Tau Positron Emission Tomography Imaging in Degenerative Parkinsonisms

In recent years, several radiotracers that selectively bind to pathological tau proteins have been developed. Evidence is emerging that binding patterns of in vivo tau positron emission tomography (PET) studies in Alzheimer’s disease (AD) patients closely resemble the distribution patterns of known neurofibrillary tangle pathology, with the extent of tracer binding reflecting the clinical and pathological progression of AD. In Lewy body diseases (LBD), tau PET imaging has clearly revealed cortical tau burden with a distribution pattern distinct from AD and increased cortical binding within the LBD spectrum. In progressive supranuclear palsy, the globus pallidus and midbrain have shown increased binding most prominently. Tau PET patterns in patients with corticobasal syndrome are characterized by asymmetrical uptake in the motor cortex and underlying white matter, as well as in the basal ganglia. Even in the patients with multiple system atrophy, which is basically a synucleinopathy, ¹⁸F-flortaucipir, a widely used tau PET tracer, also binds to the atrophic posterior putamen, possibly due to off-target binding. These distinct patterns of tau-selective radiotracer binding in the various degenerative parkinsonisms suggest its utility as a potential imaging biomarker for the differential diagnosis of parkinsonisms.

Clinical impact of delayed catheter removal for patients with central-venous-catheter-related Gram-negative bacteraemia

BACKGROUND

Gram-negative bacteria are increasingly the cause of catheter-related bloodstream infection (CRBSI), and the prevalence of multi-drug-resistant strains is rising rapidly. This study evaluated the impact of delayed central venous catheter (CVC) removal on clinical outcomes in patients with Gram-negative CRBSI.

METHODS

Between January 2007 and December 2016, patients with Gram-negative bacteraemia and CVC placement, from two tertiary care hospitals, were included retrospectively. Cases with CVC removal more than three days after onset of bacteraemia or without CVC removal were classified as having delayed CVC removal.

RESULTS

In total, 112 patients were included. Of these, 78 had CRBSI (43 definite and 35 probable) and 34 had Gram-negative bacteraemia from another source (non-CRBSI). Enterobacteriaceae were less common pathogens in patients with CRBSI than in patients with non-CRBSI (11.5% vs 41.3%; P<0.001). Delayed CVC removal was associated with increased 30-day mortality (40.5% vs 11.8%; P=0.01) in patients with Gram-negative CRBSI; this was not seen in patients with non-CRBSI (25.0% vs 14.3%; P>0.99). Delayed CVC removal [odds ratio (OR) 6.8], multi-drug-resistant (MDR) Gram-negative bacteraemia (OR 6.3) and chronic renal failure (OR 11.1) were associated with 30-day mortality in patients with CRBSI. The protective effect of early CVC removal on mortality was evident in the MDR group (48.3% vs 18.2%; P=0.03), but not in the non-MDR group (11.1% vs 0%; P=0.43).

CONCLUSION

CVCs should be removed early to improve clinical outcomes in patients with Gram-negative CRBSI, especially in settings where MDR isolates are prevalent.

Early administration of neuraminidase inhibitors in adult patients hospitalized for influenza does not benefit survival: a retrospective cohort study

The administration of neuraminidase inhibitors (NAIs) within 2 days after the onset of symptoms (early NAI therapy) has been shown to reduce mortality in adult patients with severe influenza. However, there is no sufficiently solid evidence supporting the effectiveness of early NAI therapy on mortality. We reviewed the clinical data from 506 adult patients who were hospitalized for influenza between March 2010 and March 2014, to investigate the impact of early NAI therapy on mortality. Nearly one-third of the study patients were infected with influenza B (influenza A, influenza B, and co-infection of both in 68.8%, 28.1%, and 3.2%, respectively), and were diagnosed using the polymerase chain reaction (PCR) method (33.6%). Less than half (233, 46.0%) had received early NAI therapy. Patients with early NAI therapy were admitted to the hospital earlier, more frequently infected with influenza A, and more frequently diagnosed using rapid influenza detection tests compared to those without early NAI therapy. Although patients without early NAI therapy presented with more serious clinical manifestations, such as an initial symptom of dyspnea, pneumonia, and intensive care unit admission, than those with early NAI therapy, the in-hospital mortality of the former (2.9%, 8/273) did not differ from that of the latter (3.4%, 8/233) (p = 0.75). We did not find a reduction in mortality associated with early NAI therapy in adult patients hospitalized for influenza. Further clinical studies including a large number of influenza B-infected patients with virus identification using PCR methodology rather than viral culture may be required to confirm the beneficial impact of early NAI therapy on mortality.

