Neuralgia
Encyclopedia
Neuralgia is pain
in one or more nerves that occurs without stimulation of pain receptor (nociceptor
) cells. Neuralgia pain is produced by a change in neurological structure or function rather than by the excitation of pain receptors that causes nociceptive pain. Neuralgia falls into two categories: central neuralgia and peripheral neuralgia. This unusual pain is thought to be linked to four possible mechanisms: ion gate malfunctions; the nerve becomes mechanically sensitive and creates an ectopic signal; cross signals between large and small fibers; and malfunction due to damage in the central processor.
(1829–1914), a neurologist in the American Civil War
, who noticed hyperalgesia
and chronic pain
in patients who had nerve lesions in the extremities and also some cases where no lesion was observed: These causalgias were certainly major by the importance of the symptoms, but stemmed from minor neurological lesions". Mitchell termed the condition “causalgia” which has since become known as “Complex Regional Pain Syndrome
Type 1 and Type 2” (CRPS). CRPS Type I is a syndrome that develops after an initiating noxious event, and Type 2 describes a case when nerve damage is clear.
test or a nerve conduction test. Neuralgia is more difficult to treat than other types of pain because it does not respond well to normal pain medications. Special medications have become more specific to neuralgia and typically fall under the category of membrane stabilizing drugs or antidepressants such as Cymbalta. The antiepileptic medication(AED) Lyrica (pregabalin) was developed specifically for neuralgia and other neuropathic pain as a successor to Neurontin (gabapentin).
Under the general heading of neuralgia are trigeminal neuralgia
(TN), atypical trigeminal neuralgia (ATN), and postherpetic neuralgia
(caused by shingles or herpes). Neuralgia is also involved in disorders such as sciatica
and brachial plexopathy
with neuropathia. Neuralgias that do not involve the trigeminal nerve are occipital neuralgia
and glossopharyngeal neuralgia.
In the case of trigeminal neuralgia the affected nerves are responsible for sensing touch, temperature sensation
and pressure sensation
in the facial
area from the jaw
to the forehead
. The disorder generally causes short episodes of excruciating pain
, usually for less than two minutes and usually only one side of the face. The pain can be described in a variety of ways such as "stabbing," "sharp," "like lightning," "burning," and even "itchy". In the atypical form of TN, the pain presents itself as severe constant aching along the nerve. The pain associated with TN is recognized as one of the most excruciating pains that can be experienced.
Simple stimuli such as eating, talking, making facial expressions, washing the face, or any light touch or sensation can trigger an attack (even the sensation of a cool breeze). The attacks can occur in clusters, as an isolated attack, or be completely constant. Some patients will have a muscle spasm which led to the original term for TN of "" ("", meaning 'spasm
', and "", meaning 'painful', in French
).
Neuralgia is a form of chronic pain
and can be extremely difficult to diagnose. Postherpetic neuralgia is the easiest to diagnose because it follows an obvious cause (shingles). Neuralgia is a rare disease. Women are more likely to be affected than men. In some cases, multiple sclerosis
is related to nerve damage, causing the pain, so doctors will likely ask about family history to help diagnose. Nothing unusual can be seen in brain scans, so diagnosis is usually based on the description of the symptoms and the response to the medication or procedures.
, musculoskeletal issues, and hypochondriasis. ATN can have a wide range of symptoms and the pain can fluctuate in intensity from mild aching to a crushing or burning sensation, and also to the extreme pain experienced with the more common trigeminal neuralgia. ATN pain can be described as heavy, aching, and burning. Sufferers have a constant migraine-like headache and experience pain in all three trigeminal nerve branches. This includes aching teeth, ear aches, feeling of fullness in sinuses, cheek pain, pain in forehead and temples, jaw pain, pain around eyes, and occasional electric shock-like stabs. Unlike typical neuralgia, this form can also cause pain in the back of the scalp and neck. Pain tends to worsen with talking, facial expressions, chewing, and certain sensations such as a cool breeze. Vascular compression of the trigeminal nerve
, infections of the teeth or sinuses, physical trauma, or past viral infections are possible causes of ATN.
