Aseptic meningitis | |
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The anatomical structure of the human brain. | |
Specialty | Neurology |
Aseptic meningitis is the inflammation of the meninges, a membrane covering the brain and spinal cord, in patients whose cerebral spinal fluid test result is negative with routine bacterial cultures. Aseptic meningitis is caused by viruses, mycobacteria, spirochetes, fungi, medications, and cancer malignancies. [1] The testing for both meningitis and aseptic meningitis is mostly the same. A cerebrospinal fluid sample is taken by lumbar puncture and is tested for leukocyte levels to determine if there is an infection and goes on to further testing to see what the actual cause is. The symptoms are the same for both meningitis and aseptic meningitis but the severity of the symptoms and the treatment can depend on the certain cause.
The most common cause of aseptic meningitis is by viral infection. Other causes may include side-effects from drugs and connective tissue disorders.
Aseptic meningitis is a disease that can depend on the patient's age, however, research has shown some distinct symptoms that indicate the possibility of aseptic meningitis. A variety of patients notice a change in body temperatures (higher than normal temperatures 38-40 °C), marked with the possibility of vomiting, headaches, firm neck pain, and even lack of appetite. In younger patients, like babies, a meningeal inflammation can be noticed along with the possibility of hepatic necrosis and myocarditis. In serious cases, a multiple organ failure can also signal aseptic meningitis and oftentimes, in babies, seizures and focal neurological deficits can be early symptoms of aseptic meningitis. In fact, in newborns, the mortality rate is 70%. The next set of age group, like children, have similar but varying symptoms of sore throat, rashes, and diarrhea. In adults, symptoms and the harshness of them tend to be less in duration. Additionally, the probability of developing aseptic meningitis increases when patients have a case of mumps or herpes. [2]
Symptoms of meningitis caused by an acute viral infection last between one and two weeks. When aseptic meningitis is caused by cytomegalovirus 20 percent of individuals face mortality or morbidity. If left untreated it can affect an individual's hearing and learning abilities. [3]
The most common cause of aseptic meningitis is a viral infection, specifically by enteroviruses. In fact, 90 percent of all meningitis cases that are viral are caused by enteroviruses. [2] Other viruses that may cause aseptic meningitis are varicella zoster virus, herpes, and mumps. [4] Other causes may include mycobacteria, fungi, spirochetes, and complications from HIV. Side effects of certain drugs such as nonsteroidal anti-inflammatory drugs (NSAIDs), antibiotics (e.g., trimethoprim-sulfamethoxazole or amoxicillin), and antiepileptic drugs can also cause aseptic meningitis. [1]
There are multiple types of aseptic meningitis that are differentiated based on their cause.
The term aseptic can be misleading, implying a lack of infection. On the contrary, many cases of aseptic meningitis represent infection with viruses or mycobacteria that cannot be detected with routine methods. Medical professionals will take into consideration the season of the year, the medical history of the individual and family, physical examination, and laboratory results when diagnosing aseptic meningitis. [3]
One common medical test used when diagnosing aseptic meningitis is lumbar puncture. [3] A medical professional inserts a needle between two vertebrae to remove cerebrospinal fluid (CSF) from the spinal cord. [6] The cerebrospinal fluid collected from the lumbar puncture is analyzed by microscope examination or by culture to distinguish between bacterial and aseptic meningitis. Samples of CSF undergo cell count, Gram stains, and viral cultures, and polymerase chain reaction (PCR). Polymerase chain reaction has increased the ability of clinicians to detect viruses such as enterovirus, cytomegalovirus, and herpes virus in the CSF, but many viruses can still escape detection. Other laboratory tests include blood, urine, and stool collection. Medical professionals also have the option of performing a computed tomographic (CT) scan or magnetic resonance imaging (MRI), these tests help observe calcifications or abscesses. [3]
If CSF levels are irregular among individuals, they will undergo hospitalization where they receive antiviral therapy. If aseptic meningitis was caused by herpes simplex virus (HSV), the individual will receive acyclovir, an antiviral drug. [3]
Aseptic meningitis was first described by Wallgren in 1925. [7] Aseptic meningitis cases have varied historically. Aseptic meningitis caused by mumps has declined in the United States due to the increased use of vaccination which prevents mumps cases from occurring. [2]
Cerebrospinal fluid (CSF) is a clear, colorless body fluid found within the tissue that surrounds the brain and spinal cord of all vertebrates.
