The lumbosacral nerves | |
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Anatomical terms of neuroanatomy |
Radiation-induced lumbar plexopathy (RILP) or radiation-induced lumbosacral plexopathy (RILSP) is nerve damage in the pelvis and lower spine area caused by therapeutic radiation treatments. RILP is a rare side effect of external beam radiation therapy [1] [2] [3] and both interstitial and intracavity brachytherapy radiation implants. [4] [5] RILP is a Pelvic Radiation Disease symptom. [6]
In general terms, such nerve damage may present in stages, earlier as demyelination and later as complications of chronic radiation fibrosis. RILP occurs as a result of radiation therapy administered to treat lymphoma or cancers within the abdomen or pelvic area such as cervical, ovarian, bladder, kidney, pancreatic, prostate, testicular, colorectal, colon, rectal or anal cancer. [7] [8] The lumbosacral plexus area is radiosensitive and radiation plexopathy can occur after exposure to mean or maximum radiation levels of 50-60 Gray [7] with a significant rate difference noted within that range. [9]
Lumbosacral plexopathy is characterized by any of the following symptoms; usually bi-lateral and symmetrical, though unilateral is known. [8]
Symptoms are typically a step-wise progression with periods of stability in between, [1] [3] weakness often appearing years later. [8] Weakness frequently presents in the lower leg muscle groups. [8] Symptoms are usually irreversible. [10]
Initial onset of symptoms may occur as early as 2 [8] to 3 [11] [1] months after radiotherapy. The median onset is approximately 5 years, [8] but can be highly variable, 2-3 decades after radiation therapy. [8] One case study recorded the initial onset occurring 36 years post treatment. [12]
The treatment's ionizing radiation is an activation mechanism for apoptosis (cell death) within the targeted cancer, [13] but it can also impact nearby healthy radiosensitive tissues, like the lumbosacral plexus. The occurrence and severity of RILP is related to the magnitude of ionizing radiation [10] and the radiosensitivity of peripheral nerves may be further aggravated when combined with chemotherapy, like taxanes and platinum drugs, during treatment. [14]
The pathophysiological process behind radiation's RILP nerve damage has been discussed since the 1960s [10] and is still without a precise definition. [1] [13] Consensus does exist on a progression of RILP symptoms, with a stepping (a time delay) between two periods of plexopathy onset, the first from radiation injury and the later from fibrosis. Proposed mechanisms of the early nerve damage include microvascular damage (ischemia) supplying the myelin, [1] radiation damage of the myelin, [15] and oxygen free radical cell damage. [1] [15] The delayed nerve damage is attributed to compression neuropathy [1] and a late fibro-atrophic ischemia from retractile fibrosis. [1] [15]
The more common source of lumbar plexopathy is a direct or secondary [2] tumor involvement of the plexus with MRI being the typical confirmation tool. [15] Tumors typically present with enhancement of nerve roots and T2-weighted hyperintensity. [2] The differential consideration of RILP requires taking a medical history and neurologic examination. [15]
RILP's neurological symptoms can mimic other nerve disorders. People may present with pure lower motor neuron syndrome, a symptom of amyotrophic lateral sclerosis (ALS). [4] [16] RILP may also be misdiagnosed as leptomeningeal metastasis often showing nodular MRI enhancement of the cauda equina nerve roots or having increased CSF protein content. [4]
Other differential diagnoses to consider are Chronic Inflammatory Demyelinating Polyradiculoneuropathy, neoplastic lumbosacral plexopathy, paraneoplastic neuronopathy, diabetic lumbosacral plexopathy, degenerative disk disease (osteoporosis of the spine), Osteoarthritis of the spine, Lumbar Spinal Stenosis, post-infectious plexopathy, carcinomatous meningitis (CM), mononeuritis multiplex, and chemotherapy-induced plexopathy. [1]
The testing to resolve a RILP diagnosis involves blood serum analysis, X-rays, EMG, MRI and cerebrospinal fluid analysis. [2] [1] [15]
Since RILP's neurological changes are typically irreversible and a curative strategy has yet to be defined, prevention is the best approach. [1] Treating the primary cancer remains an obvious requirement, but lower levels of lumbar plexus radiation dosing will minimize or eliminate RILP. [1] [15]
One method to reduce the lumbosacral plexus' dosing is to include it with other at-risk organs that get spared from radiation. [17] [18]