(CN IX), which moves the muscles of the throat and carries information from the throat, tonsils, and tongue to the brain.
Glossopharyngeal neuralgia, a rare disorder, usually begins after age 40 and occurs more often in men. Often, its cause is unknown. But sometimes glossopharyngeal neuralgia results from an abnormally positioned artery that compresses the glossopharyngeal nerve near where it exits the brain stem. Rarely, the cause is a tumor in the brain or neck.
, also known as C2 neuralgia, or Arnold's neuralgia, is a medical condition characterized by chronic pain in the upper neck, back of the head and behind the eyes.
and malnutrition
can be secondary consequences of neuralgic pain.
, axonotmesis
, or neurotmesis
. Following trauma to the nerve, a short onset of afferent impulses, termed “injury discharge”, occurs. While lasting only minutes, this occurrence has been linked to the onset of neuropathic pain.
When an axon
is severed, the segment of the axon distal to the cut degenerates and is absorbed by Schwann cells. The proximal segment fuses, retracts, and swells, forming a “retraction bulb.” The synaptic terminal function is lost, as axoplasmic transport ceases and no neurotransmitters are created. The nucleus of the damaged axon undergoes chromatolysis
in preparation for axon regeneration. Schwann cells in the distal stump of the nerve and basal lamina
components secreted by Schwann cells guide and help stimulate regeneration. The regenerating axon must make connections with the appropriate receptors in order to make an effective regeneration. If proper connections to the appropriate receptors are not established, aberrant reinnervation
may occur. If the regenerating axon is halted by damaged tissue, neurofibrils may create a mass known as a neuroma
.
In the event that an injured neuron degenerates or does not regenerate properly, the neuron loses its function or may not function properly. Neuron trauma is not an isolated event and may cause degenerative changes in surrounding neurons. When one or more neurons lose their function or begin to malfunction, abnormal signals sent to the brain may be translated as painful signals.
(CNS) typically leads to local degeneration of the nerve axon and myelin sheath. Axonal debris in the CNS is eliminated by macrophages. Trauma to neurons in the CNS also causes a proliferation of glial cells that form a glial scar. Development of the glial scar is thought to inhibit regeneration of central neural connections. The damaged nerve terminal begins to swell and glial cells push the defective terminal away from connections to other neurons. Often, aberrant sprouting of damaged CNS neurons, specifically sensory neurons, results in neuralgia.
, such as using microneurography
in which the peripheral nerve is stimulated and recordings are taken from a purely-sensory portion of the nerve.
When assessing neuralgia to find the underlying mechanism, a history of the pain, description of pain, clinical examination, and experimental examination are required. Since pain is subjective to the patient, it is important to use a pain assessment scale, such as the McGill Pain Questionnaire
. Qualifying the severity of the pain is essential in diagnosis and in evaluating the effectiveness of the treatment. Clinical examinations usually involve testing responses to stimuli such as touch, temperature, and vibration. Neuralgia can be further classified by the type of stimuli that elicits a response: mechanical, thermal, or chemical. Response to the course of treatment is the final tool used to determine the mechanism of the pain. Future research must focus on the relationships between all of these categories.
One problem with QST is that abnormalities may be observed in non-neuralgia pains, often making it inconclusive in diagnosis. Also, QST is very time consuming and relies on expensive equipment.
High doses of anticonvulsant medicines—used to block nerve firing— and tricyclic antidepressants are generally effective in treating neuralgia. If medication fails to relieve pain or produces intolerable side effects, surgical treatment may be recommended.
Neural augmentative surgeries are used to stimulate the affected nerve. By stimulating the nerve the brain can be “fooled” into thinking it is receiving normal input. Electrodes are carefully placed in the dorsal root and subcutaneous nerve stimulation is used to stimulate the targeted nerve pathway. A technician can create different electrical distributions in the nerve to optimize the efficiency, and a patient controls the stimulation by passing a magnet over the unit.
