RESUMO
Background: Fluorodeoxyglucose-positron emission tomography (FDG-PET) in autoimmune encephalitis (AE) as an adjunctive investigation helps in characterizing the type of AE based on characteristic metabolic patterns. Objectives: We aimed to study the following: (i) the sensitivity of FDG-PET in the diagnosis of AE, (ii) describe abnormal patterns of metabolism of various subtypes of AE, and (iii) correlate serum serology with FDG-PET abnormalities. Materials and Methods: This study was conducted at a tertiary university hospital in South India. The demographic profile, clinical features, and investigations (FDG-PET, magnetic resonance imaging (MRI) brain, electroencephalography (EEG), cerebrospinal fluid (CSF)) were reviewed. The nuclear medicine physician performed blinded qualitative visual and semi-quantitative analysis of the 18-FDG-PET (fluorine 18-FDG-PET) findings of these patients. Results: Twenty-nine (M:F: 11:18) patients were recruited; among them, 22 (75.8%) patients had autoimmune antibodies; the rest seven (24.1%) patients were seronegative. Among the 22 seropositive patients, 9 (31%) patients were positive for anti-N-methyl-D-aspartate receptor (NMDAR), 8 (28%) for anti-leucine-rich glioma inactivated 1 (LGI-1), 4 (14%) for anti-contactin-associated protein 2 (CASPR2), 1 (3%) for anti-glutamic acid decarboxylase (GAD)-65, and rest 7 (24%) patients were seronegative. The patterns most commonly observed were isolated hypermetabolism (41%), isolated hypometabolism (41%), and combined hypermetabolism with hypometabolism (18%). The fraction of abnormalities was lower for MRI (17/22; 73.9%) than for FDG-PET (27/29; 93.1%). FDG-PET correlated with serology in 10 (34%) cases [NMDAR: 6 (60%) and LGI-1: 4 (40%)]. The sensitivity of FDG-PET was 94.1% when compared with MRI. Discussion and Conclusion: FDG-PET correlated with serology in only one-third of patients. The most consistent pattern in both seropositive and seronegative AE is characterized by parieto-occipital hypometabolism and fronto-temporal with basal ganglia hypermetabolism.
RESUMO
Encephalopathy and Myopathy in children of varying ages can be due to variety of causes including Mitochondrial diseases, metabolic diseases like renal tubular acidosis, storage diseases as well as fatty acid oxidation (FAO) disorders. FAO related disorders have variable clinical presentation and manifest in different ages. They may present with hypoglycemia, effort intolerance, multi organ involvement with or without ketonuria. High degree of suspicion and appropriate investigations are mandatory for diagnosis. Here we describe an 11 Year old boy, born to non - consanguineous parents. Presented with exertion induced muscle pain and fatigue of 1year duration, which slowly progressed to severe weakness and vomiting. His reflexes were retained. Therefore metabolic vs inflammatory muscle diseases were considered. Patient had ketonuria with elevated blood levels of medium chain acyl carnitine and long chain acyl carnitine suggestive of MADD. Urine organic acid assessment showed elevated excretion of 2-hydroxyglutarate (2HG), adipate and arabitol. Muscle biopsy showed multiple fine vacuoles on Eosin- hematoxylin stained preparation. Modified Gomori - trichrome stain showed vacuolated fibers with red granular material consistent with ragged red fibers. Oil Red O stains showed vacuolated fibers with 'oil red O' positive material suggesting lipid storage. Above combination of features is consistent of MADD. Genetic evaluation is not done due to financial constraint. Patient was started on high dose riboflavin and carnitine, with which the child became near normal. Our patient is a case of MADD presenting as Reye's syndrome like features and showed excellent response to riboflavin, carnitine, dietary and life style changes. High degree of suspicion is lifesaving.