18F-AV-1451 binds to motor-related subcortical gray and white matter in corticobasal syndrome

OBJECTIVE

To investigate tau distribution in patients with corticobasal syndrome (CBS) using ¹⁸F-AV-1451 PET.

METHODS

Six consecutively recruited patients with CBS and 20 age-matched healthy controls underwent 2 PET scans with ¹⁸F-AV-1451 (for tau) and ¹⁸F-florbetaben (for β-amyloid). We compared standardized uptake value ratio maps of the ¹⁸F-AV-1451 PET images between the patients with CBS and controls.

RESULTS

Compared to controls, patients with CBS exhibited asymmetrically increased ¹⁸F-AV-1451 binding in the putamen, globus pallidus, and thalamus contralateral to the clinically more affected side and in the ipsilateral globus pallidus and dentate nucleus. Voxel-based comparison additionally showed asymmetrically increased ¹⁸F-AV-1451 binding in the focal regions of the precentral gray and white matter and in the midbrain, predominantly in the contralateral side. ¹⁸F-AV-1451 binding in the precentral white matter correlated with motor severity.

CONCLUSIONS

¹⁸F-AV-1451 asymmetrically binds to motor-related subcortical gray and white matter structures in patients with CBS. This pattern corresponds to tau pathology distribution in postmortem studies, and motor deficit in patients with CBS may be associated with tau accumulation predominantly in the subcortical white matter underlying the motor cortex, leading to disruptions in motor-related networks.

Off-Target 18F-AV-1451 Binding in the Basal Ganglia Correlates with Age-Related Iron Accumulation

Off-target binding in the basal ganglia is commonly observed in the ¹⁸F-AV-1451 PET studies of the elderly. We sought to investigate the relationship between this phenomenon in the basal ganglia and iron accumulation using iron-sensitive R₂* MRI. Methods: Fifty-nine healthy controls and 61 patients with Alzheimer disease and mild cognitive impairment underwent ¹⁸F-AV-1451 PET and R₂* MRI studies. A correlation analysis was performed for age, ¹⁸F-AV-1451 binding, and R₂* values. Results: There was an age-related increase in both ¹⁸F-AV-1451 binding in the basal ganglia and R₂* values in the putamen in both the controls and the Alzheimer disease/mild cognitive impairment patients. ¹⁸F-AV-1451 binding in the basal ganglia increased with R₂* values. Conclusion: Off-target ¹⁸F-AV-1451 binding in the basal ganglia is associated with the age-related increases in iron accumulation. Postmortem studies are required to further investigate the nature of this association.

Parkinsonian Patients with Striatal Cribriform State Present Rapidly Progressive Axial Parkinsonism

OBJECTIVE

To define the significance of striatal cribriform state (SCS) observed in patients with primary progressive parkinsonism.

METHODS

We reviewed medical records and brain magnetic resonance imaging studies of 1,260 patients with primary progressive parkinsonism. We identified 23 patients with SCS and analyzed their clinical features.

RESULTS

All 23 patients had rapidly progressive parkinsonism predominated by postural instability and gait disturbance. Clinical features of 18 of the 23 patients were compatible with progressive supranuclear palsy (PSP); 2 patients were compatible with parkinsonian type multiple system atrophy; 2 patients were compatible with mixed clinical features of both; and 1 patient had PSP-like clinical features.

CONCLUSIONS

Most parkinsonian patients with SCS present rapidly progressive parkinsonism predominated by postural instability and gait disturbance. SCS observed in patients with parkinsonism does not seem to be a coincidental finding associated with the generalized cerebrovascular process.

Paroxysmal freezing of gait in a patient with mesial frontal transient ischemic attacks

BACKGROUND

Rare patients have been reported who developed a mixture of gait disturbances following a focal lesion in the frontal lobe. Thus, the exact location of frontal lesion responsible for a specific gait disturbance is not well defined.

CASE PRESENTATION

We describe a 47-year-old man who experienced two episodes of paroxysmal freezing of gait of the right leg. During the attacks, he had no motor weakness, sensory change, or disequilibrium. He had past history of panic attacks. Recently, he had been under severe emotional stress. T2 and diffusion brain magnetic resonance imaging scans were normal. So far, the most likely clinical diagnosis might be functional freezing of gait. However, magnetic resonance angiography showed atherosclerosis in the proximal left anterior cerebral artery. Perfusion scans showed a delayed mean transit time in the left mesial frontal lobe. He developed two more attacks during the four months of follow up.

CONCLUSIONS

The presented case illustrates that the mesial frontal lobe may be important in the pathophysiology of freezing of gait. We speculate that the supplementary motor area may generate a neuronal command for the initiation of locomotion that in our case may have been inhibited by a transient ischemia.