Some degree of facial numbness is expected after most of these surgical procedures, and neuralgia might return despite the procedure’s initial success. Depending on the procedure, other surgical risks include hearing loss, balance problems, infection, and stroke. These surgeries include rhizotomy
(where select nerve fibers are destroyed to block pain) and Microvascular decompression
(where the surgeon moves the vessels that are compressing the nerve away from it and places a soft cushion between the nerve and the vessels).
Some patients choose to manage neuralgia using complementary techniques, usually in combination with drug treatment. These therapies offer varying degrees of success. Options include chiropractic, acupuncture, biofeedback, vitamin therapy, nutritional therapy, hot-cold compress, and electrical stimulation of the nerves.
Pain
Pain is an unpleasant sensation often caused by intense or damaging stimuli such as stubbing a toe, burning a finger, putting iodine on a cut, and bumping the "funny bone."...
in one or more nerves that occurs without stimulation of pain receptor (nociceptor
Nociception
Nociception is defined as "the neural processes of encoding and processing noxious stimuli." It is the afferent activity produced in the peripheral and central nervous system by stimuli that have the potential to damage tissue...
) cells. Neuralgia pain is produced by a change in neurological structure or function rather than by the excitation of pain receptors that causes nociceptive pain. Neuralgia falls into two categories: central neuralgia and peripheral neuralgia. This unusual pain is thought to be linked to four possible mechanisms: ion gate malfunctions; the nerve becomes mechanically sensitive and creates an ectopic signal; cross signals between large and small fibers; and malfunction due to damage in the central processor.
History
Neuralgia was first recognized by François Louis Isidore Valleix. It was subsequently noted by Silas Weir MitchellSilas Weir Mitchell
Silas Weir Mitchell was an American physician and writer.He was son of a physician, John Kearsley Mitchell , and was born in Philadelphia, Pennsylvania....
(1829–1914), a neurologist in the American Civil War
American Civil War
The American Civil War was a civil war fought in the United States of America. In response to the election of Abraham Lincoln as President of the United States, 11 southern slave states declared their secession from the United States and formed the Confederate States of America ; the other 25...
, who noticed hyperalgesia
Hyperalgesia
Hyperalgesia is an increased sensitivity to pain, which may be caused by damage to nociceptors or peripheral nerves. Temporary increased sensitivity to pain also occurs as part of sickness behavior, the evolved response to infection.-Types:...
and chronic pain
Chronic pain
Chronic pain has several different meanings in medicine. Traditionally, the distinction between acute and chronic pain has relied upon an arbitrary interval of time from onset; the two most commonly used markers being 3 months and 6 months since the initiation of pain, though some theorists and...
in patients who had nerve lesions in the extremities and also some cases where no lesion was observed: These causalgias were certainly major by the importance of the symptoms, but stemmed from minor neurological lesions". Mitchell termed the condition “causalgia” which has since become known as “Complex Regional Pain Syndrome
Complex regional pain syndrome
Complex regional pain syndrome is a chronic progressive disease characterized by severe pain, swelling and changes in the skin. It often affects an arm or a leg and may spread to another part of the body.Though treatment is often unsatisfactory, early multimodal therapy can cause dramatic...
Type 1 and Type 2” (CRPS). CRPS Type I is a syndrome that develops after an initiating noxious event, and Type 2 describes a case when nerve damage is clear.
Pathophysiology
Neuralgia is often difficult to diagnose, and most treatments show little or no effectiveness. Diagnosis typically involves locating the damaged nerve by identifying missing sensory or motor function. This may involve tests such as an EMGElectromyography
Electromyography is a technique for evaluating and recording the electrical activity produced by skeletal muscles. EMG is performed using an instrument called an electromyograph, to produce a record called an electromyogram. An electromyograph detects the electrical potential generated by muscle...
test or a nerve conduction test. Neuralgia is more difficult to treat than other types of pain because it does not respond well to normal pain medications. Special medications have become more specific to neuralgia and typically fall under the category of membrane stabilizing drugs or antidepressants such as Cymbalta. The antiepileptic medication(AED) Lyrica (pregabalin) was developed specifically for neuralgia and other neuropathic pain as a successor to Neurontin (gabapentin).
