Role of FDG PET/CT in definitive and presumed autoimmune encephalitis.

OBJECTIVE: F-18 Fluorodeoxyglucose PET/CT (FDG-PET) is emerging as a useful imaging adjunct to MRI in the initial diagnostic evaluation of autoimmune encephalitis (AIE)-though presently it is not included in the diagnostic criteria. MATERIALS AND METHODS: In this prospective study we enrolled a total of 52 patients with clinically diagnosed and treated AIE. MRI evaluation was done in each case along with CSF and EEG where feasible. FDG-PET was done for all and images were interpreted visually and using SPM. RESULTS: The mean age group of patients included was 38.5 ± 22.6 years with 31 females and 21 males. 23 antibody-positive cases underwent PET, the most common antibody detected was anti-NMDAR type followed by anti-LGI 1. Most common metabolic pattern in NMDARE was hypermetabolism in basal ganglia and hypometabolism in parieto-occipital cortices and ovarian teratoma was detected in two of these patients on whole-body PET. A metabolic pattern consistent with AIE was demonstrated in 22/29 (75.8%) antibody-negative patients with hypermetabolism in basal ganglia and mesial temporal cortices. The overall sensitivity of FDG PET was 86% (45/52). MRI abnormalities were detected in 22/52 (42%) cases, 10/23 antibody positive and 12/29 antibody negative cases. PET was positive in 23/30 (76%) MRI negative cases. CONCLUSION: Sensitivity of FDG PET for supporting a diagnosis of AIE was higher compared to MRI in both antibody-positive (definitive) and antibody-negative (presumed) AIE. Specific metabolic patterns can be demonstrated on FDG PET in AIE, prompting an early diagnosis so that timely treatment can be instituted.

Polymicrobial Pyomyositis in a Patient with Suspected Myeloma on 18F-FDG PET-CT.

Pyomyositis is an infective involvement of systemic skeletal muscles. We discuss the case of 43-year-old male who presented with quadriparesis, anemia, and hypercalcemia, leading to suspicion of multiple myeloma, and on FDG PET-CT, incidentally, pyomyositis was found. FDG PET-CT thus helped in diagnosing an occult infection which helped in the treatment of the patient.

99mTc-Ethambutol Scan with SPECT/CT in Knee Joint Tuberculosis.

Modalities for in vivo imaging of Mycobacterium tuberculosis are limited and inadequately studied. One such modality is 99mTc-ethambutol scintigraphy which has shown promising results for diagnosis of tuberculosis (TB). Ethambutol, one of the primary antitubercular drugs, is bacteriostatic which acts on the mycolic acid cell wall synthesis of the M. tuberculosis. However, literature on its utility is scarce. The few studies that exist have reported its sensitivity and specificity between 90%- 95% and 71%-85%. We present here a case demonstrating the role of 99mTc-ethambutol scan in knee joint TB.

Serum and cerebrospinal fluid immune mediators in children with autistic disorder: a longitudinal study.

BACKGROUND: The causes of autism likely involve genetic and environmental factors that influence neurobiological changes and the neurological and behavioral features of the disorder. Immune factors and inflammation are hypothesized pathogenic influences, but have not been examined longitudinally. METHODS: In a cohort of 104 participants with autism, we performed an assessment of immune mediators such as cytokines, chemokines, or growth factors in serum and cerebrospinal fluid (n = 67) to determine potential influences of such mediators in autism. RESULTS: As compared with 54 typically developing controls, we found no evidence of differences in the blood profile of immune mediators supportive of active systemic inflammation mechanisms in participants with autism. Some modulators of immune function (e.g., EGF and soluble CD40 ligand) were increased in the autism group; however, no evidence of group differences in traditional markers of active inflammation (e.g., IL-6, TNFα, IL-1ß) were observed in the serum. Further, within-subject stability (measured by estimated intraclass correlations) of most analytes was low, indicating that a single measurement is not a reliable prospective indicator of concentration for most analytes. Additionally, in participants with autism, there was little correspondence between the blood and CSF profiles of cytokines, chemokines, and growth factors, suggesting that peripheral markers may not optimally reflect the immune status of the central nervous system. Although the relatively high fraction of intrathecal production of selected chemokines involved in monocyte/microglia function may suggest a possible relationship with the homeostatic role of microglia, control data are needed for further interpretation of its relevance in autism. CONCLUSIONS: These longitudinal observations fail to provide support for the hypothesized role of disturbances in the expression of circulating cytokines and chemokines as an indicator of systemic inflammation in autism. ClinicalTrials.gov, NCT00298246.

No Evidence of Antibodies against GAD65 and Other Specific Antigens in Children with Autism.

BACKGROUND: The presence of autoantibodies has been proposed as evidence for a role of autoimmunity in autism. This report investigates the prevalence of autoantibodies in children with autism using the luciferase immunoprecipitation systems (LIPS) immunoassay technology. A panel of autoantibody targets against several known and candidate neurological autoantigens, autoimmune-associated autoantigens and viruses was employed. METHODS: Serological analysis was performed on typically developing children (n = 55), developmentally delayed children without autism (n = 24) and children diagnosed with autism (n=104). Autoantibodies were measured against glutamic acid decarboxylase-65 (GAD65), a CNS autoantigen proposed to be associated with autism and against Ro52, glial fibrillary acidic protein, tyrosine hydroxylase, aquaporin-4, and gamma-enolase, the mouse mammary tumor virus and the xenotropic murine leukemia virus. Antibody levels and seropositivity prevalence were analyzed for statistically significant differences between the three groups. RESULTS: The majority of the children (98%) were seronegative for all targets in the antigen panel. No GAD65 seropositive children were detected in the cohort. Several low level seropositive sera against several of the protein targets were identified in isolated children in each of the three groups, but there was no difference in prevalence. CONCLUSION: Using this panel of antigens and a sensitive, robust assay, no evidence of unusual immunoreactivity was detected in children with autism, providing evidence against a role of autoimmunity against several previously implicated proteins in autism spectrum disorder pathogenesis. GENERAL SIGNIFICANCE: The idea that autoantibodies represent an underlying cause or are biomarkers for autism pathophysiology is not supported by this report.

Children with obsessive-compulsive disorder: are they just "little adults"?

Childhood-onset obsessive-compulsive disorder (OCD) affects 1%-2% of children and adolescents. It is characterized by recurrent obsessions and compulsions that create distress and interfere with daily life. The symptoms reported by children are similar to those seen among individuals who develop OCD in adulthood, and the two groups of patients are treated with similar symptom-relieving behavior therapies and medications. However, there are differences in sex ratios, patterns of comorbidity, and the results of neuroimaging studies that might be important. Here we review the diagnosis and treatment of childhood-onset OCD in light of pediatric and adult studies. We also discuss current knowledge of the pathophysiology of the disorder. Despite advances in this area, further research is needed to understand better the etiopathogenesis of the disorder and to develop new, more effective therapeutic options.