Transverse myelitis (TM) is a rare neurological condition wherein the spinal cord is inflamed. The adjective transverse implies that the spinal inflammation (myelitis) extends horizontally throughout the cross section of the spinal cord; the terms partial transverse myelitis and partial myelitis are sometimes used to specify inflammation that affects only part of the width of the spinal cord. TM is characterized by weakness and numbness of the limbs, deficits in sensation and motor skills, dysfunctional urethral and anal sphincter activities, and dysfunction of the autonomic nervous system that can lead to episodes of high blood pressure. Signs and symptoms vary according to the affected level of the spinal cord. The underlying cause of TM is unknown. The spinal cord inflammation seen in TM has been associated with various infections, immune system disorders, or damage to nerve fibers, by loss of myelin. As opposed to leukomyelitis which affects only the white matter, it affects the entire cross-section of the spinal cord. Decreased electrical conductivity in the nervous system can result.
Encephalitis is inflammation of the brain. The severity can be variable with symptoms including reduction or alteration in consciousness, headache, fever, confusion, a stiff neck, and vomiting. Complications may include seizures, hallucinations, trouble speaking, memory problems, and problems with hearing.
Viral meningitis, also known as aseptic meningitis, is a type of meningitis due to a viral infection. It results in inflammation of the meninges. Symptoms commonly include headache, fever, sensitivity to light and neck stiffness.
Lumbar puncture (LP), also known as a spinal tap, is a medical procedure in which a needle is inserted into the spinal canal, most commonly to collect cerebrospinal fluid (CSF) for diagnostic testing. The main reason for a lumbar puncture is to help diagnose diseases of the central nervous system, including the brain and spine. Examples of these conditions include meningitis and subarachnoid hemorrhage. It may also be used therapeutically in some conditions. Increased intracranial pressure is a contraindication, due to risk of brain matter being compressed and pushed toward the spine. Sometimes, lumbar puncture cannot be performed safely. It is regarded as a safe procedure, but post-dural-puncture headache is a common side effect if a small atraumatic needle is not used.
Enterovirus is a genus of positive-sense single-stranded RNA viruses associated with several human and mammalian diseases. Enteroviruses are named by their transmission-route through the intestine.
Viral encephalitis is inflammation of the brain parenchyma, called encephalitis, by a virus. The different forms of viral encephalitis are called viral encephalitides. It is the most common type of encephalitis and often occurs with viral meningitis. Encephalitic viruses first cause infection and replicate outside of the central nervous system (CNS), most reaching the CNS through the circulatory system and a minority from nerve endings toward the CNS. Once in the brain, the virus and the host's inflammatory response disrupt neural function, leading to illness and complications, many of which frequently are neurological in nature, such as impaired motor skills and altered behavior.
Meningoencephalitis, also known as herpes meningoencephalitis, is a medical condition that simultaneously resembles both meningitis, which is an infection or inflammation of the meninges, and encephalitis, which is an infection or inflammation of the brain tissue.
Neurosyphilis is the infection of the central nervous system in a patient with syphilis. In the era of modern antibiotics, the majority of neurosyphilis cases have been reported in HIV-infected patients. Meningitis is the most common neurological presentation in early syphilis. Tertiary syphilis symptoms are exclusively neurosyphilis, though neurosyphilis may occur at any stage of infection.
Mollaret's meningitis is a recurrent or chronic inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges. Since Mollaret's meningitis is a recurrent, benign (non-cancerous), aseptic meningitis, it is also referred to as benign recurrent lymphocytic meningitis. It was named for Pierre Mollaret, the French neurologist who first described it in 1944.
The central nervous system (CNS) controls most of the functions of the body and mind. It comprises the brain, spinal cord and the nerve fibers that branch off to all parts of the body. The CNS viral diseases are caused by viruses that attack the CNS. Existing and emerging viral CNS infections are major sources of human morbidity and mortality.
