVE: To elucidate whether Parkinson's disease subtypes show a different pattern of Iodine-123 fluoropropyl-;carbomethoxy-3 ß-(FP-CIT) single photon emission computed tomography (SPECT) binding in accordance with neuropathological findings. METHODS: We analyzed a database of consecutive patients with FP-CIT scan (n = 190) over a 3-year period and identified 122 patients (50 women, 72 men, mean age 62 ± 11.1 years) with a diagnosis of idiopathic Parkinson's disease. Patient's characteristics and FP-CIT scan results were analyzed and compared for the subgroups tremor-dominant versus akinetic-rigid and equivalent type of Parkinson's disease. RESULTS: The analysis of all Parkinson's disease patients showed a significant difference between the FP-CIT uptake in the subgroups tremor-dominant and akinetic-rigid. After matching these samples for age, disease duration, disease severity (Hoehn & Yahr grade, Unified Parkinson's Disease Rating Scale score), and levodopa-equivalent dose, these findings were balanced between both groups (n = 23/23) without a significant difference (P > 0.05). However, there was a clear, significant association of visually analyzed shapes of the striatum in FP-CIT SPECT and clinical Parkinson's disease subtype. CONCLUSION: These results confirm neuropathological models for a reduced dopaminergic projection to the dorsal putamen in akinetic-rigid patients as well as the lateral putamen and caudate nucleus in tremor-dominant patients in vivo.

Progressive encephalomyelitis with rigidity and myoclonus preceding otherwise asymptomatic Hodgkin's lymphoma.

Stiff-person syndrome (SPS), a rare neuroimmunological disorder, is characterized by symmetrical rigidity and muscle stiffness, particularly of axial and proximal limb muscles. Progressive encephalomyelitis with rigidity and myoclonus (PERM) is a variant of SPS which includes additional clinical features (e.g. sensory symptoms, brain stem signs and pathological CSF findings). An association of both SPS and PERM with (solid) malignancies has been previously reported. Beyond this, there have been single reports of SPS in the setting of Hodgkin's lymphoma (HL). Here, we present a case of PERM associated with HL, with PERM preceding occurrence of lymphoma by more than seven months. Our observation has obvious implications for the management and, in particular, diagnostic evaluation of patients with PERM.

Use of a single [123I]-FP-CIT SPECT to predict the severity of clinical symptoms of Parkinson disease.

The aim of this study was to assess the ability of a single SPECT performed in the early stage of Parkinson's disease (PD) to predict disease severity in 19 patients with early PD. [(123)I]-FP-CIT striatal uptake was expressed as a ratio of specific:nonspecific uptake for defined brain areas. Clinical severity was determined by the UPDRS at baseline and 12-15 months following the SPECT procedure. [(123)I]-FP-CIT uptake in the contralateral putamen and striatum was correlated with UPDRS score at baseline, with a more significant correlation after 1-year interval. [(123)I]-FP-CIT uptake in all areas was correlated with bradykinesia and rigidity subscores only at follow up visit. Significant correlations were found between [(123)I]-FP-CIT uptake in the contralateral striatum, putamen and caudate and the difference between motor scores of 1-year interval (DeltaUPDRS). These results suggest that disease severity might be anticipated by a single SPECT at an early stage of the disease.

Ultrasonographic findings of shoulder disorders in patients with Parkinson's disease.

The prevalence of a history of shoulder complaints is higher in patients with Parkinson's disease (PD) than in healthy individuals. The aims of this study were to evaluate shoulder disease in PD patients with ultrasonography (US) and to identify the relationship between the US findings of shoulder disease and the motor signs in patients with PD. Thirty-three PD patients completed a shoulder disability questionnaire, a musculoskeletal examination, and US of the shoulder. Twenty-two patients had abnormal US findings. Tendon tearing was the most common abnormal US finding (22/22), and the supraspinatus tendon was the most common site involved (15/22). Patients with tendon tearing had a significantly longer duration of disease than patients without tendon tearing (P = 0.027). Patients with adhesive capsulitis had a significantly higher rigidity score than patients without adhesive capsulitis (P = 0.035). Disease duration and rigidity were the contributing factors for the development of tendon tearing and adhesive capsulitis, respectively.

[123I]FP-CIT striatal binding in early Parkinson's disease patients with tremor vs. akinetic-rigid onset.

We performed [123I]FP-CIT/SPECT in 20 drug-naive Parkinson's disease (PD) patients, 10 with unilateral akinesia/rigidity at onset (arPD) and 10 with additional tremor-at-rest (tPD), to evaluate whether resting tremor at onset is associated with differences in striatal dopamine transporter binding. Patients of the two cohorts were matched for age, disease duration (<3 years) and severity of non-tremor motor symptoms; 31 healthy participants served as controls. Mean striatal dopamine transporter binding reduction in PD patients vs. controls was 42% for arPD and 50% for tPD; mean ipsilateral striatum and caudate nucleus uptake values were lower by 12 and 24%, respectively, in tPD than arPD. We conclude that widespread degeneration of the nigrostriatal dopaminergic pathway might be necessary for the development of parkinsonian tremor-at-rest.