Mbb Shelf Pathologies Already Passed

Fragile X Syndrome {Ans: X-linked defect affecting methylation and expression of FMR1 gene. Trinucleotide repeat disorder (CGG)n. 2nd most common cause of genetic mental retardation. Findings: macroorchidism (enlarged testes), long face with a large jaw, large everted ears, autism, mitral valve prolapse.}Arnold-Chiari malformation II {Ans: Significant cerebellar tonsillar and vermian herniation through foramen magnum with aqueductal stenosis and hydrocephalus. Often present with thoraco-lumbar myelomeningocele and paralysis below the defect. Arnold-Chiari malformation with or without myelomeningocele is characterized by a cerebellomedullary malformation that may not develop until adolescence or adult life. The results, in addition to producing severe headaches, cause cerebellar dysfunction and weakness and impaired movement of the limbs.}Hydrocephalus ex vacuo {Ans: Appearance of increased CSF in atrophy (e.g., Alzheimer's disease, advanced HIV, Pick's disease). Intracranial pressure is normal; triad not seen}Alzheimer's Disease {Ans: Most common Dementia. Nucleus basalis of Meynert undergoes degeneration --> loss of ACh in cortex leading to neural atrophy in cortex and hippocampus Cholinesterase inhibitors (galantamine) are treatment - increase available ACh (caution with bradycardia and ulcers patients); cause GI side effects (possible anorexia, insomnia) Glutamate-mediated excitotoxicity also implicated in pathogenesis - memantine (trade name Namenda) is an NMDA antagonist Down Syndrome