Clinical Features Indicating Nigrostriatal Dopaminergic Degeneration in Drug-Induced Parkinsonism

OBJECTIVE

Patients with drug-induced parkinsonism (DIP) may have nigrostriatal dopaminergic degeneration. We studied the clinical features that may indicate nigrostriatal dopaminergic degeneration in patients with DIP.

METHODS

Forty-one DIP patients were classified into normal and abnormal [¹⁸F] FP-CIT scan groups. Differences in 32 clinical features and drug withdrawal effects were studied.

RESULTS

Twenty-eight patients had normal (Group I) and 13 patients had abnormal (Group II) scans. Eight patients of Group I, but none of Group II, had taken calcium channel blockers (p = 0.040). Three patients of Group I and six of Group II had hyposmia (p = 0.018). After drug withdrawal, Group I showed greater improvement in Unified Parkinson's Disease Rating Scale total motor scores and subscores for bradykinesia and tremors than Group II. Only hyposmia was an independent factor associated with abnormal scans, but it had suboptimal sensitivity.

CONCLUSION

None of the clinical features were practical indicators of nigrostriatal dopaminergic degeneration in patients with DIP.

Tau Accumulation in Primary Motor Cortex of Variant Alzheimer's Disease with Spastic Paraparesis

We studied topographic distribution of tau and amyloid-β in a patient with variant Alzheimer's disease with spastic paraparesis (VarAD) by comparing AD patients. The proband developed progressive memory impairment, dysarthria, and spastic paraparesis at age 23. Heterozygous missense mutation (L166P) was found in exon 6 of presenilin-1 gene. The proband showed prominently increased amyloid binding in striatum and cerebellum and asymmetrical tau binding in the primary sensorimotor cortex contralateral to the side more affected by spasticity. We suspect that upper motor neuron dysfunctions may be attributed to excessive abnormal tau accumulation rather than amyloid-β in the primary motor cortex.

In vivo cortical spreading pattern of tau and amyloid in the Alzheimer disease spectrum

OBJECTIVE

To determine the in vivo cortical spreading pattern of tau and amyloid and to establish positron emission tomography (PET) image-based tau staging in the Alzheimer disease (AD) spectrum.

METHODS

We included 195 participants (53 AD, 52 amnestic mild cognitive impairment [MCI], 23 nonamnestic MCI, and 67 healthy controls) who underwent 2 PET scans ((18) F-florbetaben for amyloid-β and (18) F-AV-1451 for tau). We assumed that regions with earlier appearances of pathology may show increased binding in a greater number of participants and acquired spreading order of tau accumulation by sorting the regional frequencies of involvement. We classified each participant into image-based tau stage based on the Z score of the composite region for each stage.

RESULTS

Tau accumulation was most frequently observed in the medial temporal regions and spread stepwise to the basal and lateral temporal, inferior parietal, posterior cingulate, and other association cortices, and then ultimately to the primary cortical regions. In contrast, amyloid accumulation was found with similar frequency in the diffuse neocortical areas and then finally spread to the medial temporal regions. The image-based tau stage correlated with the general cognitive status, whereas cortical thinning was found only in the advanced tau stages: medial temporal region in stage V and widespread cortex in stage VI.

INTERPRETATION

Our PET study replicated postmortem spreading patterns of tau and amyloid-β pathologies. Unlike the diffuse accumulation of amyloid throughout the neocortex, tau spreading occurred in a stepwise fashion through the networks. Image-based tau staging may be useful for the objective assessment of AD progression. Ann Neurol 2016;80:247-258.

Tau PET in Alzheimer disease and mild cognitive impairment

OBJECTIVE

To investigate the topographical distribution of tau pathology and its effect on functional and structural changes in patients with Alzheimer disease (AD) and mild cognitive impairment (MCI) by using (18)F-AV-1451 PET.

METHODS

We included 20 patients with AD, 15 patients with MCI, and 20 healthy controls, and performed neuropsychological function tests, MRI, as well as (18)F-florbetaben (for amyloid) and (18)F-AV-1451 (for tau) PET scans. By using the regional volume-of-interest masks extracted from MRIs, regional binding values of standardized uptake value ratios and volumes were measured. We compared regional binding values among 3 diagnostic groups and identified correlations among the regional binding values, performance in each cognitive function test, and regional atrophy.

RESULTS

(18)F-AV-1451 binding was increased only in the entorhinal cortex in patients with MCI, while patients with AD exhibited greater binding in most cortical regions. In the 35 patients with MCI and AD, (18)F-AV-1451 binding in most of the neocortex increased with a worsening of global cognitive function. The visual and verbal memory functions were associated with the extent of (18)F-AV-1451 binding, especially in the medial temporal regions. The (18)F-AV-1451 binding also correlated with the severity of regional atrophy of the cerebral cortex.

