Encephalitis (“Brain Inflammation”) Signs and Symptoms (& Why They Occur)

 Encephalitis (“Brain Inflammation”) Signs and Symptoms 

this lesson is on the signs and symptoms of encephalitis or brain inflammation if you want more information on this condition please check out my full lesson on this topic before we get into the signs and symptoms let's talk about what encephalitis is it is a condition involving inflammation of the brain parenchyma so the brain tissue itself becomes inflamed in this condition so if we actually look at the word encephalitis itis means inflammation and encephal refers to the brain so encephalitis means brain inflammation now encephalitis may be due to a variety of causes some of these include viruses which are actually the most common causes of encephalitis so viral encephalitis is the most common and some of these viruses include herpes simplex virus or hsv west nile virus and epstein-barr virus and there are many many other viruses that can cause encephalitis some of these include rabies st louis virus and some other viruses like the equine viruses now there are other infective organisms and other conditions that can lead to encephalitis as well and some of these include the protozoa known as toxoplasmosis there are metabolic conditions that can lead to encephalitis and there are some autoimmune conditions that can lead to encephalitis like anti-nmda receptor

encephalitis

or lupus encephalitis now what is the epidemiology and risk factors for getting encephalitis so the highest incidence of encephalitis occurs in the young and old or elderly populations so oftentimes it can be extremes of age and there's an increased risk in patients who have immunocompromised so in patients who have issues with their immune system functioning they're at an increased risk for getting encephalitis or inflammation of their brain tissue some of these patients include hiv positive patients or aids patients organ transplant patients and other patients as well so these patients are at an increased risk for getting infections in general and they're also at an increased risk for getting encephalitis from infective causes and then another risk factor for getting encephalitis is being exposed to infective vectors in endemic areas so if you travel to a country where there are mosquitoes that carry west nile virus or carry dengue virus which is another cause of encephalitis.

if you're in those areas you're more likely to get infected by those viruses and get encephalitis now the topic of this lesson is that encephalitis causes a particular set of signs and symptoms we're going to talk about each of those signs and symptoms and why they occur in the next upcoming slides so now let's talk about the signs and symptoms of encephalitis they're going to be some prodromal signs and symptoms of encephalitis which are signs and symptoms that occur early on in the disease process one of them is going to be headache so oftentimes this headache is going to be a severe headache and it may feel different than a normal headache so the patient may have a sensation that this headache is not quite a normal headache there's something different about it and it's often times again severe and this is due to brain inflammation and swelling so because of this brain inflammation and swelling there are pain receptors that become activated due to that swelling leading to a headache or sensation of a headache myalgias are another prodromal symptom of encephalitis so myalgias are muscle aches and pains so this is another early symptom of encephalitis and then malaise is also another early symptom of encephalitis malaise is a sensation of feeling generally unwell you can imagine that if there is an infection of brain tissue and there's some brain swelling you're going to feel very unwell so again this is due to the state of inflammation and or infection so whatever the effective cause might be this can also lead the patient to feeling very unwell now after those prodromal symptoms the patient becomes more acutely ill within hours to days so those are the first symptoms but the following symptoms are very important to recognize as well one of those important signs of encephalitis that occurs after those prodromal signs and symptoms is fever so oftentimes the temperature is going to be greater than 38 degrees celsius or greater than 100 degrees fahrenheit by oral temperature recordings but it's often even higher than this it's often a high fever and this fever can occur suddenly and it's due to infection and inflammation of brain tissue and then another very important symptom of encephalitis is altered mental status this is going to be a very key symptom of encephalitis so altered mental status may manifest as difficulty concentrating so it can start off very vaguely patient feels a little off they have difficulty concentrating they have difficulty staying alert oftentimes they're going to have decreased alertness and decreased consciousness and they're going to have some issue with confusion or altered sensorium so they feel like they're just not quite aware of their surroundings and you can imagine that the reason this happens is because the brain becomes inflamed and swelled this is going to cause issues and reduction in cognitive ability so this is the reason why we're going to see altered mental status in encephalitis now i have asterisks on these two signs and symptoms because these are going to be very important in recognizing encephalitis if there's a fever altered mental status and a headache and i didn't mention this before but a headache is also important those are going to be some classic symptoms of encephalitis now because of that continuing inflammation of the brain tissue.

