Though on the relatively uncommon, and brain tumor has always made a grim prognosis for unfortunate animal that is diagnosed with one. Traditionally they were often assumed but seldom confirmed, but since the MRI and CT scanning has become more mainstream "they can be diagnosed correctly. Here we discuss the different types of brain tumor that affect tapeworms, the clinical investigations that can be performed, the treatments available and the likely outcomes.Brain tumors seem to be more common in dogs than cats, and certain breeds are over represented such as Boxers, Golden Retrievers, Scottish Terriers, Dobermans and Old English Sheepdogs. Primary vs SecondaryBrain tumors can be primary or secondary (metastasis from other sites). Primary brain tumors are usually solitary, the most common ones in the dog being gliomas and meningiomas. In cats, the most common type are meningiomas and these can occur at multiple locations.Secondary tumors in dogs include extension of a nasal tumor, metastases from breast, lung or prostate cancer, hemangiosarcoma or extension of a pituitary gland tumor. Nerve sheath tumors and skull tumors have also been reported. Secondary tumors in cats include pituitary gland tumors, metastatic carcinomas, local extension of nasal tumors, tumors and skull middle ear cavity tumors.What causes a brain tumor?The cause of brain tumors is not known. Diet, environment, chemical, genetic, immunologic and viral, trauma have all been considered. In cats with meningiomas, because they often occur in very young animals, and genetic element is suspected.Benign vs. malignant and benign MalignantThe terms must be used with care when referring to brain tumors. Normally these terms apply to various characteristics on a cellular level, but on a biological level, even benign brain tumors can kill the animal due to the secondary effects like increased intracranial pressure or cerebral edema. In short, any brain tumor can kill.What are the symptoms?There can be huge variety here. Many animals will present with vague signs, such as one or several of the following: 1. Loss of trained habits2. Decreased levels of activity3. Decreased frequency of purring in cats4. Disorientation5. Confusion More specific symptoms are dependent upon where exactly the tumor is located within the brain, the size of the tumor and how quickly it is growing. As a tumor symptoms tend it enlarges, become more severe. These can include: 6. Seizures (may indicate a tumor in the cerebral cortex) 7. Facial paralysis (may indicate a brainstem tumor) 8. Tremors (may indicate a tumor in the cerebellum) 9. Wobbliness (may indicate a tumor in the cerebellum) 10. Full or partial blindness (may indicate tumor in hypothalamus or optic nerve) 11. Loss of smell (may indicate tumor of olfactory system) The physical presence of the tumor can cause knock on effects due to inflammation and edema of the Vale do area. This can cause symptoms such as: 12. Changes in behaviour or temperament (irritability, lethargy) 13. Compulsive walking14. Circling15. Pressing head against a wall or hard surfaceAnimals can sometimes carry brain tumors for several years before presenting to a veterinary clinic, if the tumor is slow growing. In these cases the symptoms develop gradually, and the owner tends to get used to them so that by the time the animal is examined, the tumor has reached a considerable size.How is a brain tumor diagnosed?History and Clinical ExaminationThe the first step for a veterinarian is to take a thorough "history of all of the clinical signs, and when they developed. This is followed by a full general clinical examination and a full neurological examination.BloodsAfter that, blood should be taken for routine haematology and biochemistry profiles. This is to look for any disease outside the brain. Results will be normal for brain tumors, with the possible exception of some pituitary gland tumors.RadiographyPlain skull radiographs (xrays) under general anesthetic have little value in detecting a brain tumor, but they can be useful if there is a tumor in the nasal cavities or the middle ear which could extend into the skull. On rare occasions, they can identify changes in the bony skull which can accompany a brain tumor, or mineralization within the tumor itself. Radiographs and ultrasound of the chest and abdomen are useful to look for a tumor elsewhere in the body, in cases where the brain is a secondary tumor metastasis.MRI and CT ScansConfirmation of a brain tumor can is usually only achieved using the advanced imaging techniques, CT scans or MRI. Both of these have pros and cons when compared to one another. CT is better for bony changes, while MRI is better for soft tissue definition, for the detection of many of the knock on effects of brain tumors such as cysts, edema and bleeding. MRI is the preferred option for diagnosing primary brain tumors.BiopsyThis is the only way to definitively diagnose a brain tumor. The advanced imaging techniques above offer much information, but they can occasionally confuse a non cancerous tumor with a mass of cysts, or a and they also do not tell us the exact type of tumor present, and therefore the appropriate treatment and prognosis. The best type of biopsy is the CT guided stereotactic brain biopsy system, which is quite rapid, accurate and safe. Since exploratory surgery is high risk, it is not usually attempted unless there is a reasonable chance of removing the whole tumor with minimal collateral damage. Many brain tumors in cats and dogs are not categorized on a cellular level until post-mortem inspection.Cerebrospinal Fluid (CSF) analysis is a useful AnalysisCSF for ruling out inflammatory causes of the symptoms, but tumor cells are rarely identified here. Increased levels of white blood cells and increased protein levels may be present in the CSF with many brain tumors, though this is not diagnostic. This test can be high risk when intracranial pressure is increased, as brain herniation can occur.TreatmentTreatment is aimed at being either curative or palliative. Curative treatment eradicates the tumor or reduces its size, whilst palliative therapy reduces the cerebral edema and Vale do slows down the growth of the tumor. Palliative therapy also involves administering antiepileptic drugs, if seizures are occurring as a result of the tumor.SurgeryWhether: this is an option depends on the general health of the animal, and the precise location, size, extent, invasiveness and nature of the tumor. Tumors such as meningiomas in cats can be removed successfully by surgery. However, surgery to remove tumors in certain locations such as the brainstem can be extremely dangerous, possibly resulting in death. Even partial removal can benefit the animal though, particularly if the tumor is slow growing.RadiotherapyThis is probably the most widely used forms of treatment for brain tumors. Radiation therapy can be used alone or in combination with other treatments. It is also useful in the treatment of secondary brain tumors. The aim is to destroy the tumor without harming the normal tissue too much.ChemotherapyThe main problem with chemotherapy for brain tumors is that many drugs do not cross the blood brain barrier. In addition, the tumor may only be sensitive to high doses, doses which are toxic to normal brain tissue and therefore unsuitable for use. However, several drugs have been used for this purpose that can cross the blood brain barrier with reported success, cytosine arabinoside, including lomustine and carmustine.Probable OutcomeStudies of animals that receive palliative treatment (corticosteroids) for brain tumors for the show and post diagnosis of survival range 64 is 307 days. This demonstrates the inability to accurately predict the life expectancy in these cases. What is certain is that the survival times significantly increase with surgery, radiotherapy or chemotherapy. Radiation therapy seems to offer the best results, alone or in combination with other treatments. Generally, the more severe the symptoms, the shorter the life expectancy.
Niciun comentariu:
Trimiteți un comentariu