What is Acute Disseminated Encephalomyelitis (ADEM)?
This is a rare pathological condition involving the central nervous system. Acute Disseminated Encephalomyelitis is a condition that is characterized by inflammation of vital structures of the body like brain and spinal cord(1). At times, even the optic nerves get affected(2). This inflammation results in a variety of symptoms, which have variable severity. Acute Disseminated Encephalomyelitis or ADEM also affects the myelin sheath(3). This is the outer covering of the nerves, which not only protects the nerves, but also promotes faster and smooth transmission of signals to and from the brain to various parts of the body(4).
There is no specific age related to the development of Acute Disseminated Encephalomyelitis or ADEM, but it has been observed to occur more during the spring and winter months(5). More specifically, Acute Disseminated Encephalomyelitis is seen to occur after a bacterial or viral illness within a span of a couple of weeks after the infection(1).
The main symptoms of Acute Disseminated Encephalomyelitis or ADEM include: high fever, frequent bouts of severe headaches, acute stiffness in the neck, tingling and numbness in the upper and lower extremities, muscle weakness in the upper and lower extremities making it tough to walk or grasp objects, balance difficulties, diplopia or blurred vision, speech difficulties, trouble swallowing, difficulties with bladder and bowels(2).
There have been some instances where seizures have been noticed in an individual with Acute Disseminated Encephalomyelitis or ADEM. Additionally, in some rare cases, the patient suffering from Acute Disseminated Encephalomyelitis has also gone into a coma(2). The diagnosis of this condition is crucial for prompt and successful treatment of Acute Disseminated Encephalomyelitis or ADEM. This article gives an overview of some of the tests that confirm the diagnosis of Acute Disseminated Encephalomyelitis or ADEM.
How is The Diagnosis Of Acute Disseminated Encephalomyelitis (ADEM) Confirmed?
A confirmative diagnosis of Acute Disseminated Encephalomyelitis or ADEM depends on various clinical findings and radiographic studies. As of now, there is no specific test that can definitively diagnose ADEM(6). Thus an advice from an expert holds the key to an early and prompt diagnosis of Acute Disseminated Encephalomyelitis or ADEM.
To begin with, a diagnosis of Acute Disseminated Encephalomyelitis or ADEM is suspected when the patient complains of symptoms common with this disorder; especially mental confusion, alteration of awareness, muscle weakness, irritable mood, which has been observed immediately after a bacterial or viral infection. In such cases, the cause of the symptoms is first identified. This is done by doing a series of blood tests to include complete blood count to look for signs of remnants of the infection.
Other laboratory investigations include stool cultures to check for the presence of bacteria or virus(7). The next step towards confirming the diagnosis of Acute Disseminated Encephalomyelitis or ADEM is to do a lumbar puncture(8). In this test, CSF fluid is taken out from the spinal cord and is analyzed closely under a microscope, which helps in confirming the diagnosis of Acute Disseminated Encephalomyelitis. In cases of Acute Disseminated Encephalomyelitis or ADEM, there will be signs of increased white blood count and increased proteins. There may also be presence of oligoclonal bands, which although is specific only for multiple sclerosis, but may also be seen in some cases of Acute Disseminated Encephalomyelitis or ADEM and helps with the confirmation of its diagnosis(9).
Radiological studies in the form of MRI of the brain with contrast and spinal cord; especially with T12 weighted images and FLAIR sequences is crucial for a prompt and confirmed diagnosis of Acute Disseminated Encephalomyelitis or ADEM even though these images are normally taken to diagnose multiple sclerosis (9). The MRI will clearly show inflammation or lesions classic for multiple sclerosis or abnormalities seen with Acute Disseminated Encephalomyelitis or ADEM.
The MRI scan may have to be repeated after a few months to ensure there is no worsening of the inflammation if seen. Based on the type of inflammation and the characteristic of the lesions seen on MRI, a definitive diagnosis can be made of Acute Disseminated Encephalomyelitis or ADEM.