Under the general heading of neuralgia are trigeminal neuralgia
Trigeminal neuralgia
Trigeminal neuralgia , tic douloureux is a neuropathic disorder characterized by episodes of intense pain in the face, originating from the trigeminal nerve. It has been described as among the most painful conditions known...
(TN), atypical trigeminal neuralgia (ATN), and postherpetic neuralgia
Postherpetic neuralgia
Postherpetic neuralgia is a neuralgia caused by the varicella zoster virus. Typically, the neuralgia is confined to a dermatomic area of the skin and follows an outbreak of herpes zoster in that same dermatomic area...
(caused by shingles or herpes). Neuralgia is also involved in disorders such as sciatica
Sciatica
Sciatica is a set of symptoms including pain that may be caused by general compression or irritation of one of five spinal nerve roots that give rise to each sciatic nerve, or by compression or irritation of the left or right or both sciatic nerves. The pain is felt in the lower back, buttock, or...
and brachial plexopathy
Brachial plexus
The brachial plexus is a network of nerve fibers, running from the spine, formed by the ventral rami of the lower four cervical and first thoracic nerve roots...
with neuropathia. Neuralgias that do not involve the trigeminal nerve are occipital neuralgia
Occipital neuralgia
Occipital neuralgia, also known as C2 neuralgia, Arnold's neuralgia, is a medical condition characterized by chronic pain in the upper neck, back of the head and behind the eyes. These areas correspond to the locations of the lesser and greater occipital nerves.-Causes:Occipital neuralgia is...
and glossopharyngeal neuralgia.
In the case of trigeminal neuralgia the affected nerves are responsible for sensing touch, temperature sensation
Temperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...
and pressure sensation
Pressure
Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...
in the facial
Face
The face is a central sense organ complex, for those animals that have one, normally on the ventral surface of the head, and can, depending on the definition in the human case, include the hair, forehead, eyebrow, eyelashes, eyes, nose, ears, cheeks, mouth, lips, philtrum, temple, teeth, skin, and...
area from the jaw
Jaw
The jaw is any opposable articulated structure at the entrance of the mouth, typically used for grasping and manipulating food. The term jaws is also broadly applied to the whole of the structures constituting the vault of the mouth and serving to open and close it and is part of the body plan of...
to the forehead
Forehead
For the Arsenal striker see GervinhoIn human anatomy, the forehead is the fore part of the head. It is, formally, an area of the head bounded by three features, two of the skull and one of the scalp. The top of the forehead is marked by the hairline, the edge of the area where hair on the scalp...
. The disorder generally causes short episodes of excruciating pain
Pain
Pain is an unpleasant sensation often caused by intense or damaging stimuli such as stubbing a toe, burning a finger, putting iodine on a cut, and bumping the "funny bone."...
, usually for less than two minutes and usually only one side of the face. The pain can be described in a variety of ways such as "stabbing," "sharp," "like lightning," "burning," and even "itchy". In the atypical form of TN, the pain presents itself as severe constant aching along the nerve. The pain associated with TN is recognized as one of the most excruciating pains that can be experienced.
Simple stimuli such as eating, talking, making facial expressions, washing the face, or any light touch or sensation can trigger an attack (even the sensation of a cool breeze). The attacks can occur in clusters, as an isolated attack, or be completely constant. Some patients will have a muscle spasm which led to the original term for TN of "" ("", meaning 'spasm
Spasm
In medicine a spasm is a sudden, involuntary contraction of a muscle, a group of muscles, or a hollow organ, or a similarly sudden contraction of an orifice. It is sometimes accompanied by a sudden burst of pain, but is usually harmless and ceases after a few minutes...
', and "", meaning 'painful', in French
French language
French is a Romance language spoken as a first language in France, the Romandy region in Switzerland, Wallonia and Brussels in Belgium, Monaco, the regions of Quebec and Acadia in Canada, and by various communities elsewhere. Second-language speakers of French are distributed throughout many parts...
