The pathological defining feature of acute disseminated encephalomyelitis is Perivenous encephalomyelitis. Acute disseminated encephalomyelitis (ADEM) is characterized by a brief but intense inflammatory onslaught that affects the myelin, the nerve fibers’ protective covering, in the brain and spinal cord. Perivenous encephalomyelitis, which is assumed to be an autoimmune condition, frequently occurs after bacterial or viral illnesses or, less frequently, after receiving measles, mumps, or rubella vaccination.  Since the symptoms and the look of the white matter lesion on brain imaging may be identical, it is occasionally mistaken for a severe first onset of multiple sclerosis (MS).

 

Introduction:

 

Perivenous encephalomyelitis is a neurological, immune-mediated condition where white matter tissue is damaged by extensive inflammation of the central nervous system (brain and spinal cord). The nerve fibers that make up white matter are protected by a layer of lipids and proteins called myelin. The myelin sheath, commonly known as myelin, serves as an insulator, protects the nerve fibers, and speeds up the transmission of nerve signals. The ability of the neurons to carry information is impacted by damage to the myelin sheath (demyelination), which has the potential to lead to a variety of neurological disorders.

Arm/leg vulnerability, seizures, coldness or tingling, modifications to mental status, and vision loss are among the most typical neurological signs; however, particular signs and severity might vary from person to person. Although onset can occur at any age, children are more likely than adults to be affected. Patient long-term outcomes are often positive. Although the exact root cause of Perivenous encephalomyelitis is unidentified it is believed to be linked to an autoimmune reaction brought on by an infection or, in rare cases, specific immunisations.

 

Causes:

 

Perivenous encephalomyelitis’ precise cause is unknown, but it may be related to an abnormal immune response that followed an infectious stimulus. In 70 to 80 percent of patients, a first sickness or infection is seen. For instance, it may manifest after an infection of the upper respiratory tract with a virus. Influenza, measles, mumps, rubella, varicella-zoster, Epstein-Barr virus, cytomegalovirus, and herpes simplex virus are among other illnesses that can cause perivenous encephalomyelitis.

Less frequently, it may arise after a vaccination, however, this is now extremely unusual and only occurs in around 5% of instances of Perivenous encephalomyelitis. These case reports do not prove conclusively that vaccinations cause. According to recent research, the existence of antibodies against MOG may also be associated with perivenous encephalomyelitis. The CNS contains a protein called MOG, which is a part of the myelin sheath. A number of inflammatory demyelinating disorders, including Perivenous encephalomyelitis, have been associated to antibodies to the MOG protein, which are more frequently found in youngsters.

 

Symptoms:

 

The severity and course of Perivenous Encephalomyelitis symptoms vary from patient to patient and may be influenced by the age at which symptoms first appear as well as the location of the brain lesions. While some people may only experience a moderate form of the disorder, others may experience more severe symptoms. Life-threatening consequences including respiratory collapse are conceivable in the worst-case scenarios. Initial symptoms typically appear quickly and are typical of many infections, including the flu. These symptoms headache, fever, agitation, weariness, lethargy, and a generalized feeling of bad health (malaise) are regarded as non-specific. Unintentional weight loss might result from nausea and vomiting, which may be present. Patients who are badly affected may go into a coma and experience delirium, stupor, and confusion as well.

The course of perivenous encephalomyelitis is monophasic and has an abrupt beginning. Typically, 1-3 weeks after infection, symptoms appear. Fever, headache, nausea, vomiting, confusion, blurred vision, sleepiness, seizures, and coma are some of the most serious symptoms. The symptoms typically start off modest, but they quickly deteriorate over a span of hours to days, with an average of around four and a half days before they reach their peak severity. Hemiparesis, paraparesis, and cerebral nerve palsies are further signs.

 

Diagnosis:

 

On early presentation, Perivenous encephalomyelitis might look like other demyelinating illnesses including MS and NMO. The start, duration, aggravating circumstances and history of past neurologic episodes should all be elicited from the patient. The patient’s age should also be noted by the healthcare professional because Perivenous encephalomyelitis more frequently affects young children between the ages of 5 and 8 while MS has a median age of 29. Despite the fact that this history finding is not required for the diagnosis, a recent infection or vaccination may increase clinical suspicion for Perivenous encephalomyelitis. Clinicians should have a broad differential diagnosis in place when they suspect a demyelinating process after taking the patient’s history because there is no biomarker that distinguishes Perivenous encephalomyelitis from MS, NMO, or other demyelinating illnesses.

In order to ascertain the location, gravity, and extent of any neurological deficit in individuals with probable Perivenous encephalomyelitis, a comprehensive neurologic exam should be carried out and recorded. Additionally, if the patient exhibits symptoms that point to optic neuritis or another visual pathology, ocular assessment is advised. Testing should be done for extraocular movements, relative Afferent Pupillary Defect (rAPD), extraocular movements, pupil responsiveness, pupil size, depth perception, stereopsis, color vision, and confrontation visual field. To rule out any problems with the corneal surface or anterior chamber that might be causing vision impairment, the patient should be checked under a slit lamp. It is necessary to see the fundus to check for optic disc edema.

 

Treatment for Perivenous encephalomyelitis:

 

Perivenous encephalomyelitis has no acknowledged standard treatment. The majority of treatments for Perivenous encephalomyelitis have a certain impact on the host immune system’s activities. These treatments include plasmapheresis, immunoglobulin (IVIg) therapy, and corticosteroids. The most efficient therapy for Perivenous encephalomyelitis is high doses of corticosteroids. The two corticosteroids that are most frequently administered are methylprednisolone and dexamethasone. These drugs often lessen the severity of signs and speed up recovery in patients, but they can also have serious adverse effects such as changes in mood and behavior, irritation of the stomach lining, and increased blood pressure or glucose levels.

Individuals who do not respond to or are intolerant to corticosteroid therapy may benefit from receiving intravenous immunoglobulin (IVIg). IVIg is an antibody-concentrated solution that has been made from healthy donor blood. Because the extracted antibodies counteract the detrimental effects of antigens, IVIg is helpful against autoimmune illnesses. People with Perivenous encephalomyelitis that do not react to other forms of therapy have been treated with plasmapheresis. Toxic and metabolic chemicals are removed from the blood using plasmapheresis. By extracting blood cells from plasma, the process is effective. The patient’s blood (including blood cells and plasma) is then administered back into the body in place of the patient’s plasma.