Nerve compression syndrome, or compression neuropathy, or nerve entrapment syndrome, is a

medical condition A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medical conditions that a ...

caused by direct pressure on a

nerve A nerve is an enclosed, cable-like bundle of nerve fibers (called axons) in the peripheral nervous system. A nerve transmits electrical impulses. It is the basic unit of the peripheral nervous system. A nerve provides a common pathway for the ...

. It is known colloquially as a ''trapped nerve'', though this may also refer to

nerve root A nerve root (Latin: ''radix nervi'') is the initial segment of a nerve leaving the central nervous system. Nerve roots can be classified as: *Cranial nerve roots: the initial or proximal segment of one of the twelve pairs of cranial nerves leaving ...

compression (by a

herniated disc Spinal disc herniation is an injury to the cushioning and connective tissue between vertebrae, usually caused by excessive strain or trauma to the spine. It may result in back pain, pain or sensation in different parts of the body, and physica ...

, for example). Its symptoms include

pain Pain is a distressing feeling often caused by intense or damaging stimuli. The International Association for the Study of Pain defines pain as "an unpleasant sensory and emotional experience associated with, or resembling that associated with, ...

tingling Paresthesia is an abnormal sensation of the skin (tingling, pricking, chilling, burning, numbness) with no apparent physical cause. Paresthesia may be transient or chronic, and may have any of dozens of possible underlying causes. Paresthesias ar ...

numbness Hypoesthesia or numbness is a common side effect of various medical conditions that manifests as a reduced sense of touch or sensation, or a partial loss of sensitivity to sensory stimuli. In everyday speech this is generally referred to as num ...

and

muscle weakness Muscle weakness is a lack of muscle strength. Its causes are many and can be divided into conditions that have either true or perceived muscle weakness. True muscle weakness is a primary symptom of a variety of skeletal muscle diseases, includi ...

. The symptoms affect just one particular part of the body, depending on which nerve is affected.

Nerve conduction studies A nerve conduction study (NCS) is a medical diagnostic test commonly used to evaluate the function, especially the ability of electrical conduction, of the motor and sensory nerves of the human body. These tests may be performed by medical speci ...

help to confirm the diagnosis. In some cases,

surgery 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 ...

may help to relieve the pressure on the nerve but this does not always relieve all the symptoms.

Nerve injury Nerve injury is an injury to nervous tissue. There is no single classification system that can describe all the many variations of nerve injuries. In 1941, Seddon introduced a classification of nerve injuries based on three main types of nerve f ...

by a single episode of

physical trauma An injury is any physiological damage to living tissue caused by immediate physical stress. An injury can occur intentionally or unintentionally and may be caused by blunt trauma, penetrating trauma, burning, toxic exposure, asphyxiation, or ...

is in one sense a compression neuropathy but is not usually included under this heading.

Syndromes

* Upper limb * Lower limb, abdomen and pelvis

Signs and symptoms

Tingling, numbness, and/or a burning sensation in the area of the body affected by the corresponding nerve. These experiences may occur directly following

insult An insult is an expression or statement (or sometimes behavior) which is disrespectful or scornful. Insults may be intentional or accidental. An insult may be factual, but at the same time pejorative, such as the word "inbred". Jocular exc ...

or may occur several hours or even days afterwards. Pain is less common than tingling or numbness as a symptom of nerve entrapment, although a burning sensation, if it occurs, may ( subjectively) be classified as pain.

Causes

A nerve may be compressed by prolonged or repeated external force, such as sitting with one's arm over the back of a chair (

radial nerve The radial nerve is a nerve in the human body that supplies the posterior portion of the upper limb. It innervates the medial and lateral heads of the triceps brachii muscle of the arm, as well as all 12 muscles in the posterior osteofascial compa ...

), frequently resting one's elbows on a table (

ulnar nerve In human anatomy, the ulnar nerve is a nerve that runs near the ulna bone. The ulnar collateral ligament of elbow joint is in relation with the ulnar nerve. The nerve is the largest in the human body unprotected by muscle or bone, so injury is c ...

), or an ill-fitting cast or brace on the leg (

peroneal nerve The common fibular nerve (also known as the common peroneal nerve, external popliteal nerve, or lateral popliteal nerve) is a nerve in the lower leg that provides sensation over the posterolateral part of the leg and the knee joint. It divides at ...