).
Neuralgia is a form of chronic pain
Chronic pain
Chronic pain has several different meanings in medicine. Traditionally, the distinction between acute and chronic pain has relied upon an arbitrary interval of time from onset; the two most commonly used markers being 3 months and 6 months since the initiation of pain, though some theorists and...
and can be extremely difficult to diagnose. Postherpetic neuralgia is the easiest to diagnose because it follows an obvious cause (shingles). Neuralgia is a rare disease. Women are more likely to be affected than men. In some cases, multiple sclerosis
Multiple sclerosis
Multiple sclerosis is an inflammatory disease in which the fatty myelin sheaths around the axons of the brain and spinal cord are damaged, leading to demyelination and scarring as well as a broad spectrum of signs and symptoms...
is related to nerve damage, causing the pain, so doctors will likely ask about family history to help diagnose. Nothing unusual can be seen in brain scans, so diagnosis is usually based on the description of the symptoms and the response to the medication or procedures.
Atypical (trigeminal)
Atypical trigeminal neuralgia (ATN) is a rare form of neuralgia and may also be the most misdiagnosed form. The symptoms can be mistaken for migraines, dental problems such as temporomandibular joint disorderTemporomandibular joint disorder
Temporomandibular joint disorder , or TMJ syndrome, is an umbrella term covering acute or chronic inflammation of the temporomandibular joint, which connects the mandible to the skull. The disorder and resultant dysfunction can result in significant pain and impairment...
, musculoskeletal issues, and hypochondriasis. ATN can have a wide range of symptoms and the pain can fluctuate in intensity from mild aching to a crushing or burning sensation, and also to the extreme pain experienced with the more common trigeminal neuralgia. ATN pain can be described as heavy, aching, and burning. Sufferers have a constant migraine-like headache and experience pain in all three trigeminal nerve branches. This includes aching teeth, ear aches, feeling of fullness in sinuses, cheek pain, pain in forehead and temples, jaw pain, pain around eyes, and occasional electric shock-like stabs. Unlike typical neuralgia, this form can also cause pain in the back of the scalp and neck. Pain tends to worsen with talking, facial expressions, chewing, and certain sensations such as a cool breeze. Vascular compression of the trigeminal nerve
Trigeminal nerve
The trigeminal nerve contains both sensory and motor fibres. It is responsible for sensation in the face and certain motor functions such as biting, chewing, and swallowing. Sensory information from the face and body is processed by parallel pathways in the central nervous system...
, infections of the teeth or sinuses, physical trauma, or past viral infections are possible causes of ATN.
Glossopharyngeal
Glossopharyngeal neuralgia consists of recurring attacks of severe pain in the back of the throat, the area near the tonsils, the back of the tongue, and part of the ear. The pain is due to malfunction of the glossopharyngeal nerveGlossopharyngeal nerve
The glossopharyngeal nerve is the ninth of twelve pairs of cranial nerves . It exits the brainstem out from the sides of the upper medulla, just rostral to the vagus nerve...
(CN IX), which moves the muscles of the throat and carries information from the throat, tonsils, and tongue to the brain.
Glossopharyngeal neuralgia, a rare disorder, usually begins after age 40 and occurs more often in men. Often, its cause is unknown. But sometimes glossopharyngeal neuralgia results from an abnormally positioned artery that compresses the glossopharyngeal nerve near where it exits the brain stem. Rarely, the cause is a tumor in the brain or neck.
Occipital
Occipital neuralgiaOccipital neuralgia
Occipital neuralgia, also known as C2 neuralgia, Arnold's neuralgia, is a medical condition characterized by chronic pain in the upper neck, back of the head and behind the eyes. These areas correspond to the locations of the lesser and greater occipital nerves.-Causes:Occipital neuralgia is...
, also known as C2 neuralgia, or Arnold's neuralgia, is a medical condition characterized by chronic pain in the upper neck, back of the head and behind the eyes.
