Pavithra Mannam

The CNS imaging manifestations of acute intermittent porphyria (AIP) are poorly systematized. We aimed to characterize the spectrum of MRI brain findings and evaluate the association between dysautonomia, CNS findings, and enteric manifestations. We retrospectively identified patients with biochemically confirmed AIP who presented between 2008 and 2018 with acute neurovisceral episodes. This observational study did not include a control group. MRI brain studies performed during acute presentations were reviewed at the study level and categorized by predominant anatomical distribution into lobar-cortical, hippocampal, cortical-subcortical, deep gray matter, and normal patterns. Clinical and biochemical parameters were analyzed at the episode level with respect to dysautonomia status. Twenty-three patients with 27 acute neurovisceral episodes were identified; 17 underwent MRI, yielding 28 studies. The lobar-cortical pattern was most frequent (9/28; 32.1%), followed by hippocampal (6/28; 21.4%), cortical-subcortical (3/28; 10.7%), and deep gray matter (3/28; 10.7%); 7 of 28 studies (25.0%) were normal. Two patients showed evolving findings across serial MRI. Dysautonomia, documented in 12/27 (44.4%) episodes, was significantly associated with ileus (p < 0.001) and hyponatremia (p = 0.02). AIP is associated with a broader range of MRI brain appearances than classical PRES alone, with overlap from seizure-related, metabolic, and electrolyte-related processes; no single pattern is diagnostic on its own. The observed clustering of dysautonomia, ileus, and hyponatremia, together with the inverse correlation between aminolevulinic acid and serum sodium, supports a shared autonomic basis for these manifestations. Recognizing this combined imaging and clinical pattern may help raise AIP as a diagnostic consideration.

Affective blindsight, the capacity to discriminate emotional stimuli despite bilateral damage to the primary visual cortex (V1) and without conscious awareness, offers a unique model of non-conscious visual processing. Subcortical pathways involving the pulvinar and amygdala have been proposed, but putative cortical contributions remain unclear. We examined 182 patients, including 31 with bilateral V1 lesions. Among these, 15 had cortical visual loss and 7 showed affective blindsight. Using behavioral testing, lesion symptom mapping, and tractography, we found that preserved pulvinar connectivity with both the posterior superior temporal sulcus (STS) and the amygdala is necessary for affective blindsight. These findings provide causal evidence for a multi-route architecture, identifying the pulvinar–STS pathway, alongside the pulvinar–amygdala pathway, as a critical substrate for non-conscious affective processing.

BACKGROUND AND PURPOSE: Neuroimaging has an important role in detecting CNS involvement in children with systemic or CNS isolated hemophagocytic lymphohistiocytosis. We characterized a cohort of pediatric patients with CNS hemophagocytic lymphohistiocytosis focusing on neuroradiologic features and assessed whether distinct MR imaging patterns and genotype correlations can be recognized. MATERIALS AND METHODS: We retrospectively enrolled consecutive pediatric patients diagnosed with hemophagocytic lymphohistiocytosis with CNS involvement treated at 2 pediatric neurology centers between 2010 and 2018. Clinical and MR imaging data were analyzed. RESULTS: Fifty-seven children (40 primary, 70%) with a median age of 36 months (interquartile range, 5.5–80.8 months) were included. One hundred twenty-three MR imaging studies were assessed, and 2 broad imaging patterns were identified. Pattern 1 (significant parenchymal disease, 32/57, 56%) was seen in older children (P = .004) with worse clinical profiles. It had 3 onset subpatterns: multifocal white matter lesions (21/32, 66%), brainstem predominant disease (5, 15%), and cerebellitis (6, 19%). All patients with the brainstem pattern failed to meet the radiologic criteria for chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids. An attenuated imaging phenotype (pattern 2) was seen in 25 patients (44%, 30 studies) and was associated with younger age. CONCLUSIONS: Distinct MR imaging patterns correlating with clinical phenotypes and possible genetic underpinnings were recognized in this cohort of pediatric CNS hemophagocytic lymphohistiocytosis. Disruptive mutations and missense mutations with absent protein expression correlate with a younger onset age. Children with brainstem and cerebellitis patterns and a negative etiologic work-up require directed assessment for CNS hemophagocytic lymphohistiocytosis.

SUMMARY: Acute necrotizing encephalopathy after an acute febrile illness, although initially described exclusively in the pediatric age group, has been recently shown to have an adult onset as well. In this study, we describe 10 patients (16 years of age or older) with acute necrotizing encephalopathy. In our study, bilateral thalamic involvement with the trilaminar pattern of diffusion restriction on MR imaging was the predominant finding seen in all of the patients reviewed. Ancillary findings of cerebral white matter, brain stem, and cerebellum involvement with sparing of the basal ganglia were also noted. A poorer outcome was observed in patients with a higher degree of thalamic involvement. The cause of an underlying infection was identified in 4 patients (dengue in 3 and influenza in 1). Overall, a sizeable portion of young adults with acute necrotizing encephalopathy have shown a poorer outcome, with dengue being an important underlying trigger in an endemic region.

BACKGROUND AND PURPOSE: Dengue is a common arboviral disease, which uncommonly involves the brain. There has been a recent surge in dengue cases and dengue-related deaths in tropical countries. The aim of this study was to describe brain imaging findings in patients with dengue infection having neurologic symptoms. MATERIALS AND METHODS: Thirty-five patients with positive serology for dengue with CNS symptoms undergoing imaging of the brain were included in the study. Clinical, laboratory, and imaging parameters were assessed and correlated to poor outcome. RESULTS: A Glasgow Coma Scale score of ≤12 at presentation, clinical classification of severe-type dengue, and the presence of acute renal failure were associated with poor outcome. Imaging parameters associated with poor outcome were involvement of the thalami and cerebellar peduncles and the presence of diffusion restriction and hemorrhagic foci in the brain parenchyma. CONCLUSIONS: Although not specific, dengue infection has imaging findings that can be used to narrow down the differential list and help in prognostication.