Sensory function in severe semilobar holoprosencephaly

Abstract

We report a 4-year-old child with severe semi-lobar holoprosencephaly (HPE) not expected to survive after birth. Magnetic resonance imaging (MRI) revealed agenesis of the corpus callosum, absence of the third ventricle, fused thalami and basal ganglia. To investigate sensory function, visual, auditory and somatosensory evoked potential and imaging studies were carried out. The visual response evoked by human face stimuli evoked larger responses over the left side of the holosphere as compared to responses evoked by checkerboard pattern, while auditory evoked potentials were evident over the frontal regions to both pure tones and speech stimuli. No consistent scalp somatosensory evoked potentials were evident. This case demonstrates that electrophysiological measures are able to identify and quantify sensory processing not expected to be present based on the anatomical presentation of the cortex in a child with severe HPE.

Early bilateral and massive compromise of the frontal lobes

“…Partial frontal compromise has been described in cases of temporal agenesis ( Kansu and Zacks, 1979 ), frontal ependymal or arachnoid cysts ( Sarnat and Flores-Sarnat, 2016 ), hydrocephalus ( Feuillet et al, 2007 ), and early or adult-onset strokes ( Payne and Lomber, 2001 ; Price et al, 1990 ). Moreover, although extended patterns of frontal insult have been observed in holoprosencephaly (e.g., Liasis et al, 2009 ), hydranencephaly ( Segawa et al, 2007 ), and other neurodevelopmental conditions ( Li et al, 2016 ; Sarnat and Flores-Sarnat, 2016 ), these are accompanied by massive damage to temporal and posterior regions. Thus, a case of nearly complete and selective bilateral frontal affectation represents an unprecedented source of insights into this structure's functional and plastic properties, with potential implications for neurocognitive modeling.…”

Semilobar Holoprosencephaly Associated with Multiple Malformations in a Foal

“…Although relatively rare, HPE is the most common malformation of the human forebrain and occurs in 1/250 foetuses and 1/16 000 live births (Dubourg et al., ; Geng and Oliver, ). At present, human classification system includes 4 subtypes of HPE depending on the degree of forebrain cleavage: alobar, semilobar, lobar and a middle inter‐hemispheric fusion variant (Liasis et al., ). Alobar HPE is the most severe form, characterized by complete failure of cleavage of the two cerebral hemispheres, with the presence of a single cerebral ventricle and the absence of corpus callosum and olfactory bulbs (arrhinencephaly).…”

“…In the semilobar HPE, the inter‐hemispheric fissure is visible only in the caudal portion of the cerebrum, and olfactory bulbs and corpus callosum are absent or hypoplastic. In lobar HPE, a distinct inter‐hemispheric fissure is present, but some midline continuity of the cingulate gyrus persists (Dubourg et al., ; Geng and Oliver, ; Liasis et al., ). The fourth subtype, called middle inter‐hemispheric variant of HPE or syntelencephaly, is characterized by incomplete separation of the middle cerebral hemispheres at the posterior frontal and parietal regions; the anterior frontal and occipital lobes are separated normally (Barkovich and Quint, ; Lewis et al., ; Simon et al., ).…”