Primary tumors of the central nervous system have an annual incidence rate of between 4.8 and 20 per 100 000 population; on average, this results in 23 100 new cases and 14 080 deaths annually in the United States of America (Siegel et al., 2013). Between 2000 and 2002, the rates were similar in Canada and Israel for men, and for both genders in New Zealand, Spain and the UK. Deaths in women were less frequent in Canada (2.76%), Israel (3.26%) and Japan (0.72%) (Cancer Mondial, 2012).

The actual age incidence is bimodal, with an early peak in infancy and childhood and another more sustained peak in the fifth to eighth decades. In adults, primary brain cancer is the thirteenth most frequent of all cancers. Because brain tumors affect the organ of intellect, humanity and function, they evoke powerful emotional and psychosocial sentiments. Contemporary neurooncology emphasizes some of the more hopeful clinical features of these tumors. Approximately 50% of patients with primary brain tumors are now successfully treated, many with an excellent long-term prognosis (Thapar & Laws, 1995). Older patients may be treated suboptimally, as comorbidity and age discrimination may influence the treatment choices (Basso et al., 2003; Brandes & Monfardini, 2003; McNamara, 2012).

Some very unique therapeutic considerations govern the diagnosis and management of tumors in the central nervous system, where the distinction between benign and malignant histology is not an absolute concept. A benign tumor of the brain will be just as lethal if it recurs and is surgically ineradicable as one that is similarly located but frankly malignant in histology. The brain lacks a defined lymphatic drainage system; this, in conjunction with the fact that brain neoplasms rarely, if ever, metastasize outside the central nervous system, gives these tumors special significance (Thapar & Laws, 1995). Tumors can be locally progressive and invasive, compressing nearby structures. Cerebral edema, especially in metastatic lesions, complicates the clinical picture and may be responsible, in part, for the symptomatology that is observed.

The exact pathophysiology and etiological features of most brain tumors remain obscure, despite the fact that, in small discrete groups of subpatients, a genetic predilection to brain tumor development has been identified. There is an increased incidence in patients with neurofibromatosis; familiar clustering has been observed (Blatt et al., 1986; Brandes & Monfardini, 2003). However, the fact that as many as 7% of patients with primary brain tumors have a blood relative with a history of a brain tumor is intriguing and demands further study (Thapar & Laws, 1995). Although there is currently scant evidence supporting a viral etiology of brain tumors, the concept cannot be completely ignored, considering the relationship between cerebral lymphomas and the Epstein–Barr virus (O’Neil & Illig, 1989).

Results of studies implicating environmental carcinogens in brain tumor etiology and development have been conflicting. There are some questionable positive statistical associations between brain tumor occurrence and working in the rubber, petrochemical and farming industries. Much work remains to be done regarding the etiology and pathogenesis of brain tumors. Tumors of the spinal cord and pituitary gland are excluded in this chapter; they are much less common than primary or secondary brain tumors, although they are just as important clinically for those elderly individuals who develop them.

Brain tumors are classified on the basis of both cellular origin and histological grade. Tumor location, independent of tumor pathology, may be a critical factor governing therapy and prognosis (Taphoom et al., 2005). Although neurons themselves have an extreme tissue density in the central nervous system, they have no reproductive capabilities and, therefore, are rarely the cause of tumors. Glial cells, on the other hand, have tremendous replicative ability and are the most common cell of origin of central nervous system tumors and account for more than half of all primary brain tumors. Tumors may also arise from the meninges, choroid plexus, blood vessels and primitive embryonal cells. Primary lymphomas of the brain, once uncommon and accounting for only 1–2% of brain tumors, have seen an appreciable rise in incidence in the last two decades, partly because they tend to occur in patients with acquired immunodeficiency syndrome (AIDS), transplant recipients and those who are immunocompromised (Roth et al., 2012).

The astrocytomas, graded from I to IV depending on their differentiation and degree of malignancy, are the most common tumors seen by healthcare practitioners. The glioblastoma multiforme is a grade IV astrocytoma, characterized by cellular atypia, high mitotic activity, florid endothelial proliferation and necrosis. These tumors are the classic type that can kill a patient in less than 6 months. They most often occur in patients between 45 and 65 years of age, which is somewhat later than lower grade gliomas (Thapar & Laws, 1995). Oligodendrogliomas comprise 30% of brain tumors and are characterized by a somewhat earlier age of occurrence, slow growth, calcification and indolent course; however, they are still seen in the elderly population. Meningiomas make up approximately 20% of brain tumors, have a 3:1 female–male ratio, occur more commonly in elderly individuals and carry a good prognosis with surgical removal. Regardless of tumor type, tumor recurrence after surgical removal is common and the tumors typically recur with a higher grade pathology, rendering difficult treatment decisions.

