1/2. Beyond re-membering: phantom sensations of congenitally absent limbs.Phantom limbs are traditionally conceptualized as the phenomenal persistence of a body part after deafferentation. Previous clinical observations of subjects with phantoms of congenitally absent limbs are not compatible with this view, but, in the absence of experimental work, the neural basis of such "aplasic phantoms" has remained enigmatic. In this paper, we report a series of behavioral, imaging, and neurophysiological experiments with a university-educated woman born without forearms and legs, who experiences vivid phantom sensations of all four limbs. Visuokinesthetic integration of tachistoscopically presented drawings of hands and feet indicated an intact somatic representation of these body parts. Functional magnetic resonance imaging of phantom hand movements showed no activation of primary sensorimotor areas, but of premotor and parietal cortex bilaterally. Movements of the existing upper arms produced activation expanding into the hand territories deprived of afferences and efferences. transcranial magnetic stimulation of the sensorimotor cortex consistently elicited phantom sensations in the contralateral fingers and hand. In addition, premotor and parietal stimulation evoked similar phantom sensations, albeit in the absence of motor evoked potentials in the stump. These data indicate that body parts that have never been physically developed can be represented in sensory and motor cortical areas. Both genetic and epigenetic factors, such as the habitual observation of other people moving their limbs, may contribute to the conscious experience of aplasic phantoms.- - - - - - - - - - ranking = 1keywords = physical (Clic here for more details about this article) |
2/2. Caudal regression syndrome: etiopathogenesis, prenatal diagnosis, and perinatal management.Caudal regression syndrome represents a continuum of congenital malformations ranging from agenesis of the lumbosacral spine to the most severe cases of sirenomelia with lower extremities fusion and major visceral anomalies. The etiology of this syndrome is not well known. Maternal diabetes, genetic predisposition, and vascular hypoperfusion have been suggested as possible causative factors. The degree of associated anomalies usually parallels the severity of the primary defect. ultrasonography is the diagnostic tool of choice revealing the absent distal vertebrae of the fetal spine. Amnioinfusion and magnetic resonance imaging (MRI) are of help in better evaluation of the fetal anatomy in cases with oligohydramnios. Perinatal management depends mainly on gestational age at diagnosis and severity of the lesion. It should include genetic counseling and serial sonography to assess interval growth and amniotic fluid volume. Surviving infants have usually a normal mental function and they require extensive urologic and orthopedic assistance. Their long-term morbidity consists mostly of neurogenic bladder dysfunction resulting in progressive renal damage and disabling neuromuscular deficits of the lower extremities. Neurosurgical and orthopedic intervention with physical rehabilitation is indicated to improve the quality of their lives.- - - - - - - - - - ranking = 1keywords = physical (Clic here for more details about this article) |