The Desire for Amputation or Paralyzation: Evidence for Structural Brain Anomalies in Body Integrity Identity Disorder (BIID)

Abstract

BackgroundBody Integrity Identity Disorder (BIID) is a condition in which individuals perceive a mismatch between their internal body scheme and physical body shape, resulting in an absolute desire to be either amputated or paralyzed. The condition is hypothesized to be of congenital nature, but evidence for a neuro-anatomical basis is sparse.MethodsWe collected T1-weighted structural magnetic resonance imaging scans on a 3T scanner in eight individuals with BIID and 24 matched healthy controls, and analyzed the data using voxel-based morphometry.ResultsThe results showed reduced grey matter volume in the left dorsal and ventral premotor cortices and larger grey matter volume in the cerebellum (lobule VIIa) in individuals with BIID compared to controls.ConclusionThe premotor cortex and cerebellum are thought to be crucial for the experience of body-ownership and the integration of multisensory information. Our results suggest that BIID is associated with structural brain anomalies and might result from a dysfunction in the integration of multisensory information, leading to the feeling of disunity between the mental and physical body shape.

Structural and functional hyperconnectivity within the sensorimotor system in xenomelia

“…Thirteen men suffering from an intense desire to have one leg (or both legs, n  = 3) amputated were compared with a carefully matched control group. Building on previous reports of xenomelia‐related local structural and functional anomalies (Blom et al., 2016; Hänggi et al., 2016; Hilti et al., 2013; McGeoch et al., 2011; van Dijk et al., 2013), we here describe structurally and functionally hyperconnected sensorimotor networks including mainly the right‐hemispheric SPL, SI, SII, SMA, PCL, premotor cortex as well as the bilateral cerebellum.…”

“…This study was motivated by recently discovered alterations in circumscribed regions of the SPL, PCL, post‐ and precentral gyrus, dorsal and ventral premotor cortex, basal ganglia, thalamus, cerebellum, and insula as associated with xenomelia (Blom et al., 2016; Hänggi et al., 2016; Hilti et al., 2013; McGeoch et al., 2011; van Dijk et al., 2013). In addition to the ROI‐based approach that focused on the above‐mentioned sensorimotor brain regions, we also applied whole‐brain structural and functional connectome analyses to uncover potentially additional regions associated with the condition, but also to establish the specificity of the findings reported here.…”

“…This study provides strong evidence that in addition to the anatomical alterations already reported in the literature for cortical regions (Hilti et al., 2013; McGeoch et al., 2011), the subcortical structures thalamus, putamen, caudate nucleus, and pallidum might be related to xenomelia as well (Hänggi et al., 2016). A preliminary fMRI study based on five subjects suffering from xenomelia extended the above‐mentioned findings by suggesting that the ventral as well as dorsal premotor cortex are also brain regions importantly involved in generating the clinical picture of xenomelia, both from a functional (van Dijk et al., 2013) as well as structural point of view (Blom et al., 2016). …”

“…Taken together, our structural connectome analyses provide strong evidence that in addition to the structural and functional anomalies of specific brain regions in xenomelia already reported in the literature (Blom et al., 2016; Hänggi et al., 2016; Hilti et al., 2013; McGeoch et al., 2011; van Dijk et al., 2013), the number of reconstructed streamlines from/to these brain regions is strongly increased in men with compared to without xenomelia, suggesting that these regions are hyperconnected to other brain regions inside and outside of the sensorimotor system. The network solution 1 and 2 of the 116‐node network analyses revealed that a lot of the connections showing structural hyperconnectivity have nodes located within the cerebellum, including both the cerebellar hemispheres as well as the vermis.…”

“…Sixteen nodes were derived from the eight clusters showing reduced cortical thickness or surface area in xenomelia compared with control men (Hilti et al., 2013). The 28‐node xenomelia‐specific network investigated in this study encompasses these 16 nodes in addition to the thalamus, caudate nucleus, putamen, and pallidum (Hänggi et al., 2016) as well as the ventral and dorsal premotor cortex (Blom et al., 2016; van Dijk et al., 2013). The eight subcortical nodes (bilateral thalamus, caudate nucleus, putamen, and pallidum) based on probability maps were derived from the Harvard–Oxford subcortical structural atlas (http://fsl.fmrib.ox.ac.uk/fsl/fslwiki/Atlases), whereas the remaining 20 nodes of the xenomelia‐specific 28‐node networks were spherical in nature and constructed using the MNI coordinates with a radius of 3 mm and 6 mm for the functional and structural analysis, respectively.…”