The brain has a surprisingly good tolerance for the compressive and infiltrative effects of an expanding cranial lesion but, in time, all tumors produce symptoms via several mechanisms: increased intracranial pressure, compression or destruction of brain tissue or cranial nerves and local electrochemical instability, which results in seizures (Thapar & Laws, 1995). Headache occurs in 30% of patients at diagnosis, and 70% will have headache during the course of the disease. Papilledema, increased intraoptic pressure, occurs in 50–70% of patients and is often detected early. Seizures are the presenting symptom in about one-third of patients and will occur in 50–70% of patients during the disease course.

Tumors in subcortical areas tend to be less epileptogenic. Altered mental status occurs in about 15–20% of cases; this is more commonly caused by tumors of the frontal lobe. Focal neurological signs are characterized by gradual and progressive loss of neurological function – this is especially important when the frontoparietal lobe is involved; hemiparesis and loss of sensation are of interest to rehabilitation clinicians. Tumors of the temporal lobe often cause seizure activity whereas tumors of the occipital lobe, uncommon in comparison to other brain areas, cause homonymous hemianopsia. Tumors of the cerebellum cause headaches, vertigo, ataxia, akinesia, and nausea and vomiting, all symptoms that can profoundly affect function. Many tumors cause considerable brain edema and this increased swelling may result in false localizing signs.

Computed axial tomography (CAT) scans and magnetic resonance imaging (MRI) have revolutionized the diagnosis of brain tumors. The former will detect 90% or more of tumors whereas the latter provides much greater anatomical detail and resolution in multiple planes, and is particularly useful in visualizing the skull base, brainstem and posterior cranial fossa. Cerebral angiography is rarely indicated, perhaps only when excessive vascularity is anticipated in surgery; however, outlining the blood supply of a brain tumor preoperatively can be of help to the surgeon in the planning approach and technique, especially in areas affording limited accessibility.

Metastatic complications of cancer are an escalating clinical problem, with brain metastases occurring in 20% of patients with cancer. Lung and breast tumors are the most common primary tumors, followed by renal cell carcinoma and melanoma (Talouret et al., 2012). Although usually occurring late in the clinical course of a malignancy, brain metastases are being seen earlier in some cancers, particularly lung carcinoma, where it is not uncommon to present with brain metastases as the first symptom of cancer. Tumors are more common in the frontal and parietal lobes because of the extensive vascular territory of the middle cerebral artery. Multiple metastatic lesions, many of them subclinical, are present in over one-half of cases. Solitary brain lesions may present a diagnostic problem in the face of an unknown primary tumor; histological confirmation may be necessary. Unlike primary brain tumors, the evolution of symptoms in brain metastases is rapid, often measured in days to weeks. This may be partially a result of cerebral edema, which is disproportionate when compared with edema caused by primary brain tumors. The symptoms caused by brain metastases are, in other ways, similar to those caused by a primary lesion.

Advancing age alone remains a strong and independent negative prognostic factor in glioblastoma. Although there appears to be an increase in aggressiveness of treatment provided to the elderly, the gain for the oldest group is modest at best (Gulati et al., 2012). The treatment of malignant brain tumors is guided by the principle that it is worthwhile to prolong the lifespan of patients, as most of this remaining time is qualitatively good. However, one is cautioned against thinking that glioblastoma therapy is standardized and reduced in the elderly (Nghiemphu & Cloughesy, 2012). Fortunately, serious functional loss tends to occur late in the course of brain tumors. For virtually all types of brain tumors, surgical resection is the most important form of initial therapy. Surgery establishes the tissue diagnosis, quickly relieves intracranial pressure and the mass effect, and achieves the oncological cytoreduction that will facilitate later adjuvant or first-line chemotherapy (Basso et al., 2003; Gulati et al., 2012). Collectively, many advances in neurosurgical techniques, including lasers, intraoperative ultrasound and computer-based stereotaxic resection procedures, have afforded new dimensions to neurosurgical approaches and strategies. Even if not curative, tumor resection is a reasonable goal provided that a neurological deficit is not imposed. Although surgical treatment of high-grade gliomas causes low mortality and acceptable morbidity in patients older than 60, it is less beneficial in patients aged greater than 80 or with poor preoperative functioning (Kongland et al., 2013). Corticosteroids are a mainstay because they relieve cerebral edema, believed to be responsible for much of the symptomatology that is observed. Corticosteroids can sometimes produce dramatic improvements in clinical function and neurological status. The clinician treating a patient on prolonged corticosteroids should be aware of the increased risk of osteoporotic fracture.

