brain herniation

brain herniation

Pressure-induced prolapse of part of the brain into adjacent spaces, which occurs when the brain is under high pressure.
 
Clinical findings
Coma, paralysis, unilateral dilated pupil.
 
Aetiology
Head injury, primary or metastatic brain tumour, bacterial meningitis, brain abscess.
 
Types
Cerebellar herniation, uncal (temporal) herniation, transtentorial herniation.

brain herniation

Neurology A pressure-induced prolapse of part of the brain into adjacent spaces, which occurs when the brain is under very high pressure Clinical Coma, paralysis, unilateral dilated pupil Etiology Head injury, 1º or metastatic brain tumor, bacterial meningitis, brain abscess Types Cerebellar herniation, uncal–temporal herniation, transtentorial herniation of the brain

brain

encephalon; that part of the central nervous system contained within the cranium, comprising the forebrain, midbrain and hindbrain, and developed from the embryonic neural tube. It is connected at its base with the spinal cord. The brain is a mass of soft, pinkish gray nerve tissue. For specific brain diseases see under headings relating to etiology and lesion.

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brain abscess

common signs caused by an abscess in the brain are circling, rotation of the head, abnormal reflexes in one eye. The CSF may show evidence of infection.

brain aneurysm

see berry aneurysm.

brain anoxia

acute or chronic insufficiency of the blood supply to the brain causes anoxia which causes clinical signs that vary with the severity of the deprivation. Acute anoxia causes muscle tremor, recumbency, convulsions and death or recovery if the anoxia is relieved soon enough. Chronic anoxia causes lethargy, weakness, blindness and sometimes convulsions. In either case there may be permanent damage.

brain case

the cranium.

brain cestodal cyst

see coenurosis.

brain coup lesion

a derivation from contrecoup.

brain dead

irreversible coma with apnea, loss of all brainstem reflexes and absence of activity on an electroencephalogram.

brain decompression

relieving the pressure within the cranial vault. This may be done surgically by opening the cranium, or medically by administering hypertonic solutions of slowly metabolized materials, such as mannitol, intravenously.

brain edema

an important part of a number of acute diseases, e.g. lead poisoning, encephalitis, salt poisoning in swine, polioencephalomalacia of ruminants and hypoxia due to any cause. Clinically manifested by blindness, opisthotonos, nystagmus, recumbency and tonic convulsions. Inherited in polled and horned Herefords; calves are recumbent at birth and are never able to stand but consciousness is normal. See also neuraxial edema.

brain ependymal lining

see ependyma.

brain hematoma

may occur with trauma, in extradural, subdural or intraparenchymal locations. They can cause progressive increase in intracranial pressure and eventually death.

brain hemorrhage

intracranial hemorrhage affecting the brain usually follows traumatic injury but spontaneous hemorrhage may result from an intrinsic vascular lesion. Loss of consciousness is a common sign followed by residual signs depending on the locality and size of the hemorrhage. Ataxia and convulsions are common sequelae.

brain herniation

displacement of brain from the cranial vault through the foramina (tentorial notch or foramen magnum) or ventral to dural septae. The usual causes are brain edema or hemorrhage with resulting increase in intracranial pressure.

brain hypoxia

see brain anoxia (above).

brain infarction

see feline ischemic encephalopathy.

brain inflammation

see encephalitis, encephalomyelitis, meningoencephalitis.

brain ischemia

see brain anoxia (above).

brain laceration

occurs in cranial trauma that fractures the skull, causes severe acceleration or deceleration, or penetrates the skull and brain tissue.

brain necrosis

see encephalomalacia.

brain pigmentation

occurs in phalaris spp. poisoning; a characteristic greenish brown color grossly of the gray matter in brainstem nuclei and spinal cord, caused by a suspected lysosomal storage of granules of pigment material; usually associated with some degree of Wallerian degeneration within spinal cord tracts.

brain sand

see acervuli.

brain scanning

a radiographic, magnetic or nuclear medical procedure for the detection of brain tumors, abscesses, hematomas and other intracranial lesions. Not widely used in veterinary medicine because of the expensive equipment required.

brain spongy degeneration

see bovine spongiform encephalopathy.

brain staggers

see dummy.

brain trauma

injury to the brain, including that caused by migrating worm larvae, will have diffuse effects including the development of edema, and local effects due to pressure by displaced bone or to hemorrhage. Initial shock, manifested as unconsciousness, is likely to be followed by residual localizing signs, e.g. facial paralysis, head rotation.

brain tumors

cause signs suggestive of local space-occupying lesion in the cranial cavity, including the increased intracranial pressure syndrome, blindness with disturbance of ocular reflexes, head rotation, circling and jacksonian epileptic episodes.

brain ventricles

see third, fourth, fifth ventricle.