Congenital hemiparesis: different functional reorganization of somatosensory and motor pathways.
ABSTRACT To investigate the reorganization of somatosensory and motor cortex in congenital brain injury.
We recorded motor evoked potentials (MEPs) following transcranial magnetic stimulation (TMS) and somatosensory evoked potentials (SEPs) in a 41 year old man with severe congenital right hemiparesis but only mild proprioceptive impairment. Brain magnetic resonance imaging showed a large porencephalic cavitation in the left hemisphere mainly involving the frontal and parietal lobes.
TMS showed fast-conducting projections from the undamaged primary motor cortex to both hands, whereas MEPs were not elicited from the damaged hemisphere. Left median nerve stimulation evoked normal short-latency SEPs in the contralateral undamaged somatosensory cortex. Right median nerve stimulation did not evoke any SEP in the contralateral damaged hemisphere, but a middle-latency SEP (positive-negative-positive, 39-44-48 ms) in the ipsilateral undamaged hemisphere, with a fronto-central scalp distribution.
Our data show that somatosensory function of the affected arm is preserved, most likely through slow-conducting non-lemniscal connections between the affected arm and ipsilateral non-primary somatosensory cortex. In contrast, motor function was poor despite fast-conducting ipsilateral cortico-motoneuronal output from the primary motor cortex of the undamaged hemisphere to the affected arm. This suggests that different forms of reorganization operate in congenital brain injury and that fast-conducting connections between primary cortex areas and ipsilateral spinal cord are not sufficient for preservation or recovery of function.
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ABSTRACT: Although cerebral palsy (CP) is usually defined as a group of permanent motor disorders due to non-progressive disturbances in the developing fetal or infant brain, recent research has shown that CP individuals are also characterized by altered somatosensory perception, increased pain and abnormal activation of cortical somatosensory areas. The present study was aimed to examine hemispheric differences on somatosensory brain processing in individuals with bilateral CP and lateralized motor impairments compared with healthy controls. Nine CP individuals with left-dominant motor impairments (LMI) (age range 5-28 yrs), nine CP individuals with right-dominant motor impairments (RMI) (age range 7-29 yrs), and 12 healthy controls (age range 5-30 yrs) participated in the study. Proprioception, touch and pain thresholds, as well as somatosensory evoked potentials (SEP) elicited by tactile stimulation of right and left lips and thumbs were compared. Pain sensitivity was higher, and lip stimulation elicited greater beta power and more symmetrical SEP amplitudes in individuals with CP than in healthy controls. In addition, although there was no significant differences between individuals with RMI and LMI on pain or touch sensitivity, lip and thumb stimulation elicited smaller beta power and more symmetrical SEP amplitudes in individuals with LMI than with RMI. Our data revealed that brain processing of somatosensory stimulation was abnormal in CP individuals. Moreover, this processing was different depending if they presented right- or left-dominant motor impairments, suggesting that different mechanisms of sensorimotor reorganization should be involved in CP depending on dominant side of motor impairment.BMC Neuroscience 01/2014; 15(1):10. · 3.00 Impact Factor
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ABSTRACT: The permanent nature of motor deficits is a consistent cornerstone of cerebral palsy definitions. Such pessimism is disheartening to children, families, and researchers alike and may no longer be appropriate for it ignores the fantastic plastic potential of the developing brain. Perinatal stroke is presented as the ideal human model of developmental neuroplasticity following distinct, well-defined, focal perinatal brain injury. Elegant animal models are merging with human applied technology methods, including noninvasive brain stimulation for increasingly sophisticated models of plastic motor development following perinatal stroke. In this article, how potential central therapeutic targets are identified and potentially modulated to enhance motor function within these models is discussed. Also, future directions and emerging clinical trials are reviewed.Seminars in pediatric neurology 06/2013; 20(2):116-26.
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ABSTRACT: Androgen deprivation therapy for prostate cancer causes accelerated loss of bone mineral density and is associated with increased fracture risk. We evaluated risk factors associated with vertebral fractures among men enrolled in a fracture prevention trial. Analysis included men receiving androgen deprivation therapy for prostate cancer and enrolled in a phase III fracture prevention trial. All men were 70 years old or older or had a low bone mineral density (T-score less than -1.5 for the lumbar spine or total hip). We analyzed demographic and laboratory characteristics of men with and those without vertebral fractures at study entry. Of the 1,244 subjects 162 (13.0%) had a vertebral fracture at baseline. The 2 factors significantly associated with vertebral fractures were white race (p=0.028 compared with nonwhite race) and osteoporosis (p=0.002 for osteoporosis at any site, p=0.053 for osteoporosis at the spine, p=0.002 for osteoporosis at the hip). Lower bone mineral density was also significantly associated with vertebral fractures when analyzed as a continuous variable. Factors not associated with vertebral fractures included age, country of residence, androgen deprivation therapy duration at baseline, androgen deprivation therapy mode, body mass index, testosterone, estradiol, C-telopeptide, bone specific alkaline phosphatase and osteocalcin. Results were similar in analyses limited to men 70 years old or older. White race and low bone mineral density were significantly associated with vertebral fractures in this study of men treated with androgen deprivation for prostate cancer. These observations should inform the assessment and management of fracture risk among such men.The Journal of urology 06/2011; 186(2):482-6. · 4.02 Impact Factor