Radiation therapy is a proven effective method of treatment for most brain tumors. The elderly may exhibit a poor clinical course and lower tolerance to radiation therapy; therefore, prospective randomized studies should be performed to define the best option for efficacy in light of the toxicity and effect on quality of life (Chinot, 2003; Tanaka et al., 2005). Older and younger individuals do not differ significantly in their response to radiation therapy; therefore, age alone should not be a consideration in decision-making. At the very least, a short-term survival advantage is obtained from radiation therapy and so it is often used in conjunction with surgery in tumor treatment. Recently, Barker et al. (2012) found that radiotherapy and concomitant temozolomide (TMZ) increased the 2-year overall survival rate from 14% to 41%. Effects of radiation therapy can be divided into acute and chronic; the acute brain syndromes seen as a result of edema and irritation of the brain microvasculature are self-limiting and respond well to steroid administration. Long-term chronic effects are fortunately uncommon and they include brain necrosis, endocrine disturbances and neurooncogenesis. The newer techniques of interstitial brachytherapy and stereotaxic radiotherapy employ different radiation physics compared with conventional external beam radiation; they are designed to deliver a highly concentrated, discrete and well-controlled dose of radiation directly to the tumor, sparing uninvolved brain tissue in the process. As the availability of these procedures has increased, so have the favorable clinical results that are reported.

Although chemotherapy has not made major breakthroughs in brain tumor treatment, some brain tumors in children have responded well. Chemotherapy can provide modest increases in survival for some patients but the gains may be overshadowed by other variables, such as age, performance status and neurological deficit. Immunotherapy has some clinical appeal, as brain tumors cause a marked reduction in immunocompetence. The potential use of biological response modifiers is being explored.

In terms of rehabilitation, clinical problems frequently arise that are amenable to therapeutic intervention. Any patient with a hemiparesis or other motor syndrome secondary to the tumor or its treatment will respond to therapeutic strategies structured to return and enhance motor function. All neurophysiological approaches are appropriate and may be tried sequentially or concomitantly. The efficacy of many of the standard exercise and facilitative approaches is empirical, and the choice of treatment is sometimes by trial and error. Postural and balance control exercises may be necessary, even in the absence of frank hemiparesis. For balance and coordination problems, location of the tumor may be a factor; rehabilitation may be more efficacious with cerebellopontine angle tumors than with posterior fossa tumors (Karakaya et al., 2000). Pain management and proper breathing exercises are useful in many patients. Because so many patients exhibit symptoms attributable to brain edema, relief of this complication with corticosteroids will assist the healthcare practitioner in bringing improved clinical function to the patient.

Wheelchair prescription and management, evaluation for assistive devices and teaching skills used in activities of daily living (ADLs) and related activities are tantamount to a good functional outcome. The various therapeutic disciplines should combine their efforts in a team approach, each field contributing its own expertise. Nutrition intake should be monitored to prevent malnourishment, dehydration or excessive weight gain. To this end, patients should be evaluated for dysphagia, as dehydration and aspiration pneumonia can result from swallowing difficulties (Wesling et al., 2003). Nursing must attend to skin, bowel and bladder integrity, as well as infection control. Social interaction with other patients may be crucial to success. Family involvement and teaching are also integral; psychosocial support and intervention are very helpful, especially when the family is confronted with an individual who has altered mental status and severe motor/sensory deficit. Formal rehabilitation in an inpatient rehabilitation center setting is sometimes indicated, and the rehabilitation professional should be available to assist in this transition when it occurs. Patients may make functional gains during and after inpatient rehabilitation, but the gain in quality of life may not be significant until 1 month or more post discharge (Huang et al., 2001). Also, quality of life may not correlate well with functional outcome in rehabilitation.

In summary, the treatment of primary and metastatic tumors of the central nervous system offers unique and challenging clinical opportunities for the healthcare practitioner. Because the clinical course may be prolonged and sometimes indolent, the rehabilitation staff should be on hand to provide the services necessary to bring patients to their highest level of function. Newer and more exciting treatment techniques, particularly in the delivery of radiation therapy, will result in increased survival in selected patients and longer periods when the healthcare professional will be needed to respond to the clinical syndromes and rehabilitative problems that ensue.