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.
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 nerves, Cranial nerve roots: the initial or proximal segment of one of the twelve pairs of crania ...
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 physical ...
, for example). Its symptoms include
pain,
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. 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 spec ...
help to confirm the diagnosis. In some cases,
surgery 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 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 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), frequently resting one's elbows on a table (
ulnar nerve), 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 ...
or
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, then ...
), a
ganglion cyst or a
haematoma. 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
Carpal tunnel syndrome (CTS) is the collection of symptoms and signs associated with median neuropathy at the carpal tunnel. Most CTS is related to idiopathic
An idiopathic disease is any disease with an unknown cause or mechanism of apparen ...
. 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 w ...
or
peripheral oedema (especially in
pregnancy
Pregnancy is the time during which one or more offspring develops (gestation, gestates) inside a woman, woman's uterus (womb). A multiple birth, multiple pregnancy involves more than one offspring, such as with twins.
Pregnancy usually occur ...
), or to a specific condition such as
acromegaly,
hypothyroidism or
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 ...
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 ...
, 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
Vasa nervorum are small arteries that provide blood supply to peripheral nerves, specifically to the interior parts of nerves, and their coverings.
Associated pathologic conditions
Small vessels like vasa vasorum and vasa nervorum are particular ...
). This causes local
ischaemia
Ischemia American and British English spelling differences#ae and oe, or ischaemia is a restriction in blood supply to any tissue (biology), tissue, Skeletal muscle, muscle group, or Organ (biology), organ of the body, causing a shortage of oxyg ...
, which has an immediate effect on the ability of the nerve
axons 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 ...
. 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 na ...
.
Diagnosis
The
symptoms 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
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 ...
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 is usually noticed later, and is often associated with
muscle atrophy.
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 spec ...
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 ...
or
polyneuropathy). A
scan
Scan may refer to:
Acronyms
* Schedules for Clinical Assessment in Neuropsychiatry (SCAN), a psychiatric diagnostic tool developed by WHO
* Shared Check Authorization Network (SCAN), a database of bad check writers and collection agency for bad ...
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
surgery:
carpal tunnel syndrome
Carpal tunnel syndrome (CTS) is the collection of symptoms and signs associated with median neuropathy at the carpal tunnel. Most CTS is related to idiopathic
An idiopathic disease is any disease with an unknown cause or mechanism of apparen ...
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 from ...
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 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 ede ...
), or for ameliorating
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 ...
.
A textbook on massage
[Orthopedic 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.
See also
References
External links
{{Authority control
Peripheral nervous system disorders
Syndromes affecting the nervous system