there's going to be other cognitive disturbances that occur in encephalitis so again there's inflammation of that brain tissue it's going to lead to a variety of cognitive disturbances that depend on what part of the brain is more inflamed some of these are going to include hallucinations changes to temperament behavior mood so oftentimes the patient's family is going to notice that their loved one is not quite the same they're a very different person so their personality can have some alterations and changes as well the patient can be disoriented so they may not know their name where they are or what the date is and then there can be some general cognitive decline as well and then there can be some memory deficits and this more likely occurs in herpes simplex virus encephalitis herpes simplex virus likes to affect the temporal lobes and parts of the frontal lobes so the temporal lobes are an area that's very important for memory functioning so because herpes simplex virus affects the temporal lobes we're going to see memory deficits especially in herpes simplex virus encephalitis again depending on the infective cause we're going to see some slightly different clinical features and one of them is again memory deficits with hsv encephalitis patients can become so bad and so severe that they can lead to seizures and coma and in fact seizures and coma are relatively common complications of encephalitis this is due to brain swelling and increased intracranial pressure or icp so you can imagine that the brain is swelling and there's no place for the brain to go you have a solid cranium that the brain is encased in so because of that increasing swelling of the brain there's going to be increased intracranial pressure this can cause a variety of issues and some of them include seizures in coma focal neurological deficits can also occur in encephalitis patients so inflamed tissue in particular regions of the brain can cause specifi functional or neurological deficits so if parts of the brain that are more inflamed include the frontal lobe this may affect personality

if certain parts of the brain like broca's area or wernicke's area are affected this can lead to aphasia or difficulty speaking or difficulty understanding speech and if certain parts of the motor or sensory cortex are affected sensation may be affected or ability to move limbs can be affected as well so again decreased ability to speak is one of those focal neurological deficits and being able to use a particular limb so this focal neurological deficit can be very similar to what happens in a stroke so focal neurological deficits are important findings in encephalitis patients as well and there are some other findings that can occur depending on the infected etiology some infective etiologies can show up on the skin so there can be some skin manifestations one example is vesicles in hsv encephalitis so if there's reactivation of herpes simplex virus and retrograde transmission to the brain causing encephalitis there may be some vesicles on the mouth or in the lips of patients that are affected lymphadenopathy so swollen tender lymph nodes or enlarged spleen or splenomegaly may be found in epstein-barr virus encephalitis and then there can be some other important motor features that can occur including parkinsonian features so tremors and restlessness.

they may be found in encephalitis caused by arboviruses like the west nile virus so there are many different other clinical features that can occur in encephalitis depending on the cause now along with brain inflammation there can be inflammation of the meninges or the layers that cover the brain and spinal cord so there can be signs and symptoms of meningitis so meningitis is inflammation of the meninges so this can lead to other signs and symptoms that can occur with encephalitis sometimes there may be something we call meningoencephalitis so there can be both encephalitis so inflammation of the brain but also inflammation of the meninges as well leading to meningitis so meningoencephalitis can occur one of the signs and symptoms that can occur if the meninges are involved include a stiff and painful neck this is also known as nuchal rigidity and what happens is there's a resistance to neck flexion so in the patient.

if you try to passively flex their neck it becomes very very difficult you can imagine that in the brain the brain is surrounded by these meninges but the spinal cord is also surrounded by these meninges as well and if they are inflamed any bending motion can lead to irritation of meninges in the spinal cord causing a lot of resistance in these patients it may be very painful or even impossible to lower the chin to the chest and again this is due to inflamed meninges the inflamed meninges can activate certain nerve fibers that can cause the sensation of a stiff and painful neck now there are particular clinical signs of meningitis that i want to briefly talk about here one of them is known as brzezinski sign this is where there's a passive flexion of the neck that results in involuntary flexion of hips and knees so you can see in this image here if you had someone laying down on the table and trying to bend or flex their neck forward to try to touch their chin to their chest the patient would also involuntarily flex their hips and knees as well and then the other important clinical sign is called kernig's sign so kerning sign is when a patient is lying down flat

they have their hip flexed at a 90 degree angle and the clinician tries to extend their knees so there is resistance when the clinician tries to extend their knees when their hips are flexed at a 90 degree angle because this can cause pressure within the spinal cord in the meninges so this is resisted so those are two clinical signs that can occur in meningitis that can also be found in encephalitis so we would call this a meningoencephalitis and some other important signs and symptoms that can occur in meningitis if the meninges are involved include nausea and vomiting this is actually an early symptom of meningitis and it is due to inflamed and swollen meninges and increased pressure or intracranial pressure within

the central nervous system and then photophonia and possibly phonophobia can also occur photophobia is a sensitivity to light and phonophobia is a sensitivity to sound more likely photophobia or sensitivity to light is more likely to occur but phonophobia can also occur as well in some cases and this is again caused by meningeal irritation from inflamed meninges so those are also some very important signs and symptoms of meningitis that can occur in some patients who have encephalitis if you want to learn more about signs and symptoms of meningitis please check out my full lesson on that topic and if you haven't already.