Key to prevention is resolving the lack of clinical evidence between radiation treatments and the onset of neurological problems. That relationship is hidden by RILP's low toxicity rate, the lack of a large monitored population size and the lack of data pooling across multiple institutions. [1] [19]
Treatment of RILP is primarily supportive [15] with mental, [2] [10] physiological [2] [1] [10] [15] and social aspects [10] and consideration of any aggravating (synergistic) neurological factors. [1] [10]
To prevent compounding existing RILP symptoms and to minimize further progression
The effect on the person with the condition, depends upon the type of impairment. Handicaps may include physical challenges, bowel and/or bladder dysfunction and may occur in multiple settings of work and home. [10] Physical and occupational therapy are important elements in maintaining mobility and use of the lower extremities, along with assistive aides such as Ankle-Foot-Orthotics (AFOs), cane, walkers, etc. [2] [10] [15] Sensory reeducation techniques may be necessary for balance [2] and lymphedema management may be required. [10]
Pharmaceuticals that may be effective for RILP's neuropathic pain are
Non-pharmaceutical RILP considerations are
Functional impairment and residual pain can lead to social isolation. [10] Cancer support groups are valuable resources to learn about the syndrome and therapeutic options, and are a means to voice emotions related to having cancer and surviving it. [10] [1] [15]
With increasing cancer treatment survival rates, the quality of life for its survivors has become a public health priority. [1] The effects of RILP can be debilitating. With no effective treatment to control radiation damage's progressive nature, limb dysfunction is the likely result. [10]
Radiation damage's outcome is related to its initial onset time.
An exact occurrence rate has not been established. Literature on the topic is sparse. [21] Clinical occurrences of RILP are rare, affecting between 0.3 and 1.3% of those treated with abdominal or pelvic radiation. [2] The incidence rate is variable, dependent upon the irradiated zone, dosage level and method of delivery. For example, when alternate dosing levels were compared, higher rates were observed, from 12 to 23%, the higher RILP rates occurring with higher dosages. [21]
As of 1977 lumbosacral neuropathy arising from radiation therapy had been rarely reported. One of the earliest cases was in 1948. [7] [11] [22]
The incidence rate of peripheral neuropathy has been demonstrated to decrease when lower therapeutic radiation dosing levels are used. [21] [1] A similar nerve injury, Radiation-induced Brachial Plexopathy (RIBP), may occur secondary to breast radiation therapy. [23] Studies on RIBP have observed the brachial plexus' radiosensitivity. Injury was observed after dosages of 40 Gy in 20 fractions and RIBP significantly increased with doses greater than 2 Gy per fraction. [21] RIBP is more common than lumbosacral radiculoplexopathy [4] and has a clinical history with reduced dosing levels. RIBP occurrence rates were in the 60% range in the 1960s when 60 Gray treatments were applied in 5 Gray fractions; RIBP occurrences in the 2010s approach 1% with 50 Gray treatments applied in 3 Gy fractions. [1]
RILP occurrence rates are estimated at 0.3% to 1.3%, though the actual rate is likely higher. The soft tissue damage leading to RILP is more commonly seen with exposure levels over 50 Gy, though has occurred with as little as 30 Gy. [24] A major step toward reducing RILP occurrences is by limiting the lumbosacral plexus' dosing level when treating pelvic malignancies, limiting the mean dose to < 45 Gy. One approach to reduced levels, the plexus' mapping with other organs at risk, was clinically evaluated during the 2010s. [17] [18]
Clinical evidence of the cause-and-effect for prevention and the management of radiation induced polyneuropathy is limited. [10]
In 2011 the Radiation Oncology Institute (ROI) announced the National Radiation Oncology Registry (NROR). ROI and Massachusetts General Hospital would initially focus the NROR on prostate cancer, collecting efficacy and side effect information (like radiation induced neuropathy, RILP) from people treated with radiotherapy. [25] In 2013 the American Society for Radiation Oncology (ASTRO) joined the effort [26] and the number of data collection sites increased to 30 for a 1-year pilot project. Pitfalls of medical data collection arose with only 14 sites being able to provide data and all those requiring significant manual entry efforts. [27] The first NROR project conclusion was that future registries would need to cope with Big data analytics. In 2015 ASTRO, the National Cancer Institute and the American Association of Physicists in Medicine sponsored a Big Data Workshop at the National Institutes of Health.