). Part of the patient's body can cause the compression and the term ''entrapment neuropathy'' is used particularly in this situation. The offending structure may be a well-defined lesion such as a

tumour 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 a

lipoma A lipoma is a benign tumor made of fat tissue. They are generally soft to the touch, movable, and painless. They usually occur just under the skin, but occasionally may be deeper. Most are less than in size. Common locations include upper back, ...

neurofibroma A neurofibroma is a benign nerve-sheath tumor in the peripheral nervous system. In 90% of cases, they are found as stand-alone tumors (solitary neurofibroma, solitary nerve sheath tumor or sporadic neurofibroma), while the remainder are found in p ...

metastasis Metastasis is a pathogenic agent's spread from an initial or primary site to a different or secondary site within the host's body; the term is typically used when referring to metastasis by a cancerous tumor. The newly pathological sites, the ...

), a

ganglion cyst A ganglion cyst is a fluid-filled bump associated with a joint or tendon sheath. It most often occurs at the back of the wrist, followed by the front of the wrist. Onset is often over several months, typically with no further symptoms. Occasional ...

or a

haematoma 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 ...

. Alternatively, there may be expansion of the tissues around a nerve in a space where there is little room for this to occur, as is often the case in carpal tunnel syndrome. This may be due to

weight gain Weight gain is an increase in body weight. This can involve an increase in muscle mass, fat deposits, excess fluids such as water or other factors. Weight gain can be a symptom of a serious medical condition. Description Weight gain occurs wh ...

or peripheral oedema (especially in

pregnancy Pregnancy is the time during which one or more offspring develops ( gestates) inside a woman's uterus (womb). A multiple pregnancy involves more than one offspring, such as with twins. Pregnancy usually occurs by sexual intercourse, but can ...

), or to a specific condition such as

acromegaly Acromegaly is a disorder that results from excess growth hormone (GH) after the growth plates have closed. The initial symptom is typically enlargement of the hands and feet. There may also be an enlargement of the forehead, jaw, and nose. Othe ...

hypothyroidism Hypothyroidism (also called ''underactive thyroid'', ''low thyroid'' or ''hypothyreosis'') is a disorder of the endocrine system in which the thyroid gland does not produce enough thyroid hormone. It can cause a number of symptoms, such as po ...

scleroderma Scleroderma is a group of autoimmune diseases that may result in changes to the skin, blood vessels, muscles, and internal organs. The disease can be either localized to the skin or involve other organs, as well. Symptoms may include areas of t ...

and

psoriasis Psoriasis is a long-lasting, noncontagious autoimmune disease characterized by raised areas of abnormal skin. These areas are red, pink, or purple, dry, itchy, and scaly. Psoriasis varies in severity from small, localized patches to complete ...

. Some conditions cause nerves to be particularly susceptible to compression. These include

diabetes Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level (hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ap ...

, in which the blood supply to the nerves is already compromised, rendering the nerve more sensitive to minor degrees of compression. The genetic condition HNPP is a much rarer cause.

Pathophysiology

External pressure reduces flow in the vessels supplying the nerve with blood (the vasa nervorum). This causes local

ischaemia Ischemia or ischaemia is a restriction in blood supply to any tissue, muscle group, or organ of the body, causing a shortage of oxygen that is needed for cellular metabolism (to keep tissue alive). Ischemia is generally caused by problems wi ...

, which has an immediate effect on the ability of the nerve

axons An axon (from Greek ἄξων ''áxōn'', axis), or nerve fiber (or nerve fibre: see spelling differences), is a long, slender projection of a nerve cell, or neuron, in vertebrates, that typically conducts electrical impulses known as action po ...

to transmit

action potentials An action potential occurs when the membrane potential of a specific cell location rapidly rises and falls. This depolarization then causes adjacent locations to similarly depolarize. Action potentials occur in several types of animal cells, ca ...

. As the compression becomes more severe over time, focal

demyelination A demyelinating disease is any disease of the nervous system in which the myelin sheath of neurons is damaged. This damage impairs the conduction of signals in the affected nerves. In turn, the reduction in conduction ability causes deficiency i ...

occurs, followed by axonal damage and finally

scarring A scar (or scar tissue) is an area of fibrous tissue that replaces normal skin after an injury. Scars result from the biological process of wound repair in the skin, as well as in other organs, and tissues of the body. Thus, scarring is a n ...

