Anatomical pathology4/16/2023 ![]() In addition to basal ganglia involvement in dystonia, recent animal and human studies have implicated the cerebellum in the pathogenesis of dystonia. However, further research is required to confirm these changes and to determine whether abnormal inhibition or abnormal plasticity is primary. Repetitive TMS studies have demonstrated increased plasticity in organic but not in psychogenic dystonia ( Quartarone et al., 2009). This is supported clinically by the development of focal dystonia in response to repetitive use or injury of the involved body part, and this has been induced in non-human primates ( Byl et al., 1996). These sensory abnormalities have also been found in non-manifesting carriers of dystonia genes and in psychogenic dystonia ( Espay et al., 2006).Īnother aberrant physiologic finding in dystonia is increased cortical plasticity. Spatial and temporal discrimination thresholds are abnormal, and correspond to enlargement and disorganization of cortical sensory receptive area representation ( Fiorio et al., 2007 Deik et al., 2012). Similarly, the sensory system displays abnormal processing and inhibition in dystonia. Therefore, there appears to be abnormal inhibition at multiple levels of the motor control neuraxis. Transcranial magnetic stimulation studies have revealed defective surround inhibition as well as increased motor cortex excitability and reduced intracortical inhibition when repetitive stimuli are rapidly applied ( Hallett, 2009). Electromyography in dystonia demonstrates prolonged agonist muscle contraction, abnormal antagonist muscle contraction, and loss of reciprocal inhibitory reflexes via the brainstem and spinal cord ( Tolosa et al., 1988). ![]() In dystonia, various electrophysiological modalities have demonstrated center-surround imbalance. When this balance becomes disturbed, unwanted movements may fail to be inhibited (abnormal inhibitory ‘surround’) and intended movements may become excessive or prolonged (abnormal ‘center’ activation). This is termed the center-surround model. Normally, voluntary movements require a complex balance of basal ganglia pathway activity in order to perform the intended movement with accuracy and precision, and to suppress unwanted movements. This is because lesions of the basal ganglia may cause secondary dystonia ( Berardelli et al., 1998), and because dystonia may be associated with other disorders of the basal ganglia, such as parkinsonism and chorea. Deik, in Reference Module in Biomedical Sciences, 2015 PathophysiologyĪlthough no anatomical pathology is consistently identified on conventional neuroimaging or post-mortem studies, dystonia has historically been classified as a basal ganglia disorder. Ilan Weinreb is our Division Head of Anatomic Pathology.K. Our areas of expertise include breast pathology, cardiovascular pathology, cytopathology, dermatopathology, endocrine pathology, gastrointestinal and hepatic pathology, genitourinary pathology, gynecologic pathology, head and neck pathology, hematopathology, neuropathology, pulmonary pathology and renal pathology.ĭr. Services range from consultations that provide diagnostic advice on complex cases, to routine interpretation of tests, collaborative diagnosis, and technical services. ![]() These resources enable our team to provide opinions that meet the level of sophistication required by our clients. Our pathologists have access to many integrated techniques, including advanced cytology, automated histology, immunohistochemistry, flow cytometry, electron microscopy, cancer cytogenetics, and molecular diagnostics. The staff's commitment to research, teaching and clinical services keeps them at the forefront of oncology, transplant, cardiovascular and neuroscience diagnostics. We are Canada's largest and most experienced group of pathologists. ![]() Javascript:if (typeof CalloutManager != 'undefined' & Boolean(CalloutManager) & Boolean(CalloutManager.closeAll)) CalloutManager.closeAll() commonShowModalDialog(', null)
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