medicine Medicine is the science and practice of caring for a patient, managing the diagnosis, prognosis, prevention, treatment, palliation of their injury or disease, and promoting their health. Medicine encompasses a variety of health care pract ...

, 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 in the neck and consists of two connected lobe (anatomy), lobes. The lower two thirds of the lobes are connected by a thin band of Connective tissue, tissue cal ...

may cause symptoms due to compressions of certain structures of the head and neck; pressure on the

laryngeal nerve The recurrent laryngeal nerve (RLN) is a branch of the vagus nerve (cranial nerve X) that supplies all the intrinsic muscles of the larynx, with the exception of the cricothyroid muscles. There are two recurrent laryngeal nerves, right and le ...

s may cause voice changes, narrowing of the

windpipe The trachea, also known as the windpipe, is a cartilaginous tube that connects the larynx to the bronchi of the lungs, allowing the passage of air, and so is present in almost all air-breathing animals with lungs. The trachea extends from the la ...

may cause

stridor Stridor (Latin for "creaking or grating noise") is a high-pitched extra-thoracic 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 pha ...

, pressure on the

gullet The esophagus (American English) or oesophagus (British English; both ), non-technically known also as the food pipe or gullet, is an organ in vertebrates through which food passes, aided by peristaltic contractions, from the pharynx to the ...

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 disease#Terminology, condition in its own right. It may be a sensation that suggests difficulty in the passag ...

and so on.

Surgical Surgery ''cheirourgikē'' (composed of χείρ, "hand", and ἔργον, "work"), via la, chirurgiae, meaning "hand work". is a medical specialty that uses operative manual and instrumental techniques on a person to investigate or treat a pat ...

removal or

debulking Debulking is the reduction of as much of the bulk (volume) of a tumour without the intention of a complete eradication. It is usually achieved by surgical removal. When performed for curative intent, it is a different procedure, which is called sur ...

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 an accumulation of cerebrospinal fluid (CSF) occurs within the brain. This typically causes increased intracranial pressure, pressure inside the skull. Older people may have headaches, double vision, poor ...

(cerebrospinal fluid buildup) or an evolving

intracranial hemorrhage Intracranial hemorrhage (ICH), also known as intracranial bleed, is bleeding within the skull. Subtypes are intracerebral bleeds ( intraventricular bleeds and intraparenchymal bleeds), subarachnoid bleeds, epidural bleeds, and subdural bleeds. ...

(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 capillary, capillaries. A he ...

. 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 Millimeter of mercury, mmHg ...

and potentially causing

midline shift Midline shift is a shift of the brain past its center line. The sign may be evident on neuroimaging such as CT scanning. The sign is considered ominous because it is commonly associated with a distortion of the brain stem that can cause serious ...

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 brain is squeezed across structures within the skull. The brain can shift across such structures as the falx cerebri, the te ...

. 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 form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio waves ...

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 Hematoma, 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 ...

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 Pneumoencephalography (sometimes abbreviated PEG; also referred to as an "air study") was a common medical procedure in which most of the cerebrospinal fluid (CSF) was drained from around the brain by means of a lumbar puncture and replaced with a ...

. 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