CONCLUSIONS

Tau PET imaging with (18)F-AV-1451 could serve as an in vivo biomarker for the evaluation of AD-related tau pathology and monitoring disease progression. The accumulation of pathologic tau is more closely related to functional and structural deterioration in the AD spectrum than β-amyloid.

Prescribing Pattern of Antidepressants in Children and Adolescents: Findings from the Research on Asia Psychotropic Prescription Pattern

OBJECTIVE

Pharmacotherapy of depression in children and adolescents is complex. In the absence of research into the efficacy and safety of antidepressants in this group of patients, their off-label prescription is common. This paper aimed to illustrate the prescription pattern of antidepressants in children and adolescents from major psychiatric centres in Asia.

METHODS

The Research on Asia Psychotropic Prescription Pattern on Antidepressants worked collaboratively in 2013 to study the prescription pattern of antidepressants in Asia using a unified research protocol and questionnaire. Forty psychiatric centres from 10 Asian countries / regions participated and 2321 antidepressant prescriptions were analysed.

RESULTS

A total of 4.7% antidepressant prescriptions were for children and adolescents. Fluoxetine, sertraline, and escitalopram were the most common antidepressants prescribed for children and adolescents. Almost one-third (30.3%) of prescriptions were for diagnoses other than depressive and anxiety disorders. There was less antidepressant polypharmacy and concomitant use of benzodiazepine, but more concomitant use of antipsychotics in children and adolescents compared with adults.

CONCLUSION

Off-label use of antidepressants in children and adolescents was reported by 40 Asian psychiatric institutions that participated in the study. In-service education and regulatory mechanisms should be reinforced to ensure efficacy and safety of antidepressants in children and adolescents.

Evaluation of salivary function by sialoscintigraphy in locally advanced nasopharyngeal cancer patients after intensity modulated radiotherapy

PURPOSE

This study aimed to evaluate the salivary gland function changes by sialoscintigraphy in locally advanced nasopharyngeal cancer (NPC) after intensity modulated radiotherapy (IMRT).

MATERIALS AND METHODS

Salivary function was assessed by sialoscintigraphy. Quantitative sialoscintigraphy was performed in 24 NPC patients prior to and after IMRT. Results were categorized in four groups according to the duration of treatment. The sialoscintigraphy parameters were examined.

RESULTS

Sialoscintigraphy showed a significant difference in the secretion of each interval groups. The parameters of scintigraphy, except maximum accumulation (MA) of submandibular glands, decreased first after radiotherapy, and then recovered. However, the MA of submandibular glands was continuously downhill after radiation.

CONCLUSIONS

The sialoscintigraphy parameters of each gland changed with the different radiation dose and follow-up intervals. The salivary function was influenced after radiotherapy in locally advanced NPC, especially, in the submandibular gland. Strategies to improve the salivary function should be assessed.

Clinical Heterogeneity of Atypical Pantothenate Kinase-Associated Neurodegeneration in Koreans

Objective

Neurodegeneration with brain iron accumulation (NBIA) represents a group of inherited movement disorders characterized by iron accumulation in the basal ganglia. Recent advances have included the identification of new causative genes and highlighted the wide phenotypic variation between and within the specific NBIA subtypes. This study aimed to investigate the current status of NBIA in Korea.

Methods

We collected genetically confirmed NBIA patients from twelve nationwide referral hospitals and from a review of the literature. We conducted a study to describe the phenotypic and genotypic characteristics of Korean adults with atypical pantothenate kinase-associated neurodegeneration (PKAN).

Results

Four subtypes of NBIA including PKAN (n = 30), PLA2G6-related neurodegeneration (n = 2), beta-propeller protein-associated neurodegeneration (n = 1), and aceruloplasminemia (n = 1) have been identified in the Korean population. The clinical features of fifteen adults with atypical PKAN included early focal limb dystonia, parkinsonism-predominant feature, oromandibular dystonia, and isolated freezing of gait (FOG). Patients with a higher age of onset tended to present with parkinsonism and FOG. The p.R440P and p.D378G mutations are two major mutations that represent approximately 50% of the mutated alleles. Although there were no specific genotype-phenotype correlations, most patients carrying the p.D378G mutation had a late-onset, atypical form of PKAN.

Conclusions

We found considerable phenotypic heterogeneity in Korean adults with atypical PKAN. The age of onset may influence the presentation of extrapyramidal symptoms.