medicine Medicine is the science and Praxis (process), practice of caring for patients, managing the Medical diagnosis, diagnosis, prognosis, Preventive medicine, prevention, therapy, treatment, Palliative care, palliation of their injury or disease, ...

, a mass effect is the effect of a growing mass that results in secondary pathological effects by pushing on or displacing surrounding tissue. In oncology, the mass typically refers to a

tumor A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

. For example, cancer of the

thyroid gland The thyroid, or thyroid gland, is an endocrine gland in vertebrates. In humans, it is a butterfly-shaped gland located in the neck below the Adam's apple. It consists of two connected lobes. The lower two thirds of the lobes are connected by ...

may cause symptoms due to compressions of certain structures of the head and neck; pressure on the laryngeal nerves may cause voice changes, narrowing of the windpipe may cause

stridor Stridor () is an extra-thoracic high-pitched breath sound resulting from turbulent air flow in the larynx or lower in the bronchial tree. It is different from a stertor, which is a noise originating in the pharynx. Stridor is a physical sig ...

, pressure on the gullet may cause

dysphagia Dysphagia is difficulty in swallowing. Although classified under " symptoms and signs" in ICD-10, in some contexts it is classified as a condition in its own right. It may be a sensation that suggests difficulty in the passage of solids or l ...

and so on.

Surgical Surgery is a medical specialty that uses manual and instrumental techniques to diagnose or treat pathological conditions (e.g., trauma, disease, injury, malignancy), to alter bodily functions (e.g., malabsorption created by bariatric surgery ...

removal or debulking is sometimes used to palliate symptoms of the mass effect even if the underlying pathology is not curable. In neurology, a mass effect is the effect exerted by any mass, including, for example,

hydrocephalus Hydrocephalus is a condition in which cerebrospinal fluid (CSF) builds up within the brain, which can cause pressure to increase in the skull. Symptoms may vary according to age. Headaches and double vision are common. Elderly adults with n ...

(cerebrospinal fluid buildup) or an evolving

intracranial hemorrhage Intracranial hemorrhage (ICH) refers to any form of Hemorrhage, bleeding Internal bleeding, within the Human skull, skull. It can result from trauma, vascular abnormalities, hypertension, or other medical conditions. ICH is broadly categorized ...

(bleeding within the skull) presenting with a clinically significant

hematoma A hematoma, also spelled haematoma, or blood suffusion is a localized bleeding outside of blood vessels, due to either disease or trauma including injury or surgery and may involve blood continuing to seep from broken capillaries. A hematoma is ...

. The

can exert a mass effect on the brain, increasing

intracranial pressure Intracranial pressure (ICP) is the pressure exerted by fluids such as cerebrospinal fluid (CSF) inside the skull and on the brain tissue. ICP is measured in millimeters of mercury ( mmHg) and at rest, is normally 7–15 mmHg for a supine adu ...

and potentially causing midline shift or deadly

brain herniation Brain herniation is a potentially deadly side effect of very high pressure within the skull that occurs when a part of the human brain, brain is squeezed across structures within the human skull, skull. The brain can shift across such structures ...

. In the past this effect held additional diagnostic importance since prior to the invention of modern tomographic soft-tissue imaging utilizing

MRI Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to generate pictures of the anatomy and the physiological processes inside the body. MRI scanners use strong magnetic fields, magnetic field gradients, and rad ...

or CT it was not possible to directly image many kinds of primary intracranial lesions. Therefore, in those days, the mass effect of these abnormalities on surrounding structures was sometimes used to indirectly infer the existence of the primary abnormalities themselves, for example by using a

cerebral angiography Cerebral angiography is a form of angiography which provides images of blood vessels in and around the brain, thereby allowing detection of abnormalities such as arteriovenous malformations and aneurysms. It was pioneered in 1927 by the Portugues ...

to observe the secondary vascular displacement caused by a

subdural hematoma A subdural hematoma (SDH) is a type of bleeding in which a collection of blood—usually but not always associated with a traumatic brain injury—gathers between the inner layer of the dura mater and the arachnoid mater of the meninges surrou ...

pushing on the brain, or by looking for a distortion caused by a tumor on the normal outline of the ventricles as depicted on a pneumoencephalogram. These studies were often invasive and uncomfortable for patients and provided only a partial assessment of the primary condition being evaluated. Nowadays modern diagnostic tools exist which allow physicians to easily locate and visualize all kinds of intracranial lesions without having to rely on indirect effects to make a reliable diagnosis.

References

Oncology Medical terminology {{oncology-stub