Signs and symptoms
It has been reported that Sleep deprivationSleep deprivation
Sleep deprivation is the condition of not having enough sleep; it can be either chronic or acute. A chronic sleep-restricted state can cause fatigue, daytime sleepiness, clumsiness and weight loss or weight gain. It adversely affects the brain and cognitive function. Few studies have compared the...
and malnutrition
Malnutrition
Malnutrition is the condition that results from taking an unbalanced diet in which certain nutrients are lacking, in excess , or in the wrong proportions....
can be secondary consequences of neuralgic pain.
Mechanisms
By understanding the neuroplastic changes following nerve damage, researchers may be able to better understand the mechanism of hyperexcitability in the nervous system that is believed to cause neuropathic pain.Peripheral nerve injury
A neuron’s response to trauma can often be determined by the severity of the injury, classified by Seddon's classification. In Seddon’s Classification, nerve injury is described as either neurapraxiaNeurapraxia
Neurapraxia is a disorder of the peripheral nervous system in which there is a temporary loss of motor and sensory function due to blockage of nerve conduction, usually lasting an average of six to eight weeks before full recovery...
, axonotmesis
Axonotmesis
Axonotmesis is a disruption of nerve cell axon, with Wallerian degeneration occurring below and slightly proximal to the site of injury. If axons, and their myelin sheath are damaged, but schwann cells, the endoneurium, perineurium and epineurium remain intact is called axonotmesis. Axonotmesis is...
, or neurotmesis
Neurotmesis
Neurotmesis is part of Seddon's classification scheme used to classify nerve damage.It is the most serious nerve injury in the scheme.In this type of injury, both the nerve and the nerve sheath are disrupted....
. Following trauma to the nerve, a short onset of afferent impulses, termed “injury discharge”, occurs. While lasting only minutes, this occurrence has been linked to the onset of neuropathic pain.
When an axon
Axon
An axon is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neuron's cell body or soma....
is severed, the segment of the axon distal to the cut degenerates and is absorbed by Schwann cells. The proximal segment fuses, retracts, and swells, forming a “retraction bulb.” The synaptic terminal function is lost, as axoplasmic transport ceases and no neurotransmitters are created. The nucleus of the damaged axon undergoes chromatolysis
Chromatolysis
Chromatolysis is the dissolution of the Nissl bodies in the cell body of a neuron. It is an induced response of the cell usually triggered by axotomy , ischemia, toxicity to the cell, cell exhaustion, virus infections, and hibernation in lower vertebrates. Neuronal recovery can occur after...
in preparation for axon regeneration. Schwann cells in the distal stump of the nerve and basal lamina
Basal lamina
The basal lamina is a layer of extracellular matrix secreted by the epithelial cells, on which the epithelium sits. It is often confused with the basement membrane, and sometimes used inconsistently in the literature, see below....
components secreted by Schwann cells guide and help stimulate regeneration. The regenerating axon must make connections with the appropriate receptors in order to make an effective regeneration. If proper connections to the appropriate receptors are not established, aberrant reinnervation
Reinnervation
In living tissues, reinnervation describes the process by which post-synaptic neurons form new synapses or increase existing synaptic efficacy in order to compensate for a lack of pre-synaptic input from dead or otherwise dysfunctional pre-synaptic neurons....
may occur. If the regenerating axon is halted by damaged tissue, neurofibrils may create a mass known as a neuroma
Neuroma
A neuroma is a growth or tumor of nerve tissue. Just as the Latin word for swelling is now restricted to neoplasias, the equivalent Greek suffix -oma has shared in that fate. Thus, the typical modern usage of neuroma is for nerve tumors...
.
In the event that an injured neuron degenerates or does not regenerate properly, the neuron loses its function or may not function properly. Neuron trauma is not an isolated event and may cause degenerative changes in surrounding neurons. When one or more neurons lose their function or begin to malfunction, abnormal signals sent to the brain may be translated as painful signals.