Experimental approaches for RILP treatment and management include:
Radiation therapy or radiotherapy is a treatment using ionizing radiation, generally provided as part of cancer therapy to either kill or control the growth of malignant cells. It is normally delivered by a linear particle accelerator. Radiation therapy may be curative in a number of types of cancer if they are localized to one area of the body, and have not spread to other parts. It may also be used as part of adjuvant therapy, to prevent tumor recurrence after surgery to remove a primary malignant tumor. Radiation therapy is synergistic with chemotherapy, and has been used before, during, and after chemotherapy in susceptible cancers. The subspecialty of oncology concerned with radiotherapy is called radiation oncology. A physician who practices in this subspecialty is a radiation oncologist.
Diabetic neuropathy includes various types of nerve damage associated with diabetes mellitus. The most common form, diabetic peripheral neuropathy, affects 30% of all diabetic patients. Symptoms depend on the site of nerve damage and can include motor changes such as weakness; sensory symptoms such as numbness, tingling, or pain; or autonomic changes such as urinary symptoms. These changes are thought to result from a microvascular injury involving small blood vessels that supply nerves. Relatively common conditions which may be associated with diabetic neuropathy include distal symmetric polyneuropathy; third, fourth, or sixth cranial nerve palsy; mononeuropathy; mononeuropathy multiplex; diabetic amyotrophy; and autonomic neuropathy.
Peripheral neuropathy, often shortened to neuropathy, refers to damage or disease affecting the nerves. Damage to nerves may impair sensation, movement, gland function, and/or organ function depending on which nerve fibers are affected. Neuropathies affecting motor, sensory, or autonomic nerve fibers result in different symptoms. More than one type of fiber may be affected simultaneously. Peripheral neuropathy may be acute or chronic, and may be reversible or permanent.
Glioblastoma, previously known as glioblastoma multiforme (GBM), is the most aggressive and most common type of cancer that originates in the brain, and has a very poor prognosis for survival. Initial signs and symptoms of glioblastoma are nonspecific. They may include headaches, personality changes, nausea, and symptoms similar to those of a stroke. Symptoms often worsen rapidly and may progress to unconsciousness.
In medicine, proton therapy, or proton radiotherapy, is a type of particle therapy that uses a beam of protons to irradiate diseased tissue, most often to treat cancer. The chief advantage of proton therapy over other types of external beam radiotherapy is that the dose of protons is deposited over a narrow range of depth; hence in minimal entry, exit, or scattered radiation dose to healthy nearby tissues.
Neuritis, from the Greek νεῦρον), is inflammation of a nerve or the general inflammation of the peripheral nervous system. Inflammation, and frequently concomitant demyelination, cause impaired transmission of neural signals and leads to aberrant nerve function. Neuritis is often conflated with neuropathy, a broad term describing any disease process which affects the peripheral nervous system. However, neuropathies may be due to either inflammatory or non-inflammatory causes, and the term encompasses any form of damage, degeneration, or dysfunction, while neuritis refers specifically to the inflammatory process.
Mucositis is the painful inflammation and ulceration of the mucous membranes lining the digestive tract, usually as an adverse effect of chemotherapy and radiotherapy treatment for cancer. Mucositis can occur anywhere along the gastrointestinal (GI) tract, but oral mucositis refers to the particular inflammation and ulceration that occurs in the mouth. Oral mucositis is a common and often debilitating complication of cancer treatment.
The lumbosacral trunk is nervous tissue that connects the lumbar plexus with the sacral plexus. It is formed by the union of parts of the fourth and fifth lumbar nerves and descends to join the sacral plexus.
Radiation enteropathy is a syndrome that may develop following abdominal or pelvic radiation therapy for cancer. Many affected people are cancer survivors who had treatment for cervical cancer or prostate cancer. It has also been termed pelvic radiation disease with radiation proctitis being one of its principal features and radiation-induced lumbar plexopathy (RILP) being a rare consequence.
A paraneoplastic syndrome is a syndrome that is the consequence of a tumor in the body. It is specifically due to the production of chemical signaling molecules by tumor cells or by an immune response against the tumor. Unlike a mass effect, it is not due to the local presence of cancer cells.
Particle therapy is a form of external beam radiotherapy using beams of energetic neutrons, protons, or other heavier positive ions for cancer treatment. The most common type of particle therapy as of August 2021 is proton therapy.
Plexopathy is a disorder of the network of nerves in the brachial or lumbosacral plexus. Symptoms include pain, muscle weakness, and sensory deficits (numbness).
