Abstract
Purpose: There are few studies on the glucose metabolic characteristics of the extra-hypothalamic cortex in the hypothalamic hamartomas (HH). A comprehensive understanding of pathogenic progression of the disease is required from the perspective of cortical metabolism; therefore, we aimed to characterize metabolic characteristics of extra-hypothalamic in HH patients.Methods: We investigated the metabolic characteristics of 16 HH patients, all of whom underwent epilepsy evaluation at Xuan Wu Hospital between 2017 and 2019. The lateralization and cortical distribution pattern of hypometabolism was assessed and related to HH mass neuroanatomy on magnetic resonance imaging (MRI) as well as scalp-electroencephalogram (scalp-EEG) abnormalities. Furthermore, asymmetry measurements of region of interest (ROI) in the temporal cortex (hippocampal formation, amygdala, and lateral temporal neocortex) were quantitatively assessed based on the normalized average positron emission tomography (PET) voxel values. The surgery prognosis was assessed using the International League Against Epilepsy (ILAE) classification system.Results: The lateralization of hypometabolism in global visual ratings was consistent with the HH mass lateralization seen on MRI. Cortical hypometabolism showed three patterns depending whether the HH mass involved mammillary bodies, middle hypothalamus nucleus, or both. The three patterns were hypometabolism of the mesial temporal cortex with symptom of mesial temporal epilepsy (3/16, pattern I), lateral temporal, and extratemporal (frontal or parietal) cortex with symptom of neocortex temporal or frontal epilepsy (5/16, pattern II), and mesial and lateral temporal cortex and extratemporal (frontal or parietal) cortex with varied symptoms (8/16, pattern III), respectively. A significant difference in PET voxel values was found between bilateral hippocampal formation (P = 0.001) and lateral temporal neocortex in the third group (P = 0.005). We suggest that the hypometabolic characteristics of the extra-hypothalamic cortex in HH patients have three patterns. The final cortical hypometabolic pattern depends on the neuroanatomic location of the HH mass and was consistent with the main involved cortex of the interictal and ictal discharges. The third hypometabolic pattern with the most extensive cortical hypometabolism has a poorer prognosis.
Highlights
Hypothalamic hamartomas (HH) are characterized by a variety of clinical spectrum, evolving from disease with epilepsy, central precocious puberty, or cognitive and behavioral impairment to catastrophic epileptic encephalopathy [1,2,3,4,5,6]
We aim to investigate the abnormality of extra-hypothalamic cortex from the perspective of cortical metabolism in patients with HH and further to find whether the cortical distribution characteristics are correlated with the neuroanatomical location of HH mass and scalp-EEG findings
With respect to the cortical glucose metabolic characteristics in patients with HH, we found that HH mass lateralization seen on magnetic resonance imaging (MRI) was significantly correlated with the lateralization of cortical hypometabolism
Summary
Hypothalamic hamartomas (HH) are characterized by a variety of clinical spectrum, evolving from disease with epilepsy, central precocious puberty, or cognitive and behavioral impairment to catastrophic epileptic encephalopathy [1,2,3,4,5,6]. Various surgical interventions targeting HH do not abate seizures, and the electrophysiological evidence in ineffective cases suggests that distant cortical regions are involved, especially the temporal and frontal cortex [12]. This progressive epileptogenic encephalopathy suggests that the evolution of disease may correlate with abnormal cortical network external to the HH. Studies have confirmed that gelastic seizures are correlated with abnormal neural activation within the HH [10] and other seizure types are related to neural activation involved with cortical regions [14] These findings suggest that an independent, third-stage kindling like secondary epileptogenesis may exist in patients with HH [2, 15]
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