Central neuronal injury
Neuronal injury in the central nervous systemCentral nervous system
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
(CNS) typically leads to local degeneration of the nerve axon and myelin sheath. Axonal debris in the CNS is eliminated by macrophages. Trauma to neurons in the CNS also causes a proliferation of glial cells that form a glial scar. Development of the glial scar is thought to inhibit regeneration of central neural connections. The damaged nerve terminal begins to swell and glial cells push the defective terminal away from connections to other neurons. Often, aberrant sprouting of damaged CNS neurons, specifically sensory neurons, results in neuralgia.
Diagnosis
Diagnosis of neuralgia is difficult, and misdiagnosis is common. Diagnosis typically involves locating the damaged nerve by stimulation of the specific damaged pathway or by identifying missing sensory function. The most common test for neuralgia is a nerve conduction studyNerve conduction study
A nerve conduction study is a test commonly used to evaluate the function, especially the ability of electrical conduction, of the motor and sensory nerves of the human body.Nerve conduction velocity is a common measurement made during this test...
, such as using microneurography
Microneurography
Human microneurography or simply microneurography involves the insertion of metal microelectrodes into nerve fascicles. -Applications:Microneurography is used to study autonomic nervous system function. This is accomplished by recording muscle sympathetic nerve activity...
in which the peripheral nerve is stimulated and recordings are taken from a purely-sensory portion of the nerve.
When assessing neuralgia to find the underlying mechanism, a history of the pain, description of pain, clinical examination, and experimental examination are required. Since pain is subjective to the patient, it is important to use a pain assessment scale, such as the McGill Pain Questionnaire
McGill Pain Questionnaire
The McGill Pain Questionnaire, also known as McGill pain index, is a scale of rating pain developed at McGill University by Melzack and Torgerson in 1971....
. Qualifying the severity of the pain is essential in diagnosis and in evaluating the effectiveness of the treatment. Clinical examinations usually involve testing responses to stimuli such as touch, temperature, and vibration. Neuralgia can be further classified by the type of stimuli that elicits a response: mechanical, thermal, or chemical. Response to the course of treatment is the final tool used to determine the mechanism of the pain. Future research must focus on the relationships between all of these categories.
Laser evoked potentials
Neuropathic pain is often the result of a lesion in spinothalamic pathways. Laser evoked potentials (LEPs) are measurements of cortical responses using lasers to selectively stimulate thermonociceptors in the skin. Lasers can emit a radiant-heat pulse stimulus to selectively activate A-delta and C free nerve endings. By specifically targeting pain and temperature pathways and measuring cortical responses, clinicians can identify even minute lesions in the spinothalamic pathways. LEP abnormalities are strongly indicative of neuropathic pain, while a normal LEP is often more ambiguous. LEPs have high sensitivity and are very reliable in assessing damage to both central and peripheral nervous systems.Quantitative sensory testing
Another method for testing the proper function of a nerve is Quantitative sensory testing (QST). QST relies on analysis of a patient’s response to external stimuli of controlled intensity. A stimulus is applied to the skin of the nerve area being tested in ascending and descending orders of magnitude. Clinicians can quantify the mechanical sensitivity of the tactile stimulus using von Frey hairs or Semmes-Weinstein monofilaments. Also, weighted needles can be used to measure pin-prick sensation, and an electronic vibrameter is used to measure vibration sensitivity. Thermal stimuli are quantified by using a probe that operates on the Peltier principle.One problem with QST is that abnormalities may be observed in non-neuralgia pains, often making it inconclusive in diagnosis. Also, QST is very time consuming and relies on expensive equipment.
Punch skin biopsy
Recently, skin biopsy has been used to investigate mechanoreceptors and their myelinated afferents. Though available in only a few research centers, skin punch biopsy is an easy procedure and is minimally invasive. Punch skin biopsy is used to quantify nerve fibers C fibers and A-delta nerve fibers through measurement of the density of intra-epidermal nerve fibers (IENF). Loss of IENF has been observed in several cases of neuropathic pain.Treatment
Treatment options include medicines, surgery, and complementary approaches.High doses of anticonvulsant medicines—used to block nerve firing— and tricyclic antidepressants are generally effective in treating neuralgia. If medication fails to relieve pain or produces intolerable side effects, surgical treatment may be recommended.
