brain tumor word.docx

Brain Tumors A brain tumor occupies space within the skull, growing as a spherical mass or diffusely infiltrating tissue. The effects of brain tumors are caused by inflammation, compression, and infiltration of tissue. A variety of physiologic changes result, causing any or all of the following path...

Brain Tumors A brain tumor occupies space within the skull, growing as a spherical mass or diffusely infiltrating tissue. The effects of brain tumors are caused by inflammation, compression, and infiltration of tissue. A variety of physiologic changes result, causing any or all of the following pathophysiologic events: Increased intracranial pressure (ICP) and cerebral edema Focal neurologic signs such as headache Seizure activity Hydrocephalus Altered pituitary function Types of Primary Brain Tumors Brain tumors may be classified into several groups: those arising from the coverings of the brain (e.g., dural meningioma), those developing in or on the cranial nerves (e.g., acoustic neuroma), those originating within brain tissue (e.g., glioma), and metastatic lesions originating elsewhere in the body. Tumors of the pituitary and pineal glands and of cerebral blood vessels are also types of brain tumors. Relevant clinical considerations include the location and the histologic character of the tumor. About 70% of the time tumors are benign but even benign tumors, such as colloid cysts, can occur in vital areas and can grow large enough to have serious effects for the classification of brain tumors. Many tumors can be localized by correlating the signs and symptoms to specific areas in the brain, as follows (Hickey & Strayer, 2020): A tumor in the motor cortex of the frontal lobe produces hemiparesis and partial seizures on the opposite side of the body or generalized seizures. A frontal lobe tumor may also produce changes in emotional state and behavior, as well as an apathetic mental attitude. The patient often becomes impulsive, inappropriate in speech, gestures, and behavior. A parietal lobe tumor may cause decreased sensation on the opposite side of the body or generalized seizures. A temporal lobe tumor may cause seizures as well as psychological disorders. An occipital lobe tumor produces visual manifestations: contralateral homonymous hemianopsia (visual loss in half of the visual field on the opposite side of the tumor) and visual hallucinations. A cerebellar tumor causes dizziness; an ataxic or staggering gait with a tendency to fall toward the side of the lesion; marked muscle incoordination; and nystagmus (involuntary rhythmic eye movements), usually in the horizontal direction. Medical managements Surgical Management The objective of surgical management is to remove as much tumor as possible without increasing the neurologic deficit (paralysis, blindness), or to relieve symptoms by partial removal (decompression). Surgery also provides the opportunity to biopsy tissue to establish a definitive diagnosis. A variety of surgical approaches may be used; the specific approach depends on the type of tumor, its location, and its accessibility. Conventional surgical approaches require a craniotomy (incision into the skull). See Chapter 61 for a discussion of care of the patient who has undergone a craniotomy. This approach is used in patients with meningiomas, acoustic neuromas, cystic astrocytomas of the cerebellum, colloid cysts of the third ventricle, congenital tumors such as dermoid cyst, and some of the granulomas. With improved imaging techniques and the availability of the operating microscope and microsurgical instrumentation, even large tumors can be removed through a relatively small craniotomy. For patients with malignant glioma, complete removal of the tumor and cure are not possible, but the rationale for resection includes relief of ICP, removal of any necrotic tissue, and reduction in the bulk of the tumor, which theoretically leaves behind fewer cells to become resistant to radiation or chemotherapy. Most pituitary adenomas are treated by transsphenoidal microsurgical removal (see Chapter 61), and the remainder of tumors that cannot be removed completely are treated by radiation (Hickey & Strayer, 2020). Radiation Therapy Radiation therapy the cornerstone of treatment for many brain tumors decreases the incidence of recurrence of incompletely resected tumors (AANN, 2016). Gamma radiation is delivered via an external beam to the tumor in multiple fractions. Brachytherapy (the surgical implantation of radiation sources to deliver high doses at a short distance) is an option for some types of tumors depending on their location. It is usually used as an adjunct to conventional radiation therapy or as a rescue measure for recurrent disease. Radioisotopes such as iodine 131 (131I) are used to minimize effects on surrounding brain tissue. Stereotactic procedures may be performed using a linear accelerator or gamma knife to perform radiosurgery (Hickey & Strayer, 2020). These procedures allow treatment of deep, inaccessible tumors, often in a single session. Precise localization of the tumor is accomplished by the stereotactic approach and by minute measurements and precise positioning of the patient. Multiple narrow beams then deliver a very high dose of radiation. An advantage of this method is that no surgical incision is needed. Disadvantages include the lag time between treatment and the desired result as well as the potential for developing radiation necrosis (AANN, 2016). Chemotherapy Chemotherapy may be used in conjunction with radiation therapy, or as the sole therapy, with the goal of increasing survival time. The greatest challenge in chemotherapy of brain tumors is that the blood–brain barrier prevents drugs from getting to the tumor in effective doses without causing systemic toxicity (AANN, 2016). Malignant glioma is usually treated with 6 weeks of oral temozolomide during radiation therapy, followed by 6 to 12 months of oral temozolomide. Low-grade gliomas may be treated with 6 months of oral temozolomide alone. Temozolomide is an oral chemotherapy that crosses the blood–brain barrier (McFaline-Figueroa & Lee, 2018). Several other chemotherapy agents are used alone or in combination depending on the type of tumor. Autologous bone marrow transplantation is used in some patients who will receive chemotherapy or radiation therapy, because it can “rescue” the patient from the bone marrow toxicity associated with high doses of chemotherapy and radiation. A fraction of the patient’s bone marrow is aspirated, usually from the iliac crest, and stored. The patient receives large doses of chemotherapy or radiation therapy to destroy large numbers of malignant cells. The marrow is then reinfused intravenously after treatment is completed. See Chapter 12 for discussion of bone marrow transplant. Pharmacologic Therapy Corticosteroids are useful in relieving headache and alterations in level of consciousness. Corticosteroids such as dexamethasone are thought to reduce inflammation and edema around tumors (AANN, 2016). Other medications used include osmotic diuretics (e.g., mannitol and hypertonic saline) to decrease the fluid content of the brain, which leads to a decrease in ICP. Anticonvulsant medications are used to treat and control seizures (Comerford & Durkin, 2020). Cerebral Metastases A significant number of patients with cancer experience neurologic deficits caused by metastasis to the nervous system, which can include the brain, CSF, and meninges. Metastatic lesions to the brain are more common than primary brain tumors and have an associated 2-year survival rate of less than 10% (Achrol et al., 2019). The high number of metastatic brain tumors is clinically important, as more patients with all forms of cancer live longer because of improved therapies. Neurologic signs and symptoms include headache, gait disturbances, visual impairment, personality changes, altered mentation (memory loss and confusion), focal weakness, paralysis, aphasia, and seizures (McFaline-Figueroa & Lee, 2018). These signs and symptoms can be devastating to both patient and family. Metastases to the CSF and meninges, known as leptomeningeal metastases, can produce symptoms of headache and isolated cranial nerve deficits.