Interstitial brain edema

The encephalopathy induced by lead toxicity is most hkely due to a compromise in the blood-brain barrier. Brain edema occurs in the interstitial area and appears due to compromised blood vessels integrity. The brain capillaries and blood vessels have endothelial cells that contain tight junctions and act as a seal or carrier that excludes many plasma proteins and organic molecules and impedes Na and K exchange. Elevated lead levels disrupt these vessels, and plasma proteins such as albumin enter the interstitial spaces, as do some ions. This increases osmotic pressure, and water accumulates in response. The increased interstitial fluid flows into the cerebrospinal fluid. The edema causes in an increase in intracranial pressure and restricts blood flow to the brain. The direct mechanisms by which the blood-brain barrier and blood vessels that compose the barrier may be compromised may be due to astrocytes appearing to be vulnerable to the toxic effects of lead. The astrocytes cover the walls of the brain blood vessels, and lead can injure these structures. 

Osmotherapy employs agents such as mannitol, glycerol, and hypertonic saline to create an osmotic gradient between the brain (optimally, the edematous infarcted tissue) and the bloodstream, such that water is drawn out from the brain, thereby reducing edema. Each of these agents has been shown to be effective, and may be used alone or in combination with a diuretic, such as furosemide. Their action, however, depends upon an intact blood-brain barrier (BBB), and concerns have been raised for possible paradoxical worsening when one is absent. In this hypothesis, mannitol extravasates from the vessel into the interstitial tissue and water follows a new osmotic... 

Dexamethasone Testing of adrenal cortical hyperfunction cerebral edema associated with primary or metastatic brain tumor, craniotomy, or head injury. Tnamc/no/one Treatment of pulmonary emphysema where bronchospasm or bronchial edema plays a significant role, and diffuse interstitial pulmonary fibrosis (Hamman-Rich syndrome) in conjunction with diuretic agents to induce a diuresis in refractory CHF and in cirrhosis of the liver with refractory ascites and for postoperative dental inflammatory reactions. 

Fig. 5 Diffusion of molecules cein be restricted in closed spaces, such as cells. Diffusion might also be hindered by obstacles that result in tortuous pathways. Exchange between compartments also slows down molecular displacements. Left panel shows a model of the movement of fluids (diffusion and bulk flow) with three compartments of heeilthy brain tissues. Bulk flow is seen in vascular compartment while the diffusion happens in the interstitial spaces and cell compartments. Right panel shows the changes in diffusion of water as a result of edema. Molecular displacement between compartments increases as a result of BBB breakdown in vasogenic edema. Tortuosity will decrease as intracellular space is reduced...

Rosenberg GA, Kyner WT, Estrada E (1980) Bulk flow of brain interstitial fluid under normal and hyperosmolar conditions. Am J Physiol 238 F42-F49 Rosenberg GA, NavratU M (1997) MetaUoproteinase inhibition blocks edema in intracerebral hemorrhage in the rat. Neurology 48 921-926... 

There are no case reports of toxicity in man for monoalkyltin compounds. Diiodo diethyl tin contaminated with 10% triethyl-tin iodide in STALINON capsules (a preparation proposed for the treatment of furuncles) caused 100 fatalities in France between 1953 and 1954. The lesion was an interstitial edema of the white matter of the brain, and the symptoms included headache, vertigo, psychic and visual disturbances, hypothermia, loss of vigilance, paresthesia, vomiting, abdominal pain, urinary retention, tremors, and convulsions. Another 100 patients survived the intoxication, but presented headaches and weakness over a period of several years (Alajouanine etal. 1958)... 

ACUTE HEALTH RISKS irritation of skin, eyes, and respiratory system headache vertigo dizziness giddiness weakness convulsions hallucinations delirium nausea vomiting diarrhea rapid respiration coughing pain and tightness in the chest pulmonary edema cerebral edema diffuse interstitial pneumonitis systemic effects on the brain epigastric pain substemal pain cyanosis leukocytosis (increased blood leukocytes) death. 

Tamargo RJ, Sills AKJ, Reinhard CS, Pinn ML, Long DM, Brem H. Interstitial delivery of dexamethasone in the brain for the reduction of peritumoral edema. J Neurosurg 1991 74 956-961. 

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