Meningitis is acute or chronic inflammation of the protective membranes covering the brain and spinal cord, collectively called the meninges. The most common symptoms are fever, intense headache, vomiting, and neck stiffness and occasionally photophobia.
Herpes meningitis is inflammation of the meninges, the protective tissues surrounding the spinal cord and brain, due to infection from viruses of the Herpesviridae family - the most common amongst adults is HSV-2. Symptoms are self-limiting over 2 weeks with severe headache, nausea, vomiting, neck-stiffness, and photophobia. Herpes meningitis can cause Mollaret's meningitis, a form of recurrent meningitis. Lumbar puncture with cerebrospinal fluid results demonstrating aseptic meningitis pattern is necessary for diagnosis and polymerase chain reaction is used to detect viral presence. Although symptoms are self-limiting, treatment with antiviral medication may be recommended to prevent progression to Herpes Meningoencephalitis.
Herpes simplex encephalitis (HSE), or simply herpes encephalitis, is encephalitis due to herpes simplex virus. It is estimated to affect at least 1 in 500,000 individuals per year, and some studies suggest an incidence rate of 5.9 cases per 100,000 live births.
Drug-Induced Aseptic Meningitis (DIAM) is a type of aseptic meningitis related to the use of medications such as nonsteroidal anti-inflammatory drugs (NSAIDs) or biologic drugs such as intravenous immunoglobulin (IVIG). Additionally, this condition generally shows clinical improvement after cessation of the medication, as well as a tendency to relapse with resumption of the medication.
Neurovirology is an interdisciplinary field which represents a melding of clinical neuroscience, virology, immunology, and molecular biology. The main focus of the field is to study viruses capable of infecting the nervous system. In addition to this, the field studies the use of viruses to trace neuroanatomical pathways, for gene therapy, and to eliminate detrimental populations of neural cells.
Lymphocytic pleocytosis is an abnormal increase in the amount of lymphocytes in the cerebrospinal fluid (CSF). It is usually considered to be a sign of infection or inflammation within the nervous system, and is encountered in a number of neurological diseases, such as pseudomigraine, Susac's syndrome, and encephalitis. While lymphocytes make up roughly a quarter of all white blood cells (WBC) in the body, they are generally rare in the CSF. Under normal conditions, there are usually less than 5 white blood cells per μL of CSF. In a pleocytic setting, the number of lymphocytes can jump to more than 1,000 cells per μL. Increases in lymphocyte count are often accompanied by an increase in cerebrospinal protein concentrations in addition to pleocytosis of other types of white blood cells.
Neonatal meningitis is a serious medical condition in infants that is rapidly fatal if untreated. Meningitis, an inflammation of the meninges, the protective membranes of the central nervous system, is more common in the neonatal period than any other time in life, and is an important cause of morbidity and mortality globally. Mortality is roughly half in developing countries and ranges from 8%-12.5% in developed countries.
Chronic meningitis is a long-lasting inflammation of the membranes lining the brain and spinal cord. By definition, the duration of signs, symptoms and inflammation in chronic meningitis last longer than 4 weeks. Infectious causes are a leading cause and the infectious organisms responsible for chronic meningitis are different than the organisms that cause acute infectious meningitis. Tuberculosis and the fungi cryptococcus are leading causes worldwide. Chronic meningitis due to infectious causes are more common in those who are immunosuppressed, including those with HIV infection or in children who are malnourished. Chronic meningitis sometimes has a more insidious course than acute meningitis. Also, some of the infectious agents that cause chronic infectious meningitis such as mycobacterium tuberculosis, many fungal species and viruses are difficult to isolate from the cerebrospinal fluid making diagnosis challenging. No cause is identified during initial evaluation in one third of cases. Magnetic resonance imaging (MRI) of the brain is more sensitive than computed tomography and may show radiological signs that suggest chronic meningitis, however no radiological signs are considered pathognomonic or characteristic. MRI is also normal in many cases further limiting its diagnostic utility.