Neural augmentative surgeries are used to stimulate the affected nerve. By stimulating the nerve the brain can be “fooled” into thinking it is receiving normal input. Electrodes are carefully placed in the dorsal root and subcutaneous nerve stimulation is used to stimulate the targeted nerve pathway. A technician can create different electrical distributions in the nerve to optimize the efficiency, and a patient controls the stimulation by passing a magnet over the unit.
Some degree of facial numbness is expected after most of these surgical procedures, and neuralgia might return despite the procedure’s initial success. Depending on the procedure, other surgical risks include hearing loss, balance problems, infection, and stroke. These surgeries include rhizotomy
Rhizotomy
A rhizotomy is a term chiefly referring to a neurosurgical procedure that selectively severs problematic nerve roots in the spinal cord, most often to relieve the symptoms of neuromuscular conditions such as spastic diplegia and other forms of spastic cerebral palsy...
(where select nerve fibers are destroyed to block pain) and Microvascular decompression
Microvascular decompression
Microvascular decompression , also known as the Jannetta procedure, is a neurosurgical procedure used to treat trigeminal neuralgia, a pain syndrome characterized by severe episodes of intense facial pain and hemifacial spasm.-History:...
(where the surgeon moves the vessels that are compressing the nerve away from it and places a soft cushion between the nerve and the vessels).
Some patients choose to manage neuralgia using complementary techniques, usually in combination with drug treatment. These therapies offer varying degrees of success. Options include chiropractic, acupuncture, biofeedback, vitamin therapy, nutritional therapy, hot-cold compress, and electrical stimulation of the nerves.
Literature
- Shankland, Dr. Wesley E. Face the Pain - The Challenge of Facial Pain, (Omega Publishing, 2001) Dr. Shankland is a former associate editor of The Journal of Craniomandibular Practice.
- In R. C. SherriffR. C. Sherriff-External links:**...
's play Journey's EndJourney's EndJourney's End is a 1928 drama, the seventh of English playwright R. C. Sherriff. It was first performed at the Apollo Theatre in London by the Incorporated Stage Society on 9 December 1928, starring a young Laurence Olivier, and soon moved to other West End theatres for a two-year run...
, the character Hibbert lies about having neuralgia to his commanding officer, and demands to be sent home.
See also
- Cranial nervesCranial nervesCranial nerves are nerves that emerge directly from the brain, in contrast to spinal nerves, which emerge from segments of the spinal cord. In humans, there are traditionally twelve pairs of cranial nerves...
- NerveNerveA peripheral nerve, or simply nerve, is an enclosed, cable-like bundle of peripheral axons . A nerve provides a common pathway for the electrochemical nerve impulses that are transmitted along each of the axons. Nerves are found only in the peripheral nervous system...
- Neuralgia-inducing cavitational osteonecrosisNeuralgia-inducing cavitational osteonecrosisNeuralgia-inducing cavitational osteonecrosis refers to presence of cavitations in jaw bones in conjunction with chronic facial neuralgia. The concept implies direct and causal relationship between the bone pathology and pain itself. Pain in this setting is commonly described as atypical facial...
- Neuritis
- Neuropathy
- Somatosensory Rehabilitation of PainSomatosensory Rehabilitation of PainThe Somatosensory Rehabilitation of Pain, is a method, who’s aim is to treat conditions of a reduced sense of touch or sensation in order to decrease neuropathic pain. Neuropathic pain, with a prevalency of 6.9 % of the general population, represents an important public health problem. i.e. Carpal...
External links
- Good Pictures of the affected nerves
- The Facial Pain Association
- Medical Information
- Information on post-herpetic neuralgia
- Mayo Clinic on post-herpetic neuralgia
- Mayo Clinic on Trigeminal Neuralgia
- Atypical Neuralgia
- Medical Information on Atypical Neuralgia
- Interesting website of Dr. Ramin Naraghi on neurovascular compression syndromes (NVC)