Venous spread may occur when intra-abdominal or thoracic pressure increases and venous flow is retrograde which then allows tumor cells in the systemic venous system to enter the vertebral venous system. Centripetal migration from systemic tumors along perineural, invasion of nerve space, or perivascular spaces. Malignant cells can migrate along spinal or cranial nerve epineurium-perineurium, invade the subpial space, and travel along blood vessels into the endoneurial space, or invade the nerve parenchyma.Infiltration happens most often at the base of the brain, dorsal surface, and especially at the cauda equina, which is largely due to the effect of gravity. Once in the CSF, malignant cells can extend along the membrane surfaces or spread freely in the CSF and attach to other locations. These cells have the ability to penetrate the pial membrane and invade the spinal cord and cranial nerves. Infiltration to spinal cord
Infiltration from the subarachnoid space into the spinal cord occurs primarily along the perivascular tissues that surround blood vessels at the brain entrance. Infiltration from the anterior median fissure, a 3mm deep furrow on the anterior side of the spinal cord, to the anterior horn of the spinal cord, the ventral grey matter of the spinal cord, is found along the central artery.
Nevertheless, pneumonia remains a leading cause of death in developing countries, and also among the very old, the very young, and the chronically ill. Pneumonia often shortens the period of suffering among those already close to death and has thus been called "the old mans friend". Signs and symptoms
People with infectious pneumonia often have a productive cough, fever accompanied by shaking chills, shortness of breath, sharp or stabbing chest pain during deep breaths, and an increased rate of breathing. In elderly people, confusion may be the most prominent sign.The typical signs and symptoms in children under five are fever, cough, and fast or difficult breathing. Fever is not very specific, as it occurs in many other common illnesses and may be absent in those with severe disease, malnutrition or in the elderly. In addition, a cough is frequently absent in children less than 2 months old. More severe signs and symptoms in children may include blue-tinged skin, unwillingness to drink, convulsions, ongoing vomiting, extremes of temperature, or a decreased level of consciousness.Bacterial and viral cases of pneumonia usually result in similar symptoms. Some causes are associated with classic, but non-specific, clinical characteristics. Pneumonia caused by Legionella may occur with abdominal pain, diarrhea, or confusion. Pneumonia caused by Streptococcus pneumoniae is associated with rusty colored sputum. Pneumonia caused by Klebsiella may have bloody sputum often described as "currant jelly". Bloody sputum (known as hemoptysis) may also occur with tuberculosis, Gram-negative pneumonia, lung abscesses and more commonly acute bronchitis.