Diagnosis

The

symptoms Signs and symptoms are the observed or detectable signs, and experienced symptoms of an illness, injury, or condition. A sign for example may be a higher or lower temperature than normal, raised or lowered blood pressure or an abnormality showin ...

and signs depend on which nerve is affected, where along its length the nerve is affected, and how severely the nerve is affected. Positive sensory symptoms are usually the earliest to occur, particularly

and

neuropathic pain Neuropathic pain is pain caused by damage or disease affecting the somatosensory system. Neuropathic pain may be associated with abnormal sensations called dysesthesia or pain from normally non-painful stimuli ( allodynia). It may have continuous ...

, followed or accompanied by reduced sensation or complete numbness.

Muscle weakness Muscle weakness is a lack of muscle strength. Its causes are many and can be divided into conditions that have either true or perceived muscle weakness. True muscle weakness is a primary symptom of a variety of skeletal muscle diseases, includi ...

is usually noticed later, and is often associated with

muscle atrophy Muscle atrophy is the loss of skeletal muscle mass. It can be caused by immobility, aging, malnutrition, medications, or a wide range of injuries or diseases that impact the musculoskeletal or nervous system. Muscle atrophy leads to muscle weakness ...

. A compression neuropathy can usually be diagnosed confidently on the basis of the symptoms and signs alone. However,

nerve conduction studies A nerve conduction study (NCS) is a medical diagnostic test commonly used to evaluate the function, especially the ability of electrical conduction, of the motor and sensory nerves of the human body. These tests may be performed by medical speci ...

are helpful in confirming the diagnosis, quantifying the severity, and ruling out involvement of other nerves (suggesting a

mononeuritis multiplex Peripheral neuropathy, often shortened to neuropathy, is a general term describing disease affecting the peripheral nerves, meaning nerves beyond the brain and spinal cord. Damage to peripheral nerves may impair sensation, movement, gland, or or ...

polyneuropathy Polyneuropathy ( poly- + neuro- + -pathy) is damage or disease affecting peripheral nerves (peripheral neuropathy) in roughly the same areas on both sides of the body, featuring weakness, numbness, and burning pain. It usually begins in the hand ...

). A scan is not usually necessary, but may be helpful if a tumour or other local compressive lesion is suspected. Nerve injury, as a mononeuropathy, may cause similar symptoms to compression neuropathy. This may occasionally cause diagnostic confusion, particularly if the patient does not remember the injury and there are no obvious physical signs to suggest it.

Treatment

When an underlying medical condition is causing the neuropathy, treatment should first be directed at this condition. For example, if weight gain is the underlying cause, then a weight loss program is the most appropriate treatment. Compression neuropathy occurring in pregnancy often resolves after delivery, so no specific treatment is usually required. Some compression neuropathies are amenable to

: carpal tunnel syndrome and

cubital tunnel syndrome Ulnar nerve entrapment is a condition where the ulnar nerve becomes physically trapped or pinched, resulting in pain, numbness, or weakness, primarily affecting the little finger and ring finger of the hand. Entrapment may occur at any point fro ...

are two common examples. Whether or not it is appropriate to offer surgery in any particular case depends on the severity of the symptoms, the risks of the proposed operation, and the

prognosis Prognosis (Greek: πρόγνωσις "fore-knowing, foreseeing") is a medical term for predicting the likely or expected development of a disease, including whether the signs and symptoms will improve or worsen (and how quickly) or remain stable ...

if untreated. After surgery, the symptoms may resolve completely, but if the compression was sufficiently severe or prolonged then the nerve may not recover fully and some symptoms may persist. Drug treatment may be useful for an underlying condition (including

peripheral edema Peripheral edema is edema (accumulation of fluid causing swelling) in tissues perfused by the peripheral vascular system, usually in the lower limbs. In the most dependent parts of the body (those hanging distally), it may be called dependent edem ...

), or for ameliorating

. A textbook on massageOrthopedic Assessment in Massage Therapy by Whitney Lowe states that massage can alleviate at least some entrapment symptoms:

The primary goal in treating nerve compression or tension pathology is to relieve adverse forces on the nerve. If soft tissue is binding or entrapping the nerve, reduce tension in that tissue so the nerve is no longer restricted. Use caution during treatment to ensure that additional pressure is not applied to the affected nerve, thereby aggravating symptoms. Soft-tissue treatment helps reduce the adverse compression or tension, but does not speed the healing of nerve pathologies, which are very slow to heal. However, creating an optimum environment for the body’s healing process is essential for the most efficient recovery process. Massage is an effective adjunct treatment to neural mobilization techniques, which are used to free bound or restricted nerves in neural tension disorders.

References

External links

{{Authority control Peripheral nervous system disorders Syndromes affecting the nervous system