Oklahoma City Community College脑积水俄克拉荷马城社区学院课件.ppt

HYDROCEPHALUS W W 495-503 Hydrocephalus A syndrome, or sign, resulting from disturbances in the dynamics of cerebrospinal fluid (CSF), which may be caused by several diseases. Incidence Occurs in 3-4 of every 1000 births. Cause may be congenital or acquired. Congenital- may be due to maldevelopment or intrauterine infection Acquired- may be due to infection, neoplasm or hemorrhage. Pathophysiology CSF is formed by two mechanisms: Secretion by the choroid plexus, Lymphatic-like drainage by the extracellular fluid in brain. CSF circulates thru ventricular system and is absorbed within subarachnoid spaces by unknown mechanism. Mechanisms of Fluid Imbalance Hydrocephalus results from: 1. Impaired absorption of CSF within the subarachnoid space (communicating hydrocephalus), or 2. Obstruction to the flow of CSF through the ventricular system (non-communicating hydrocephalus) Mechanisms of fluid imbalance Both lead to increase accumulation of CSF in the ventricles! Ventricles become dilated and compress the brain. When this happens before cranial sutures are closed, skull enlarges. In children 10-12, previously closed sutures may open. Hydrocephalus Most cases of non-communicating (obstructive) hydrocephalus are a result of developmental malformations. Other causes: neoplasms, intrauterine infections, trauma. Developmental defects account for most causes of hydrocephalus from birth to 2 years of age. (Table 11-3, sites and types of hydrocephalus) Common Defects Arnold-Chiari Malformation (ACM) Type 2 malformation of brain seen most exclusively with myelomeningocele, is characterized by herniation of a small cerebellum, medulla, pons, and fourth ventricle into the cervical spinal canal through an enlarged foramen magnum. Clinical manifestations Clinical picture depends on acuity of onset and presence of preexisting structural lesions. Infancy Head grows at alarming rate with hydrocephalus. First signs- bulging of fontanels without head enlargement. Tense, bulgin