Nerve compression syndrome, or compression neuropathy, or nerve entrapment syndrome, is a medical condition caused by chronic, direct pressure on a peripheral nerve. It is known colloquially as a trapped nerve, though this may also refer to nerve root compression. Its symptoms include pain, tingling, numbness and muscle weakness. The symptoms affect just one particular part of the body, depending on which nerve is affected. The diagnosis is largely clinical and can be confirmed with diagnostic nerve blocks. Occasionally imaging and electrophysiology studies aid in the diagnosis. Timely diagnosis is important as untreated chronic nerve compression may cause permanent damage. A surgical nerve decompression can relieve pressure on the nerve but cannot always reverse the physiological changes that occurred before treatment. Nerve injury by a single episode of physical trauma is in one sense an acute compression neuropathy but is not usually included under this heading, as chronic compression takes a unique pathophysiological course.
Neuro-oncology is the study of brain and spinal cord neoplasms, many of which are very dangerous and life-threatening. Among the malignant brain cancers, gliomas of the brainstem and pons, glioblastoma multiforme, and high-grade astrocytoma/oligodendroglioma are among the worst. In these cases, untreated survival usually amounts to only a few months, and survival with current radiation and chemotherapy treatments may extend that time from around a year to a year and a half, possibly two or more, depending on the patient's condition, immune function, treatments used, and the specific type of malignant brain neoplasm. Surgery may in some cases be curative, but, as a general rule, malignant brain cancers tend to regenerate and emerge from remission easily, especially highly malignant cases. In such cases, the goal is to excise as much of the mass and as much of the tumor margin as possible without endangering vital functions or other important cognitive abilities. The Journal of Neuro-Oncology is the longest continuously published journal in the field and serves as a leading reference to those practicing in the area of neuro-oncology.
Chemotherapy-induced peripheral neuropathy (CIPN) is a nerve-damaging side effect of antineoplastic agents in the common cancer treatment, chemotherapy. CIPN afflicts between 30% and 40% of patients undergoing chemotherapy. Antineoplastic agents in chemotherapy are designed to eliminate rapidly dividing cancer cells, but they can also damage healthy structures, including the peripheral nervous system. CIPN involves various symptoms such as tingling, pain, and numbness in the hands and feet. These symptoms can impair activities of daily living, such as typing or dressing, reduce balance, and increase risk of falls and hospitalizations. They can also give cause to reduce or discontinue chemotherapy. Researchers have conducted clinical trials and studies to uncover the various symptoms, causes, pathogenesis, diagnoses, risk factors, and treatments of CIPN.
Cancer pain can be caused by pressure on, or chemical stimulation of, specialised pain-signalling nerve endings called nociceptors, or by damage or illness affecting nerve fibers themselves.
Vaginal stenosis is an abnormal condition in which the vagina becomes narrower and shorter due to the formation of fibrous tissue. Vaginal stenosis can contribute to sexual dysfunction, dyspareunia and make pelvic exams difficult and painful. The lining of the vagina may also be thinner and drier and contain scar tissue. This condition can result in pain during sexual intercourse or a pelvic exam. Vaginal stenosis is often caused by radiation therapy to the pelvis, an episiotomy, or other forms of surgical procedures. Chemotherapy can also increase the likelihood of developing vaginal stenosis. Vaginal stenosis can also result from genital reconstructive surgery in people with congenital adrenal hyperplasia.
The side effects of radiotherapy on fertility are a growing concern to patients undergoing radiotherapy as cancer treatments. Radiotherapy is essential for certain cancer treatments and often is the first point of call for patients. Radiation can be divided into two categories: ionising radiation (IR) and non-ionising radiation (NIR). IR is more dangerous than NIR and a source of this radiation is X-rays used in medical procedures, for example in radiotherapy.
FLASH radiotherapy is an emerging form of radiotherapy which delivers a high dose of radiation to the patient in an ultra-short time frame which produces a tumour killing effect comparable to conventional radiotherapy but with less damage to surrounding healthy tissue. The treatment is in the early stages of development and is not yet widely available as a form of cancer therapy.
Peripheral nerve tumors, also called tumors of peripheral nerves or tumors of the peripheral nervous system, are a diverse category with a range of morphological characteristics and biological potential. They are categorized as either benign or malignant peripheral nerve sheath tumors.
This article incorporates text in the public domain from the 20th edition of Gray's Anatomy (1918)