Nd transcalvarial are forms of supratentorial herniation, while upward transtentorial and tonsillar are infratentorial. buy 4 viagra Central herniation in central herniation, (also called "transtentorial herniation") the diencephalon and parts of the temporal lobes of both of the cerebral hemispheres are squeezed through a notch in the tentorium cerebelli. Downward herniation can stretch branches of the basilar artery (paramedian artery), causing them to tear and bleed, known as a duret hemorrhage. buy generic viagra online The result is usually fatal. viagra for sale Uncal herniation in uncal herniation, a common subtype of transtentorial herniation, the innermost part of the temporal lobe, the uncus, can be squeezed so much that it goes by the tentorium and puts pressure on the brainstem. 150 mg viagra for sale The tentorium is a structure within the skull formed by the meningeal layer the dura mater. viagra cost Tissue may be stripped from the cerebral cortex in a process called decortication. The uncus can squeeze the third cranial nerve, which controls parasympathetic input to the eye on the side of the affected nerve. liquid viagra better This interrupts the parasympathetic neural transmission, causing the pupil of the affected eye to dilate and fail to constrict in response to light as it should, so a dilated unresponsive pupil is an important sign of increased intracranial pressure. Pupillary dilation often precedes a later finding of cranial nerve iii compression, which is deviation of the eye to a "down and out" position due to loss of innervation to all ocular motility muscles except for the lateral rectus (innervated by cranial nerve vi) and the superior oblique (innervated by cranial nerve iv). liquid viagra better Cranial arteries may be compressed during the herniation. buy viagra cheap Compression of the posterior cerebral artery may result in loss of the contralateral visual field. A later important finding, the false localizing sign, results from compression of the contralateral cerebral crus, which contains descending corticospinal fibers. cheap generic viagra This leads to ipsilateral (to herniating uncus) hemiparesis of the body. This type of herniation can also damage the brain stem, causing lethargy, slow heart rate, respiratory abnormalities, and pupil dilation. viagra pills Uncal herniation may advance to central herniation. Cerebellar herniation increased pressure in the posterior fossa can cause the cerebellum to move up through the tentorial opening in upward, or cerebellar herniation. The midbrain is pushed through the tentorial notch. liquid viagra better This also pushes the midbrain down. can i buy viagra over the counter boots Tonsillar herniat.